def __init__(self, filename):
# read entire file into memory
f = open(filename, "rb")
file_data = f.read()
f.close()
self.bitbfr = BitBfr(file_data)
# info needed block to block
self.hybrid_prevblck = zeros((2, 32, 18), dtype=double)
self.sbs_bufOffset = [64, 64]
self.sbs_buf = zeros((2, 1024), dtype=double)
self.sbs_filter = zeros((64, 32), dtype=double)
self.pcm = [[], []]
self.first_frame = True
self.init_tables()
def __init__(self, filename):
# read entire file into memory
f = open(filename, "rb")
file_data = f.read()
f.close()
self.bitbfr = BitBfr(file_data)
# info needed block to block
self.hybrid_prevblck = zeros((2, 32, 18), dtype=double)
self.sbs_bufOffset = [64, 64]
self.sbs_buf = zeros((2, 1024), dtype=double)
self.sbs_filter = zeros((64, 32), dtype=double)
self.pcm = [[], []]
self.first_frame = True
self.init_tables()
class pyMP3:
def __init__(self, filename):
# read entire file into memory
f = open(filename, "rb")
file_data = f.read()
f.close()
self.bitbfr = BitBfr(file_data)
# info needed block to block
self.hybrid_prevblck = zeros((2, 32, 18), dtype=double)
self.sbs_bufOffset = [64, 64]
self.sbs_buf = zeros((2, 1024), dtype=double)
self.sbs_filter = zeros((64, 32), dtype=double)
self.pcm = [[], []]
self.first_frame = True
self.init_tables()
def init_tables(self):
#=======MDCT======
self.mdct_win = zeros((4, 36), dtype=double)
self.mdct_cos_tbl = zeros((4 * 36), dtype=double)
self.mdct_cos_tbl_2 = zeros((36, 18), dtype=double)
# block type 0
for i in range(36):
self.mdct_win[0][i] = sin(PI / 36 * (i + 0.5))
# block type 1
for i in range(18):
self.mdct_win[1][i] = sin(PI / 36 * (i + 0.5))
for i in range(18, 24):
self.mdct_win[1][i] = 1.0
for i in range(24, 30):
self.mdct_win[1][i] = sin(PI / 12 * (i + 0.5 - 18))
for i in range(30, 36):
self.mdct_win[1][i] = 0.0
# block type 2
for i in range(12):
self.mdct_win[2][i] = sin(PI / 12 * (i + 0.5))
for i in range(12, 36):
self.mdct_win[2][i] = 0.0
# block type 3
for i in range(6):
self.mdct_win[3][i] = 0.0
for i in range(6, 12):
self.mdct_win[3][i] = sin(PI / 12 * (i + 0.5 - 6))
for i in range(12, 18):
self.mdct_win[3][i] = 1.0
for i in range(18, 36):
self.mdct_win[3][i] = sin(PI / 36 * (i + 0.5))
for i in range(4 * 36):
self.mdct_cos_tbl[i] = cos(PI / (2 * 36) * i)
N = 36
for p in range(N):
for m in range(N // 2):
self.mdct_cos_tbl_2[p][m] = self.mdct_cos_tbl[(
(2 * p + 1 + N / 2) * (2 * m + 1)) % (4 * 36)]
#======SUB BAND SYNTHESIS===
# create filter
for i in range(64):
for k in range(32):
self.sbs_filter[i][k] = 1e9 * \
cos(((PI / 64 * i + PI / 4) * (2 * k + 1)))
if (self.sbs_filter[i][k] >= 0):
dummy, self.sbs_filter[i][k] = modf(self.sbs_filter[i][k] +
0.5)
else:
dummy, self.sbs_filter[i][k] = modf(self.sbs_filter[i][k] -
0.5)
self.sbs_filter[i][k] *= 1e-9
def decode(self, filename):
print("Starting Decode")
self.frame_num = 0
while (self.bitbfr.bits_left() > 0):
self.cur_frame = mp3_frame()
st = time.time()
# Decode the data
self.find_next_syncword()
self.decode_frame_header()
self.decode_CRC()
self.decode_side_info()
self.decode_main_info()
# Process the Data
self.dequantize_samples()
self.process_stereo()
self.reorder_samples()
self.antialias_samples()
self.hybrid_synthesis()
self.polyphase_synthesis()
# timing
tt = (time.time() - st) * 1000
if (tt == 0):
tt = 1
print("frame #%d - %.1f %.3fx" % (self.frame_num + 1, tt, 26 / tt))
self.frame_num += 1
if (self.frame_num == frame_cnt_limit):
break
self.write_wav(filename)
def write_wav(self, filename):
file_sz = len(self.pcm[0]) * 2 + 36
n_channels = 1
smpl_rate = 44100
f = open(filename, "wb")
f.write("RIFF")
f.write(pack("<i", file_sz))
f.write("WAVE")
f.write("fmt ")
f.write(pack("<i", 16))
f.write(pack("<h", 1))
f.write(pack("<h", n_channels))
f.write(pack("<i", smpl_rate))
f.write(pack("<i", smpl_rate * n_channels * 2))
f.write(pack("<h", n_channels * 2))
f.write(pack("<h", 16))
f.write("data")
f.write(pack("<i", file_sz - 36))
for x in self.pcm[0]:
f.write(pack("<h", x))
f.close()
def dequantize_samples(self):
if (dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print("dq", self.frame_num, gr, sb, ss,
self.cur_frame.main_data.q_vals[gr][0][sb][ss])
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
cb = 0
# get initial boundary
if (self.cur_frame.side_info.window_switching_flag[ch][gr] and
(self.cur_frame.side_info.block_type[ch][gr] == 2)):
if (self.cur_frame.side_info.mixed_block_flag[ch][gr]):
# mixed (long first)
next_cb_boundary = sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][1]
else:
# pure short
next_cb_boundary = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][1] * 3
cb_width = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][1]
cb_begin = 0
else:
# long blocks
next_cb_boundary = sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][1]
# apply formula per block type */
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
if ((sb * 18) + ss == next_cb_boundary):
if (self.cur_frame.side_info.
window_switching_flag[ch][gr] and
(self.cur_frame.side_info.block_type[ch][gr]
== 2)):
if (self.cur_frame.side_info.
mixed_block_flag[ch][gr]):
if (((sb * 18) + ss) == sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][8]):
next_cb_boundary = sfBandIndex_s[
self.cur_frame.hdr.
smpl_rate][4] * 3
cb = 3
cb_width = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][
cb + 1] - sfBandIndex_s[
self.cur_frame.hdr.
smpl_rate][cb]
cb_begin = sfBandIndex_s[
self.cur_frame.hdr.
smpl_rate][cb] * 3
elif (((sb * 18) + ss) < sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][8]):
cb += 1
next_cb_boundary = sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][cb +
1]
else:
cb += 1
next_cb_boundary = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][
cb + 1] * 3
cb_width = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][
cb + 1] - sfBandIndex_s[
self.cur_frame.hdr.
smpl_rate][cb]
cb_begin = sfBandIndex_s[
self.cur_frame.hdr.
smpl_rate][cb] * 3
else:
cb += 1
next_cb_boundary = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][cb +
1] * 3
cb_width = sfBandIndex_s[
self.cur_frame.hdr.
smpl_rate][cb + 1] - sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][cb]
cb_begin = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][cb] * 3
else:
cb += 1
next_cb_boundary = sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][cb + 1]
# Compute global scaling
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] = pow(2.0, (
0.25 *
(self.cur_frame.side_info.global_gain[ch][gr] -
210.0)))
val_a = self.cur_frame.decoded_data.dq_vals[gr][ch][
sb][ss]
# Compute block dependent scaling
if (self.cur_frame.side_info.window_switching_flag[ch]
[gr] and
(((self.cur_frame.side_info.block_type[ch][gr]
== 2) and
(self.cur_frame.side_info.mixed_block_flag[ch]
[gr] == 0)) or
((self.cur_frame.side_info.block_type[ch][gr]
== 2) and
self.cur_frame.side_info.mixed_block_flag[ch][gr]
and (sb >= 2)))):
# SHORT
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] *= pow(
2.0, 0.25 * -8.0 *
self.cur_frame.side_info.subblock_gain[ch]
[gr][(((sb * 18) + ss) - cb_begin) /
cb_width])
val_a2 = self.cur_frame.decoded_data.dq_vals[gr][
ch][sb][ss]
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] *= pow(
2.0, 0.25 * -2.0 *
(1.0 + self.cur_frame.side_info.
scalefac_scale[ch][gr]) *
self.cur_frame.main_data.scalefac_s[ch][gr]
[(((sb * 18) + ss) - cb_begin) /
cb_width][cb])
val_a3 = self.cur_frame.decoded_data.dq_vals[gr][
ch][sb][ss]
else:
# LONG block types 0,1,3 & 1st 2 subbands of
# switched blocks
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] *= pow(
2.0,
-0.5 * (1.0 + self.cur_frame.side_info.
