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Thread: Audio/video desync during encoding

  1. #1

    Default Audio/video desync during encoding

    Another very frustrating issue that doesn't seem to have an apparent cause.

    I am having audio/video desync issues where the video seems to lag behind the audio by a split second. It seems to occur after I encode the video. The encoded video file plays fine on VLC and a little out of sync on WMP. However, when I upload to Youtube or Vimeo, it gets much worse (particularly on Firefox, though Chrome isn't too much better).

    I have tried many tests, but nothing seems to fix it. I did notice however that Mediainfo is saying my compressed video has a variable bit rate, yet I specified constant bit rate (320kbs). When I look in Premiere at the length, the audio appears slightly longer than the video, Mediainfo says 8:15 video vs 8:16 audio. This occurs when I encode with X264/AAC using Avisynth/Megui or Handbrake and even straight from Premiere using H.264/AAC. If I try encoding with WMV or using AC-3 or MP3 as audio codecs, it stays solid CBR and it seems more in sync.

    While this suggests that soemthing is wrong, I still have no idea what is causing the audio/video desync and it is extremely frustrating.

    Details below:

    Original source: 1280x720, 120fps from a video game, audio is from a range of sources (mostly 44100 khz but some higher/lower sample rates)

    Premiere sequence settings: 1280x720, 59.97 fps, progressive, square pixels, 48000khz, stereo

    Export settings: Uncompressed AVI, 1280x720, progressive, square pixels, 59.97 fps (for downloadable copy) or 29.97 fps (for Youtube/Vimeo), 48000khz, stereo, 16 bit sample type

    Avisynth script:

    AVISource("J:\Final Render\59.94 fps\Vimeo\Part 1\Film Sequence Part 1.avi", audio=false).AssumeFPS(30000,1001)

    Final encode settings:

    Complete name : J:\Final Render\59.94 fps\Vimeo\Part 1\SWR Ep1 P1.mp4
    Format : MPEG-4
    Format profile : Base Media
    Codec ID : isom
    File size : 434 MiB
    Duration : 8mn 16s
    Overall bit rate mode : Variable
    Overall bit rate : 7 344 Kbps
    Encoded date : UTC 2014-04-09 05:54:02
    Tagged date : UTC 2014-04-09 05:54:02

    ID : 1
    Format : AVC
    Format/Info : Advanced Video Codec
    Format profile : High@L4.1
    Format settings, CABAC : Yes
    Format settings, ReFrames : 5 frames
    Codec ID : avc1
    Codec ID/Info : Advanced Video Coding
    Duration : 8mn 15s
    Bit rate : 7 000 Kbps
    Maximum bit rate : 29.7 Mbps
    Width : 1 280 pixels
    Height : 720 pixels
    Display aspect ratio : 16:9
    Frame rate mode : Constant
    Frame rate : 29.970 fps
    Color space : YUV
    Chroma subsampling : 4:2:0
    Bit depth : 8 bits
    Scan type : Progressive
    Bits/(Pixel*Frame) : 0.253
    Stream size : 415 MiB (96%)
    Writing library : x264 core 138 r2358 9e941d1
    Encoding settings : cabac=1 / ref=5 / deblock=1:-1:0 / analyse=0x3:0x113 / me=umh / subme=10 / psy=1 / psy_rd=1.00:0.15 / mixed_ref=1 / me_range=32 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=-3 / threads=12 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=4 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=30 / keyint_min=15 / scenecut=40 / intra_refresh=0 / rc_lookahead=30 / rc=2pass / mbtree=1 / bitrate=7000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / aq=1:1.00
    Encoded date : UTC 2014-04-09 05:48:58
    Tagged date : UTC 2014-04-09 05:54:02

    ID : 2
    Format : AAC
    Format/Info : Advanced Audio Codec
    Format profile : LC
    Codec ID : 40
    Duration : 8mn 16s
    Bit rate mode : Variable
    Bit rate : 320 Kbps
    Maximum bit rate : 328 Kbps
    Channel(s) : 2 channels
    Channel positions : Front: L R
    Sampling rate : 48.0 KHz
    Compression mode : Lossy
    Stream size : 18.9 MiB (4%)
    Encoded date : UTC 2014-04-09 05:50:04
    Tagged date : UTC 2014-04-09 05:54:02

    What I've tried (all without success):

    -- Tried exporting at 30 fps
    -- Tried resampling some clips at 44100khz and exporting at 44100khz
    -- Tried different sample types
    -- Tried encoding with Handbrake instead of Megui

    I'm looking for a solution to this problem, no matter how tedious. The release of this movie has completely stalled and I'm quite concerned because I have no idea what the cause of the problem is to fix it.

  2. #2


    Purhapse if you gave us a few more technical details we may be able to help you.

    Sorry I couldn't help it.

    I don't have an answer for your issue but I looked at the video and I couldn't tell there is a problem.

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