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  1. Assume I have a video with the video codec
    H.264/AVC and an audio codec AAC

    As I found out I can (lossless) convert a video from AVI container to MP4 container with a ffmpeg cmd like

    FFmpeg.exe" -i "foobar.avi" -vcodec copy -acodec copy "foobar.mp4"

    Fine.

    Now I want to do the other way: to (lossless) convert a video from MP4 container to AVI container. I though

    FFmpeg.exe" -i "foobar.mp4" -vcodec copy -acodec copy "foobar.avi"

    will do the job. But unfortunately I cannot hear audio in the resulting *.avi video.
    Video is ok and audio tracks seems to be present but not played (with VLC player).

    So how else do I lossless convert MP4 video to AVI?
    Yes, AAC ACM codec is installed on (64bit) Win7 system.

    Thank you
    Peter
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  2. DECEASED
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    The various muxers in ffmpeg are far from being flawless.

    Here is what I'd do:

    --- extract the .264 and the .aac streams from the MP4 source

    --- .264 file --> (avc2avi) --> .AVI w/ video

    --- use AVIMux-GUI for joining the intermediate .AVI and the .AAC stream

    Hope this helps.

    P.S.: AAC ACM is good and necessary for VirtualDub, but it's not required by WMP, MPC-HC, VLC, or Mplayer.
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  3. Banned
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    Using VirtualDub you can extract the video and audio streams separately using the Direct Stream Copy option. Once you have these streams you can mux them together using something like MKVMerge. I have done this before.
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  4. Member bat999's Avatar
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    Originally Posted by pxstein View Post
    Assume I have a video with the video codec
    H.264/AVC and an audio codec AAC

    FFmpeg.exe" -i "foobar.mp4" -vcodec copy -acodec copy "foobar.avi"

    will do the job. But unfortunately I cannot hear audio in the resulting *.avi video.
    Video is ok and audio tracks seems to be present but not played (with VLC player).
    Hi
    I have found that VLC won't play aac audio in avi container.
    But other players, such as FFplay and mPlayer, will play aac audio OK in avi files.


    Have you tried to play that avi file with a different player?
    Last edited by bat999; 5th Aug 2012 at 09:11.
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  5. Originally Posted by pxstein View Post
    Yes, AAC ACM codec is installed on (64bit) Win7 system.
    Be aware that the 32 bit and 64 bit A/V systems in Windows are completely separate. 32 bit players require 32 bit codecs, 64 bit players require 64 bit codes.

    Also, most media players will use DirectShow for all their A/V dcoding, not VFW/ACM. So they may not be able to use VFW/ACM decoders.
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  6. Member AlanHK's Avatar
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    Originally Posted by pxstein View Post
    So how else do I lossless convert MP4 video to AVI?
    Avidemux.
    Audio and video at "copy" and container "AVI".

    But AVI is an aging format and players probably don't expect it to use newer codecs like AAC.
    If it still doesn't work, convert the audio to MP3 or AC3.
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