scalefac_scale[ch][gr]) *
(self.cur_frame.main_data.scalefac_l[ch]
[gr][cb] +
self.cur_frame.side_info.preflag[ch][gr] *
pretab[cb]))
val_b = self.cur_frame.decoded_data.dq_vals[gr][ch][
sb][ss]
val_b2 = self.cur_frame.side_info.scalefac_scale[ch][
gr]
val_b3 = self.cur_frame.main_data.scalefac_l[ch][gr][
cb]
# Scale quantized value
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] *= pow(
abs(self.cur_frame.main_data.q_vals[gr][ch][sb]
[ss]), (4.0 / 3.0))
if (self.cur_frame.main_data.q_vals[gr][ch][sb][ss] <
0):
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] = -self.cur_frame.decoded_data.dq_vals[gr][
ch][sb][ss]
val_c = self.cur_frame.decoded_data.dq_vals[gr][ch][
sb][ss]
def process_stereo(self):
has_intensity_stereo = (self.cur_frame.hdr.mode_extention
& INTENSITY_STEREO_BIT)
has_mid_side_stereo = (self.cur_frame.hdr.mode_extention
& MID_SIDE_STEREO_BIT)
lr = self.cur_frame.decoded_data.lr_vals
dq_vals = self.cur_frame.decoded_data.dq_vals
if (dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print("s", self.frame_num, gr, sb, ss,
dq_vals[gr][0][sb][ss])
for gr in range(2):
if (self.cur_frame.hdr.n_channels == 2):
is_pos = [7 for dummy in range(576)]
if (has_intensity_stereo):
is_ratio = self.process_intensity_stereo(gr, is_pos)
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
i = (sb * 18) + ss
if (is_pos[i] == 7):
if (has_mid_side_stereo):
lr[gr][0][sb][ss] = (
dq_vals[gr][0][sb][ss] +
dq_vals[gr][1][sb][ss]) / 1.41421356
lr[gr][1][sb][ss] = (
dq_vals[gr][0][sb][ss] -
dq_vals[gr][1][sb][ss]) / 1.41421356
else:
lr[gr][0][sb][ss] = dq_vals[gr][0][sb][ss]
lr[gr][1][sb][ss] = dq_vals[gr][1][sb][ss]
elif (has_intensity_stereo):
lr[gr][0][sb][ss] = dq_vals[gr][0][sb][ss] * (
is_ratio[i] / (1 + is_ratio[i]))
lr[gr][1][sb][ss] = dq_vals[gr][0][sb][ss] * (
1 / (1 + is_ratio[i]))
else:
print("Stereo - Error")
else:
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
lr[gr][0][sb][ss] = dq_vals[gr][0][sb][ss]
def process_intensity_stereo(self, gr, is_pos):
ch = 0
if (self.cur_frame.side_info.window_switching_flag[ch][gr]
and (self.cur_frame.side_info.block_type[ch][gr] == 2)):
is_ratio = self.process_intensity_stereo__non_standard_window(
gr, is_pos)
else:
is_ratio = self.process_intensity_stereo__standard_window(
gr, is_pos)
return is_ratio
def process_intensity_stereo__standard_window(self, gr, is_pos):
smpl_rate = self.cur_frame.hdr.smpl_rate
i = 31
ss = 17
sb = 0
while (i >= 0):
if (self.decoded_data.dq_vals[1][i][ss] != 0.0):
sb = i * 18 + ss
i = -1
else:
ss -= 1
if (ss < 0):
i -= 1
ss = 17
i = 0
while (sfBandIndex_l[smpl_rate][i] <= sb):
i += 1
sfb = i
i = sfBandIndex_l[smpl_rate][i]
for sfb in range(sfb, 21):
sb = sfBandIndex_l[smpl_rate][sfb +
1] - sfBandIndex_l[smpl_rate][sfb]
for sb in range(sb, 0, -1):
is_pos[i] = self.cur_frame.main_data.scalefac_l[1][gr][sfb]
if (is_pos[i] != 7):
is_ratio[i] = tan(is_pos[i] * (PI / 12))
i += 1
sfb = sfBandIndex_l[smpl_rate][20]
for sb in range(576 - sfBandIndex_l[smpl_rate][21], 0, -1):
is_pos[i] = is_pos[sfb]
is_ratio[i] = is_ratio[sfb]
i += 1
return is_ratio
def process_intensity_stereo__non_standard_window(self, gr, is_pos):
ch = 0
smpl_rate = self.cur_frame.hdr.smpl_rate
if (self.cur_frame.side_info.mixed_block_flag[ch][gr]):
max_sfb = 0
for j in range(3):
sfbcnt = 2
for sfb in range(12, 2, -1):
lines = sfBandIndex_s[smpl_rate][
sfb + 1] - sfBandIndex_s[smpl_rate][sfb]
i = 3 * sfBandIndex_s[sfreq][sfb] + (j + 1) * lines - 1
while (lines > 0):
if (self.decoded_data.dq_vals[1][i / SSLIMIT][i %
SSLIMIT]
!= 0.0):
sfbcnt = sfb
sfb = -10
lines = -10
lines -= 1
i -= 1
sfb = sfbcnt + 1
if (sfb > max_sfb):
max_sfb = sfb
while (sfb < 12):
sb = sfBandIndex_s[smpl_rate][
sfb + 1] - sfBandIndex_s[sfreq][sfb]
i = 3 * sfBandIndex_s[smpl_rate][sfb] + j * sb
for sb in range(sb, 0, -1):
is_pos[i] = self.cur_frame.main_data.scalefac_s[1][gr][
j][sfb]
if (is_pos[i] != 7):
is_ratio[i] = tan(is_pos[i] * (PI / 12))
i += 1
sfb += 1
sb = sfBandIndex_s[smpl_rate][11] - sfBandIndex_s[smpl_rate][10]
sfb = 3 * sfBandIndex_s[smpl_rate].s[10] + j * sb
sb = sfBandIndex_s[smpl_rate][12] - sfBandIndex_s[smpl_rate][11]
i = 3 * sfBandIndex_s[smpl_rate][11] + j * sb
for sb in range(sb, 0, -1):
is_pos[i] = is_pos[sfb]
is_ratio[i] = is_ratio[sfb]
i += 1
if (max_sfb <= 3):
i = 2
ss = 17
sb = -1
while (i >= 0):
if (self.decoded_data.dq_vals[1][i][ss] != 0.0):
sb = i * 18 + ss
i = -1
else:
ss -= 1
if (ss < 0):
i -= 1
ss = 17
i = 0
while (sfBandIndex_l[smpl_rate][i] <= sb):
i += 1
sfb = i
i = sfBandIndex_l[smpl_rate][i]
for sfb in range(sfb, 8):
sb = sfBandIndex_l[smpl_rate][
sfb + 1] - sfBandIndex_l[sfreq][sfb]
for sb in range(sb, 0, -1):
is_pos[i] = self.cur_frame.main_data.scalefac_l[1][gr][
sfb]
if (is_pos[i] != 7):
is_ratio[i] = tan(is_pos[i] * (PI / 12))
i += 1
else:
for j in range(3):
sfbcnt = -1
for sfb in range(12, -1, -1):
lines = sfBandIndex_s[smpl_rate][
sfb + 1] - sfBandIndex_s[smpl_rate][sfb]
i = 3 * sfBandIndex_s[smpl_rate][sfb] + (j + 1) * lines - 1
while (lines > 0):
if (self.decoded_data.dq_vals[1][i / SSLIMIT][i %
SSLIMIT]
!= 0.0):
sfbcnt = sfb
sfb = -10
lines = -10
lines -= 1
i -= 1
sfb = sfbcnt + 1
while (sfb < 12):
sb = sfBandIndex_s[smpl_rate][
sfb + 1] - sfBandIndex_s[smpl_rate][sfb]
i = 3 * sfBandIndex_s[smpl_rate][sfb] + j * sb
for sb in range(sb, 0, -1):
is_pos[i] = self.cur_frame.main_data.scalefac_s[1][gr][j][
sfb]
if (is_pos[i] != 7):
is_ratio[i] = tan(is_pos[i] * (PI / 12))
i += 1
sfb += 1
sb = sfBandIndex_s[smpl_rate][11] - sfBandIndex_s[sfreq][10]
sfb = 3 * sfBandIndex_s[smpl_rate][10] + j * sb
sb = sfBandIndex_s[smpl_rate][12] - sfBandIndex_s[sfreq][11]
i = 3 * sfBandIndex_s[smpl_rate][11] + j * sb
for sb in range(sb, -1, -1):
is_pos[i] = is_pos[sfb]
is_ratio[i] = is_ratio[sfb]
i += 1
return is_ratio
def reorder_samples(self):
smpl_rate = self.cur_frame.hdr.smpl_rate
lr = self.cur_frame.decoded_data.lr_vals
ro = self.cur_frame.decoded_data.reordered_vals
if (dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print("ro", self.frame_num, gr, sb, ss,
lr[gr][0][sb][ss])
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
