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• On-demand and seamless transcoding of individual HLS segments

  5 janvier 2024, par Omid Ariyan

  Background

  


  I've been meaning to implement on-demand transcoding of certain video formats such as ".mkv", ".wmv", ".mov", etc. in order to serve them on a media management server using ASP.NET Core 6.0, C# and ffmpeg.

  


  My Approach

  


  The approach I've decided to use is to serve a dynamically generated .m3u8 file which is simply generated using a segment duration of choice e.g. 10s and the known video duration. Here's how I've done it. Note that the resolution is currently not implemented and discarded :

  


  public string GenerateVideoOnDemandPlaylist(double duration, int segment)
{
   double interval = (double)segment;
   var content = new StringBuilder();

   content.AppendLine("#EXTM3U");
   content.AppendLine("#EXT-X-VERSION:6");
   content.AppendLine(String.Format("#EXT-X-TARGETDURATION:{0}", segment));
   content.AppendLine("#EXT-X-MEDIA-SEQUENCE:0");
   content.AppendLine("#EXT-X-PLAYLIST-TYPE:VOD");
   content.AppendLine("#EXT-X-INDEPENDENT-SEGMENTS");

   for (double index = 0; (index * interval) < duration; index++)
   {
      content.AppendLine(String.Format("#EXTINF:{0:#.000000},", ((duration - (index * interval)) > interval) ? interval : ((duration - (index * interval)))));
      content.AppendLine(String.Format("{0:00000}.ts", index));
   }

   content.AppendLine("#EXT-X-ENDLIST");

   return content.ToString();
}

[HttpGet]
[Route("stream/{id}/{resolution}.m3u8")]
public IActionResult Stream(string id, string resolution)
{
   double duration = RetrieveVideoLengthInSeconds();
   return Content(GenerateVideoOnDemandPlaylist(duration, 10), "application/x-mpegURL", Encoding.UTF8);
}


  


  Here's an example of how the .m3u8 file looks like :

  


  #EXTM3U
#EXT-X-VERSION:6
#EXT-X-TARGETDURATION:10
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD
#EXT-X-INDEPENDENT-SEGMENTS
#EXTINF:10.000000,
00000.ts
#EXTINF:3.386667,
00001.ts
#EXT-X-ENDLIST


  


  So the player would ask for 00000.ts, 00001.ts, etc. and the next step is to have them generated on demand :

  


