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• ffmpeg output at wrong fps

  20 août 2018, par Christoph

  I’m doing the following to capture a jpg image from a stream every 5 seconds :

  fps="1/5"
  
  rm out.jpg
  
  streamlink -O http://ustream.tv/channel/iss-hdev-payload worst | ffmpeg -i - -r $fps -f image2 -update 1 out.jpg

  However, the image is apparently only updated every 6 seconds, whereas I’d expect the update period to be 5 seconds. This seems to be the case also when I set fps to, for example, 1/10 or 1/2.

  Why ?

• lavc/opusdsp : rewrite R-V V postfilter

  2 novembre 2023, par Rémi Denis-Courmont

  lavc/opusdsp : rewrite R-V V postfilter
  This uses a more traditional approach allowing up processing of up to
  
  period minus two elements per iteration. This also allows the algorithm
  
  to work for all and any vector length.
  As the T-Head C908 device under test can load 16 elements loop, there is
  
  unsurprisingly a little performance drop when the period is minimal and
  
  the parallelism is capped at 13 elements :
  Before :
  
  postfilter_15_c :         21222.2
  
  postfilter_15_rvv_f32 :   22007.7
  
  postfilter_512_c :        20189.7
  
  postfilter_512_rvv_f32 :  22004.2
  
  postfilter_1022_c :       20189.7
  
  postfilter_1022_rvv_f32 : 22004.2
  After :
  
  postfilter_15_c :         20189.5
  
  postfilter_15_rvv_f32 :    7057.2
  
  postfilter_512_c :        20189.5
  
  postfilter_512_rvv_f32 :   5667.2
  
  postfilter_1022_c :       20192.7
  
  postfilter_1022_rvv_f32 :  5667.2
  

  • [DH] libavcodec/riscv/opusdsp_init.c
  • [DH] libavcodec/riscv/opusdsp_rvv.S

• Error in av_write_frame when streaming over network (libavformat of ffmpeg)

  4 décembre 2014, par user4324788

  I have been using the ffmpeg libraries (libavcodec, libavformat, etc.) in my C# application to encode buffer data retrieved from my camera/microphone (using DirectShow.Net) and stream it over the network to a destination IP address using MPEG-TS and UDP.

  I communicate with the C++ libraries of ffmpeg through a C# wrapper (.dll) which I call with DllImport. I send the raw video and audio buffer data from C# to the C++ libraries for the purpose of encoding, muxing, and streaming.

  The encoding and streaming works perfectly, however I sometimes seem to encounter a problem with the “av_write_frame” function which is used to write the encoded packet to the output media. After a seemingly random period of time, the following line produces an error ("oc" being the AVFormatContext and "pkt" being the AVPacket) :

  av_write_frame(oc, &pkt)

  One of two errors occurs :

  • An I/O error is returned (return value -5).
  • A ’System.AccessViolationException’ (Attempted to read or write protected memory. This is often an indication that other memory is corrupt.) is thrown.

  This error sometimes occurs after a few minutes of streaming, other times after a much longer period (up to 20 minutes). Also, this error occurs at both video and audio encoding/writing, so I haven’t been able to pinpoint the exact reason behind this problem. Unfortunately it always results in my application either crashing or the streaming to stop working.

  I have tried catching the AccessViolationException, which sometimes allows the application to continue for a little longer, but eventually it ends up exiting without any warning.
  In case of the I/O error, I can reset my application, but eventually it still crashes.

  Any help with fixing this issue would be greatly appreciated !

  Thank you very much in advance.