if (self.cur_frame.side_info.window_switching_flag[ch][gr] and
(self.cur_frame.side_info.block_type[ch][gr] == 2)):
if (self.cur_frame.side_info.mixed_block_flag[ch][gr]):
# NO REORDER FOR LOW 2 SUBBANDS
for sb in range(2):
for ss in range(SSLIMIT):
ro[gr][ch][sb][ss] = lr[gr][ch][sb][ss]
# REORDERING FOR REST SWITCHED SHORT
sfb_start = sfBandIndex_s[smpl_rate][3]
sfb_lines = sfBandIndex_s[smpl_rate][4] - sfb_start
for sfb in range(3, 13):
for window in range(3):
for freq in range(sfb_lines):
src_line = sfb_start * 3 + \
window * sfb_lines + freq
des_line = (sfb_start *
3) + window + (freq * 3)
ro[gr][ch][des_line /
SSLIMIT][des_line %
SSLIMIT] = lr[gr][ch][
src_line /
SSLIMIT][src_line %
SSLIMIT]
sfb_start = sfBandIndex_s[smpl_rate][sfb]
sfb_lines = sfBandIndex_s[smpl_rate][sfb +
1] - sfb_start
else:
# pure short
sfb_start = 0
sfb_lines = sfBandIndex_s[smpl_rate][1]
for sfb in range(13):
for window in range(3):
for freq in range(sfb_lines):
src_line = sfb_start * 3 + \
window * sfb_lines + freq
des_line = (sfb_start *
3) + window + (freq * 3)
ro[gr][ch][des_line /
SSLIMIT][des_line %
SSLIMIT] = lr[gr][ch][
src_line /
SSLIMIT][src_line %
SSLIMIT]
sfb_start = sfBandIndex_s[smpl_rate][sfb]
sfb_lines = sfBandIndex_s[smpl_rate][sfb +
1] - sfb_start
else:
# long blocks */
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
ro[gr][ch][sb][ss] = lr[gr][ch][sb][ss]
def antialias_samples(self):
cs = [1.0 / sqrt(1.0 + ci * ci) for ci in antialias_Ci]
ca = [ci / sqrt(1.0 + ci * ci) for ci in antialias_Ci]
ro = self.cur_frame.decoded_data.reordered_vals
aa = self.cur_frame.decoded_data.antialiased_vals
if (dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print("aa", self.frame_num, gr, sb, ss,
ro[gr][0][sb][ss])
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
aa[gr][ch][sb][ss] = ro[gr][ch][sb][ss]
if ((self.cur_frame.side_info.window_switching_flag[ch][gr] and
(self.cur_frame.side_info.block_type[ch][gr] == 2)) and
(not self.cur_frame.side_info.mixed_block_flag[ch][gr])):
continue
if (self.cur_frame.side_info.window_switching_flag[ch][gr]
and self.cur_frame.side_info.mixed_block_flag[ch][gr]
and
(self.cur_frame.side_info.block_type[ch][gr] == 2)):
sblim = 1
else:
sblim = SBLIMIT - 1
# 31 alias-reduction operations between each pair of sub-bands
# with 8 butterflies between each pair
for sb in range(sblim):
for ss in range(8):
bu = ro[gr][ch][sb][17 - ss]
bd = ro[gr][ch][sb + 1][ss]
aa[gr][ch][sb][17 - ss] = (bu * cs[ss]) - (bd * ca[ss])
aa[gr][ch][sb + 1][ss] = (bd * cs[ss]) + (bu * ca[ss])
def hybrid_synthesis(self):
data_in = self.cur_frame.decoded_data.antialiased_vals
data_out = self.cur_frame.decoded_data.hybrid_vals
if (dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print(
"hs", self.frame_num, gr, sb, ss,
self.cur_frame.decoded_data.antialiased_vals[gr][0]
[sb][ss])
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
for sb in range(SBLIMIT):
if (self.cur_frame.side_info.window_switching_flag[ch][gr]
and
self.cur_frame.side_info.mixed_block_flag[ch][gr]
and sb < 2):
blk_type = 0
else:
blk_type = self.cur_frame.side_info.block_type[ch][gr]
rawout = self.inv_mdct(data_in[gr][ch][sb], blk_type)
# overlap addition
for ss in range(SSLIMIT):
data_out[gr][ch][sb][
ss] = rawout[ss] + self.hybrid_prevblck[ch][sb][ss]
self.hybrid_prevblck[ch][sb][ss] = rawout[ss + 18]
def inv_mdct(self, data_in, blk_type):
out = zeros((36), dtype=double)
if (blk_type == 2):
tmp = zeros((12), dtype=double)
N = 12
for i in range(3):
for p in range(N):
total = 0.0
for m in range(N / 2):
total += data_in[i + 3 * m] * \
cos(PI / (2 * N) * (2 * p + 1 + N / 2)
* (2 * m + 1))
tmp[p] = total * self.mdct_win[blk_type][p]
for p in range(N):
out[6 * i + p + 6] += tmp[p]
else:
cos_tbl = self.mdct_cos_tbl_2
win = self.mdct_win[blk_type]
for p in range(36):
out[p] = sum(data_in * cos_tbl[p]) * win[p]
return out
def polyphase_synthesis(self):
data_in = self.cur_frame.decoded_data.hybrid_vals
data_out = self.pcm
bfr = zeros((SBLIMIT), dtype=double)
if (dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print("pps %d %d %d %d %.3e" %
(self.frame_num, gr, sb, ss, self.cur_frame.
decoded_data.hybrid_vals[gr][0][sb][ss]))
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
# frequency inversion
for ss in range(18):
for sb in range(SBLIMIT):
if ((ss % 2) and (sb % 2)):
self.cur_frame.decoded_data.hybrid_vals[gr][ch][sb][
ss] = -self.cur_frame.decoded_data.hybrid_vals[
gr][ch][sb][ss]
# subBand synthesis
for ss in range(18):
for sb in range(SBLIMIT):
bfr[sb] = data_in[gr][ch][sb][ss]
pcm_bfr = self.subBandSynthesis(bfr, ch)
# copy to final output
data_out[ch].extend(pcm_bfr)
def subBandSynthesis(self, data_in, ch):
pcm = zeros((32), dtype=int32)
self.sbs_buf[ch] = roll(self.sbs_buf[ch], 64)
# init
bfr = self.sbs_buf[ch]
# fir filter
for i in range(64):
bfr[i] = sum(data_in * self.sbs_filter[i])
# window output
for j in range(32):
total = 0
for i in range(16):
k = j + i * 32
idx = (k + (((i + 1) >> 1) * 64))
total += sbs_window[k] * bfr[idx]
# clip
pcm[j] = min(max(total * SCALE, -SCALE), SCALE - 1)
return pcm
def decode_main_info(self):
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
# Get scale factors
part2_start = self.bitbfr.get_pos()
if (self.cur_frame.side_info.window_switching_flag[ch][gr] == 1
and self.cur_frame.side_info.block_type[ch][gr] == 2):
if (self.cur_frame.side_info.mixed_block_flag[ch][gr]):
# mixed blocks
print("mixed scale blocks not supported yet")
else:
# short blocks
for i in range(2):
for sfb in range(sfbtable_s[i], sfbtable_s[i + 1]):
for window in range(3):
self.cur_frame.main_data.scalefac_s[ch][gr][
window][sfb] = self.bitbfr.read_bits(
slen[i][self.cur_frame.side_info.
scalefac_compress[ch][gr]])
sfb = 12
for window in range(3):
self.cur_frame.main_data.scalefac_s[ch][gr][
window][sfb] = 0
else:
# long blocks
for i in range(4):
if ((self.cur_frame.side_info.scfsi[ch][i] == 0)
or (gr == 0)):
for sfb in range(sfbtable_l[i], sfbtable_l[i + 1]):
if (i < 2):
k = 0
else:
k = 1
self.cur_frame.main_data.scalefac_l[ch][gr][
sfb] = self.bitbfr.read_bits(
slen[k][self.cur_frame.side_info.
