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• Problem accessing audio track from mp4 file

  20 décembre 2019, par Thomas Spycher

  For a TV Project we want to transcode the source videofiles to other formats. The Sourcefiles are fragmented mp4 files. Destination format could be mp4 or any other format.
  The sourcefile contains multiple audio tracks for different codes (aac, eac3, aac-otherlanguage).

  Something with this files is odd. I can play them without problems on quicktime or VLC. Import them into Premiere for example ends up with the video but without sound.

  Converting them on AWS MediaConvert results in weird issues as well like (depending on the settings) :

  • No audio frames decoded on [selector-(Audio Selector 1)-track-1-drc] (selecting aac audiotrack (Track:1))
  • Decoder : [Dolby decoder error : failed to configure to stream in first 100 frames] (selecting eac3 audiotrack (Track:2) )

  I’m able to convert the files with Handbreak and the result is a MP4 file with one audiotrack which is working everywhere. I’m trying to figure out whats odd with this file to make them working with AWS MediaConvert.

  Here is the ffprobe output of one of the files :

  ffprobe version 4.1 Copyright (c) 2007-2018 the FFmpeg developers
  
    built with Apple LLVM version 10.0.0 (clang-1000.10.44.4)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/4.1 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gpl --enable-libmp3lame --enable-libopus --enable-libsnappy --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfreetype --enable-opencl --enable-videotoolbox
  
    libavutil      56. 22.100 / 56. 22.100
  
    libavcodec     58. 35.100 / 58. 35.100
  
    libavformat    58. 20.100 / 58. 20.100
  
    libavdevice    58.  5.100 / 58.  5.100
  
    libavfilter     7. 40.101 /  7. 40.101
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  3.100 /  5.  3.100
  
    libswresample   3.  3.100 /  3.  3.100
  
    libpostproc    55.  3.100 / 55.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '123893.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isomiso2iso5dashavc1dby1mp41
  
    Duration: 00:01:24.02, start: 0.000000, bitrate: 5600 kb/s
  
      Stream #0:0(deu): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 4869 kb/s, 50 fps, 50 tbr, 1k tbn, 100 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(deu): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
      Stream #0:2(deu): Audio: eac3 (ec-3 / 0x332D6365), 48000 Hz, 5.1(side), fltp, 256 kb/s
  
      Metadata:
  
        handler_name    : SoundHandler
  
      Side data:
  
        audio service type: main

  An example file can get downloaded here : https://wilmaa-rnd.s3-eu-west-1.amazonaws.com/124041.mp4

• FFMPEG generated h264/aac mp4 video first frame doesn't report a zero mediaTime using requestVideoFrameCallback html api [closed]

  12 mai 2023, par Daniel Robinson

  I have noticed that mp4 files generated using ffmpeg aren’t reporting a mediaTime of 0 via requestVideoFrameCallback for the first frame however files encoded as webm or via another encoder such as mainconcept its 0.

  


  You can see a demo of the issue here https://randomstuffdr.s3.eu-west-1.amazonaws.com/TEST-v3.HTML
As you increment the frames with video 1 you don’t see video progress until the third button press.

  


  With video 2-4, the mediaTime is 0 and a single press of the button increments the video by one frame.

  


  Browser : Chrome 113.0.5672.92 (Windows 10)

  


  FFMPEG Version : 6.0-essentials_build-www.gyan.dev or N-109421-g9adf02247c-20221216

  


  There was an interesting note on this page related to mediaTime implementation in chrome https://web.dev/requestvideoframecallback-rvfc/

  


  


  Of special interest in this list is mediaTime. In Chromium's
implementation, we use the audio clock as the time source that backs
video.currentTime, whereas the mediaTime is directly populated by the
presentationTimestamp of the frame. The mediaTime is what you should
use if you want to exactly identify frames in a reproducible way,
including to identify exactly which frames you missed.

  


  


  The led me to compare the PTS files of the video and audio stream between the ffmpeg and MC files using ffprobe however these are all zero for the first frames. The one interesting note, is that ffmpeg file seems to interleave video and audio packets in ffprobe while the mainconcept file has 8 video frames before audio, I have no idea if this is significant.

  


  What I would like to know is if there is any way I can make ffmpeg generate a file in a similar manner to mainconcept ? So far I have tried ; disabling b-frames, use baseline profile and avoid_negative_ts

  


  Video 1 – (Video : H264 /Audio : AAC / Wrapper : MP4 / Transcoder : FFMPEG)
.\ffmpeg.exe -i '720p50 Flash and Beep.mxf' -map 0:0 -map 0:1 -map_metadata -1 -c:v libx264 -crf 28 -b:v 118k -maxrate 118k -bufsize 236k -vf scale="480 :-1" -preset veryfast -c:a aac "..\low-res\720p50FlashandBeep_V_A.mp4"

  


  Video 2 – (Video : H264 /Audio : No Audio / Wrapper : MP4 / Transcoder : FFMPEG)
.\ffmpeg.exe -i '720p50 Flash and Beep.mxf' -map 0:0 -map 0:1 -map_metadata -1 -c:v libx264 -crf 28 -b:v 118k -maxrate 118k -bufsize 236k -vf scale="480 :-1" -preset veryfast -an "..\low-res\720p50FlashandBeep_V.mp4"

  


  Video 3 – (Video : vp8 /Audio : ogg / Wrapper : webm / Transcoder : FFMPEG)
.\ffmpeg.exe -i '720p50 Flash and Beep.mxf' -map 0:0 -map 0:1 -map_metadata -1 -c:v vp8 -crf 28 -b:v 118k -maxrate 118k -bufsize 236k -vf scale="480 :-1" -preset veryfast "..\low-res\720p50FlashandBeep_V_A.webm"

  


  Video 4 – (Video : H264 /Audio : AAC / Wrapper : MP4 / Transcoder : MainConcept)

  


• FFmpeg not Working when double click [on hold]

  29 janvier 2018, par Anime GAG

  I dont know describe this problem
  watch video to know
  https://drive.google.com/open?id=1gTHlwNnip2A7dG7ayZ7KTT4CbKX8Mmu0