video - FFMPEG Cutting Commercials puts audio out of sync -
ubuntu 14.04.1 real ffmpeg loaded (same problem avconv version).
i'm trying take files created in mythtv hdpvr, cut commercials , put video mp4 container use mythroku.
the command
ffmpeg -i $file -acodec copy -vcodec copy -f mp4 file.mp4
works fine. once update database, can watch file in mythroku or plex.
however, when try cut out commercials, audio gets out of sync on 1 second (audio delayed) whenever cut past 0 mark. totem video player , vlc both play resulting video fine, can see "hitch" @ beginning while syncing audio, know information on audio sync in file somewhere. mythroku , plex both out of sync when playing file. mythtv frontend player play correctly, , can hear "hitch" syncs audio.
after hours of reading posts , playing settings, i've got down this:
if say:
ffmpeg -i $file -acodec copy -vcodec copy -f mp4 -ss 0 -t <anything> out.mp4
the file fine, plays both locally , in mythroku/plex
but if advance start amount - 1 second - audio out of sync
ffmpeg -i $file -acodec copy -vcodec copy -f mp4 -ss 1 -t <anything> out.mp4
i've tried splitting video (as mp4) , audio (as ac3) first, splitting them separately, , putting them last step, same results.
the information in file - totem, vlc , frontend can figure out. how can ffmpeg figure out sync , write file it's correct?
original file:
mythtv@marvin:~$ mediainfo /var/lib/mythtv/recordings/2225_20140824001500.mpg general id : 0 (0x0) complete name : /var/lib/mythtv/recordings/2225_20140824001500.mpg format : mpeg-ts file size : 4.03 gib duration : 1h 45mn overall bit rate mode : variable overall bit rate : 5 491 kbps video id : 4113 (0x1011) menu id : 1 (0x1) format : avc format/info : advanced video codec format profile : main@l4.0 format settings, cabac : yes format settings, reframes : 4 frames format settings, gop : m=4, n=32 codec id : 27 duration : 1h 45mn bit rate mode : variable bit rate : 4 831 kbps maximum bit rate : 20.0 mbps width : 1 280 pixels height : 720 pixels display aspect ratio : 16:9 frame rate : 59.940 fps color space : yuv chroma subsampling : 4:2:0 bit depth : 8 bits scan type : progressive bits/(pixel*frame) : 0.087 stream size : 3.55 gib (88%) color primaries : bt.709 transfer characteristics : bt.709 matrix coefficients : bt.709 audio id : 4352 (0x1100) menu id : 1 (0x1) format : ac-3 format/info : audio coding 3 mode extension : cm (complete main) format settings, endianness : big codec id : 129 duration : 1h 45mn bit rate mode : constant bit rate : 384 kbps channel(s) : 2 channels channel positions : front: l r sampling rate : 48.0 khz bit depth : 16 bits compression mode : lossy delay relative video : -6ms stream size : 289 mib (7%) file cut 0:
mythtv@marvin:~$ mediainfo 2225_20140824001500_1.mp4 general complete name : 2225_20140824001500_1.mp4 format : mpeg-4 format profile : base media codec id : isom file size : 58.5 mib duration : 1mn 45s overall bit rate mode : variable overall bit rate : 4 676 kbps writing application : lavf54.63.104 video id : 1 format : avc format/info : advanced video codec format profile : main@l4.0 format settings, cabac : yes format settings, reframes : 4 frames format settings, gop : m=4, n=32 codec id : avc1 codec id/info : advanced video coding duration : 1mn 45s bit rate mode : variable bit rate : 4 281 kbps maximum bit rate : 20.0 mbps width : 1 280 pixels height : 720 pixels display aspect ratio : 16:9 frame rate mode : variable frame rate : 59.940 fps minimum frame rate : 59.920 fps maximum frame rate : 59.960 fps color space : yuv chroma subsampling : 4:2:0 bit depth : 8 bits scan type : progressive bits/(pixel*frame) : 0.077 stream size : 53.6 mib (92%) color primaries : bt.709 transfer characteristics : bt.709 matrix coefficients : bt.709 audio id : 2 format : ac-3 format/info : audio coding 3 mode extension : cm (complete main) format settings, endianness : big codec id : ac-3 duration : 1mn 45s bit rate mode : constant bit rate : 384 kbps channel(s) : 2 channels channel positions : front: l r sampling rate : 48.0 khz bit depth : 16 bits compression mode : lossy stream size : 4.81 mib (8%) file cut 1 second audio sync problem:
mythtv@marvin:~$ mediainfo 2225_20140824001500_2.mp4 general complete name : 2225_20140824001500_2.mp4 format : mpeg-4 format profile : base media codec id : isom file size : 68.0 mib duration : 2mn 0s overall bit rate mode : variable overall bit rate : 4 750 kbps writing application : lavf54.63.104 video id : 1 format : avc format/info : advanced video codec format profile : main@l4.0 format settings, cabac : yes format settings, reframes : 4 frames format settings, gop : m=4, n=32 codec id : avc1 codec id/info : advanced video coding duration : 1mn 58s bit rate mode : variable bit rate : 4 394 kbps maximum bit rate : 20.0 mbps width : 1 280 pixels height : 720 pixels display aspect ratio : 16:9 frame rate mode : variable frame rate : 59.940 fps minimum frame rate : 59.920 fps maximum frame rate : 59.960 fps color space : yuv chroma subsampling : 4:2:0 bit depth : 8 bits scan type : progressive bits/(pixel*frame) : 0.080 stream size : 62.3 mib (92%) color primaries : bt.709 transfer characteristics : bt.709 matrix coefficients : bt.709 audio id : 2 format : ac-3 format/info : audio coding 3 mode extension : cm (complete main) format settings, endianness : big codec id : ac-3 duration : 2mn 0s bit rate mode : constant bit rate : 384 kbps channel(s) : 2 channels channel positions : front: l r sampling rate : 48.0 khz bit depth : 16 bits compression mode : lossy stream size : 5.49 mib (8%)
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