M4V video stutter on iPad due to audio order?

Discussion in 'Apple TV and Home Theater' started by stiwi, Jan 17, 2013.

  1. macrumors regular

    Joined:
    Nov 13, 2010
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    Singapore
    #1
    I have couple of movies converted to M4V with different kind of quality and bit-rate. I was surprised to notice that some videos stutter (stop every 2-3 seconds) while being streamed to iPad 4th through Home Sharing feature.

    Today by coincidence I made two M4V videos of the same video, both converted by iVI (same video bitrate, audio etc). They are exactly the same except that one has a AAC track in first order while AC3 in 2nd, while the other AC3 first. The one that has AAC track first plays excellent, while the other stutter.

    I was able to confirm the above observation with other movies and even the ones converted by Handbrake are stuttering (having AC3 track set as first).

    All movies play fine in iTunes / VLC / Mplayerx.

    Now is it really possible that audio order could be a reason for this kind of behaviour? Has anyone experienced something similar? Is there any way to quickly change the audio track order in M4V files?
     
  2. thread starter macrumors regular

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    Singapore
    #2
    I found the issue. When I convert movie with included (soft) subtitles, video stutter on iPad. However if I convert video only and then add subtitles separately via Subler or MP4 Tools, video doesn't stutter at all!

    There is not even a need to do conversion again, as one can simply remove subtitles via Subler / MP4 Tools and re-add SRT.
     
  3. macrumors 603

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    Jun 7, 2011
    #3
    Can you post a (short - a 30-60 Mbyte one would do) "problematic" video slice? I'd like to know whether there's an even easier way of making them iOS / iPad-compliant.
     
  4. thread starter macrumors regular

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    #4
    Hard to post a video slice since there is no particular slice of video that is problematic. My observation is that regardless of which app I use (handbrake, iFlicks, iVI) if I include subtitles the M4V video stutter on iPad 4th / iPhone 5.

    So best advice is to get rid of subtitles if there are any (if you have mkv this can be done through Mkvtoolnix), convert video using one of the apps mentioned above to M4V and then add subtitles using Subler or MP4Tools. Work like a charm and no stuttering issues whatsoever when streaming to iDevices through Home Sharing feature.
     
  5. Menneisyys2, Jan 19, 2013
    Last edited: Jan 19, 2013

    macrumors 603

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    Jun 7, 2011
    #5
    I've tested this with the standard Monsters test MKV video (10 Mbps H.264 + DTS audio + textual sub) using a late 2009 MBP with 10.8 and cabled Ethernet connection to the router + iPhone 5 (6.0.2), standing about 2 metres from the router (WRT320N), streaming over Home Sharing from the latest iTunes. (Being in the next room & the MBP running over Wi-Fi everything was hopelessly stuttering, no matter the format, the order of audio tracks / presence of SRT subtitle, whether it's optimized for streaming or not etc.)

    Every possible HB reencoding combination was absolutely stuttering-free:

    - AC3 and AAC in this (and the opposite) order

    - included SRT or leaving it out (default: left out)

    - enabled big filesize mode or not (default: not; “Large file size” checkbox)

    - enabled streaming optimized mode (“Web optimized” checkbox) or not (default: disabled; enabling it doesn't seem to result in any kind of a measurable conversion speed hit)

    Could you please give the same MKV file a try? I'd very like to know whether you encounter stuttering with this file. It's at http://www.auby.no/files/video_tests/h264_1080p_hp_4.1_10mbps_dts_unstyled_subs_monsters.mkv

    EDIT: my HB config: (I've also tested all this with the two checkboxes disabled in the Video tab; with an opposite audio config in the Audio tab and with disabled SRT in the Subtitles tab):

    [​IMG]

    [​IMG]

    [​IMG]

    (Original, full-size images: https://dl.dropbox.com/u/81986513/012013/hb-1.png , https://dl.dropbox.com/u/81986513/012013/hb-2.png , https://dl.dropbox.com/u/81986513/012013/hb-3.png )
     
  6. thread starter macrumors regular

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    Singapore
    #6
    I just checked and converted it with HB:
    - I didn't include subtitles
    - Audio AAC + AC3
    - Used high profile settings
    - Retained High Profile 4.1 video setting (that's possible in HB recent nightlies)
    - CQ RF = 20

    It doesn't stutter for me streaming to either iPad 4 or iPhone 5 via WiFi.

    Try force closing the video app and reopen it. It always resolve any stuttering issues for me.
     

    Attached Files:

  7. macrumors 603

    Joined:
    Jun 7, 2011
    #7
    What happens if you do include the subtitle while converting with HB? Does playback stutter?
     
  8. thread starter macrumors regular

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    #8
    I have been pulling my hair with this issue and spent few nice hours to find out the reason. When I convert video via MP4Tools (MKV -> MP4, passing through AC3 and adding AAC) if I include subtitles, the video stutter (no matter if subs enabled or disabled). If I don't include subtitles, the video doesn't stutter, play smoothly all the time.

    MP4Tools do optimization by default (there is no option to use it or not). It looks like if subtitles are included there is perhaps an issue with the optimized file. If I open the stuttering file in Subler and either:
    - remove subtitles
    - re-add them
    - save

    or
    - optimize it (again)

    There is no stutter whatsoever.

    Can you launch Subler / choose File and optimize the affected video and see if it helps?
     
  9. macrumors 68020

    Joined:
    Mar 15, 2012
    #9
    First off, make sure you have downloaded the latest mp4tools (v3.2.2 released 1/2/13). If it does come down to mp4tools optimization issue, you should communicate that to the developer. The app has been totally re-written and bugs are being addressed, but only if he is made aware of them.
     
  10. thread starter macrumors regular

    Joined:
    Nov 13, 2010
    Location:
    Singapore
    #10
    The problem with reporting an issue like that is that it everything works properly through iTunes or when loaded to iPad but stutter (video stops) through home sharing to iPad and the issue is not being a speed of WiFi.

    Since I have to edit the MP4Tools files by Subler anyway in order to add metadata and check default tracks, I still need to re-run optimization. According to my observation if you edit an optimized video with Subler, add or remove something (e.g. metadata), optimization is lost and you need to re-run it.
     
  11. macrumors 68020

    Joined:
    Mar 15, 2012
    #11
    Well, if as you say, mp4tools has an optimization bug that is corrected by re-optimization with Subler, the developer should be made aware so it can be fixed. He has been on this forum (while app was in beta) asking for feedback and is really good about supporting his product. Let's help him make it better, that's all.
     

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