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• lavc/dxv : align to 4x4 blocks instead of 16x16

  9 février 2024, par Connor Worley

  lavc/dxv : align to 4x4 blocks instead of 16x16
  The previous assumption that DXV needs to be aligned to 16x16 was
  
  erroneous. 4x4 works just as well, and FATE decoder tests pass for all
  
  texture formats.
  On the encoder side, we should reject input that isn't 4x4 aligned,
  
  like the HAP encoder does, and stop aligning to 16x16. This both solves
  
  the uninitialized reads causing current FATE tests to fail and produces
  
  smaller encoded outputs.
  With regard to correctness, I've checked the decoding path by encoding a
  
  real-world sample with git master, and decoding it with
  
    ffmpeg -i dxt1-master.mov -c:v rawvideo -f framecrc -
  
  The results are exactly the same between master and this patch.
  On the encoding side, I've encoded a real-world sample with both master
  
  and this patch, and decoded both versions with
  
    ffmpeg -i dxt1-master,patch.mov -c:v rawvideo -f framecrc -
  
  Under this patch, results for both inputs are exactly the same.
  In other words, the extra padding gained by 16x16 alignment over 4x4
  
  alignment has no impact on decoded video.
  Signed-off-by : Connor Worley <connorbworley@gmail.com>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavcodec/dxv.c
  • [DH] libavcodec/dxvenc.c
  • [DH] tests/ref/fate/dxv3enc-dxt1

• H.264 adds broken still frames to the end

  14 mai 2015, par Panupat

  I’ve been using ffmpeg to encode raw AVI into H.264 MP4 for about 2 years without problem. However, in my recent project we’re using 60 fps for the first time and face some weird results.

  Here’s an example file. It has 82 frames. FFMPEG would produce the correct result from frame 1 to 82. Here’s a capture at frame 82.

  http://imgur.com/VCIcoVH

  Then, we get this still frame added to the end, from frame 83 to 157.

  

  Am I doing something wrong in my command ? I tried with almost no options.

  ffmpeg -y -i "C:\tmp\uncompressed.avi" -r 60 -vcodec libx264 "C:\tmp\compressed.mp4"

  Tried a couple different options, the problem still occurs.

  ffmpeg -y -i "C:\tmp\uncompressed.avi" -r 60 -vcodec libx264 -keyint_min 12 -vb 4000k -vprofile high -pix_fmt yuv420p -f mp4 "C:\tmp\compressed.mp4"

  Tried with FFmpeg Win64 Static and Shared build by Kyle Schwarz.

  Appreciate any help, thank you !

• Reusing FFMPEG AVFilterGraph

  11 avril 2022, par Sapozhnikov Andrey

  In my code I apply same filtering on multiple input files. In first version of code I created AVFilterGraph for every input, but I think these actions might be excessive.
  
However, when I try to reuse the same graph, I face with the error during sending frame to abuffer filter. At the previous iteration over input files, I passed EOF to it for flushing, and the av_buffersrc_add_frame function has a check for this :

  


  BufferSourceContext *s = ctx->priv;
...
if (s->eof)
    return AVERROR(EINVAL);


  


  which crashes the execution on the second iteration.
Unfortunately, I couldn't find any functions that can restore buffer filter or something like that.

  


  I would like to know if avfilter implies the possibility to reuse once created filter graph, or there are some fundamental misconceptions in my understanding of ffmpeg logic by passing input after EOF.

  


  Thank you !