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• ffmpeg video streaming deep understanding

  14 novembre 2012, par Stefan Alexandru

  The main question is if it is possible to somehow go around the frame index checking that ffmpeg does when writing the frame to a file.

  Now I will explain my exact problem so you can understand better what I need or maybe think of an alternative solution.

  Problem n0.1 : I am getting video stream from two independent cameras and for some reason I want to save it in the same video file. First the frames from the first camera and then the frames from the second. When writing the frames from the second camera av_write_frame would return the error code -22 and will fail to add the frame. That's because the writing context is expecting a frame index following the index of the previously written frame (the last frame from camera 1) but he receives a frame with the index 0, the first frame from the second camera.

  Problem no.2 : Consider the following problem independently to the first one.
  I am trying to save a video stream to a file but the frame rate is double the real speed. So because I couldn't find any working solution to speed down the frame rate i thought to write every frame twice in the video file. But it won't make any difference to the frame rate.
  I also tried a different approach on the frame rate problem but it also failed(question here).

  Any kind of working solution would be highly appreciated.

  Also it's important that I can't use console commands, I need C code, as I need to integrate those functionalities in an Android application that is automated.

• What hardware can I use to convert MP4 files to MPEG2 transport streams ? All software solutions have failed

  30 avril 2014, par dsimms

  I have tried FFMPEG, as well as a number of other software encoders and converters. Nothing has worked so far.

  I have several MP4 files that I need to convert into MPEG2 transport streams to run on set top boxes. I’m hoping there is a hardware solution for this because all software solutions have failed. The output file doesn’t run reliably without jitters and corruption on screen.

• GStreamer Tee (Multiple Multiplexer)

  14 novembre 2012, par user1595257

  I'm trying to store a video stream (coming from my webcam) into a MKV and FLV file. This means I have to split the video and audio pipeline after the h264 Encoding and mux each path with a different muxer.

  This is how I imagine it should be working :

                                               |->queue->matroskamux->filesink
  
  v4l2src->videorate->videoscale->x264enc->tee-|
  
                                               |->queue->flvmux->filesink

  Is this assumption correct ? Are all the queues at the right places ? How would a GStreamer command like this look like ? I'm having especially troubles with the concept of "Tees". How/where to start them in a command and how to manipulate different Tee-Paths. I looked up "Tee" in the GStreamer documentation but I'm still having troubles to apply them.

  Thanks in advance !

  EDIT : Ok, Thanks to mreithub I got it working for video. This is how the command looks like for now :

  gst-launch-0.10 -v -m v4l2src ! videorate ! videoscale ! ffmpegcolorspace ! x264enc ! tee name=muxtee ! queue2 ! matroskamux name=mkvmux ! filesink location=file1.mkv muxtee. ! queue ! flvmux name=flvmux ! filesink location=file1.flv

  Here is my attempt to get audio running :

  gst-launch-0.10 -v -m v4l2src ! videorate ! videoscale ! ffmpegcolorspace ! x264enc ! tee name=muxtee ! queue2 ! matroskamux name=mkvmux pulsesrc ! ffenc_aac ! filesink location=file1.mkv muxtee. ! queue ! flvmux name=flvmux pulsesrc ! ffenc_aac ! filesink location=file1.flv

  This does not work (command executes but immediately stops - no error message). But I'm also having trouble determining the position where to put the audio encoding. In my attempted solution I encode the audio in each Tee-Pipeline (right ?). But I'd like to encode audio only once and then just mux it in both pipeline-paths accordingly.

  Here's another try : after the audio encoding I split the pipleine using a Tee and assign it to the mkvmuxer and flvmuxer :

  gst-launch-0.10 -v -m v4l2src ! videorate ! videoscale ! ffmpegcolorspace ! x264enc ! tee name=muxtee ! queue2 ! matroskamux name=mkvmux ! filesink location=file1.mkv muxtee. ! queue ! flvmux name=flvmux ! filesink location=file1.flv pulsesrc ! ffenc_aac ! tee name=t2 ! queue ! mkvmux. t2. ! queue ! flvmux.

  But with this one I'm getting the following error message :

  could not link queue1 to flvmux

  Thanks !