scalefac_compress[ch][gr]])
self.cur_frame.main_data.scalefac_l[ch][gr][22] = 0
self.decode_main_data_huffman(ch, gr, part2_start)
def decode_main_data_huffman(self, ch, gr, part2_start):
# calculate region boundries
if (self.cur_frame.side_info.window_switching_flag[ch][gr] == 1
and self.cur_frame.side_info.block_type[ch][gr] == 2):
# short block
region1Start = 36
region2Start = 576
else:
# long block
region1Start = sfBandIndex_l[self.cur_frame.hdr.smpl_rate][
self.cur_frame.side_info.region0_count[ch][gr] + 1]
region2Start = sfBandIndex_l[self.cur_frame.hdr.smpl_rate][
self.cur_frame.side_info.region0_count[ch][gr] +
self.cur_frame.side_info.region1_count[ch][gr] + 2]
# read big value area
for i in range(0, self.cur_frame.side_info.big_values[ch][gr] * 2, 2):
if (i < region1Start):
ht_idx = self.cur_frame.side_info.table_select[ch][gr][0]
elif (i < region2Start):
ht_idx = self.cur_frame.side_info.table_select[ch][gr][1]
else:
ht_idx = self.cur_frame.side_info.table_select[ch][gr][2]
ht = ht_list[ht_idx]
v, w, x, y = self.huffman_decoder(ht)
self.cur_frame.main_data.q_vals[gr][ch][i / SSLIMIT][i %
SSLIMIT] = x
self.cur_frame.main_data.q_vals[gr][ch][(i + 1) /
SSLIMIT][(i + 1) %
SSLIMIT] = y
# read count1 area
idx = self.cur_frame.side_info.big_values[ch][gr] * 2
# 32 is offset to count1 tables
ht = ht_list[self.cur_frame.side_info.count1table_select[ch][gr] + 32]
while (
(self.bitbfr.get_pos() <
(part2_start + self.cur_frame.side_info.part2_3_length[ch][gr]))
and (idx < SBLIMIT * SSLIMIT)):
v, w, x, y = self.huffman_decoder(ht)
self.cur_frame.main_data.q_vals[gr][ch][idx / SSLIMIT][idx %
SSLIMIT] = v
self.cur_frame.main_data.q_vals[gr][ch][(idx + 1) /
SSLIMIT][(idx + 1) %
SSLIMIT] = w
self.cur_frame.main_data.q_vals[gr][ch][(idx + 2) /
SSLIMIT][(idx + 2) %
SSLIMIT] = x
self.cur_frame.main_data.q_vals[gr][ch][(idx + 3) /
SSLIMIT][(idx + 3) %
SSLIMIT] = y
idx += 4
# the rest are zeros
def huffman_decoder(self, ht):
MXOFF = 250
v = w = x = y = 0
# check for empty tree
if (ht.treelen == 0):
return (0, 0, 0, 0)
# run through huffman tree
success = False
pos = 0
nbits = 0
while (pos < ht.treelen and nbits < 32):
# check for end of tree
if (ht.values[pos][0] == 0):
x = ht.values[pos][1] >> 4
y = ht.values[pos][1] & 0xf
success = True
break
# get more bits to transverse tree
bit = self.bitbfr.read_bits(1)
while (ht.values[pos][bit] >= MXOFF):
pos += ht.values[pos][bit]
pos += ht.values[pos][bit]
nbits += 1
if (not success):
print("Failure during huffman decode")
return (0, 0, 0, 0)
# read sign bits
if (ht.tbl_type == "quad"):
v = (y >> 3) & 1
w = (y >> 2) & 1
x = (y >> 1) & 1
y = y & 1
if (v != 0):
if (self.bitbfr.read_bits(1)):
v = -v
if (w != 0):
if (self.bitbfr.read_bits(1)):
w = -w
if (x != 0):
if (self.bitbfr.read_bits(1)):
x = -x
if (y != 0):
if (self.bitbfr.read_bits(1)):
y = -y
else:
# process escape encodings
if (ht.linbits > 0):
if ((ht.xlen - 1) == x):
x += self.bitbfr.read_bits(ht.linbits)
if (x != 0):
if (self.bitbfr.read_bits(1)):
x = -x
if (ht.linbits > 0):
if ((ht.ylen - 1) == y):
y += self.bitbfr.read_bits(ht.linbits)
if (y != 0):
if (self.bitbfr.read_bits(1)):
y = -y
return (v, w, x, y)
def decode_side_info(self):
self.cur_frame.side_info.main_data_begin = self.bitbfr.read_bits(9)
if (self.cur_frame.side_info.main_data_begin != 0):
print("Error - dont support bitreservoir yet")
if (self.cur_frame.hdr.n_channels == 1):
self.cur_frame.side_info.private_bits = self.bitbfr.read_bits(5)
else:
self.cur_frame.side_info.private_bits = self.bitbfr.read_bits(3)
for ch in range(self.cur_frame.hdr.n_channels):
for i in range(4):
self.cur_frame.side_info.scfsi[ch][i] = self.bitbfr.read_bits(
1)
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
self.cur_frame.side_info.part2_3_length[ch][
gr] = self.bitbfr.read_bits(12)
self.cur_frame.side_info.big_values[ch][
gr] = self.bitbfr.read_bits(9)
self.cur_frame.side_info.global_gain[ch][
gr] = self.bitbfr.read_bits(8)
self.cur_frame.side_info.scalefac_compress[ch][
gr] = self.bitbfr.read_bits(4)
self.cur_frame.side_info.window_switching_flag[ch][
gr] = self.bitbfr.read_bits(1)
if (self.cur_frame.side_info.window_switching_flag[ch][gr]):
self.cur_frame.side_info.block_type[ch][
gr] = self.bitbfr.read_bits(2)
self.cur_frame.side_info.mixed_block_flag[ch][
gr] = self.bitbfr.read_bits(1)
for i in range(2):
self.cur_frame.side_info.table_select[ch][gr][
i] = self.bitbfr.read_bits(5)
for i in range(3):
self.cur_frame.side_info.subblock_gain[ch][gr][
i] = self.bitbfr.read_bits(3)
if (self.cur_frame.side_info.block_type[ch][gr] == 2 and
self.cur_frame.side_info.mixed_block_flag[ch][gr]
== 0):
self.cur_frame.side_info.region0_count[ch][gr] = 8
else:
self.cur_frame.side_info.region0_count[ch][gr] = 7
self.cur_frame.side_info.region1_count[ch][
gr] = 20 - self.cur_frame.side_info.region0_count[ch][
gr]
else:
for i in range(3):
self.cur_frame.side_info.table_select[ch][gr][
i] = self.bitbfr.read_bits(5)
self.cur_frame.side_info.region0_count[ch][
gr] = self.bitbfr.read_bits(4)
self.cur_frame.side_info.region1_count[ch][
gr] = self.bitbfr.read_bits(3)
self.cur_frame.side_info.block_type[ch][gr] = 0
self.cur_frame.side_info.preflag[ch][
gr] = self.bitbfr.read_bits(1)
self.cur_frame.side_info.scalefac_scale[ch][
gr] = self.bitbfr.read_bits(1)
self.cur_frame.side_info.count1table_select[ch][
gr] = self.bitbfr.read_bits(1)
if (dbg_output):
print("main_data_begin:", self.cur_frame.side_info.main_data_begin)
print("privatebits:", self.cur_frame.side_info.private_bits)
print("scale factor select info:", self.cur_frame.side_info.scfsi)
print("part 2_3 len:", self.cur_frame.side_info.part2_3_length)
print("big values:", self.cur_frame.side_info.big_values)
print("global gain:", self.cur_frame.side_info.global_gain)
print("scalefac_compress",
self.cur_frame.side_info.scalefac_compress)
print("win switch flag:",
self.cur_frame.side_info.window_switching_flag)
print("block type:", self.cur_frame.side_info.block_type)
print("mixed block flag:",
self.cur_frame.side_info.mixed_block_flag)
print("table select:", self.cur_frame.side_info.table_select)
print("subblock gain:", self.cur_frame.side_info.subblock_gain)
print("region0_count", self.cur_frame.side_info.region0_count)
print("region1_count", self.cur_frame.side_info.region1_count)
print("preflag", self.cur_frame.side_info.preflag)
print("scalefac_scale", self.cur_frame.side_info.scalefac_scale)
print("count1table select:",
self.cur_frame.side_info.count1table_select)
def decode_CRC(self):
if (self.cur_frame.hdr.has_CRC):
crc = self.bitbfr.read_bits(16)
def decode_frame_header(self):
self.cur_frame.hdr.mpeg_version = mp3_hdr_ver_tbl[
self.bitbfr.read_bits(1)]
self.cur_frame.hdr.layer = mp3_hdr_layer_tbl[self.bitbfr.read_bits(2)]
self.cur_frame.hdr.has_CRC = not self.bitbfr.read_bits(1)
self.cur_frame.hdr.bitrate = mp3_hdr_bitrate_tbl[self.bitbfr.read_bits(
4)]
self.cur_frame.hdr.smpl_rate = mp3_hdr_smpl_rate_tbl[
self.bitbfr.read_bits(2)]
self.cur_frame.hdr.padding = self.bitbfr.read_bits(1)
self.bitbfr.read_bits(1) # private bit
self.cur_frame.hdr.channel_mode = mp3_hdr_channel_mode_tbl[
self.bitbfr.read_bits(2)]
self.cur_frame.hdr.mode_extention = self.bitbfr.read_bits(2)
self.cur_frame.hdr.copyrighted = self.bitbfr.read_bits(1)