  public byte[] GenerateVideoOnDemandSegment(int index, int duration, string path)&#xA;{&#xA;   int timeout = 30000;&#xA;   int totalWaitTime = 0;&#xA;   int waitInterval = 100;&#xA;   byte[] output = Array.Empty<byte>();&#xA;   string executable = "/opt/homebrew/bin/ffmpeg";&#xA;   DirectoryInfo temp = Directory.CreateDirectory(System.IO.Path.Combine(System.IO.Path.GetTempPath(), System.IO.Path.GetRandomFileName()));&#xA;   string format = System.IO.Path.Combine(temp.FullName, "output-%05d.ts");&#xA;&#xA;   using (Process ffmpeg = new())&#xA;   {&#xA;      ffmpeg.StartInfo.FileName = executable;&#xA;&#xA;      ffmpeg.StartInfo.Arguments = String.Format("-ss {0} ", index * duration);&#xA;      ffmpeg.StartInfo.Arguments &#x2B;= String.Format("-y -t {0} ", duration);&#xA;      ffmpeg.StartInfo.Arguments &#x2B;= String.Format("-i \"{0}\" ", path);&#xA;      ffmpeg.StartInfo.Arguments &#x2B;= String.Format("-c:v libx264 -c:a aac ");&#xA;      ffmpeg.StartInfo.Arguments &#x2B;= String.Format("-segment_time {0} -reset_timestamps 1 -break_non_keyframes 1 -map 0 ", duration);&#xA;      ffmpeg.StartInfo.Arguments &#x2B;= String.Format("-initial_offset {0} ", index * duration);&#xA;      ffmpeg.StartInfo.Arguments &#x2B;= String.Format("-f segment -segment_format mpegts {0}", format);&#xA;&#xA;      ffmpeg.StartInfo.CreateNoWindow = true;&#xA;      ffmpeg.StartInfo.UseShellExecute = false;&#xA;      ffmpeg.StartInfo.RedirectStandardError = false;&#xA;      ffmpeg.StartInfo.RedirectStandardOutput = false;&#xA;&#xA;      ffmpeg.Start();&#xA;&#xA;      do&#xA;      {&#xA;         Thread.Sleep(waitInterval);&#xA;         totalWaitTime &#x2B;= waitInterval;&#xA;      }&#xA;      while ((!ffmpeg.HasExited) &amp;&amp; (totalWaitTime &lt; timeout));&#xA;&#xA;      if (ffmpeg.HasExited)&#xA;      {&#xA;         string filename = System.IO.Path.Combine(temp.FullName, "output-00000.ts");&#xA;&#xA;         if (!File.Exists(filename))&#xA;         {&#xA;            throw new FileNotFoundException("Unable to find the generated segment: " &#x2B; filename);&#xA;         }&#xA;&#xA;         output = File.ReadAllBytes(filename);&#xA;      }&#xA;      else&#xA;      {&#xA;         // It&#x27;s been too long. Kill it!&#xA;         ffmpeg.Kill();&#xA;      }&#xA;   }&#xA;&#xA;   // Remove the temporary directory and all its contents.&#xA;   temp.Delete(true);&#xA;&#xA;   return output;&#xA;}&#xA;&#xA;[HttpGet]&#xA;[Route("stream/{id}/{index}.ts")]&#xA;public IActionResult Segment(string id, int index)&#xA;{&#xA;   string path = RetrieveVideoPath(id);&#xA;   return File(GenerateVideoOnDemandSegment(index, 10, path), "application/x-mpegURL", true);&#xA;}&#xA;</byte>

  


  So as you can see, here's the command I use to generate each segment incrementing -ss and -initial_offset by 10 for each segment :

  


  ffmpeg -ss 0 -y -t 10 -i "video.mov" -c:v libx264 -c:a aac -segment_time 10 -reset_timestamps 1 -break_non_keyframes 1 -map 0 -initial_offset 0 -f segment -segment_format mpegts /var/folders/8h/3xdhhky96b5bk2w2br6bt8n00000gn/T/4ynrwu0q.z24/output-%05d.ts


  


  The Problem

  


  Things work on a functional level, however the transition between segments is slightly glitchy and especially the audio has very short interruptions at each 10 second mark. How can I ensure the segments are seamless ? What can I improve in this process ?

  


• Remove characters from string using cmd.exe batch file and ffmpeg

  26 décembre 2023, par user2498772

  Here is the code...

  


  @echo off
:: set paths (no quotes)
set ffmpeg=F:\Video\Ffmpeg\ffmpeg.exe
set infolder=F:\Downloads
set outfolder=F:\Video\Finished



@echo.
@echo on
for %%f in (%infolder%\*.mp4) do "%ffmpeg%" -i "%%~dpnf.mp4" -c copy "%outfolder%\%%~nf.mp4"
@echo off
if errorlevel 1 pause
@echo.


  


  This code converts an mpeg-dash file to mp4.
An mpeg-dash is a streaming file format.

  


  The input and output file looks like this : "filename - DASH_V.mp4". (no quotes)

  


  I would like the output file to have the " - DASH_V" removed, so it looks like "filename.mp4". (no quotes)

  


  Any help would be appreciated. Could be a quick fix like changing "%% dpnf -13.0.mp4" to last command, but I am clueless on syntax as you can see.

  


  Tried a million things and got nowhere. Clueless on syntax.

