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Sound Out of Sync, MP4 on iPad

Discussion in 'Video playback problems' started by Hot4ts, Nov 6, 2014.

  1. Hot4ts

    Hot4ts Member

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    I'm trying to watch a video on my iPad 4 (system 8.1) and the sound is just out of sync. I've done some Googling and I'm having a hard time - it looks like this is common for certain types of files, but what I can't quite discern is some of the specs of the different files.

    According to MediaInfo:

    The file is MPEG-4, with an "Overall bit rate" of 1.641 Kbps.

    The "first" video stream is 1.575 Kbps, 1920*800 at 23.976 fps, AVC (High@L4.0) (CABAC / 5 Ref Frames).

    The "first" audio stream is 64.0 Kbps, 48.0KHz/24.0KHz, 2 cahhnels, AAC (HE-AAC/LC).
    So the question is, is there something wrong with the file, or is the iPad just not capable of playing this type of file correctly?

    thanks
     
  2. attar

    attar Senior member

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    Is it ok played on the pc.
     
  3. Hot4ts

    Hot4ts Member

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    Sorry, yes. Seems to be OK in Windows Media Player.
     
  4. attar

    attar Senior member

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  5. Hot4ts

    Hot4ts Member

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    OK, thanks. I'll give that a try. How badly will that compromise the video quality? The picture looks really sharp!
     
  6. attar

    attar Senior member

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  7. Hot4ts

    Hot4ts Member

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    Trying it now, thank you.

    Seems ike a very slow process!
     
  8. scorpNZ

    scorpNZ Active member

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    Speed is relative to the specs of the computer doing the encoding,not to mention other processes that may be working if you use the comp while it encodes,the lower the specs of the machine the longer it takes.
     
  9. Hot4ts

    Hot4ts Member

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    So this is interesting. The "new" (post-Handbrake) file, besides being a bigger file, has playback problems on the PC (haven't moved it to iPad yet).

    The original file played correctly in WMP. (It "stuttered" a bit in QuickTime.) The new file, in WMP, is fine, but on QT - the sound is off now, as well.
     
  10. attar

    attar Senior member

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    Can you have MediaInfo open the original video, then click 'File' > 'Export' and save the info as a text file.
    Same for the new file and post both results.
     
  11. Hot4ts

    Hot4ts Member

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    See attached.
     

    Attached Files:

  12. attar

    attar Senior member

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    I can't see anything significant.
    The audio is larger compared to the original, but that's not relevant.
    Try the VideoHelp site and ask for iPad assistance, you will get more responses there.

    If it was simply out of sync on the PC, you could use VLC etc to find out the value then use AviDemux to to shift the audio by the same amount;it can do that without re-encoding the video - but I don't have any experience with these devices so I can't offer anything else.

    http://forum.videohelp.com/
     
  13. wibrese

    wibrese Newbie

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    We all know that MP4 is a container which is used to store video and audio, but can also be used to store other data such as subtitles and still images. So this format contains various kinds of audio and video codecs. However, iPad has strict limitation on the input MP4 file: only compatible with H.264, MPEG-4 or Motion JPEG video with the following specification:

    H.264 video up to 720p @ 30 frames per second
    - Main Profile level 3.1 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats


    MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels @ 30 frames per second
    - Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats


    Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels @ 30 frames per second
    - Audio in ulaw, PCM stereo audio in .avi file format


    Maybe you should convert your MP4 to iPad MP4. Faasoft MP4 to iPad Converter is a nice choice.
     
  14. Nepheler

    Nepheler Member

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    I'm using Pavtube iMedia Converter for Mac, iPad Air preset. I was suggested to set bitrate (or quality settings) to around 1500~2500 kbps. That will output a 2~4GB movie which works fine for me. So far so good. Btw, is your original movie in 23.976 fps too?
     

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