self.cur_frame.hdr.original = self.bitbfr.read_bits(1)
self.cur_frame.hdr.emphasis = mp3_hdr_emphasis_tbl[
self.bitbfr.read_bits(2)]
if (self.cur_frame.hdr.channel_mode == "mono"):
self.cur_frame.hdr.n_channels = 1
else:
self.cur_frame.hdr.n_channels = 2
if (dbg_output):
print("frame header info")
print("ver:", self.cur_frame.hdr.mpeg_version)
print("layer:", self.cur_frame.hdr.layer)
print("has CRC:", self.cur_frame.hdr.has_CRC)
print("bitrate(kps):", self.cur_frame.hdr.bitrate)
print("sample rate:", self.cur_frame.hdr.smpl_rate)
print("padding:", self.cur_frame.hdr.padding)
print("channel mode:", self.cur_frame.hdr.channel_mode)
print("n channels:", self.cur_frame.hdr.n_channels)
print("mode extention:", self.cur_frame.hdr.mode_extention)
print("copyrighted:", self.cur_frame.hdr.copyrighted)
print("original copy:", self.cur_frame.hdr.original)
print("emphasis:", self.cur_frame.hdr.emphasis)
if (self.first_frame):
print("bitrate(kps):", self.cur_frame.hdr.bitrate)
print("sample rate:", self.cur_frame.hdr.smpl_rate)
print("channel mode:", self.cur_frame.hdr.channel_mode)
self.first_frame = False
def find_next_syncword(self):
# align to byte boundry
align = self.bitbfr.get_pos() % 8
if (align != 0):
self.bitbfr.read_bits(8 - align)
cnt = 0
while (self.bitbfr.bits_left() > 0):
b = self.bitbfr.read_bits(4)
if (b == 0xf):
cnt += 1
if (cnt == 3):
break
else:
cnt = 0
if (dbg_output):
print("sync found at %d" % (self.bitbfr.get_pos()))
class pyMP3:
def __init__(self, filename):
# read entire file into memory
f = open(filename, "rb")
file_data = f.read()
f.close()
self.bitbfr = BitBfr(file_data)
# info needed block to block
self.hybrid_prevblck = zeros((2, 32, 18), dtype=double)
self.sbs_bufOffset = [64, 64]
self.sbs_buf = zeros((2, 1024), dtype=double)
self.sbs_filter = zeros((64, 32), dtype=double)
self.pcm = [[], []]
self.first_frame = True
self.init_tables()
def init_tables(self):
#=======MDCT======
self.mdct_win = zeros((4, 36), dtype=double)
self.mdct_cos_tbl = zeros((4 * 36), dtype=double)
self.mdct_cos_tbl_2 = zeros((36, 18), dtype=double)
# block type 0
for i in range(36):
self.mdct_win[0][i] = sin(PI / 36 * (i + 0.5))
# block type 1
for i in range(18):
self.mdct_win[1][i] = sin(PI / 36 * (i + 0.5))
for i in range(18, 24):
self.mdct_win[1][i] = 1.0
for i in range(24, 30):
self.mdct_win[1][i] = sin(PI / 12 * (i + 0.5 - 18))
for i in range(30, 36):
self.mdct_win[1][i] = 0.0
# block type 2
for i in range(12):
self.mdct_win[2][i] = sin(PI / 12 * (i + 0.5))
for i in range(12, 36):
self.mdct_win[2][i] = 0.0
# block type 3
for i in range(6):
self.mdct_win[3][i] = 0.0
for i in range(6, 12):
self.mdct_win[3][i] = sin(PI / 12 * (i + 0.5 - 6))
for i in range(12, 18):
self.mdct_win[3][i] = 1.0
for i in range(18, 36):
self.mdct_win[3][i] = sin(PI / 36 * (i + 0.5))
for i in range(4 * 36):
self.mdct_cos_tbl[i] = cos(PI / (2 * 36) * i)
N = 36
for p in range(N):
for m in range(N // 2):
self.mdct_cos_tbl_2[p][m] = self.mdct_cos_tbl[
((2 * p + 1 + N / 2) * (2 * m + 1)) % (4 * 36)]
#======SUB BAND SYNTHESIS===
# create filter
for i in range(64):
for k in range(32):
self.sbs_filter[i][k] = 1e9 * \
cos(((PI / 64 * i + PI / 4) * (2 * k + 1)))
if (self.sbs_filter[i][k] >= 0):
dummy, self.sbs_filter[i][k] = modf(
self.sbs_filter[i][k] + 0.5)
else:
dummy, self.sbs_filter[i][k] = modf(
self.sbs_filter[i][k] - 0.5)
self.sbs_filter[i][k] *= 1e-9
def decode(self, filename):
print("Starting Decode")
self.frame_num = 0
while(self.bitbfr.bits_left() > 0):
self.cur_frame = mp3_frame()
st = time.time()
# Decode the data
self.find_next_syncword()
self.decode_frame_header()
self.decode_CRC()
self.decode_side_info()
self.decode_main_info()
# Process the Data
self.dequantize_samples()
self.process_stereo()
self.reorder_samples()
self.antialias_samples()
self.hybrid_synthesis()
self.polyphase_synthesis()
# timing
tt = (time.time() - st) * 1000
if(tt == 0):
tt = 1
print("frame #%d - %.1f %.3fx" % (self.frame_num + 1, tt, 26 / tt))
self.frame_num += 1
if(self.frame_num == frame_cnt_limit):
break
self.write_wav(filename)
def write_wav(self, filename):
file_sz = len(self.pcm[0]) * 2 + 36
n_channels = 1
smpl_rate = 44100
f = open(filename, "wb")
f.write("RIFF")
f.write(pack("<i", file_sz))
f.write("WAVE")
f.write("fmt ")
f.write(pack("<i", 16))
f.write(pack("<h", 1))
f.write(pack("<h", n_channels))
f.write(pack("<i", smpl_rate))
f.write(pack("<i", smpl_rate * n_channels * 2))
f.write(pack("<h", n_channels * 2))
f.write(pack("<h", 16))
f.write("data")
f.write(pack("<i", file_sz - 36))
for x in self.pcm[0]:
f.write(pack("<h", x))
f.close()
def dequantize_samples(self):
if(dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print("dq", self.frame_num, gr, sb, ss,
self.cur_frame.main_data.q_vals[gr][0][sb][ss])
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
cb = 0
# get initial boundary
if (self.cur_frame.side_info.window_switching_flag[ch][gr] and (self.cur_frame.side_info.block_type[ch][gr] == 2)):
if (self.cur_frame.side_info.mixed_block_flag[ch][gr]):
# mixed (long first)
next_cb_boundary = sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][1]
else:
# pure short
next_cb_boundary = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][1] * 3
cb_width = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][1]
cb_begin = 0
else:
# long blocks
next_cb_boundary = sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][1]
# apply formula per block type */
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
if ((sb * 18) + ss == next_cb_boundary):
if (self.cur_frame.side_info.window_switching_flag[ch][gr] and (self.cur_frame.side_info.block_type[ch][gr] == 2)):
if (self.cur_frame.side_info.mixed_block_flag[ch][gr]):
if (((sb * 18) + ss) == sfBandIndex_l[self.cur_frame.hdr.smpl_rate][8]):
next_cb_boundary = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][4] * 3
cb = 3
cb_width = sfBandIndex_s[self.cur_frame.hdr.smpl_rate][
cb + 1] - sfBandIndex_s[self.cur_frame.hdr.smpl_rate][cb]
cb_begin = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][cb] * 3
elif (((sb * 18) + ss) < sfBandIndex_l[self.cur_frame.hdr.smpl_rate][8]):
cb += 1
next_cb_boundary = sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][cb + 1]
else:
cb += 1
next_cb_boundary = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][cb + 1] * 3
cb_width = sfBandIndex_s[self.cur_frame.hdr.smpl_rate][
cb + 1] - sfBandIndex_s[self.cur_frame.hdr.smpl_rate][cb]
cb_begin = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][cb] * 3
else:
cb += 1
next_cb_boundary = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][cb + 1] * 3
cb_width = sfBandIndex_s[self.cur_frame.hdr.smpl_rate][
cb + 1] - sfBandIndex_s[self.cur_frame.hdr.smpl_rate][cb]
cb_begin = sfBandIndex_s[
self.cur_frame.hdr.smpl_rate][cb] * 3
else:
cb += 1
next_cb_boundary = sfBandIndex_l[
self.cur_frame.hdr.smpl_rate][cb + 1]
# Compute global scaling
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][ss] = pow(
2.0, (0.25 * (self.cur_frame.side_info.global_gain[ch][gr] - 210.0)))
val_a = self.cur_frame.decoded_data.dq_vals[
gr][ch][sb][ss]
# Compute block dependent scaling
if (self.cur_frame.side_info.window_switching_flag[ch][gr] and (
((self.cur_frame.side_info.block_type[ch][gr] == 2) and (self.cur_frame.side_info.mixed_block_flag[ch][gr] == 0)) or
