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• Why does ffmpeg hang indefinitely when composing videos ?

  11 octobre 2022, par Brendan Hill

  I am executing ffmpeg commands in a Java microservice (which runs dockerised in kubernetes in a temporary pod created by KEDA from an Amazon SQS queue... but unlikely to be relevant).

  


  About 30% of the time, the ffmpeg process hangs indefinitely :

  


  
/usr/local/bin/ffmpeg 
     -i /tmp/transcode-3b928f5f-3cd9-4cd6-9175-b7c1621aa7ce13592236077853079159/person1.mkv 
     -i /tmp/transcode-3b928f5f-3cd9-4cd6-9175-b7c1621aa7ce13592236077853079159/person2.mkv
     -filter_complex [0:v][1:v]hstack=inputs=2[v];[0:a]aresample=async=1000[0sync];[1:a]aresample=async=1000[1sync];[0sync][1sync]amix[a] 
     -map [v] 
     -map [a] 
     -c:v libx264 
     -crf 18 
     -ac 2 
     -vsync 1 
     -r 25 
     -shortest /tmp/transcode-3b928f5f-3cd9-4cd6-9175-b7c1621aa7ce13592236077853079159/composed.mp4



  


  This causes the Java code to wait indefinitely :

  


  
        Process proc = Runtime.getRuntime().exec(cmd);

        StreamConsumer outConsumer = new StreamConsumer(proc.getInputStream(), stdout);
        StreamConsumer errConsumer = new StreamConsumer(proc.getErrorStream(), stderr);

        // execute data read/write in separate threads
        outExecutor.submit(outConsumer);
        errorExecutor.submit(errConsumer);

        proc.waitFor() // Hangs indefinitely, with ~30% probability



  


  It is not specifically about the video files because they generally work on retry (with similar 30% failure probability so sometimes several retries are necessary). Of course, since it hangs indefinitely instead of exiting with failure, it has to wait hours before we risk another retry.

  


  


  1. Why is ffmpeg hanging indefinitely and how to fix ?

     


  


  2. Can I get ffmpeg to fail early instead of hanging indefinitely (so I can trigger retry immediately) ?

     


  


  3. I see many questions and posts about ffmpeg hanging indefinitely. Is ffmpeg inherently unstable ?

     


  


  


• Is there any library in python or can we use FFMPEG to detect the appearance of the lines pattern in video that is shown in the image attached below ? [closed]

  21 septembre 2022, par Shreyas R

  Video defect appearing frame

  


  Hi All,

  


  I am trying to find a way to detect the appearance of this lines pattern embedded in the link below.
If I get any match of this pattern in a video, I need to record that particular timestamp of the video where I got the pattern match.

  


  My idea is to take the image and compare it against the video to find for approximate match percentage. If I get it, then I record that particular timestamp within a .txt file.

  


  Is there any better way to achieve this ?
I think we can use Python or FFMPEG video filters to get a solution for this.

  


  It would really help if anyone can support with a solution. Thanks

  


  Update :
I got a reference where they have proposed a solution similar to my concern.

  


  https://aws.amazon.com/blogs/media/metfc-automatically-compare-two-videos-to-find-common-content/

  


  So we can try to achieve some output from this solution.

  


• checkasm : updated tests for sw_scale

  13 août 2022, par Swinney, Jonathan

  checkasm : updated tests for sw_scale
  Change the reference to exactly match the C reference in swscale,
  
  instead of exactly matching the x86 SIMD implementations (which
  
  differs slightly). Test with and without SWS_ACCURATE_RND - if this
  
  flag isn't set, the output must match the C reference exactly,
  
  otherwise it is allowed to be off by 2.
  Mark a couple x86 functions as unavailable when SWS_ACCURATE_RND
  
  is set - apparently this discrepancy hasn't been noticed in other
  
  exact tests before.
  Add a test for yuv2plane1.
  Signed-off-by : Jonathan Swinney <jswinney@amazon.com>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libswscale/x86/swscale.c
  • [DH] tests/checkasm/sw_scale.c