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• ffmpeg shutting down when stream is silent

  7 février 2017, par chr_lt_ney

  I am running ffmpeg in a Linux environment, where I merge the audio stream from an Icecast-stream and a static image in order to be able to stream that to Youtube.

  At times, the Icecast stream get’s very silent, sometimes for almost a minute. That is intended to happen, due to the nature of the content. But, when the stream get’s too silent, ffmpeg just shuts down with no notice.

  This is how I start ffmpeg :

  ffmpeg -loop 1 -r 30  -s 1280x720 -i /var/www/html/files/youtube/image.png -i http://my-stream-to-icecast:8000/my-mount -c:v libx264 -preset fast -tune stillimage -crf 18 -c:a copy -shortest -pix_fmt yuv420p -f flv rtmp://a.rtmp.youtube.com/live2/my-youtube-key

  Any ideas on how to solve this ? And/or how to optimize the above ?

  Thanks a lot !

• minimum delay for mpeg-dash stream using ffmpeg

  9 février 2017, par evan

  I am trying to stream my video files using MP4Box and ffmpeg and using mpeg-dash, I transcoded my video using this command for video :

  ffmpeg -i main720.MTS -movflags faststart -vcodec libx264 -r 24 -tune zerolatency -tune fastdecode -bf 0 -slices 0 -x264opts intra_refresh=1 -g 96 -b:v 700k -maxrate 700k -bufsize 400k -an -s 640*360 -ss 00:00:00 -t 00:02:00 main720_700_video.mp4

  and this for audio :

  ffmpeg -i main720.MTS -movflags faststart -acodec libmp3lame -b:a 128k -vn -ss 00:00:00 -t 00:02:00 main720_700_audio.mp4

  and this to make the mpeg-dash file :

  MP4Box -dash 4000 -frag 4000 -profile onDamand -rap -segment-name %s_ -out manifest.mpd main720_300_video.mp4 main720_700_video.mp4 main720_300_audio.mp4

  but I am NOT getting a fast stream and it has got some delay, any suggestions on how to make this delay lower ??

• How to efficiently create H264 mpeg from two clips with known different motion intensity ?

  14 février 2017, par Serge

  Given an audio and an image we create a static image "video" and then append a short clip that has a rather intense motion.

  Audio and image varies from run to run. Appended animation is always the same. Rendering is done with ffmpeg on a remote server. Rendered file must be in h264 codec mpg.

  Speed of encoding is crucial. Is there a fast and effective way to generate and merge the two clips quickly ?

  Atm we use the following ffmpeg commands :

  // create first clip from image
  
  ffmpeg -loop 1 -r 24 -i $IMAGE -i $AUDIO -t $AUDIO_LENGTH -c:a aac -profile:a aac_low -ar 48000 -b:a 192k -bsf:a aac_adtstoasc -strict -2 -y -c:v libx264 -profile:v high -preset veryfast  -tune stillimage -crf 24 -x264opts bframes=2 -pix_fmt yuv420p -safe 0  clip1.mpg
  
  // . . .
  
  // then append the animation
  
  ffmpeg -f concat -safe 0 -i list.txt -c copy -y -safe 0 final.mpg 

  Intuition is that we can benefit form knowing exact timing of a first clip with a static image and the second one with intense animation – like it is determined in the 1-st pass of a 2-pass compression.

  Someone experienced in tech of h264 codec and mpeg please advice.