((self.cur_frame.side_info.block_type[ch][gr] == 2) and self.cur_frame.side_info.mixed_block_flag[ch][gr] and (sb >= 2)))):
# SHORT
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] *= pow(2.0, 0.25 * -8.0 * self.cur_frame.side_info.subblock_gain[ch][gr][(((sb * 18) + ss) - cb_begin) / cb_width])
val_a2 = self.cur_frame.decoded_data.dq_vals[
gr][ch][sb][ss]
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][ss] *= pow(2.0, 0.25 * -2.0 *
(1.0 + self.cur_frame.side_info.scalefac_scale[ch][gr]) * self.cur_frame.main_data.scalefac_s[ch][gr][(((sb * 18) + ss) - cb_begin) / cb_width][cb])
val_a3 = self.cur_frame.decoded_data.dq_vals[
gr][ch][sb][ss]
else:
# LONG block types 0,1,3 & 1st 2 subbands of
# switched blocks
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][ss] *= pow(2.0, -0.5 *
(1.0 + self.cur_frame.side_info.scalefac_scale[ch][gr]) * (self.cur_frame.main_data.scalefac_l[ch][gr][cb] + self.cur_frame.side_info.preflag[ch][gr] * pretab[cb]))
val_b = self.cur_frame.decoded_data.dq_vals[
gr][ch][sb][ss]
val_b2 = self.cur_frame.side_info.scalefac_scale[
ch][gr]
val_b3 = self.cur_frame.main_data.scalefac_l[
ch][gr][cb]
# Scale quantized value
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] *= pow(abs(self.cur_frame.main_data.q_vals[gr][ch][sb][ss]), (4.0 / 3.0))
if (self.cur_frame.main_data.q_vals[gr][ch][sb][ss] < 0):
self.cur_frame.decoded_data.dq_vals[gr][ch][sb][
ss] = -self.cur_frame.decoded_data.dq_vals[gr][ch][sb][ss]
val_c = self.cur_frame.decoded_data.dq_vals[
gr][ch][sb][ss]
def process_stereo(self):
has_intensity_stereo = (
self.cur_frame.hdr.mode_extention & INTENSITY_STEREO_BIT)
has_mid_side_stereo = (
self.cur_frame.hdr.mode_extention & MID_SIDE_STEREO_BIT)
lr = self.cur_frame.decoded_data.lr_vals
dq_vals = self.cur_frame.decoded_data.dq_vals
if(dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print(
"s", self.frame_num, gr, sb, ss, dq_vals[gr][0][sb][ss])
for gr in range(2):
if (self.cur_frame.hdr.n_channels == 2):
is_pos = [7 for dummy in range(576)]
if(has_intensity_stereo):
is_ratio = self.process_intensity_stereo(gr, is_pos)
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
i = (sb * 18) + ss
if (is_pos[i] == 7):
if (has_mid_side_stereo):
lr[gr][0][sb][ss] = (
dq_vals[gr][0][sb][ss] + dq_vals[gr][1][sb][ss]) / 1.41421356
lr[gr][1][sb][ss] = (
dq_vals[gr][0][sb][ss] - dq_vals[gr][1][sb][ss]) / 1.41421356
else:
lr[gr][0][sb][ss] = dq_vals[gr][0][sb][ss]
lr[gr][1][sb][ss] = dq_vals[gr][1][sb][ss]
elif (has_intensity_stereo):
lr[gr][0][sb][ss] = dq_vals[gr][0][sb][
ss] * (is_ratio[i] / (1 + is_ratio[i]))
lr[gr][1][sb][ss] = dq_vals[gr][0][
sb][ss] * (1 / (1 + is_ratio[i]))
else:
print("Stereo - Error")
else:
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
lr[gr][0][sb][ss] = dq_vals[gr][0][sb][ss]
def process_intensity_stereo(self, gr, is_pos):
ch = 0
if (self.cur_frame.side_info.window_switching_flag[ch][gr] and (self.cur_frame.side_info.block_type[ch][gr] == 2)):
is_ratio = self.process_intensity_stereo__non_standard_window(
gr, is_pos)
else:
is_ratio = self.process_intensity_stereo__standard_window(
gr, is_pos)
return is_ratio
def process_intensity_stereo__standard_window(self, gr, is_pos):
smpl_rate = self.cur_frame.hdr.smpl_rate
i = 31
ss = 17
sb = 0
while (i >= 0):
if (self.decoded_data.dq_vals[1][i][ss] != 0.0):
sb = i * 18 + ss
i = -1
else:
ss -= 1
if (ss < 0):
i -= 1
ss = 17
i = 0
while (sfBandIndex_l[smpl_rate][i] <= sb):
i += 1
sfb = i
i = sfBandIndex_l[smpl_rate][i]
for sfb in range(sfb, 21):
sb = sfBandIndex_l[smpl_rate][
sfb + 1] - sfBandIndex_l[smpl_rate][sfb]
for sb in range(sb, 0, -1):
is_pos[i] = self.cur_frame.main_data.scalefac_l[1][gr][sfb]
if (is_pos[i] != 7):
is_ratio[i] = tan(is_pos[i] * (PI / 12))
i += 1
sfb = sfBandIndex_l[smpl_rate][20]
for sb in range(576 - sfBandIndex_l[smpl_rate][21], 0, -1):
is_pos[i] = is_pos[sfb]
is_ratio[i] = is_ratio[sfb]
i += 1
return is_ratio
def process_intensity_stereo__non_standard_window(self, gr, is_pos):
ch = 0
smpl_rate = self.cur_frame.hdr.smpl_rate
if (self.cur_frame.side_info.mixed_block_flag[ch][gr]):
max_sfb = 0
for j in range(3):
sfbcnt = 2
for sfb in range(12, 2, -1):
lines = sfBandIndex_s[smpl_rate][
sfb + 1] - sfBandIndex_s[smpl_rate][sfb]
i = 3 * sfBandIndex_s[sfreq][sfb] + (j + 1) * lines - 1
while (lines > 0):
if (self.decoded_data.dq_vals[1][i / SSLIMIT][i % SSLIMIT] != 0.0):
sfbcnt = sfb
sfb = -10
lines = -10
lines -= 1
i -= 1
sfb = sfbcnt + 1
if (sfb > max_sfb):
max_sfb = sfb
while(sfb < 12):
sb = sfBandIndex_s[smpl_rate][
sfb + 1] - sfBandIndex_s[sfreq][sfb]
i = 3 * sfBandIndex_s[smpl_rate][sfb] + j * sb
for sb in range(sb, 0, -1):
is_pos[i] = self.cur_frame.main_data.scalefac_s[
1][gr][j][sfb]
if (is_pos[i] != 7):
is_ratio[i] = tan(is_pos[i] * (PI / 12))
i += 1
sfb += 1
sb = sfBandIndex_s[smpl_rate][
11] - sfBandIndex_s[smpl_rate][10]
sfb = 3 * sfBandIndex_s[smpl_rate].s[10] + j * sb
sb = sfBandIndex_s[smpl_rate][
12] - sfBandIndex_s[smpl_rate][11]
i = 3 * sfBandIndex_s[smpl_rate][11] + j * sb
for sb in range(sb, 0, -1):
is_pos[i] = is_pos[sfb]
is_ratio[i] = is_ratio[sfb]
i += 1
if (max_sfb <= 3):
i = 2
ss = 17
sb = -1
while (i >= 0):
if (self.decoded_data.dq_vals[1][i][ss] != 0.0):
sb = i * 18 + ss
i = -1
else:
ss -= 1
if (ss < 0):
i -= 1
ss = 17
i = 0
while (sfBandIndex_l[smpl_rate][i] <= sb):
i += 1
sfb = i
i = sfBandIndex_l[smpl_rate][i]
for sfb in range(sfb, 8):
sb = sfBandIndex_l[smpl_rate][
sfb + 1] - sfBandIndex_l[sfreq][sfb]
for sb in range(sb, 0, -1):
is_pos[i] = self.cur_frame.main_data.scalefac_l[
1][gr][sfb]
if (is_pos[i] != 7):
is_ratio[i] = tan(is_pos[i] * (PI / 12))
i += 1
else:
for j in range(3):
sfbcnt = -1
for sfb in range(12, -1, -1):
lines = sfBandIndex_s[smpl_rate][
sfb + 1] - sfBandIndex_s[smpl_rate][sfb]
i = 3 * sfBandIndex_s[smpl_rate][sfb] + (j + 1) * lines - 1
while (lines > 0):
if (self.decoded_data.dq_vals[1][i / SSLIMIT][i % SSLIMIT] != 0.0):
sfbcnt = sfb
sfb = -10
lines = -10
lines -= 1
i -= 1
sfb = sfbcnt + 1
while(sfb < 12):
sb = sfBandIndex_s[smpl_rate][
sfb + 1] - sfBandIndex_s[smpl_rate][sfb]
i = 3 * sfBandIndex_s[smpl_rate][sfb] + j * sb
for sb in range(sb, 0, -1):
is_pos[i] = self.cur_frame.main_data.scalefac_s[
1][gr][j][sfb]
if (is_pos[i] != 7):
is_ratio[i] = tan(is_pos[i] * (PI / 12))
i += 1
sfb += 1
sb = sfBandIndex_s[smpl_rate][11] - sfBandIndex_s[sfreq][10]
sfb = 3 * sfBandIndex_s[smpl_rate][10] + j * sb
sb = sfBandIndex_s[smpl_rate][12] - sfBandIndex_s[sfreq][11]
i = 3 * sfBandIndex_s[smpl_rate][11] + j * sb
for sb in range(sb, -1, -1):
is_pos[i] = is_pos[sfb]
is_ratio[i] = is_ratio[sfb]
i += 1
return is_ratio
def reorder_samples(self):
smpl_rate = self.cur_frame.hdr.smpl_rate
lr = self.cur_frame.decoded_data.lr_vals
ro = self.cur_frame.decoded_data.reordered_vals
if(dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print(
"ro", self.frame_num, gr, sb, ss, lr[gr][0][sb][ss])
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
if (self.cur_frame.side_info.window_switching_flag[ch][gr] and (self.cur_frame.side_info.block_type[ch][gr] == 2)):
if (self.cur_frame.side_info.mixed_block_flag[ch][gr]):
# NO REORDER FOR LOW 2 SUBBANDS
for sb in range(2):
for ss in range(SSLIMIT):
ro[gr][ch][sb][ss] = lr[gr][ch][sb][ss]
