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• Merge commit ’6641819feedb086ebba3d2be89b8d33980f367e1’

  26 juin 2016, par Hendrik Leppkes

  Merge commit ’6641819feedb086ebba3d2be89b8d33980f367e1’
  * commit ’6641819feedb086ebba3d2be89b8d33980f367e1’ :
  
    build : Ignore generated mapfile and remove it on distclean
  Merged-by : Hendrik Leppkes <h.leppkes@gmail.com>
  

  • [DH] .gitignore
  • [DH] Makefile

• FFMPEG ignores bitrate

  24 avril 2016, par Kevin Brydon

  I am new to video encoding so bear with me.

  I am using FFMPEG. I have an mp4 file which is 640 x 350 with an average bitrate of around 2000kb (I think) and a filesize of 80Mb. I want to convert this to an ogv file with a much lower bit rate (128kb) but the same width and height. I am using the following command...

  ffmpeg -i input.mp4 -b:v 128k output.ogv

  ... but FFMPEG seems to ignore my bitrate option and outputs a file with a bitrate of around 600kb and a filesize of around 3Mb.

  I can do this using FFMPEG2THEORA using the following command ...

  ffmpeg2theora -V 128 input.mp4 -o output.ogv

  ...but I was wondering if it was possible using FFMPEG.

  Any ideas ?

  Edit

  mark4o solved my problem. It turns out that the default audio codec was bumping up the filesize. Changing it to libvorbis has reduced the filesize dramatically. Final command looks like

  ffmpeg -i input.mp4 -b:v 128k -b:a 128k -codec:a libvorbis output128.ogv

  • -i = input file
  • -b:v = the bitrate of the video stream
  • -b:a = the bitrate of the audio stream
  • -codec:a = override the default audio codec

• Normalise video aspect ratio with ffmpeg

  4 juillet 2022, par Benjamin Tamasi

  I'm parsing a video stream from an application that receives an h264 stream and writes it to a file. (The frame data is an unencrypted depacketized H.264 elementary stream).

  


  I use ffmpeg to resize it to a fixed resolution. (I overlay it on a black canvas with -f lavfi -i color=c=black:s=1920x1080:r=30) and -filter_complex [1][0]scale2ref=w='if(gt(mdar\,dar),iw,oh*mdar)':h='if(gt(mdar\,dar),ow/mdar,ih)'[2mp4][base];[base][2mp4]overlay=x='(W-w)/2':y='(H-h)/2':eof_action=pass[vout]

  


  My issue is, that since this stream is coming from a phone's camera, whenever the orientation of the phone changes, the stream's aspect ratio changes. It can go from portrait to landscape, and back, in the same stream. When I open the file in vlc, it handles it quite nicely by resizing the window of the player to match the aspect ratio as it changes.

  


  How can I "normalise" the video, so it's always nicely overlayed on my black canvas as the aspect ratio changes ? Currently it's just using the initial aspect ratio, and if that changes mid stream, it will ignore the change, effectively distorting the stream by squishing or stretching it.

  


  Is there some way I can get ffmpeg to do this ?