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• Encoding H.264 CBR videos with FFmpeg

  27 août 2015, par Cornstalks

  I’m trying to encode a video with ffmpeg into H.264 (via the libx264 library) with a constant bit rate. I know, I know, VBR is often preferred, but for this specific job I’m required to use CBR (just as long as it’s so many kilobytes per second ; it doesn’t have to be an exact kilobytes per frame, afaik). My sample video I’m using to test is from here : http://a1408.g.akamai.net/5/1408/1388/2005110403/1a1a1ad948be278cff2d96046ad90768d848b41947aa1986/sample_iTunes.mov.zip (it comes from http://support.apple.com/kb/HT1425)

  I can get a constant bit rate when encoding the video with MPEG-4 Video (using the commands ffmpeg -i sample_iTunes.mov -b 819968 -minrate 819968 -maxrate 819968 out.mov), and the bit rate is as expected. Reading the video’s specs via the QuickTime Inspector, it’s got a data rate of 844.94 kbit/s. Cool.

  However, when I change the codec to libx264, it seems to completely ignore my bitrate requests ! The command I’m trying is "ffmpeg -i sample_iTunes.mov -vcodec libx264 -vpre medium -b 819968 -vb 819968 -minrate 819968 -maxrate 819968 -bufsize 400000 test.mov". But when I check the video’s specs via the QuickTime Inspector, it’s got a data rate of 254.74 kbit/s. WTF ? That’s not even close !

  I’ve tried changing so many parameters and adding tons of different things, and I’ve spent 2 days googling this, but I can’t seem to get it to work. If I encode the video with the MainConcept H.264 encoder, I can get a constant bitrate, but I need this to work with ffmpeg.

  If someone can help me figure out how to do CBR H.264 encoding with FFmpeg, I will love you forever !

• FFmpeg-kit : Unknown encoder 'libx264' / 'mediacodec' and Gradle dependency issues in Android Studio

  15 mai, par Izzet dönertaş

  I'm working on a video editor app in Android Studio using ffmpeg-kit. My goal is to export video segments with fade transitions and audio using FFmpeg.

  


  This implementation line works fine :

  


  implementation("com.arthenica:ffmpeg-kit-full:6.0-2")


  


  What doesn't work (Encoding) :
When I try to export a video segment using :

  


  -c:v libx264 -c:a aac


  


  I get this error in the logs :

  


  [vost#0:0 @ ...] Unknown encoder 'libx264'


  


  After checking the build configuration, it turns out libx264 is not enabled in the current FFmpeg-kit build :

  


  --disable-libx264 (or rather: --enable-libx264 is missing)


  


  Tried replacing libx264 with mediacodec :
Then I tried using :

  


  -c:v mediacodec -c:a aac


  


  But again I got :

  


  Unknown encoder 'mediacodec'


  


  Apparently, mediacodec is supported for decoding, but not as an encoder in FFmpeg-kit.

  


  Tried to compile my own FFmpeg binary :
I attempted building FFmpeg manually using the following flags :

  


  --enable-libx264 --enable-gpl --enable-shared ...


  


  My plan was to access it via JNI or ProcessBuilder.

  


  But the process is extremely frustrating :

  


  

  • Missing file errors

  


  • Configuration conflicts

  


  • Dependency hell (especially on macOS/Linux NDK toolchains)

  


  


  Tried other ffmpeg-kit variants :
I also tried switching to :

  


  implementation 'com.arthenica:ffmpeg-kit-full-gpl:6.0'


  


  and other variants like ffmpeg-kit-min-gpl, etc.
But in all of them I got the same Gradle error :

  


  Caused by: org.gradle.api.internal.artifacts.ivyservice.TypedResolveException:  Could not resolve all files for configuration ':app:debugRuntimeClasspath'.

  


  My build.gradle setup (yes, mavenCentral + google are already included) :

  


  pluginManagement {
    repositories {
        google()
        mavenCentral()
    }
}

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
    }
}



  


  I also tried enabling offline mode, clearing cache, adding jetpack.io, nothing helped.

  


  I asked ChatGPT-4o, Gemini 2.5 Pro. None could provide a working solution for this combination of :

  


  

  • Working implementation

  


  • Proper video encoding (with libx264 or mediacodec)

  


  • Without breaking Gradle dependency resolution

  


  


  I just want one of the following :

  


  


  1. A working FFmpeg-kit implementation (that supports libx264) and doesn’t crash Gradle

     


  


  2. A reliable guide or build.gradle snippet that lets me use GPL version (with libx264) without resolve errors

     


  


  3. (Ideally) A prebuilt safe LGPL-compatible alternative that allows encoding and is Google Play compliant

     


  


  


  Any help or suggestions would be highly appreciated.
Thanks in advance

  


• lavc/vvc : Ensure subpictures don't overlap

  22 février, par Frank Plowman

  lavc/vvc : Ensure subpictures don't overlap
  This is essentially a re-implementation of
  
  https://patchwork.ffmpeg.org/project/ffmpeg/patch/20241005223955.54158-1-post@frankplowman.com/
  That patch was not applied last time.  Instead we opted to identify
  
  issues which could be caused by invalid subpicture layouts and remedy
  
  those issues where they manifest, either through error detection or code
  
  hardening.  This was primarily implemented in the set
  
  https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=13381.
  This has worked to some degree, however issues with subpicture layouts
  
  continue to crop up from the fuzzer and I've fixed a number of bugs
  
  related to subpicture layouts since then.  I think it's best to return
  
  to the initial plan and simply check if the subpicture layout is valid
  
  initially.
  This implementation is also lighter than the first time — by doing a
  
  bit more logic in pps_subpic_less_than_one_tile_slice, we are able to
  
  store a tile_in_subpic map rather than a ctu_in_subpic map.  This
  
  reduces the size of the map to the point it becomes possible to allocate
  
  it on the stack.  Similar to 8bd66a8c9587af61c7b46558be3c4ee317c1af5a,
  
  the layout is also validated in the slice map construction code, rather
  
  than in the CBS, which avoids duplicating some logic.
  Signed-off-by : Frank Plowman <post@frankplowman.com>
  

  • [DH] libavcodec/vvc/ps.c