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• FFMPEG, how to add background to image ?

  17 juin 2020, par Tim Hark

  I have image 1 and image 2, how to add background to image 1 look like image 2 use ffmpeg.

  



  image 1

  



  image 2

  


• Scrolling image does not stop with ffmpeg

  20 avril 2020, par Amazon

  Scrolling image does not stop when the image is over

  



  How can I stop scrolling when the image is over but the speed stays the same ?

  



  I want it scrolling at specific speed and the duration increase by size of image

  



  Can scroll an image at default speeds and durations calculated by pixel dimensions like 800x1000, 800x8000, 800x12000 ? I want it to scroll at specific speeds and the duration determined by size of image.

  



  My code

  



   ffmpeg -y -r 1 -loop 1 -t 0.08 -i 4.jpg -filter_complex "color=white:s=1280x720, fps=fps=60[bg];[bg][0]overlay=y=-'t*60':eof_action=endall:shortest=1[video]"   -preset ultrafast -map [video] output.mp4


  


• How to encode a mp4 which has high quality,fast encode speed and low bitrate using FFmpeg API？

  8 septembre 2017, par OnlYet

  I have lots of ARGB binary data and need to encode them to a mp4 file using FFmpeg API.The most difficult things is to deal with the balance between quality,speed and bitrate.

  Below is two download links for mp4 files generated from the same ARGB data.

  • Generated through FFmpeg API : MP4 #1

  • Generated through FFmpeg command line : MP4 #2

  The mp4 generated through command line has high definition and low bitrate(745kbps) while the other has not enough high quality but high bitrate(1009kbps) I don’t know the parameters of the mp4 generated through command line but a part of my code is below :

   codec_ctx->codec_type = AVMEDIA_TYPE_VIDEO;
  
   codec_ctx->width = width;
  
   codec_ctx->height = height;
  
   codec_ctx->time_base.num = 1;
  
   codec_ctx->time_base.den = fps;
  
   stream->time_base = { 1, fps };
  
  if (!strcmp(out_fmt, "mp4"))
  
      {
  
          codec_ctx->codec_id = AV_CODEC_ID_H264;
  
          codec_ctx->bit_rate = 800 * 1000;
  
          codec_ctx->rc_max_rate = 800 * 1000;
  
          //codec_ctx->rc_min_rate = 200 * 1000;
  
          codec_ctx->rc_buffer_size = 500 * 1000;
  
          /* More gop_size less file size */
  
          codec_ctx->gop_size = 30;
  
          codec_ctx->max_b_frames = 3;
  
          /* Set relevant parameters of H264 */
  
          codec_ctx->qmin = 10;   //default 2
  
          codec_ctx->qmax = 31;   //default 31
  
          codec_ctx->max_qdiff = 4;
  
          codec_ctx->me_range = 16;   //default 0 
  
          codec_ctx->max_qdiff = 4;   //default 3 
  
          codec_ctx->qcompress = 0.6; //default 0.5
  
          ret = av_dict_set(dict, "profile", "high", 0);
  
          // Keep a balance between speed and quality when encoding
  
          ret = av_dict_set(dict, "preset", "superfast", 0);
  
          ret = av_dict_set(dict, "threads", "0", 0);
  
          ret = av_dict_set(dict, "crf", "26", 0);    
  
          // set delay time
  
          ret = av_dict_set(dict, "tune", "zerolatency", 0);
  
          return;
  
      }

  I know the parameters that affect video quality are mainly these :

  bitrate, "qp", "crf", gop_size, qmin and "preset".

  I tried to increase gop_size to decrease bitrate but mp4 quality became lower. I also found that the less crf, the more quality and the more bitrate. The less qmin,the more quality and the more bitrate. And preset a higher encode speed, the more bitrate.

  In fact, I want to set "preset" to ultrafast and set "crf" to 20 but the output mp4 will be larger.So why the mp4 generated through command line can be high quality but low bitrate ? How to set the parameters of AVCodecContext to generate a mp4 with high quality,low bitrate and high speed ?

  Supplementary notes ：
  The mp4 generated through command line stay low bitrate most of the time and higher bitrate sometimes but my mp4 is always stay relatively high bitrate. I think the point is to control the bitrate.