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  1. Member
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    Hi. I've got a TS file and want to extract the audio track without re-encoding. I tried using the "Demux" mode in tsmuxer and got an AAC file but its length (02:57:56) is a bit shorter than the original video length (02:58:38) when played in MPC-HC. The AAC file length shown in the windows-included music player groove music becomes more than 3 hours long.
    I also tried just muxing the audio track to a new TS file. This time the output audio TS file length has no problem no matter what player it is being played in.
    But am I doing it right? I think demuxing is what should work not re-muxing it to a new TS file?
    Below is the video mediainfo. Thanks a lot!

    Code:
    Format                      : MPEG-TS
    File size                   : 7.41 GiB
    Duration                    : 2 h 58 min
    Overall bit rate mode       : Variable
    Overall bit rate            : 5 938 kb/s
    
    Video
    ID                          : 481 (0x1E1)
    Menu ID                     : 1 (0x1)
    Format                      : AVC
    Format/Info                 : Advanced Video Codec
    Format profile              : High@L4
    Format settings             : CABAC / 2 Ref Frames
    Format settings, CABAC      : Yes
    Format settings, ReFrames   : 2 frames
    Format settings, GOP        : M=3, N=60
    Codec ID                    : 27
    Duration                    : 2 h 58 min
    Bit rate mode               : Variable
    Maximum bit rate            : 6 000 kb/s
    Width                       : 1 920 pixels
    Height                      : 1 080 pixels
    Display aspect ratio        : 16:9
    Frame rate                  : 29.970 (30000/1001) FPS
    Color space                 : YUV
    Chroma subsampling          : 4:2:0
    Bit depth                   : 8 bits
    Scan type                   : Progressive
    Color range                 : Limited
    Color primaries             : BT.709
    Transfer characteristics    : BT.709
    Matrix coefficients         : BT.709
    
    Audio
    ID                          : 482 (0x1E2)
    Menu ID                     : 1 (0x1)
    Format                      : AAC
    Format/Info                 : Advanced Audio Codec
    Format version              : Version 4
    Format profile              : LC
    Muxing mode                 : ADTS
    Codec ID                    : 15
    Duration                    : 2 h 58 min
    Bit rate mode               : Variable
    Maximum bit rate            : 208 kb/s
    Channel(s)                  : 2 channels
    Channel positions           : Front: L R
    Sampling rate               : 96.0 kHz
    Frame rate                  : 93.750 FPS (1024 SPF)
    Compression mode            : Lossy
    Delay relative to video     : -17 ms
    Language                    : English
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  2. If the audio is in synch, then it's fine.
    Maybe the original Ts file has a timestamp problem.
    In this case a simple remux can help, because the timestamps are rewritten.
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  3. Member
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    Originally Posted by ProWo View Post
    If the audio is in synch, then it's fine.
    Maybe the original Ts file has a timestamp problem.
    In this case a simple remux can help, because the timestamps are rewritten.
    Thanks for replying. Are there any software that can help me determine if the original and output audio files are indeed identical?
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  4. I'm a Super Moderator johns0's Avatar
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    I would say with out a doubt that there are identical and no need to analyze them,as to the length of the audio lots of videos have shorter audio than video time,as long as the audio is in sync then all is ok.
    I think,therefore i am a hamster.
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    Is there any reason why the audio length is shorter than the video length? Do they use different units of time? If thereís no silence part at the start or at the end of the original file, then why would the audio length be shorter than video? Iím just really curious what leads to this situation.
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  6. Member Ennio's Avatar
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    No specific reason I think. Very often audio- and videolength don't (exactly) match. They simply don't have to and will play fine. You'll find it even on dvd and blu-ray. So why bother.

    If you want to ask the creator, who is "they"? Everybody and his dog nowadays is busy with recoding, speedchanging, crossmuxing and whatnot. I bet that a lot wouldn't even be aware (or care) if audio playtime don't match video's.
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  7. DECEASED
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    Originally Posted by Tsubasa View Post
    Hi. I've got a TS file and want to extract the audio track without re-encoding. I tried using the "Demux" mode in tsmuxer and got an AAC file but its length (02:57:56) is a bit shorter than the original video length (02:58:38) when played in MPC-HC. The AAC file length shown in the windows-included music player groove music becomes more than 3 hours long.
    FWIW... remux the AAC stream to an MP4 or an M4A container and see what MediaInfo says then.
    The ADTS container doesn't use a global header and so it may be read differently by different applications /demuxers...
    and if the application or "filter" is not very versatile (so to speak), weird results may happen.
    Last edited by El Heggunte; 3rd Aug 2022 at 05:10. Reason: edit
    "Like this facility, I don't exist."
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    I use mkvtoolnix and just output the audio track as .m4a. Shown below is the mediainfo of the output file. Am I doing it correctly? Are there any other softwares that can remux just the audio files? Avidemux doesn't allow me to input a single audio track and tsmuxer has no option of outputting as mp4 or m4a.
    Edit: But this does solve the problem of different players showing different audio lengths. Thanks.
    Code:
    Format                      : Matroska
    Format version              : Version 4 / Version 2
    File size                   : 459 MiB
    Duration                    : 2 h 58 min
    Overall bit rate            : 359 kb/s
    Encoded date                : UTC 2022-08-03 09:32:40
    Writing application         : mkvmerge v62.0.0 ('Apollo') 64-bit
    Writing library             : libebml v1.4.2 + libmatroska v1.6.4
    FileExtension_Invalid       : mkv mk3d mka mks
    
    Audio
    ID                          : 1
    Format                      : AAC
    Format/Info                 : Advanced Audio Codec
    Format profile              : LC
    Codec ID                    : A_AAC-2
    Duration                    : 2 h 58 min
    Bit rate                    : 353 kb/s
    Channel(s)                  : 2 channels
    Channel positions           : Front: L R
    Sampling rate               : 96.0 kHz
    Frame rate                  : 93.750 FPS (1024 SPF)
    Compression mode            : Lossy
    Stream size                 : 456 MiB (99%)
    Language                    : English
    Default                     : Yes
    Forced                      : No
    Last edited by Tsubasa; 3rd Aug 2022 at 04:55.
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  9. DECEASED
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    Are there any other softwares that can remux just the audio files?
    Yes. Both mp4box and ffmpeg can wrap .aac files in .MP4 /.M4A ones.
    "Like this facility, I don't exist."
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  10. Originally Posted by Tsubasa View Post
    Are there any other softwares that can remux just the audio files?
    clever FFmpeg-GUI
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  11. Member Ennio's Avatar
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    As a friendly GUI to ffmpeg, for wrapping audio I often use ShanaEncoder.
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