# REORDERING FOR REST SWITCHED SHORT
sfb_start = sfBandIndex_s[smpl_rate][3]
sfb_lines = sfBandIndex_s[smpl_rate][4] - sfb_start
for sfb in range(3, 13):
for window in range(3):
for freq in range(sfb_lines):
src_line = sfb_start * 3 + \
window * sfb_lines + freq
des_line = (
sfb_start * 3) + window + (freq * 3)
ro[gr][ch][
des_line / SSLIMIT][des_line % SSLIMIT] = lr[gr][ch][src_line / SSLIMIT][src_line % SSLIMIT]
sfb_start = sfBandIndex_s[smpl_rate][sfb]
sfb_lines = sfBandIndex_s[
smpl_rate][sfb + 1] - sfb_start
else:
# pure short
sfb_start = 0
sfb_lines = sfBandIndex_s[smpl_rate][1]
for sfb in range(13):
for window in range(3):
for freq in range(sfb_lines):
src_line = sfb_start * 3 + \
window * sfb_lines + freq
des_line = (
sfb_start * 3) + window + (freq * 3)
ro[gr][ch][
des_line / SSLIMIT][des_line % SSLIMIT] = lr[gr][ch][src_line / SSLIMIT][src_line % SSLIMIT]
sfb_start = sfBandIndex_s[smpl_rate][sfb]
sfb_lines = sfBandIndex_s[
smpl_rate][sfb + 1] - sfb_start
else:
# long blocks */
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
ro[gr][ch][sb][ss] = lr[gr][ch][sb][ss]
def antialias_samples(self):
cs = [1.0 / sqrt(1.0 + ci * ci) for ci in antialias_Ci]
ca = [ci / sqrt(1.0 + ci * ci) for ci in antialias_Ci]
ro = self.cur_frame.decoded_data.reordered_vals
aa = self.cur_frame.decoded_data.antialiased_vals
if(dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print(
"aa", self.frame_num, gr, sb, ss, ro[gr][0][sb][ss])
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
aa[gr][ch][sb][ss] = ro[gr][ch][sb][ss]
if ((self.cur_frame.side_info.window_switching_flag[ch][gr] and (self.cur_frame.side_info.block_type[ch][gr] == 2)) and
(not self.cur_frame.side_info.mixed_block_flag[ch][gr])):
continue
if (self.cur_frame.side_info.window_switching_flag[ch][gr] and self.cur_frame.side_info.mixed_block_flag[ch][gr] and
(self.cur_frame.side_info.block_type[ch][gr] == 2)):
sblim = 1
else:
sblim = SBLIMIT - 1
# 31 alias-reduction operations between each pair of sub-bands
# with 8 butterflies between each pair
for sb in range(sblim):
for ss in range(8):
bu = ro[gr][ch][sb][17 - ss]
bd = ro[gr][ch][sb + 1][ss]
aa[gr][ch][sb][17 - ss] = (bu * cs[ss]) - (bd * ca[ss])
aa[gr][ch][sb + 1][ss] = (bd * cs[ss]) + (bu * ca[ss])
def hybrid_synthesis(self):
data_in = self.cur_frame.decoded_data.antialiased_vals
data_out = self.cur_frame.decoded_data.hybrid_vals
if(dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print("hs", self.frame_num, gr, sb, ss, self.cur_frame.decoded_data.antialiased_vals[
gr][0][sb][ss])
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
for sb in range(SBLIMIT):
if(self.cur_frame.side_info.window_switching_flag[ch][gr] and self.cur_frame.side_info.mixed_block_flag[ch][gr] and sb < 2):
blk_type = 0
else:
blk_type = self.cur_frame.side_info.block_type[ch][gr]
rawout = self.inv_mdct(data_in[gr][ch][sb], blk_type)
# overlap addition
for ss in range(SSLIMIT):
data_out[gr][ch][sb][ss] = rawout[
ss] + self.hybrid_prevblck[ch][sb][ss]
self.hybrid_prevblck[ch][sb][ss] = rawout[ss + 18]
def inv_mdct(self, data_in, blk_type):
out = zeros((36), dtype=double)
if(blk_type == 2):
tmp = zeros((12), dtype=double)
N = 12
for i in range(3):
for p in range(N):
total = 0.0
for m in range(N / 2):
total += data_in[i + 3 * m] * \
cos(PI / (2 * N) * (2 * p + 1 + N / 2)
* (2 * m + 1))
tmp[p] = total * self.mdct_win[blk_type][p]
for p in range(N):
out[6 * i + p + 6] += tmp[p]
else:
cos_tbl = self.mdct_cos_tbl_2
win = self.mdct_win[blk_type]
for p in range(36):
out[p] = sum(data_in * cos_tbl[p]) * win[p]
return out
def polyphase_synthesis(self):
data_in = self.cur_frame.decoded_data.hybrid_vals
data_out = self.pcm
bfr = zeros((SBLIMIT), dtype=double)
if(dbg_output and False):
for gr in range(2):
for sb in range(SBLIMIT):
for ss in range(SSLIMIT):
print("pps %d %d %d %d %.3e" % (
self.frame_num, gr, sb, ss, self.cur_frame.decoded_data.hybrid_vals[gr][0][sb][ss]))
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
# frequency inversion
for ss in range(18):
for sb in range(SBLIMIT):
if ((ss % 2) and (sb % 2)):
self.cur_frame.decoded_data.hybrid_vals[gr][ch][sb][
ss] = -self.cur_frame.decoded_data.hybrid_vals[gr][ch][sb][ss]
# subBand synthesis
for ss in range(18):
for sb in range(SBLIMIT):
bfr[sb] = data_in[gr][ch][sb][ss]
pcm_bfr = self.subBandSynthesis(bfr, ch)
# copy to final output
data_out[ch].extend(pcm_bfr)
def subBandSynthesis(self, data_in, ch):
pcm = zeros((32), dtype=int32)
self.sbs_buf[ch] = roll(self.sbs_buf[ch], 64)
# init
bfr = self.sbs_buf[ch]
# fir filter
for i in range(64):
bfr[i] = sum(data_in * self.sbs_filter[i])
# window output
for j in range(32):
total = 0
for i in range(16):
k = j + i * 32
idx = (k + (((i + 1) >> 1) * 64))
total += sbs_window[k] * bfr[idx]
# clip
pcm[j] = min(max(total * SCALE, -SCALE), SCALE - 1)
return pcm
def decode_main_info(self):
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
# Get scale factors
part2_start = self.bitbfr.get_pos()
if(self.cur_frame.side_info.window_switching_flag[ch][gr] == 1 and
self.cur_frame.side_info.block_type[ch][gr] == 2):
if(self.cur_frame.side_info.mixed_block_flag[ch][gr]):
# mixed blocks
print("mixed scale blocks not supported yet")
else:
# short blocks
for i in range(2):
for sfb in range(sfbtable_s[i], sfbtable_s[i + 1]):
for window in range(3):
self.cur_frame.main_data.scalefac_s[ch][gr][window][sfb] = self.bitbfr.read_bits(
slen[i][self.cur_frame.side_info.scalefac_compress[ch][gr]])
sfb = 12
for window in range(3):
self.cur_frame.main_data.scalefac_s[
ch][gr][window][sfb] = 0
else:
# long blocks
for i in range(4):
if ((self.cur_frame.side_info.scfsi[ch][i] == 0) or (gr == 0)):
for sfb in range(sfbtable_l[i], sfbtable_l[i + 1]):
if(i < 2):
k = 0
else:
k = 1
self.cur_frame.main_data.scalefac_l[ch][gr][sfb] = self.bitbfr.read_bits(
slen[k][self.cur_frame.side_info.scalefac_compress[ch][gr]])
self.cur_frame.main_data.scalefac_l[ch][gr][22] = 0
self.decode_main_data_huffman(ch, gr, part2_start)
def decode_main_data_huffman(self, ch, gr, part2_start):
# calculate region boundries
if(self.cur_frame.side_info.window_switching_flag[ch][gr] == 1 and
self.cur_frame.side_info.block_type[ch][gr] == 2):
# short block
region1Start = 36
region2Start = 576
else:
# long block
region1Start = sfBandIndex_l[self.cur_frame.hdr.smpl_rate][
self.cur_frame.side_info.region0_count[ch][gr] + 1]
region2Start = sfBandIndex_l[self.cur_frame.hdr.smpl_rate][
self.cur_frame.side_info.region0_count[ch][gr] + self.cur_frame.side_info.region1_count[ch][gr] + 2]
# read big value area
for i in range(0, self.cur_frame.side_info.big_values[ch][gr] * 2, 2):
if (i < region1Start):
ht_idx = self.cur_frame.side_info.table_select[ch][gr][0]
elif (i < region2Start):
ht_idx = self.cur_frame.side_info.table_select[ch][gr][1]
else:
ht_idx = self.cur_frame.side_info.table_select[ch][gr][2]
ht = ht_list[ht_idx]
v, w, x, y = self.huffman_decoder(ht)
self.cur_frame.main_data.q_vals[gr][
ch][i / SSLIMIT][i % SSLIMIT] = x
self.cur_frame.main_data.q_vals[gr][ch][
(i + 1) / SSLIMIT][(i + 1) % SSLIMIT] = y
# read count1 area
idx = self.cur_frame.side_info.big_values[ch][gr] * 2
# 32 is offset to count1 tables
ht = ht_list[self.cur_frame.side_info.count1table_select[ch][gr] + 32]
