mirror of
https://github.com/yt-dlp/yt-dlp.git
synced 2024-11-16 13:23:20 +00:00
129 lines
5.3 KiB
Python
129 lines
5.3 KiB
Python
from math import inf
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from .common import PostProcessor
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from ..utils import prepend_extension
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from ..mp4_parser import (
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write_mp4_boxes,
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parse_mp4_boxes,
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pack_be32,
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pack_be64,
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unpack_ver_flags,
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unpack_be32,
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unpack_be64,
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)
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class MP4FixupTimestampPP(PostProcessor):
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@property
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def available(self):
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return True
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def analyze_mp4(self, filepath):
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""" returns (baseMediaDecodeTime offset, sample duration cutoff) """
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smallest_bmdt, known_sdur = inf, set()
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with open(filepath, 'rb') as r:
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for btype, content in parse_mp4_boxes(r):
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if btype == 'tfdt':
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version, _ = unpack_ver_flags(content[0:4])
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# baseMediaDecodeTime always comes to the first
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if version == 0:
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bmdt = unpack_be32(content[4:8])
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else:
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bmdt = unpack_be64(content[4:12])
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if bmdt == 0:
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continue
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smallest_bmdt = min(bmdt, smallest_bmdt)
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elif btype == 'tfhd':
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version, flags = unpack_ver_flags(content[0:4])
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if not flags & 0x08:
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# this box does not contain "sample duration"
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continue
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# https://github.com/gpac/mp4box.js/blob/4e1bc23724d2603754971abc00c2bd5aede7be60/src/box.js#L203-L209
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# https://github.com/gpac/mp4box.js/blob/4e1bc23724d2603754971abc00c2bd5aede7be60/src/parsing/tfhd.js
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sdur_start = 8 # header + track id
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if flags & 0x01:
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sdur_start += 8
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if flags & 0x02:
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sdur_start += 4
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# the next 4 bytes are "sample duration"
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sample_dur = unpack_be32(content[sdur_start:sdur_start + 4])
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known_sdur.add(sample_dur)
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maximum_sdur = max(known_sdur)
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for multiplier in (0.7, 0.8, 0.9, 0.95):
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sdur_cutoff = maximum_sdur * multiplier
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if len(set(x for x in known_sdur if x > sdur_cutoff)) < 3:
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break
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else:
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sdur_cutoff = inf
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return smallest_bmdt, sdur_cutoff
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def modify_mp4(self, src, dst, bmdt_offset, sdur_cutoff):
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with open(src, 'rb') as r, open(dst, 'wb') as w:
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def converter():
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for btype, content in parse_mp4_boxes(r):
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if btype == 'tfdt':
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version, _ = unpack_ver_flags(content[0:4])
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if version == 0:
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bmdt = unpack_be32(content[4:8])
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else:
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bmdt = unpack_be64(content[4:12])
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if bmdt == 0:
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yield (btype, content)
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continue
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# calculate new baseMediaDecodeTime
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bmdt = max(0, bmdt - bmdt_offset)
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# pack everything again and insert as a new box
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if version == 0:
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bmdt_b = pack_be32(bmdt)
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else:
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bmdt_b = pack_be64(bmdt)
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yield ('tfdt', content[0:4] + bmdt_b + content[8 + version * 4:])
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continue
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elif btype == 'tfhd':
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version, flags = unpack_ver_flags(content[0:4])
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if not flags & 0x08:
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yield (btype, content)
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continue
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sdur_start = 8
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if flags & 0x01:
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sdur_start += 8
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if flags & 0x02:
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sdur_start += 4
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sample_dur = unpack_be32(content[sdur_start:sdur_start + 4])
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if sample_dur > sdur_cutoff:
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sample_dur = 0
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sd_b = pack_be32(sample_dur)
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yield ('tfhd', content[:sdur_start] + sd_b + content[sdur_start + 4:])
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continue
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yield (btype, content)
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write_mp4_boxes(w, converter())
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def run(self, information):
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filename = information['filepath']
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temp_filename = prepend_extension(filename, 'temp')
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self.write_debug('Analyzing MP4')
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bmdt_offset, sdur_cutoff = self.analyze_mp4(filename)
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working = inf not in (bmdt_offset, sdur_cutoff)
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# if any of them are Infinity, there's something wrong
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# baseMediaDecodeTime = to shift PTS
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# sample duration = to define duration in each segment
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self.write_debug(f'baseMediaDecodeTime offset = {bmdt_offset}, sample duration cutoff = {sdur_cutoff}')
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if bmdt_offset == inf:
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# safeguard
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bmdt_offset = 0
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self.modify_mp4(filename, temp_filename, bmdt_offset, sdur_cutoff)
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if working:
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self.to_screen('Duration of the file has been fixed')
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else:
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self.report_warning(f'Failed to fix duration of the file. (baseMediaDecodeTime offset = {bmdt_offset}, sample duration cutoff = {sdur_cutoff})')
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self._downloader.replace(temp_filename, filename)
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return [], information
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