def __init__(self,
line_config,
variant=ProtoSecamVariant.SECAM_1957,
premod_luma_filter=True):
self.line_config = line_config
self.config = variant
self._premod_luma_filter = premod_luma_filter
self._carrier_phase_step = numpy.pi * variant.fsc / line_config.fs
self._chroma_precorrect_lowpass = utils.iirdesign(
2.0 * variant.bandwidth3db / line_config.fs,
2.0 * variant.bandwidth20db / line_config.fs, 3.0, 20.0)
self._demodulate_resample_factor = 3
self._extract_chroma_up, self._remove_chroma_up = utils.iirsplitter(
2.0 * variant.fsc /
(self._demodulate_resample_factor * line_config.fs),
2.0 * variant.bandwidth3db /
(self._demodulate_resample_factor * line_config.fs),
2.0 * variant.bandwidth20db /
(self._demodulate_resample_factor * line_config.fs), 3.0, 20.0)
if variant.fsc < variant.bandwidth20db:
post_demod_bandwidth = variant.bandwidth3db
else:
post_demod_bandwidth = variant.bandwidth20db
self._chroma_up_post_demod_filter = utils.iirdesign(
2.0 *
min(post_demod_bandwidth, variant.fsc - post_demod_bandwidth) /
(self._demodulate_resample_factor * line_config.fs), 2.0 *
max(post_demod_bandwidth, variant.fsc - post_demod_bandwidth) /
(self._demodulate_resample_factor * line_config.fs), 3.0, 20.0)
self._last_frame = -1
self._last_line = -1
self._last_chroma = None
def __init__(self,
line_config,
variant=SecamVariant.SECAM,
alternate_phases=False):
self._line_config = line_config
self._variant = variant
self._fsc_dr = 2.0 * variant.fsc_dr / line_config.fs
self._fsc_db = 2.0 * variant.fsc_db / line_config.fs
self._fdev_dr = 2.0 * variant.fdev_dr / line_config.fs
self._fdev_db = 2.0 * variant.fdev_db / line_config.fs
self._flimit_min = 2.0 * (variant.bell_f0 +
variant.flimit_minbell) / line_config.fs
self._flimit_max = 2.0 * (variant.bell_f0 +
variant.flimit_maxbell) / line_config.fs
self._bell_f0 = 2.0 * variant.bell_f0 / line_config.fs
if not alternate_phases:
self._start_phase_inversions = [
False, False, True, False, False, True
]
else:
self._start_phase_inversions = [
False, False, False, True, True, True
]
self._chroma_demod_bell = None
if variant.bell_kn != variant.bell_kd:
self._chroma_demod_bell = self._chroma_demod_bell_design(
self._bell_f0, self._flimit_max, variant.bell_kn,
variant.bell_kd)
self._chroma_precorrect_lowpass = utils.iirdesign(
wp=2.0 * 1300000.0 / line_config.fs,
ws=2.0 * 3500000.0 / line_config.fs,
gpass=3.0,
gstop=30.0)
self._chroma_precorrect = None
self._reverse_chroma_precorrect = None
if variant.lf_precorrect_k != 1.0:
self._chroma_precorrect, self._reverse_chroma_precorrect = SecamModem._chroma_precorrect_design(
2.0 * variant.lf_precorrect_f1 / line_config.fs,
variant.lf_precorrect_k)
center = 0.5 * (self._flimit_min + self._flimit_max)
dev = 0.5 * (self._flimit_max - self._flimit_min)
self._chroma_demod_filter_order = 3
self._chroma_demod_chroma_filter = utils.iirfilter(
3, [center - dev, center + dev],
rp=0.1,
btype='bandpass',
ftype='cheby1')
self._chroma_demod_luma_filter = utils.iirfilter(
3, [center - dev * numpy.e, center + dev * numpy.e],
btype='bandstop',
ftype='bessel')
self._chroma_demod = FmDecoder(center, dev)
self._last_frame = -1
self._last_line = -1
self._last_chroma = None
def __init__(self, wc, wp, ws, gpass, gstop):
self.carrier_phase_step = 0.5 * numpy.pi * wc
self._chroma_precorrect_lowpass = utils.iirdesign(wp, ws, gpass, gstop)
self._extract_chroma2x, self._remove_chroma2x = utils.iirsplitter(
0.5 * wc, 0.5 * wp, 0.5 * ws, gpass, gstop)
self._demod_lowpass = utils.iirfilter(6,
wc - 0.5 * ws,
rs=48.0,
btype='lowpass',
ftype='cheby2')
def _chroma_demod_bell_design(f0, f_max, kn, kd):
def gain(f):
return numpy.sqrt(
(kd * kd * f0 * f0 * f0 * f0 +
(1 - 2 * kd * kd) * f * f * f0 * f0 + kd * kd * f * f * f * f)
/ (kn * kn * f0 * f0 * f0 * f0 +
(1 - 2 * kn * kn) * f * f * f0 * f0 +
kn * kn * f * f * f * f))
def gain_db(f):
return 10.0 * numpy.log10(gain(f))
assert kn != kd
wp2 = f0 + 1 / 256.0
wp1 = f0 * f0 / wp2
ws2 = f_max
ws1 = f0 * f0 / ws2
return utils.iirdesign([wp1, wp2], [ws1, ws2],
-gain_db(wp2),
-gain_db(ws2),
shift=False)
def __init__(self,
line_config,
config=pal.PalVariant.PAL,
noise_level=0.0):
self._carrier_phase_step = 2.0 * numpy.pi * config.fsc / line_config.fs
self._noise_level = noise_level
self.line_config = line_config
self.config = config
self._chroma_precorrect_lowpass = utils.iirdesign(
2.0 * config.bandwidth3db / line_config.fs,
2.0 * config.bandwidth20db / line_config.fs, 3.0, 20.0)
self._demodulate_resample_factor = 3
self._demodulate_upsampled_baseband_filter, self._demodulate_upsampled_filter = NiirModem._demodulate_am_design(
2.0 * config.fsc / line_config.fs,
2.0 * config.bandwidth3db / line_config.fs,
2.0 * config.bandwidth20db / line_config.fs, 3.0, 20.0,
self._demodulate_resample_factor)
self._last_frame = -1
self._last_line = -1
self._last_phasemod_up = None
def _demodulate_am_design(wc, wp, ws, gpass, gstop, resample_factor):
return utils.iirdesign(wp / resample_factor, ws / resample_factor,
gpass, gstop), utils.iirdesign_wc(
wc / resample_factor, wp / resample_factor,
ws / resample_factor, gpass, gstop)