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• FFmpeg : HLS options cannot be set/get/find

  4 septembre 2013, par user2677612

  We are using FFmpeg libraries git-ee94362 libavformat v55.2.100.
  We are trying to write a simple HLS code example based on muxing.c standard one.
  Let be two input streams, video and audio (they can be synthetic, doesn't matter).
  Our purpose is to mux them into M3U8 playlist using HLS.
  Suppose, duration of every TS segment file be 3 sec, and the desirable maximum number of entries in M3U8 output file be 100.

  From the FFmpeg application sources, one can see that the Apple HTTP Live Streaming segmenter implemented in hlsenc.c file.
  And the relevant options there are, as well : "hls_list_size", "hls_time", etc.
  The problem is that we have not succeeded to set/get/find these options in a conventional way, as shown in the following code :

  ---

  // Here is a part of main() program
  
  
  
  int64_t i1 = 0;
  
  void *target_obj;
  
  
  
  AVFormatContext *ofmt_ctx = NULL;
  
  AVOutputFormat *ofmt = NULL;
  
  
  
  avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, "Example_Out.m3u8");
  
  
  
  ofmt = ofmt_ctx->oformat;
  
  
  
  // The relevant options ("hls_list_size", "hls_time") are located under ofmt->priv_class->option.
  
  // But AVClass *priv_class is not the first member of the AVOutputFormat.
  
  // So, due to the documentation, av_opt_find...(), av_opt_get...() and av_opt_set...() 
  
  // cannot be used for options within AVOutputFormat.
  
  // In practice, any of the following three lines causes exception.
  
  const AVOption *o = av_opt_find2(ofmt, "hls_list_size", NULL, 0, AV_OPT_SEARCH_CHILDREN, &target_obj);
  
  av_opt_get_int(ofmt, "hls_list_size", AV_OPT_SEARCH_CHILDREN, &i1);
  
  av_opt_set_int(ofmt, "hls_list_size", 10, AV_OPT_SEARCH_CHILDREN);

  ---

  Our question : If there is a way to overcome the problem, i.e. to set/get/find options for AVOutputFormat, like for AVCodecContext (for example) ?

  Thank you,

  Andrey Mochenov.

• Remux and segment only parts of a video file without difference in output

  20 juin 2013, par Christian P.

  I have a working program built on top of libav (alternatively ffmpeg - expertise is either is useful here).

  It takes an mp4 video, encoded with h264 video / AAC audio, and remuxes it to MPEG TS and segments it into X second chunks. It is analogous to the following ffmpeg command :

  ffmpeg -y -i video.mp4 -c:a copy -bsf:a aac_adtstoasc -c:v copy -bsf:v h264_mp4toannexb -flags -global_header -map 0 -f segment -segment_time 10 -segment_list playlist.m3u8 -segment_format mpegts chunk_%03d.ts

  The reason I am not using the command-line, is that I wish to generate only a subset of the segments. So if a video results in 10 segments of between 8 and 12 seconds (the segments are never exactly the desired length due to keyframes), I might wish to generate segments 3-7 at a later time.

  The complete code for my program can be found here.

  I use av_read_frame to read every frame from the source file, remux (including a bitfilter process) and write to output file. Once the duration since the last output becomes close/greater than the desired segment length, I flush the output file, close it, open the next segment and continue.

  I have tried altering the code to do an av_seek_frame to the end of the first segment and start from there (I also attempted to start at the end of the 2nd and 3rd segment). The new segments are the same length (in seconds and pts), but have a different size than the comparable segments from the full runthrough (within a few kilobytes) - the starting segment (whether it's the 2nd, 3rd or other) also shows as having 2 packets LESS than the comparable segment from previously.

  I assumed that av_seek_frame would give me an exact match as if I had manually done a loop with av_read_frame up to that frame, but it seems like it's not the case.

  What I wish for :

  • A way to "fast-forward" in the file to a specific (not approximate) point in the file.
  • To write from that point forward and have the output be completely identical to the output a full run provides (same size, same length, same exact bytes).

• how to configure ffserver to save the incoming feed in a different file every 30 mins or so

  29 mai 2014, par Muhammad Ali

  I want to have a backlog of my camera video in files of 30 mins duration. What i’ve read so far from the internet about ffserver has allowed me to connect all my cameras to ffserver using ffmpeg and receive the video on another system using VLC or ffplay .

  Now what I want is to store the camera video in a different file preferably named as time-stamp. And keep streaming the live video.

  Once there is a list of 30 mins files. I’d like to have a playlist which can be opened in VLC player of files that have been saved and can be played.

  sort of like a remote media player with video sources coming from ffserver with playlist and 30 mins duration video clips.