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• When capturing input with ffmpeg can't set video bitrate

  11 mai 2014, par Emanuele

  When capturing input from FFmpeg with following command line :
  ffmpeg -f x11grab -r 30 -s 1920x1080 -i :0.0 -vcodec mpeg4 -b:v 10000k -flags +aic+mv4 -f alsa -ac 2 -i pulse -strict experimental test.mp4
  this is the output I get :

  ffmpeg version 0.8.10-4:0.8.10-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav developers
    built on Feb  6 2014 20:56:59 with gcc 4.6.3
  *** THIS PROGRAM IS DEPRECATED ***
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  [x11grab @ 0x1b1c7a0] device : :0.0 -> display : :0.0 x : 0 y : 0 width : 1920 height : 1080
  [x11grab @ 0x1b1c7a0] shared memory extension  found
  [x11grab @ 0x1b1c7a0] Estimating duration from bitrate, this may be inaccurate
  Input #0, x11grab, from ’:0.0’ :
    Duration : N/A, start : 1399805986.592884, bitrate : 1990656 kb/s
      Stream #0.0 : Video : rawvideo, bgra, 1920x1080, 1990656 kb/s, 30 tbr, 1000k tbn, 30 tbc
  [alsa @ 0x1b2c600] capture with some ALSA plugins, especially dsnoop, may hang.
  [alsa @ 0x1b2c600] Estimating duration from bitrate, this may be inaccurate
  Input #1, alsa, from ’pulse’ :
    Duration : N/A, start : 1399805986.561124, bitrate : N/A
      Stream #1.0 : Audio : pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
  File ’test.mp4’ already exists. Overwrite ? [y/N] y
  Incompatible pixel format ’bgra’ for codec ’mpeg4’, auto-selecting format ’yuv420p’
  [buffer @ 0x1b4d840] w:1920 h:1080 pixfmt:bgra
  [avsink @ 0x1b40480] auto-inserting filter ’auto-inserted scaler 0’ between the filter ’src’ and the filter ’out’
  [scale @ 0x1b1c6e0] w:1920 h:1080 fmt:bgra -> w:1920 h:1080 fmt:yuv420p flags:0x4
  Output #0, mp4, to ’test.mp4’ :
    Metadata :
      encoder : Lavf53.21.1
      Stream #0.0 : Video : mpeg4, yuv420p, 1920x1080, q=2-31, 200 kb/s, 30 tbn, 30 tbc
      Stream #0.1 : Audio : aac, 48000 Hz, 2 channels, s16, 200 kb/s
  Stream mapping :
    Stream #0.0 -> #0.0
    Stream #1.0 -> #0.1
  Press ctrl-c to stop encoding
  ^Cframe= 1283 fps= 42 q=31.0 Lsize=   10882kB time=42.71 bitrate=2087.3kbits/s dup=473 drop=70    
  video:9875kB audio:980kB global headers:0kB muxing overhead 0.251384%
  Received signal 2 : terminating.
  ema@scv : $ ./capvideo.sh 
  ffmpeg version 0.8.10-4:0.8.10-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav developers
    built on Feb  6 2014 20:56:59 with gcc 4.6.3
  *** THIS PROGRAM IS DEPRECATED ***
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  [x11grab @ 0x24667a0] device : :0.0 -> display : :0.0 x : 0 y : 0 width : 1920 height : 1080
  [x11grab @ 0x24667a0] shared memory extension  found
  [x11grab @ 0x24667a0] Estimating duration from bitrate, this may be inaccurate
  Input #0, x11grab, from ’:0.0’ :
    Duration : N/A, start : 1399806153.224758, bitrate : 1990656 kb/s
      Stream #0.0 : Video : rawvideo, bgra, 1920x1080, 1990656 kb/s, 30 tbr, 1000k tbn, 30 tbc
  [alsa @ 0x2476600] capture with some ALSA plugins, especially dsnoop, may hang.
  [alsa @ 0x2476600] Estimating duration from bitrate, this may be inaccurate
  Input #1, alsa, from ’pulse’ :
    Duration : N/A, start : 1399806153.198090, bitrate : N/A
      Stream #1.0 : Audio : pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
  File ’test.mp4’ already exists. Overwrite ? [y/N] y
  Incompatible pixel format ’bgra’ for codec ’mpeg4’, auto-selecting format ’yuv420p’
  [buffer @ 0x2497840] w:1920 h:1080 pixfmt:bgra
  [avsink @ 0x2497c00] auto-inserting filter ’auto-inserted scaler 0’ between the filter ’src’ and the filter ’out’
  [scale @ 0x24a9680] w:1920 h:1080 fmt:bgra -> w:1920 h:1080 fmt:yuv420p flags:0x4
  Output #0, mp4, to ’test.mp4’ :
    Metadata :
      encoder : Lavf53.21.1
      Stream #0.0 : Video : mpeg4, yuv420p, 1920x1080, q=2-31, 200 kb/s, 30 tbn, 30 tbc
      Stream #0.1 : Audio : aac, 48000 Hz, 2 channels, s16, 200 kb/s
  Stream mapping :
    Stream #0.0 -> #0.0
    Stream #1.0 -> #0.1
  Press ctrl-c to stop encoding
  ^Cframe=  229 fps= 36 q=24.8 Lsize=    2316kB time=7.59 bitrate=2497.9kbits/s dup=43 drop=4    
  video:2134kB audio:176kB global headers:0kB muxing overhead 0.253411%
  Received signal 2 : terminating.
  

  As you can see the video is being saved with 200kbs no matter what option I set ; what am I doing wrong ?
  I’m running this on Ubuntu 12.04, ffmpeg is ffmpeg version 0.8.10-4:0.8.10-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav developers built on Feb  6 2014 20:56:59 with gcc 4.6.3.

  Cheers

• Load PNG from disk into AVFrame

  15 février 2018, par Pedro Pereira

  I can’t seem to get this to work. This is what I got so far :

  // Variables
  
  int retOp; // for holding the operations results
  
  
  
  // Initializes FFmpeg
  
  av_register_all();
  
  
  
  // Open image
  
  uint8_t *buffer = NULL;
  
  size_t buffer_size;
  
  retOp = av_file_map("in.png", &buffer, &buffer_size, 0, NULL);
  
  if(retOp < 0){
  
      cerr << "Could not load image!" << endl;
  
      system("pause");
  
      return -1;
  
  }
  
  
  
  // Initialize AVFrame
  
  AVFrame* frame = av_frame_alloc();
  
  frame->width = 1920;
  
  frame->height = 1080;
  
  frame->format = AV_PIX_FMT_RGBA;

  The examples in the FFmpeg Doxygen don’t really help and there’s no support on the web. If there is let me know.

  Uncompressed RGBA image.

• FFMPEG - convert video without losing resolution

  20 février 2020, par Srh

  I am using ffmpeg to convert mp4 video from youtube. The video is HD 1080. When I convert it to mpeg2video, the video loses its sharpness, regardless of the -s 1920x1080 parameter. How can I convert the video without losing picture sharpness ? The command I use is :

  ffmpeg -i BBB.mp4 -vcodec mpeg2video -s1920x1080 -acodec copy -f mpegts BBB.ts