  


• FFMPEG fails with seeking params before input on AWS Lambda

  18 janvier 2023, par Rashid Goshtasbi

  I am trying to run the following command on AWS Lambda that has FFMPEG layer but it fails with a SIGSEGV. The FFMPEG process starts working fine until it reaches the segment's it wants to get.

  


  /opt/ffmpeglib/ffmpeg -ss 00:02:00 -t 30 -i https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/m3u8s/f08e80da-bf1d-4e3d-8899-f0f6155f6efa-audio-only.m3u8 /tmp/out.aac -y


  


  Note : The url is a sample url for this sharing

  


  What this is doing : It will seek 2 minutes into the stream url, then capture the next 30 seconds into an out.aac file. When I run this locally, it works fine. When I run this on Lambda, it ends abruptly when reading the segments that are in the time frame I want (from 2:00min to 2:30 min).

  


  FFMPEG will skip the frames if I put the -ss 00:02:00 -t 30 before the -i which they state is faster. If i put it after the -i, it works, but of course, it's a bit slower.

  


  Example working command :

  


  /opt/ffmpeglib/ffmpeg -i https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/m3u8s/f08e80da-bf1d-4e3d-8899-f0f6155f6efa-audio-only.m3u8 -ss 00:02:00 -t 30 /tmp/out.aac -y


  


  Wondering if anyone knows a way to run this on Lambda. Thank you.

  


  Note : I have tried this on Python and Javascript. Tried also making child processes with Javascript and no luck. I also added -nostdin and piped stdin/out to dev null but nothing.

  


  Thanks.

  


  Example of me running locally :

  


  ~/D/build [1]$ ffmpeg -ss 00:02:00 -t 30 -i https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/m3u8s/f08e80da-bf1d-4e3d-8899-f0f6155f6efa-audio-only.m3u8 /tmp/out.aac -y                                                                      14:56:13
ffmpeg version 5.1.2 Copyright (c) 2000-2022 the FFmpeg developers
  built with Apple clang version 14.0.0 (clang-1400.0.29.102)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/5.1.2 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-neon
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
[hls @ 0x122f05250] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/m3u8s/f08e80da-bf1d-4e3d-8899-f0f6155f6efa_audio_1_stereo_128000.m3u8' for reading
[hls @ 0x122f05250] Skip ('#EXT-X-VERSION:3')
[hls @ 0x122f05250] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_0.ts' for reading
[hls @ 0x122f05250] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_1.ts' for reading
Input #0, hls, from 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/m3u8s/f08e80da-bf1d-4e3d-8899-f0f6155f6efa-audio-only.m3u8':
  Duration: 00:03:31.43, start: 0.000000, bitrate: 0 kb/s
  Program 0 
    Metadata:
      variant_bitrate : 128000
  Stream #0:0: Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp
    Metadata:
      variant_bitrate : 128000
Stream mapping:
  Stream #0:0 -> #0:0 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[hls @ 0x122f05250] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_30.ts' for reading
[hls @ 0x122f05250] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_31.ts' for reading
Output #0, adts, to '/tmp/out.aac':
  Metadata:
    encoder         : Lavf59.27.100
  Stream #0:0: Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s
    Metadata:
      variant_bitrate : 128000
      encoder         : Lavc59.37.100 aac
[https @ 0x12001c600] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_32.ts' for reading
[https @ 0x124038800] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_33.ts' for reading
[https @ 0x12001c600] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_34.ts' for reading
[https @ 0x124038800] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_35.ts' for reading
[https @ 0x12001c600] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_36.ts' for reading
[https @ 0x124038800] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_37.ts' for reading
[https @ 0x12001c600] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_38.ts' for reading
size=     486kB time=00:00:30.01 bitrate= 132.8kbits/s speed=10.7x    
video:0kB audio:477kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 2.018663%


  


  It doesn't do anything after this line via the lambda console logs :

  


  [hls @ 0x72faa80] Opening 'https://cdn.bitmovin.com/content/assets/art-of-motion-dash-hls-progressive/audio/1_stereo_128000/hls/segment_0.ts' for reading