def load(self, atoms, fileobj):
try:
moov = atoms[b"moov"]
except KeyError:
raise MP4StreamInfoError("not a MP4 file")
for trak in moov.findall(b"trak"):
hdlr = trak[b"mdia", b"hdlr"]
ok, data = hdlr.read(fileobj)
if not ok:
raise MP4StreamInfoError("Not enough data")
if data[8:12] == b"soun":
break
else:
raise MP4NoTrackError("track has no audio data")
mdhd = trak[b"mdia", b"mdhd"]
ok, data = mdhd.read(fileobj)
if not ok:
raise MP4StreamInfoError("Not enough data")
try:
version, flags, data = parse_full_atom(data)
except ValueError as e:
raise MP4StreamInfoError(e)
if version == 0:
offset = 8
fmt = ">2I"
elif version == 1:
offset = 16
fmt = ">IQ"
else:
raise MP4StreamInfoError("Unknown mdhd version %d" % version)
end = offset + struct.calcsize(fmt)
unit, length = struct.unpack(fmt, data[offset:end])
try:
self.length = float(length) / unit
except ZeroDivisionError:
self.length = 0
try:
atom = trak[b"mdia", b"minf", b"stbl", b"stsd"]
except KeyError:
pass
else:
self._parse_stsd(atom, fileobj)
def _parse_stsd(self, atom, fileobj):
"""Sets channels, bits_per_sample, sample_rate and optionally bitrate.
Can raise MP4StreamInfoError.
"""
assert atom.name == b"stsd"
ok, data = atom.read(fileobj)
if not ok:
raise MP4StreamInfoError("Invalid stsd")
try:
version, flags, data = parse_full_atom(data)
except ValueError as e:
raise MP4StreamInfoError(e)
if version != 0:
raise MP4StreamInfoError("Unsupported stsd version")
try:
num_entries, offset = cdata.uint32_be_from(data, 0)
except cdata.error as e:
raise MP4StreamInfoError(e)
if num_entries == 0:
return
# look at the first entry if there is one
entry_fileobj = cBytesIO(data[offset:])
try:
entry_atom = Atom(entry_fileobj)
except AtomError as e:
raise MP4StreamInfoError(e)
try:
entry = AudioSampleEntry(entry_atom, entry_fileobj)
except ASEntryError as e:
raise MP4StreamInfoError(e)
else:
self.channels = entry.channels
self.bits_per_sample = entry.sample_size
self.sample_rate = entry.sample_rate
self.bitrate = entry.bitrate
self.codec = entry.codec
self.codec_description = entry.codec_description
def test_parse_full_atom(self):
p = parse_full_atom(b"\x01\x02\x03\x04\xff")
self.assertEqual(p, (1, 131844, b'\xff'))
self.assertRaises(ValueError, parse_full_atom, b"\x00\x00\x00")
def test_parse_full_atom(self):
p = parse_full_atom(b"\x01\x02\x03\x04\xff")
self.assertEqual(p, (1, 131844, b'\xff'))
self.assertRaises(ValueError, parse_full_atom, b"\x00\x00\x00")