Newest 'ffmpeg' Questions - Stack Overflow

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• How can I acheive the best overall FLV quality with FFMPEG ?

  14 novembre 2013, par dcolumbus

  First of all, FFMPEG has the worst documentation of all time, and secondly, the syntax is so trivial that it's often hard to understand what some lines are doing.

  What I'm looking to accomplish would be the best quality FLV with the lowest file size. After all, isn't that everyone's goal? These videos will be streamed if that makes any difference.

  Do any of you have some command lines that could do this?

  For now, my video(s) are no wider than 320px, and some are widescreen, so their heights are a little smaller than 240px. As it stands, the quality of the converted FLVs is quite poor.

  Current command:

  > ffmpeg -i video.mov -ar 22050 -ab 32 -f flv -s 320x240 -aspect 4:3 video.flv
  

• Settings required to set to emulate the FFMPEG '-sameq' flag when using libavcodec

  14 novembre 2013, par Jonathan Websdale

  Currently attempting to use libavcodec to transcode MP4 (MPEG4 and H264) and MPG (MPEG2) video files into .MP4, .MPG and .AVI files. Have done this previously using FFMpeg.exe with use of the '-sameq' flag to retain the same/similar quality output file to that of the input file.

  Now using av_open_input_file, av_read_frame and avcodec_decode_video2 to open, read and decode the input file, then assigning a AVCodecContext and encoding the data using avcodec_encode_video. However the output file video quality is pretty poor.

  These are the AVCodecContext settings I'm using?:-

  codecContextOutput->width = SAME AS INPUT FILE;
  codecContextOutput->height = SAME AS INPUT FILE;
  codecContextOutput->pix_fmt = SAME AS INPUT FILE;
  /* frames per second */
  AVRational ar; 
  ar.num = 1;
  ar.den = 25;
  codecContextOutput->time_base = ar;
  codecContextOutput->gop_size = 10; /* emit one intra frame every ten frames */
  codecContextOutput->max_b_frames=1;
  codecContextOutput->bit_rate = 480000;
  

  Does anybody know the additional settings needed to emulate the '-sameq' setting or what additional settings are needed in the AVCodecContext to improve the output quality?

• how to improve quality with ffmpeg flv [closed]

  14 novembre 2013, par user692601

  i'm haveing problem when converting movies to FLV, i get a lot of small squares in the picture. maybe someone know why? and how i can remove those squares and make picture better? my code is:

  ffmpeg -i movie.mp4 -f mpegts -acodec libmp3lame -ar 48000 -ab 128k -s 320.240 -vcodec libx264 -b 320k -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -trellis 1 -refs 1 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 200k -maxrate 10M -bufsize 10M -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 -g 30 -async 2 out.flv

  thanks!

• Ffmpeg & PHP - Small Clip with Good Quality

  14 novembre 2013, par FakeHeal

  what are the best options to keep video in nearly good quality while converting it to flv and shrinking its size?

  I use the followin code now:

  exec("ffmpeg -i $faila -sameq -s 600x450  -ar 44100 $file_final");
  

• ffmpeg setting for HD and normal quality

  14 novembre 2013, par gabo84

  Hello i need to have two versions of the same file stored on my server, medium and HD quality, the thing is that don't really know ffmpeg that well so im just trying this is code at random, i'm using the code belo but I end up with a much larger file, however it works,it plays.

  ffmpeg -i inputfile.wmv  -vcodec libx264 -ar 44100 -b 200 -ab 56 -crf 22 -s 360x288 -vpre medium -f flv tmp.flv
  

  Just need the two commands to create the 2 different files