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• Play HLS segments through Media source extensions

  11 février 2018, par ler

  I got a list of m4s and init.mp4 from this FFMPEG command

  ffmpeg -i bunny.mp4 -f hls -hls_segment_type fmp4 -c:v copy playlist.m3u8

  I send those chunks using Socketand try to play them through MSE.
  When i send them in this order :

  init.mp4 + playlist0.m4s + playlist1.m4s ...

  They play without any problem, But when i want to start from the chunk number 3 meaning init.mp4 + playlist3.m4s for example i get this error :

  video frame with PTS 0us has negative DTS -80000us after applying timestampOffset, handling any discontinuity, and filtering against append window.

  I want to be able to start from any chunk, currently the only way to play the video is to star by init.mp4 + playlist0.m4s meaning playlist0.m4s because init.mp4 contain just headers of the video, This is the client code i’m using :

  var socket = io();
  
  var video = document.querySelector('video');
  
  var mimeCodec = 'video/mp4; codecs="avc1.64000d,mp4a.40.2"'; // true
  
  if ('MediaSource' in window && MediaSource.isTypeSupported(mimeCodec)) 
  
  {
  
      var mediaSource = new MediaSource;
  
      video.src = URL.createObjectURL(mediaSource);
  
      mediaSource.addEventListener('sourceopen', function () {
  
              var mediaSource = this;
  
              var sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  
             sourceBuffer.mode = 'segments'; 
  
              sourceBuffer.addEventListener('updateend', function (_) { video.play().then(function() { }).catch(function(error) { }); });
  
              socket.on('broadcast', function (chunk) {
  
                  downloadData(chunk.uri, function(arrayBuffer) {
  
                      sourceBuffer.appendBuffer(arrayBuffer);
  
                  });
  
              });
  
      });
  
  } else {
  
      console.error('Unsupported MIME type or codec: ', mimeCodec);
  
  }
  
  function downloadData(url, cb) {
  
      var xhr = new XMLHttpRequest;
  
      xhr.open('get', url);
  
      xhr.responseType = 'arraybuffer';
  
      xhr.onload = function () {
  
          cb(new Uint8Array(xhr.response));
  
      };
  
      xhr.send();
  
  }

• Ffmpeg - Generate VTT File From Sprite, Using Spatial Media Fragment

  20 octobre 2019, par David

  Hi I am looking to create a .VTT file from a sprite that i have generated using Ffmpeg.

  Ffmpeg command :

   $"-i {inputMediaFile} -vf \"select = not(mod(n\\, 30)),scale = 120:80,tile = 7x7\" -an -vsync 0 {outputMediaFile}"

  This selects every 30th frame, and then scales it to 120x80 pixels and creates 8x8 tiles in the output image.

  I would like to make a .VTT from the generated image in C#, so i know the height and width of my individual images in the sprite (120x80) and there is 64 images in total in the output image.

  From this i need to produce a VTT like this :

  WEBVTT
  
  
  
  1
  
  00:00:00.000 --> 00:00:01.000
  
  test-00001.jpg#xywh=0,0,120,80
  
  
  
  2
  
  00:00:01.000 --> 00:00:02.000
  
  test-00001.jpg#xywh=120,0,120,80
  
  
  
  3
  
  00:00:02.000 --> 00:00:03.000
  
  test-00001.jpg#xywh=240,0,120,80
  
  
  
  4
  
  00:00:03.000 --> 00:00:04.000
  
  test-00001.jpg#xywh=360,0,120,80
  
  
  
  5
  
  00:00:04.000 --> 00:00:05.000
  
  test-00001.jpg#xywh=480,0,120,80
  
  
  
  6
  
  00:00:05.000 --> 00:00:06.000
  
  test-00001.jpg#xywh=600,0,120,80
  
  
  
  7
  
  00:00:06.000 --> 00:00:07.000
  
  test-00001.jpg#xywh=720,0,120,80
  
  
  
  8
  
  00:00:07.000 --> 00:00:08.000
  
  test-00001.jpg#xywh=840,0,120,80
  
  
  
  9
  
  00:00:08.000 --> 00:00:09.000
  
  test-00001.jpg#xywh=0,80,120,80

  There is also situations when there is n amount of sprite files.

  Im hoping there may be a library out there that can handle this, or even better if i can keep it contained within Ffmpeg - based on Ffmpeg docs i dont think this is possible though.

  Thanks in advance if anyone as any ideas, its doable as ive seen Nodejs and Ruby examples.

• Matching a specific media format with ffmpeg/avconv

  5 mai 2020, par Markus A.

  I need to encode a video from static images in such a way that it format-matches another one so I can splice the video streams together.

  



  Here is the mediainfo of the file I'm trying to match :

  



  Video
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline@L3.1
Format settings, CABAC                   : No
Format settings, ReFrames                : 1 frame
Codec ID                                 : 7
Duration                                 : 2mn 46s
Bit rate                                 : 1 614 Kbps
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Variable
Standard                                 : NTSC
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Stream size                              : 32.0 MiB (87%)
Color primaries                          : BT.601 PAL
Transfer characteristics                 : BT.601
Matrix coefficients                      : BT.601


  



  So far, what I have been able to come up with is the following :

  



  avconv -f image2 -framerate 1.2 -i loop_%d.tif -c:v libx264 -preset veryslow -profile:v baseline -level:v 31 -b:v 1614K -refs 1 loop.flv


  



  This gets me to :

  



  Video
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline@L3.1
Format settings, CABAC                   : No
Format settings, ReFrames                : 1 frame
Codec ID                                 : 7
Duration                                 : 2s 917ms
Bit rate                                 : 1 614 Kbps
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 1.200 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 1.459
Stream size                              : 575 KiB
Writing library                          : x264 core 142 r2431 a5831aa
Encoding settings                        : cabac=0 / ref=1 / deblock=1:0:0 / analyse=0x1:0x131 / me=umh / subme=10 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=24 / chroma_me=1 / trellis=2 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=250 / keyint_min=1 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=abr / mbtree=1 / bitrate=1614 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00


  



  Which, unfortunately, still isn't good enough as VLC Media Player crashes hard (just closes), logging main error: Failed to compensate for the format changes, removing all filters; main error: Failed to create video converter as soon as the stream splice occurs. I tried splicing another stream in that does have the exact same encoding, and it works fine. I'm also making sure to only splice on key-frames and I am including the NALU containing the AVCDecoderConfigRecord, so I'm pretty sure I'm not doing anything else wrong, especially since a couple other programs are fine with the splice. It's just VLC that expects an even closer match.

  



  Here are things I've tried :

  



  

  • Adding -vsync 2 to get variable frame rate mode. Doesn't change anything.

  


  • Adding -color_primaries bt470bg -color_trc gamma28 -colorspace bt470bg to try to get BT.601 PAL settings (several websites mentioned this). Doesn't change anything.

  


  • Adding -s ntsc to set the standard to NTSC. This also changes the resolution to 720x480 (not OK), and specifying -s 1280x720 in addition gets rid of the NTSC tag again.

  


  



  If anyone knows what flags I need to supply to get closer, that would be super-helpful ! The stream I'm trying to match is encoded on an Android device (it's a live-stream), so I'm assuming it is built using the standard Android MediaCoder framework, in case that helps.