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• FFMPEG : Extracting 20 images from a video of variable length

  12 novembre 2013, par Vapire

  I've browsed the internet for this very intensively, but I didn't find what I needed, only variations of it which are not quite the thing I want to use.

  I've got several videos in different lengths and I want to extract 20 images out of every video from start to the end, to show the broadest impression of the video.

  So one video is 16m 47s long => 1007s in total => I have to make one snapshot of the video every 50 seconds.

  So I figured using the -r switch of ffmpeg with the value of 0.019860973 (eq 20/1007) but ffmpeg tells me that the framerate is too small for it...

  The only way I figured out to do it would be to write a script which calls ffmpeg with a manipulated -ss switch and using -vframes 1 but this is quite slow and a little bit off for me since ffmpegs numerates the images itself...

  Any suggestions or directions?

  Thanks, Vapire

• Count frames in H.264 bitstream

  12 novembre 2013, par user620297

  How to count/detect frames (pictures) in raw H.264 bitstream? I know there are 5 VCL NALU types but I don't know how to rec(k)ognize sequence of them as access unit. I suppose detect a frame means detect an access unit as access unit is

  A set of NAL units that are consecutive in decoding order and contain exactly one primary coded picture. In addition to the primary coded picture, an access unit may also contain one or more redundant coded pictures, one auxiliary coded picture, or other NAL units not containing slices or slice data partitions of a coded picture. The decoding of an access unit always results in a decoded picture.

  I want it to know what is the FPS of live stream out to server.

• How can I replace a part of an image using ffmpeg

  12 novembre 2013, par subu.purohit

  I have an image. I want to replace a part (I have coordinate of this part) of this image with other image. Is there any command available in ffmpeg to replace this part with given coordinates or is there any other option?

• forward a stream using ffmpeg

  12 novembre 2013, par user2984660

  is it possible to record a m3u8 stream and forward it as an rtmp stream? Currenty I can play the stream with VLC.

  ffmpeg -i "http://server1/ch-01.m3u8" -q:v 0 -bsf h264_mp4toannexb -f mpegts - | "/Applications/VLC.app/Contents/MacOS/VLC" - && exit
  

  I found an example how to stream a video file, but I do not know how to combine this both commands.

  ffmpeg -re -i '/usr/share/red5/webapps/oflaDemo/streams/avatar.flv' \
  -vcodec libx264 -ab 128k -ac 2 -ar 44100 -r 25 -s 320x240 -vb 660k -f \
  flv 'rtmp://localhost/oflaDemo/streamTest' 
  

  Does anyone have experience with streaming over ffmpeg?

• How to achieve proxy support in ffmpeg ?

  12 novembre 2013, par Stacked

  I searched all over the internet and there seems no way which allows me to grab http streams via a proxy from ffmpeg, so is there a method which I can use to force connecting ffmpeg process via a specific proxy server. This is what I intend to achieve :

  ffmpeg -> Proxy Server -> Content Origin

  Also, the proxy setting should NOT be system wide.