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• Mixing audio and video with ffmpeg [closed]

  3 septembre 2013, par Narendra DroidWorm

  I am having an mp4 video (without audio), to which I want to add music using ffmpeg, and also want the output video to be of the same length as the input video.

  But, as a result, I am getting an video merged with audio, but consuming a little more time (abt 1-2 seconds) in the start with a black screen.

  I am using the following command for my desired output.

  ffmpeg -i audio.mp3 -i video.avi -acodec copy -vcodec copy output.avi

  Please suggest, what modifications should I do to get my desired output.

• FFmpeg screencast recording : which codecs to use ?

  24 avril 2013, par mkaito

  I've been experimenting with recording screencasts using FFmpeg's X11grab module, which has worked more or less fine so far. I understand that a/v encoding is a complex process with many fine details, but I'm doing my best to learn.

  I'd like to do "lightweight" recording of a video stream, that puts as little strain as possible on the system while the stream is being recorded. I record two audio streams separately with pacat and sox. Later, the whole thing is filtered, normalized, encoded, and combined into a Matroska container.

  Right now, I'm having ffmpeg record a rawvideo stream to be fed to x264's yuv4 demuxer. I experimented with ffv1 and straight x264 recording before. My system can't handle real time encoding with x264 on the settings I want for the final stream, so I have to recompress separately once the recording is done. I've found that ffv1 gives me terrible frame dropping, and yuv4 too, but less so. I suspect this is due to hard drive speed, even if I'm sitting in a SATA3 Caviar Black that's being used exclusively to hold the recorded data.

  The question is, which combination of video codecs should I look at ? Record straight in x264 and recompress to "better" x264 later ? Raw video, then compress ? How would I go about pinpointing issues such as the frame drops I've been experiencing ?

  EDIT : This is the ffmpeg line I currently use.

  ffmpeg -v warning -f x11grab -s 1920x1080 -r 30000/1001 -i :0.0\
  
  -vcodec rawvideo -pix_fmt yuv420p -s 1280x720\
  
  -threads 0\
  
  recvideo.y4m

• With FFMPEG, create thumbnails proportional to the video's ratio [closed]

  28 janvier 2013, par Felipe Schenone

  I'm using the following command to create thumbnails with FFMPEG :

  ffmpeg -itsoffset -1 -i video.avi -vcodec mjpeg -vframes 1 -an -f rawvideo -s 240x180 image.png

  And it works fine. However, when the video isn't 4:3 ratio, it will still create a 240x180 image, and the extra space will be painted black. Is there some variation of the command that will prevent this and give me an image proportional to the video's ratio ? In other words, I want 240x180 to be the maximum size of the thumbnail, but not the minimum.

  Extra points if the command creates a smaller image when the video is smaller than 240x180.