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• Segmenting only specific parts of a video file

  30 May 2013, by Christian P.

  I have some video files that I wish to serve up "dynamically", given the following workflow:

  1. Convert video from MP4 container to segmented .ts files with accompanying .m3u8 playlist
  2. Delete .ts files
  3. On request, generate .ts files (but only those requested, not for the entire video)

  I can generate .ts files for the entire video using ffmpeg using this 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

  This is what I do in step 1 and it works just fine, video is playing fine. Due to disk constraints, I do not want to have two copies of every video (the original MP4 and the segmented .ts fies), so what I am trying to achieve is to find a command that will allow me to produce only the segments I need, on a per-request basis.

  Given the command above we may produce a sample playlist like this:

  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXT-X-ALLOW-CACHE:YES
  
  #EXT-X-TARGETDURATION:12
  
  #EXTINF:11.261267,
  
  chunk_000.ts
  
  #EXTINF:11.261256,
  
  chunk_001.ts
  
  #EXTINF:7.507511,
  
  chunk_002.ts
  
  #EXTINF:11.261256,
  
  chunk_003.ts
  
  #EXTINF:11.261267,
  
  chunk_004.ts
  
  #EXTINF:7.507511,
  
  chunk_005.ts

  I have tried, using the -ss and -t flags available in ffmpeg, to create only a specific segments. For instance I might skip the first to segments by adding -ss 22.522523 (the total length of the two first segments), but this produces chunks that are not byte-for-byte identical to the original chunks and as such unusable (the video playback just stops). Is there a way to have ffmpeg (or another program) reproduce the same exact chunks, without producing all of them?

  Short version: If I produce a playlist with chunks of an entire video (and accompanying .ts files), can I later reproduce a specific interval of those chunks that are byte-for-byte identical to the original chunks?

• ffmpeg - continuous file streaming over RTMP

  1 May 2013, by Sébastien Renauld

  I've been looking around for a simple (or perhaps not-so-simple) walkaround for a problem I am having in my set up for a simple test case: video streaming over red5 media server.

  I have built a small-ish library of FLV files scraped from YouTube and managed to play them in succession with the following perl script:

  use Cwd;
  
  use strict;
  
  use warnings;
  
  use DBI;
  
  use DBD::mysql;
  
  
  
  our $db = DBI->connect();
  
  my $dst = "/home/seb/youtube/";
  
  sub streamFile {
  
      my $r = $db->prepare("SELECT name FROM music_flvs ORDER BY RAND() LIMIT 1");
  
      $r->execute();
  
      my @data = $r->fetchrow_array();
  
      my $filename = $data[0]
  
      my $t = `ffmpeg -re -i '${dst}${filename}' -ab 48k -ac 1 -vcodec libx264 -crf 30 -s "640x480" -acodec libfaac -ar 44100 -threads 4 -f flv 'rtmp://server/oflaDemo/music'`;
  
      return 1;
  
  }
  
  while (&streamFile()) {
  
  }

  This script does its purpose extremely well: it plays files one by one through ffmpeg. However, it does so with a crucial problem: it causes an Unpublish event every time it swaps songs, which causes all the clients to disconnect. I would like to prevent this. The event manifests itself in ActionScript as this:

   16:33:54:209 - Playback - NetStream.Play.UnpublishNotify
  
   16:33:54:209 - Playback - NetStream.Play.PublishNotify

  I have seen the concat demuxer and believe that it might somewhat help me. The question is pretty simple: what is the best way to make ffmpeg stream a playlist to a RTMP server without ever causing an Unpublish event?

• how to save h264 stream into .264 file

  6 March 2015, by user3547405

  I’m using nginx-rtmp-module build hls server, when I play it on safari, it does not shows image,then i use this command ffmpeg -i rtmp://192.168.4.213/hls/testH264 -c copy -map 0 -f segment -segment_list playlist.m3u8 -segment_time 5 output%03d.ts, it shows missing picture in access unit with size 28184,so i think maybe the raw h264 stream has some problem,then i directly save the h264 stream into .264 file,but when i play the .264 file with vlc,the screen is fuzzy,help