Recherche avancée

Sur d’autres sites (7466)

• Compatibility of P-frames and multithreading in FFmpeg library in C

  16 mai 2023, par Rachel

  I am working on a video processing project using the FFmpeg library in C. I would like to inquire about the compatibility and support for utilizing P-frames (predictive frames) and multithreading simultaneously in FFmpeg. Currently, I am exploring two options for achieving multithreading with FFmpeg :

  


  

  1. Setting the i_threads parameter of FFmpeg to a value greater than 1.

  


  2. My application opens multiple threads, where each thread creates a codec context
and performs parallel compression/decompression of frames from a shared FIFO.

  


  


  I have tried option 1, but I did not observe any noticeable time difference compared to using only one thread. I am seeking an understanding of why this might be the case.

  


  I have tried option 2, which has resulted in improved compression/decompression times for the frames. However, I would like to understand why does it work. Since I am utilizing P-Frames, where each P-frame depends on the latest I-Frame, how can I ensure that the decompression of P-Frames starts after the I-Frame has finished processing when dealing with multiple codec contexts ?

  


  I have two proceccses one for encodeing and one for decoding.
I'd like to improve times using threads in both of them.

  


  The encoder process code :

  


  pt_handle->t_x264_param.i_threads = 24;

  


  pt_handle->pt_x264_encoder = x264_encoder_open(&pt_handle->t_x264_param);

  


  The decoder process code :

  


  pt_handle->pt_avcodec_ctx->thread_count = 23;

  


  pt_handle->pt_avcodec_ctx->thread_type = FF_THREAD_FRAME ;

  


  i_retval = avcodec_open2(pt_handle->pt_avcodec_ctx, pt_h264_decoder, NULL);

  


• FFMPEG Using video in to add Watermark

  15 janvier 2021, par Lakhan

  I have tried the below code using my Command line.

  


  ffmpeg -i ed_hd.mp4 -i watermark.png -filter_complex "overlay=20:20" 1610690297-6555.mp4

  


  But didn't works this.

  


  And getting error like that.
The encoder 'aac' is experimental but experimental codecs are not enabled, add '-strict -2' if you want to use it.

  


  tried many times didn't get any success on it. if anyone can help on then I am thankful.

  


• ffmpeg converting mp4 to gif with color palette results in truncated video

  6 décembre 2019, par Tik0

  I want to generate a gif from my mp4 movie with ffmpeg (ffmpeg version 2.8.15-0ubuntu0.16.04.1) using a color palette. Everything works fine if I do not use a palette :

  $ ffmpeg -i in.mp4 -filter_complex "scale=160:-1" out.gif
  
  ...
  
  frame= 2003 fps=251 q=-0.0 Lsize=   21172kB time=00:01:20.12 bitrate=2164.7kbits/s    
  
  video:21155kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.077667%

  But using a palette like so results in Buffer queue overflow, dropping messages and a truncated video

  $ ffmpeg -i in.mp4 -filter_complex "[0:v] scale=160:-1, split [a][b];[a] palettegen [p];[b][p] paletteuse" out.gif
  
  ....
  
  [Parsed_paletteuse_3 @ 0xc56de0] [framesync @ 0xd1af08] Buffer queue overflow, dropping.
  
  Last message repeated 36 times
  
  [Parsed_paletteuse_3 @ 0xc56de0] [framesync @ 0xd1af08] Buffer queue overflow, dropping.
  
  Last message repeated 106 times
  
  ...
  
  [Parsed_palettegen_2 @ 0xc56d40] 255(+1) colors generated out of 1347441 colors; ratio=0.000189
  
  frame=   65 fps=5.4 q=-0.0 Lsize=    1036kB time=00:01:20.12 bitrate= 105.9kbits/s    
  
  video:1035kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.124664%