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• Remove flicker, crop and upscale in ffmpeg

  22 août 2024, par Sabha

  I spent one full day on ffmpeg line commands by searching a lot on google but could not achieve what I wanted to and therefore I came here to seek some advice.
I have a video testinput.mpg which I believe is a mpeg-2 video. It is of 720x576 dimensions having 25 fps and a total bitrate of 4224 kbps

  


  First problem is that the exported footage is flickering which I wasn't able to remove using ffmpeg with lots of commands I tried like adjusting brightness, contrast, hue, saturation and all.

  


  Second problem was to extract the center portion which I was able to do it with the crop feature using following command.

  


  ffmpeg -i testinput.mpg -filter:v "crop=468:374" testoutput.mpg


  


  But after cropping I observed that that bitrate fell from 4224 kbps to 761 kbps and I assume this has reduced the quality of video.

  


  What I want to achieve is :

  


  

  1. Crop the video properly keeping the same quality (acodec copy vcodec copy) -> ffmpeg did not allow me to do both the things together (cropping and having same codec)

  


  2. Remove the flicker from video and upscale it to 4K or HD quality so that it looks nice on big televison (preferably 4K)

  


  


  I request some help on how to achieve the desired result. Can someone shed some light on it ?

  


  Here are 10 seconds sample videos on google drive that I am working on

  


  testinput.mpg

  


  testoutput.mpg

  


  Thanks

  


• Decode h264 rtsp with ffmpeg and separated AVCodecContext

  1er juillet 2012, par mmmaaak

  I need some help with decodein rtsp stream of video.
  I get it from AXIS IP-camera. I use ffmpeg library for it.
  It is neccessary to create AVCodecContext separately, not from AVFormatContext->streams[...]->codec ;

  So i create AVCodec, AVCOdecContext and try to init them.

  AVCodec *codec=avcodec_find_decoder(codec_id);
  
  if(!codec)
  
  {
  
      qDebug()<<"FFMPEG failed to create codec"</-->
  
  }
  
  
  
  AVCodecContext *context=avcodec_alloc_context3(codec);
  
  if(!context)
  
  {
  
      qDebug()<<"FFMPEG failed to allocate codec context";
  
      return false; //-->
  
  }
  
  avcodec_open2(context, codec, NULL);

  Then in main loop of application, i get frames data and try to decode :

  _preallocatedFrame = avcodec_alloc_frame();
  
  avcodec_decode_video2(_context, _preallocatedFrame, &got_picture, &_packet);

  And here I get lots of messages in console :

  [h264 @ 1f177720] decode_slice_header error
  
  [h264 @ 1f177720] no frame!
  
  [h264 @ 1f177720] non-existing PPS 0 referenced
  
  [h264 @ 1f177720] decode_slice_header error
  
  [h264 @ 1f177720] no frame!
  
  [h264 @ 1f177720] non-existing PPS 0 referenced
  
  [h264 @ 1f177720] decode_slice_header error
  
  [h264 @ 1f177720] no frame!
  
  [h264 @ 1f177720] non-existing PPS 0 referenced
  
  [h264 @ 1f177720] decode_slice_header error
  
  [h264 @ 1f177720] no frame!
  
  [h264 @ 1f177720] non-existing PPS 0 referenced
  
  [h264 @ 1f177720] decode_slice_header error
  
  [h264 @ 1f177720] no frame!
  
  [h264 @ 1f177720] non-existing PPS 0 referenced
  
  [h264 @ 1f177720] decode_slice_header error
  
  [h264 @ 1f177720] no frame!

  Can you advice me something, how to init AVCodecContext or something else to do it correct ?

• Serving live stream by using ffmpeg via rtmp protocol

  28 janvier 2019, par Yusufu

  I have been trying to serve my rtmp stream to web, struggling with videojs
  I am able to serve my static video or live stream from android screen by using ffmpeg via this command :

  ffmpeg -i video7.mp4 -c:v libx264 -g 25 -preset fast -b:v 4096k -c:a libfdk_aac -ar 44100 -f flv rtmp://127.0.0.1/media_server/video.flv

  So can connect it via ffplay. This part works like a charm.

  ffplay  rtmp://127.0.0.1/media_server/video.flv

  But couldnt watch in web. My html file here. Copied from videojs offical example

  1. question : Being able to watch via ffplay on rtmp means my nginx rtmp module works well ?

  2. I have been serving httml via http-server and rtmp on rtmp ://127.0.0.1 without port caused problem ?

  3. Any other videoplayer advice ? I have already tried hls it works but in my case creating m3u8 manifest file not desired because I am streaming live video from mobile screen record so creating new ts files nut not updated m3u8 file not for me I guess ?

  4. What else I can try as a protocol ? instead of rtmp

  I can share about my screenrecord and ffmpeg commands to help me or you. Thanks