Sur d’autres sites (7972)

• How does FFmpeg determine the dispositions of an MP4 track ?

  5 mars, par obskyr

  The Issue

  


  FFmpeg has a concept of “dispositions” – a property that describes the purpose of a stream in a media file. For example, here are the streams in a file I have lying around, with the dispositions emphasized :

  


    Stream #0:0[0x1](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo,&#xA;fltp, 251 kb/s <strong><em>(default)</em></strong>&#xA;      Metadata:&#xA;        creation_time   : 2021-11-10T20:14:06.000000Z&#xA;        handler_name    : Core Media Audio&#xA;        vendor_id       : [0][0][0][0]&#xA;&#xA;  Stream #0:1[0x2](und): Video: mjpeg (Baseline) (jpeg / 0x6765706A),&#xA;yuvj420p(pc, bt470bg/unknown/unknown), 1024x1024, 0 kb/s, 0.0006 fps, 3.08 tbr,&#xA;600 tbn <strong><em>(default) (attached pic) (timed thumbnails)</em></strong>&#xA;      Metadata:&#xA;        creation_time   : 2021-11-10T20:14:06.000000Z&#xA;        handler_name    : Core Media Video&#xA;        vendor_id       : [0][0][0][0]&#xA;&#xA;  Stream #0:2[0x3](und): Data: bin_data (text / 0x74786574)&#xA;      Metadata:&#xA;        creation_time   : 2021-11-10T20:14:06.000000Z&#xA;        handler_name    : Core Media Text&#xA;&#xA;  Stream #0:3[0x0]: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/&#xA;unknown), 1024x1024 [SAR 144:144 DAR 1:1], 90k tbr, 90k tbn <strong><em>(attached pic)</em></strong>

  


  However, if I make any modification to this file’s chapter markers using the C++ library MP4v2 (even just re-saving the existing ones : auto f = MP4Modify("test.m4a"); MP4Chapter_t* chapterList; uint32_t chapterCount; MP4GetChapters(f, &chapterList, &chapterCount); MP4SetChapters(f, chapterList, chapterCount); MP4Close(f);), some of these dispositions are removed :

  


    Stream #0:0[0x1](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo,&#xA;fltp, 251 kb/s <strong><em>(default)</em></strong>&#xA;      Metadata:&#xA;        creation_time   : 2021-11-10T20:14:06.000000Z&#xA;        handler_name    : Core Media Audio&#xA;        vendor_id       : [0][0][0][0]&#xA;&#xA;  Stream #0:1[0x2](und): Video: mjpeg (Baseline) (jpeg / 0x6765706A),&#xA;yuvj420p(pc, bt470bg/unknown/unknown), 1024x1024, 0 kb/s, 0.0006 fps, 3.08 tbr,&#xA;600 tbn <strong><em>(default)</em></strong> <kbd>← “attached pic” and “timed thumbnails” removed!</kbd>&#xA;      Metadata:&#xA;        creation_time   : 2021-11-10T20:14:06.000000Z&#xA;        handler_name    : Core Media Video&#xA;        vendor_id       : [0][0][0][0]&#xA;&#xA;  Stream #0:2[0x0]: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/&#xA;unknown), 1024x1024 [SAR 144:144 DAR 1:1], 90k tbr, 90k tbn <strong><em>(attached pic)</em></strong>&#xA;&#xA;  Stream #0:3[0x4](und): Data: bin_data (text / 0x74786574)&#xA;  <kbd>This stream was moved to the end, but that’s intended behavior. It contains chapter titles, and we just edited the chapters.</kbd>&#xA;      Metadata:&#xA;        creation_time   : 2025-03-05T09:56:31.000000Z

  


  It also renders the file unplayable in MPC-HC (but not in VLC !), which is apparently a bug in MP4v2. I’m currently investigating that bug to report and potentially fix it, but that’s a separate issue – in my journey there, I’m wracking my brain trying to understand what it is that MP4v2 changes to make FFmpeg stop reporting the “attached pic” and “timed thumbnails” dispositions. I’ve explored the before-and-afters in MP4 Box, and I can’t for the life of me find which atom it is that differs in a relevant way.

