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• How can I stream then play YUV format with/without VLC/FFMPEG ?

  13 janvier 2023, par orfruit

  I'm able to play a local YUV file through VLC (as expected)

  


  .\vlc.exe --demux rawvideo --rawvid-fps 25 --rawvid-width 480 --rawvid-height 360 --rawvid-chroma I420 out.yuv


  


  Also FFPLAY is playing well

  


  .\ffplay.exe -f rawvideo -pixel_format yuv420p -video_size 480x360 out.yuv


  


  Conversion to YUV was done with FFMPEG

  


  .\ffmpeg.exe -i "video.mp4" -c:v rawvideo -pixel_format yuv420p out.yuv


  


  However, I'm not able o stream it and play'it over local network.
I know, it sounds crazy :) but I plan to use VLC as a monitor/debugger for some YUV data.

  


  The original MP4 file is streamed/played fine with VLC (test on the same computer)

  


  .\vlc.exe "video.mp4" --sout="#std{access=http, mux=ts, dst=:55555/}"
.\vlc.exe http://192.168.0.174:55555/


  


  So the big question !
How can I stream the YUV format and VLC recognise an play it as well ?

  


  All that I tried with VLC is not playable.

  


  Thanks for any hints !

  


• avformat_write_header() changes my stream's time_base

  12 avril 2023, par greken

  I have a high framerate camera which can capture >2000 fps. My plan was to assign actual capture timestamps with µs resolution to the frames and encode with H.264 in a matroska file.

  


  So I set the time_base of both the AVStream and the AVCodecContext to {1, 1'000'000}. But after calling avformat_write_header(avFormatContext, nullptr) I notice that the stream's time_base is {1, 1'000}. Now, since my framerate is double this resolution, I get identical consecutive timestamps and half my frames get lost when I extract them from the video file.

  


  Does anyone have an idea why this is happening and what I can do about it ? Preferably in a way that preserves the correct timestamps.

  


• avfilter/vf_libplacebo : add flexible crop exprs

  1er mai 2023, par Niklas Haas

  avfilter/vf_libplacebo : add flexible crop exprs
  Motivated by a desire to use vf_libplacebo as a GPU-accelerated
  
  cropping/padding/zooming filter. This commit adds support for setting
  
  the `input/target.crop` fields as dynamic expressions.
  Re-use the same generic variables available to other scale and crop type
  
  filters, and also add some more that we can afford as a result of being
  
  able to set these properties dynamically.
  It's worth pointing out that `out_t/ot` is currently redundant with
  
  `in_t/t` since it will always contain the same PTS values, but I plan on
  
  changing this in the near future.
  I decided to also expose `crop_w/crop_h` and `pos_w/pos_h` as variables
  
  in the expression parser itself, since this enables the fairly common
  
  use case of determining dimensions first and then placing the image
  
  appropriately, such as is done in the default behavior (which centers
  
  the cropped/placed region by default).
  

  • [DH] doc/filters.texi
  • [DH] libavfilter/vf_libplacebo.c