while((self.bitbfr.get_pos() < (part2_start + self.cur_frame.side_info.part2_3_length[ch][gr])) and (idx < SBLIMIT * SSLIMIT)):
v, w, x, y = self.huffman_decoder(ht)
self.cur_frame.main_data.q_vals[gr][ch][
idx / SSLIMIT][idx % SSLIMIT] = v
self.cur_frame.main_data.q_vals[gr][ch][
(idx + 1) / SSLIMIT][(idx + 1) % SSLIMIT] = w
self.cur_frame.main_data.q_vals[gr][ch][
(idx + 2) / SSLIMIT][(idx + 2) % SSLIMIT] = x
self.cur_frame.main_data.q_vals[gr][ch][
(idx + 3) / SSLIMIT][(idx + 3) % SSLIMIT] = y
idx += 4
# the rest are zeros
def huffman_decoder(self, ht):
MXOFF = 250
v = w = x = y = 0
# check for empty tree
if(ht.treelen == 0):
return (0, 0, 0, 0)
# run through huffman tree
success = False
pos = 0
nbits = 0
while(pos < ht.treelen and nbits < 32):
# check for end of tree
if(ht.values[pos][0] == 0):
x = ht.values[pos][1] >> 4
y = ht.values[pos][1] & 0xf
success = True
break
# get more bits to transverse tree
bit = self.bitbfr.read_bits(1)
while(ht.values[pos][bit] >= MXOFF):
pos += ht.values[pos][bit]
pos += ht.values[pos][bit]
nbits += 1
if(not success):
print("Failure during huffman decode")
return (0, 0, 0, 0)
# read sign bits
if(ht.tbl_type == "quad"):
v = (y >> 3) & 1
w = (y >> 2) & 1
x = (y >> 1) & 1
y = y & 1
if(v != 0):
if(self.bitbfr.read_bits(1)):
v = -v
if(w != 0):
if(self.bitbfr.read_bits(1)):
w = -w
if(x != 0):
if(self.bitbfr.read_bits(1)):
x = -x
if(y != 0):
if(self.bitbfr.read_bits(1)):
y = -y
else:
# process escape encodings
if(ht.linbits > 0):
if((ht.xlen - 1) == x):
x += self.bitbfr.read_bits(ht.linbits)
if(x != 0):
if(self.bitbfr.read_bits(1)):
x = -x
if(ht.linbits > 0):
if((ht.ylen - 1) == y):
y += self.bitbfr.read_bits(ht.linbits)
if(y != 0):
if(self.bitbfr.read_bits(1)):
y = -y
return (v, w, x, y)
def decode_side_info(self):
self.cur_frame.side_info.main_data_begin = self.bitbfr.read_bits(9)
if(self.cur_frame.side_info.main_data_begin != 0):
print("Error - dont support bitreservoir yet")
if(self.cur_frame.hdr.n_channels == 1):
self.cur_frame.side_info.private_bits = self.bitbfr.read_bits(5)
else:
self.cur_frame.side_info.private_bits = self.bitbfr.read_bits(3)
for ch in range(self.cur_frame.hdr.n_channels):
for i in range(4):
self.cur_frame.side_info.scfsi[ch][
i] = self.bitbfr.read_bits(1)
for gr in range(2):
for ch in range(self.cur_frame.hdr.n_channels):
self.cur_frame.side_info.part2_3_length[
ch][gr] = self.bitbfr.read_bits(12)
self.cur_frame.side_info.big_values[
ch][gr] = self.bitbfr.read_bits(9)
self.cur_frame.side_info.global_gain[
ch][gr] = self.bitbfr.read_bits(8)
self.cur_frame.side_info.scalefac_compress[
ch][gr] = self.bitbfr.read_bits(4)
self.cur_frame.side_info.window_switching_flag[
ch][gr] = self.bitbfr.read_bits(1)
if(self.cur_frame.side_info.window_switching_flag[ch][gr]):
self.cur_frame.side_info.block_type[
ch][gr] = self.bitbfr.read_bits(2)
self.cur_frame.side_info.mixed_block_flag[
ch][gr] = self.bitbfr.read_bits(1)
for i in range(2):
self.cur_frame.side_info.table_select[
ch][gr][i] = self.bitbfr.read_bits(5)
for i in range(3):
self.cur_frame.side_info.subblock_gain[
ch][gr][i] = self.bitbfr.read_bits(3)
if(self.cur_frame.side_info.block_type[ch][gr] == 2 and self.cur_frame.side_info.mixed_block_flag[ch][gr] == 0):
self.cur_frame.side_info.region0_count[ch][gr] = 8
else:
self.cur_frame.side_info.region0_count[ch][gr] = 7
self.cur_frame.side_info.region1_count[ch][
gr] = 20 - self.cur_frame.side_info.region0_count[ch][gr]
else:
for i in range(3):
self.cur_frame.side_info.table_select[
ch][gr][i] = self.bitbfr.read_bits(5)
self.cur_frame.side_info.region0_count[
ch][gr] = self.bitbfr.read_bits(4)
self.cur_frame.side_info.region1_count[
ch][gr] = self.bitbfr.read_bits(3)
self.cur_frame.side_info.block_type[ch][gr] = 0
self.cur_frame.side_info.preflag[ch][
gr] = self.bitbfr.read_bits(1)
self.cur_frame.side_info.scalefac_scale[
ch][gr] = self.bitbfr.read_bits(1)
self.cur_frame.side_info.count1table_select[
ch][gr] = self.bitbfr.read_bits(1)
if(dbg_output):
print(
"main_data_begin:", self.cur_frame.side_info.main_data_begin)
print("privatebits:", self.cur_frame.side_info.private_bits)
print("scale factor select info:", self.cur_frame.side_info.scfsi)
print("part 2_3 len:", self.cur_frame.side_info.part2_3_length)
print("big values:", self.cur_frame.side_info.big_values)
print("global gain:", self.cur_frame.side_info.global_gain)
print(
"scalefac_compress", self.cur_frame.side_info.scalefac_compress)
print(
"win switch flag:", self.cur_frame.side_info.window_switching_flag)
print("block type:", self.cur_frame.side_info.block_type)
print(
"mixed block flag:", self.cur_frame.side_info.mixed_block_flag)
print("table select:", self.cur_frame.side_info.table_select)
print("subblock gain:", self.cur_frame.side_info.subblock_gain)
print("region0_count", self.cur_frame.side_info.region0_count)
print("region1_count", self.cur_frame.side_info.region1_count)
print("preflag", self.cur_frame.side_info.preflag)
print("scalefac_scale", self.cur_frame.side_info.scalefac_scale)
print(
"count1table select:", self.cur_frame.side_info.count1table_select)
def decode_CRC(self):
if(self.cur_frame.hdr.has_CRC):
crc = self.bitbfr.read_bits(16)
def decode_frame_header(self):
self.cur_frame.hdr.mpeg_version = mp3_hdr_ver_tbl[
self.bitbfr.read_bits(1)]
self.cur_frame.hdr.layer = mp3_hdr_layer_tbl[self.bitbfr.read_bits(2)]
self.cur_frame.hdr.has_CRC = not self.bitbfr.read_bits(1)
self.cur_frame.hdr.bitrate = mp3_hdr_bitrate_tbl[
self.bitbfr.read_bits(4)]
self.cur_frame.hdr.smpl_rate = mp3_hdr_smpl_rate_tbl[
self.bitbfr.read_bits(2)]
self.cur_frame.hdr.padding = self.bitbfr.read_bits(1)
self.bitbfr.read_bits(1) # private bit
self.cur_frame.hdr.channel_mode = mp3_hdr_channel_mode_tbl[
self.bitbfr.read_bits(2)]
self.cur_frame.hdr.mode_extention = self.bitbfr.read_bits(2)
self.cur_frame.hdr.copyrighted = self.bitbfr.read_bits(1)
self.cur_frame.hdr.original = self.bitbfr.read_bits(1)
self.cur_frame.hdr.emphasis = mp3_hdr_emphasis_tbl[
self.bitbfr.read_bits(2)]
if(self.cur_frame.hdr.channel_mode == "mono"):
self.cur_frame.hdr.n_channels = 1
else:
self.cur_frame.hdr.n_channels = 2
if(dbg_output):
print("frame header info")
print("ver:", self.cur_frame.hdr.mpeg_version)
print("layer:", self.cur_frame.hdr.layer)
print("has CRC:", self.cur_frame.hdr.has_CRC)
print("bitrate(kps):", self.cur_frame.hdr.bitrate)
print("sample rate:", self.cur_frame.hdr.smpl_rate)
print("padding:", self.cur_frame.hdr.padding)
print("channel mode:", self.cur_frame.hdr.channel_mode)
print("n channels:", self.cur_frame.hdr.n_channels)
print("mode extention:", self.cur_frame.hdr.mode_extention)
print("copyrighted:", self.cur_frame.hdr.copyrighted)
print("original copy:", self.cur_frame.hdr.original)
print("emphasis:", self.cur_frame.hdr.emphasis)
if(self.first_frame):
print("bitrate(kps):", self.cur_frame.hdr.bitrate)
print("sample rate:", self.cur_frame.hdr.smpl_rate)
print("channel mode:", self.cur_frame.hdr.channel_mode)
self.first_frame = False
def find_next_syncword(self):
# align to byte boundry
align = self.bitbfr.get_pos() % 8
if(align != 0):
self.bitbfr.read_bits(8 - align)
cnt = 0
while(self.bitbfr.bits_left() > 0):
b = self.bitbfr.read_bits(4)
if(b == 0xf):
cnt += 1
if(cnt == 3):
break
else:
cnt = 0
if(dbg_output):
print("sync found at %d" % (self.bitbfr.get_pos()))