  


  (I’d love to share the files, but unfortunately the contents are under copyright – if anyone knows of a way to remove the audio from an MP4 file without changing anything else, let me know and I’ll upload dummied-out versions. Without them, I can’t really ask about the issue directly. I can at least show you the files’ respective atom trees, but I’m not sure how relevant that is.)

  


  The Question

  


  I thought I’d read FFmpeg’s source code to find out how it determines dispositions for MP4 streams, but of course, FFmpeg is very complex. Could someone who’s more familiar with C and/or FFmpeg’s codebase help me sleuth out how FFmpeg determines dispositions for MP4 files (in particular, “attached pic” and “timed thumbnails”) ?

  


  Some Thoughts…

  


  

  • I figure searching for “attached_pic” might be a good start ?

  


  • Could the MP4 muxer movenc.c be helpful ?

  


  • I’d imagine what we’d really like to look at is the MP4 demuxing process, as it’s during demuxing that FFmpeg determines dispositions from the data in the file. After poring over the code for hours, however, I’ve been utterly unable to find where that happens.

  


  


• Could not find com.arthenica:ffmpeg-kit-full:6.0-2

  30 avril, par gabocalero

  I started receiving this message when I build my project

  


  > Could not find com.arthenica:ffmpeg-kit-full:6.0-2.
  Searched in the following locations:
    - https://dl.google.com/dl/android/maven2/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://repo.maven.apache.org/maven2/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://jcenter.bintray.com/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://jitpack.io/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://pkgs.dev.azure.com/MicrosoftDeviceSDK/DuoSDK-Public/_packaging/Duo-SDK-Feed/maven/v1/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://oss.sonatype.org/content/repositories/snapshots/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
  Required by:
      project :presentation > project :domain


  


  These are the project's repositories

  


  allprojects {     
   repositories {
      google()
      mavenCentral()
      jcenter()
      maven { url 'https://jitpack.io' }
      maven { url "https://oss.sonatype.org/content/repositories/snapshots" }     
   } 
}


  


  And this is the dependency I'm adding

  


      implementation(libs.arthenica.ffmpeg.full)


  


  This is my libs.version.toml

  


  ffmpeg = "6.0-2"
arthenica-ffmpeg-full = {  group = "com.arthenica", name = "ffmpeg-kit-full", version.ref = "ffmpeg" }


  


  AFAICS in the project's github page, it will not be maintained anymore


  


  In the short term, do you know any other repository that still servers this dependency ?

  


  On the other hand, do you know any other project to replace Arthenica ffmpeg-kit-full dependency ?

  


  Thank you very much

  


• RTMP Disconnects quickly when the stream is turned on and No index.m3u8 files are being generated in the assigned directory [closed]

  23 avril, par Kartik Salve

  23/4/2025 09:52:58 9408 [INFO] [rtmp connect] id=7K1RWSO1 ip=::1 app=live args={"app":"live","flashVer":"LNX 9,0,124,2","tcUrl":"rtmp://localhost:1935/live","fpad":false,"capabilities":15,"audioCodecs":4071,"videoCodecs":252,"videoFunction":1}
23/4/2025 09:52:58 9408 [INFO] [rtmp play] Join stream. id=7K1RWSO1 streamPath=/live/test  streamId=1 
23/4/2025 09:52:59 9408 [INFO] [rtmp play] Close stream. id=7K1RWSO1 streamPath=/live/test streamId=1
23/4/2025 09:52:59 9408 [INFO] [rtmp disconnect] id=7K1RWSO1


  


  These are the logs, ffmpeg pushes the stream in a different folder when tried manually.

  


  

  • I tried changing the location of my file outside of oneDrive to avoid any permission conflicts.

  


  • Manually checked if FFmpeg is correct with this command : C:\ffmpeg\bin\ffmpeg.exe -i rtmp://localhost/live/test -c:v copy -c:a aac -f hls -hls_time 2 -hls_list_size 5 -hls_flags delete_segments output/index.m3u8

  


  • Downgraded NMS to a stable version.