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• Set H264 high quality encoding in FFMPEG

  25 décembre 2015, par hiitiger

  I’m working on a function, using ffmpeg to encode a serial images to a MP4 file.
  I use H264 codec, and want to have a high quality output.

  Other things now goes well, but the video quality looks obvious loss.

  After some Google, I set codec context like this

  video_st = avformat_new_stream(oc, 0); 
  
  ....
  
  pVideoCodec  = avcodec_find_encoder(fmt->video_codec); //AV_CODEC_ID_H264
  
  ....
  
  avcodec_get_context_defaults3(video_st->codec, pVideoCodec);
  
  video_st->codec->codec_id =  fmt->video_codec;
  
  video_st->codec->width = m_outWidth;
  
  video_st->codec->height = m_outHeight;
  
  video_st->codec->time_base.den = m_fps;
  
  video_st->codec->time_base.num = 1;
  
  video_st->codec->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
  AVDictionary *param = nullptr;
  
  av_dict_set(&param, "qp", "0", 0);
  
  av_dict_set(&param, "preset", "medium", 0);

  I also try to set bit_rate. But all turned out to be bad.

  I want a visually loss less output video.

  So what parameters should I set or anything else did I missed ?

• why FFmpeg reduce video file size and quality on centos

  21 février 2018, par sadeghpro

  I use FFmpeg on centos 7 for add watermark on video with this commands

  ffmpeg -i input.mp4 -i logo.png -filter_complex "overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2" output.mp4

  and

  ffmpeg -i input.mp4 -i logo.png -filter_complex "[1]lut=a=val*0.3[m];[m][0]scale2ref=iw*0.5:-1[wm][a];[a][wm]overlay=x=(W-w)/2:y=(H-h)/2" output.mp4

  it’s work but when command done the file size and quality lower than orginal video.

  I use this commands on Debian with FFmpeg 3.2.10 and on mac osx with FFmpeg 3.4 it’s ok no problem
  but on centos with FFmpeg 2.8.13 and 3.2.10 and 3.4.2 the second command does not work on 2.8.13 because scale2ref not exist but on other versions the file size and video quality reduce

  edit

  I read your answer but your commands do not work for me. all of them have some error then I start to find a new solution with an idea you give me and find this link but -sameq remove and I use -qscale 0 and work but file size increase from 4.7M to 16M

  then I back to my real question that you don’t see that and set this question duplicate. Why my commands

  • work on Debian and mac osx correctly
  • but on centos reduce quality and file size

• ffmpge command to merge file with good quality

  21 janvier 2016, par Hemant Kumar

  Hi I am looking for a better command that can merge both audio & video files into one with a better quality.

  I found this command from Muaz Khan’s WebRTC APIs.

  "ffmpeg -i {$audioFile} -i {$videoFile} -map 0:0 -map 1:0 {$mergedFileName}"

  Later on server i had to add "-strict -2" with this command as on server it says that above command is experimental if I still want to use it you should add "-strict -2" with it.

  It is working well but my video file (.webm) with size 2.2MB and audio file (.wav) with size 1.5MB was merged into a new file (.webm) with size 422.5KB. This new video file is having lag.

  Also I want the meta information for duration of video is already written on the resulting video file.

  Is there any command which can give the merged file without lagging and both video and audio of the new file are of good quality.