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• 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.

• Media player get stuck in the middle of a buffered range on Chrome

  29 septembre 2019, par Feng Yu

  WHAT IS MY PROBLEM ?

  My website’s live streaming player use hls.js. From my server’s stat, there is many case where player get stuck in the middle of a buffered range.

  Here is my server raw stat log(removed some useless params) :

  tm=2019-09-27 12:04:41`bufferLevel=8.447303999999974`currentTime=158.4`buffered=[6.024,166.832]`readyState=4`ua=Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36 QBCore/3.53.1153.400 QQBrowser/9.0.2524.400 Tencent AppMarket/4.8 GameCenter

  currentTime is got by HTMLMediaElement.currentTime and buffered is got by HTMLMediaElement.buffered :

  currentTime=158.4
  
  buffered=[6.024,166.832]
  
  readyState=4

  From W3c :

  If HTMLMediaElement.buffered contains a TimeRange that includes the current playback position and enough data to ensure uninterrupted playback :

  1. Set the HTMLMediaElement.readyState attribute to HAVE_ENOUGH_DATA.
  2. Playback may resume at this point if it was previously suspended by a transition to HAVE_CURRENT_DATA.

  In this case, 613.3 is in the middle of [469.277,677.612], video should be progressing, but it is not.

  Hls.js will periodly check currentTime has progressed every 100ms. if currentTime has not progressed for 1000ms, then hls.js will trigger STALL event and I will send a stall stat to server.

  I cannot reproduce this problem on my side, it only appears on my server stat.

  WHAT I’VE TRIED

  shaka player has a module detect this case(https://www.ellealcatrase.eu/player2/docs/api/lib_media_stall_detector.js.html), Its comment shows that :

  Some platforms/browsers can get stuck in the middle of a
  buffered range (e.g. when seeking in a background tab). Detect when
  we get stuck so that the player can respond.

  but I cannot reproduce when my browser is in a background tab.

• How to convert the format of the media source for exoplayer ?

  18 septembre 2019, par Dinu Nicolae

  Is it possible to convert the format of the media source when playing a video with exoplayer ? I thought that I could use FFMPEG to convert the format, but I do not really know how exoplayer works and the problem is that the media source is not a file, but a stream. It is avi format, which unfortunately is not supported by exoplayer, and I could not find any working player for android that has avi support.

  I see there is a ffmpeg extension for exoplayer, but I do not know if that will solve my problem and I have no idea about NDK and compiling c++ for android and the instructions are very unclear. If someone could explain how to do it or give me a guide that would be nice. This is the link to the exoplayer extension :
  ffmpeg extension