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• Extract RTP-packages from video

  5 août 2019, par Gregor A. Lamche

  I have a proprietary REST server that acts as a sort of RTSP server and establishes a UDP stream to another program for video streaming (no audio). It works fine and I can already stream videos. The only issue is that it can only stream one (proprietary) file (container) format at the moment as I’m limited by my media source code.

  I need a code/library which I can give any video file of a common video format/encoding (MPEG-4/MJPEG/H264) and it returns me the RTP-packages that I can then stream (or how to extract the content myself). Alternatively I already got a video player which gives me YUV frames of any video I give it, which in turn I could convert into RTP-packages provided I know how.

  Rendering is done on client side, and something I don’t care about. Though, I will have to set the encoding flags correctly.

  I know roughly about the RTP-header, but have no idea what bytes to write into its content. I heard of FFmpeg and Live555, but for neither could I find example code to extract those packages from a file (let alone a c# wrapper).

• Using more than 2 NV_ENC at a time with FFMPEG

  29 décembre 2022, par lowcrawler

  I'm currently generating timelapse videos using a thread on my CPU with fluent-ffmpeg running on nodejs. It takes roughly 1 minute to generate a 10 second timelapse. I'm generating many at the same time (basically one per thread) such that I tend to get the best performance at 8 worker threads. ... overall system throughput is about one video per 12 seconds.

  


  GPU processing using h264_nvenc takes the single-thread time to about 3-4 seconds. Yippie ! I went out and bought some nVidia 1660's to take advantage.

  


  Unfortunately, when I go to generate the 3rd simultaneous video, I get "Conversion Failed !" error from FFMPEG.

  


  Some basic research seems to show you can only 2 at a time. Perhaps 3 with updated drivers.

  


  Is there a method around this ? Posts from here indicates this limit is artificial and can be worked around : https://www.techpowerup.com/268495/nvidia-silently-increases-geforce-nvenc-concurrent-sessions-limit-to-3

  


  Perhaps a way to use all the cuda/tensor/etc cores to render timelapse videos instead of just relying on the limited nv_enc ?

  


• avcodec/jpeg2000dec : jpeg2000 has its own lowres option

  9 juin 2023, par Michael Niedermayer

  avcodec/jpeg2000dec : jpeg2000 has its own lowres option
  jpeg2000 overrides the global lowres variable with a lowres field called reduction_factor
  
  ffmpeg -lowres X causes the reduction_factor to be set
  
  ffplay -lowres X causes both lowres and the reduction_factor to be set
  
  ossfuss sets only lowres
  only the ffmpeg variant works. This patch tries to make the other 2 work.
  Alternative we could just error out if things are inconsistent.
  
  More complex restructuring should be limited to the master branch
  
  to keep this reasonably easy to backport
  Fixes : out of array access
  
  Fixes : 59672/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/jpeg2000dec.c