Recherche avancée

Sur d’autres sites (2831)

• Could I configure the PLC scheme to be used in a video player ?

  27 novembre 2017, par user9013612

  First of all, I am dealing with video codec H.264.

  I am working with a recommendation which says that the decoder can work with two different modes of operations in the PLC (packet loss concealment) : FREEZING (the PLC scheme tries to repair erroneous frames (either due to packet loss or error propagation) with the previous error free frame until a decoded picture without errors has been received) and the other mode is SLICING (the PLC scheme tries to repair erroneous frames).

  So the question is : Do you know whether it exists a player/decoder in which you can configure the PLC scheme you wanna use when playing a video ?

• Revision bb260d9076 : Rework partition search skip scheme This commit enables the encoder to skip spl

  3 octobre 2014, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_rdopt.c

  
   Modify /vp9/encoder/vp9_speed_features.c

  
   Modify /vp9/encoder/vp9_tokenize.c

  
   Modify /vp9/encoder/vp9_tokenize.h

  
  
  Rework partition search skip scheme

  This commit enables the encoder to skip split partition search if
  the bigger block size has all non-zero quantized coefficients in low
  frequency area and the total rate cost is below a certain threshold.
  It logarithmatically scales the rate threshold according to the
  current block size. For speed 3, the compression performance loss :
  derf -0.093%
  stdhd -0.066%

  Local experiments show 4% - 20% encoding speed-up for speed 3.
  blue_sky_1080p, 1500 kbps
  51051 b/f, 35.891 dB, 67236 ms ->
  50554 b/f, 35.857 dB, 59270 ms (12% speed-up)

  old_town_cross_720p, 1500 kbps
  14431 b/f, 36.249 dB, 57687 ms ->
  14108 b/f, 36.172 dB, 46586 ms (19% speed-up)

  pedestrian_area_1080p, 1500 kbps
  50812 b/f, 40.124 dB, 100439 ms ->
  50755 b/f, 40.118 dB, 96549 ms (4% speed-up)

  mobile_calendar_720p, 1000 kbps
  10352 b/f, 35.055 dB, 51837 ms ->
  10172 b/f, 35.003 dB, 44076 ms (15% speed-up)

  Change-Id : I412e34db49060775b3b89ba1738522317c3239c8

• Why this simple video streaming scheme does not work ?

  8 août 2014, par Vi.

  I’ve tried setting up simple webm video streaming scheme, based on ffserver and <video></video> element :

  # relevant part of ffserver.conf
  
  <stream>
  
      Feed feed1.ffm
  
  
  
      Format webm
  
      VideoFrameRate 15
  
      AVOptionVideo flags +global_header
  
      VideoSize 640x480
  
      VideoCodec libvpx
  
      VideoBitRate 800
  
  NoAudio
  
  </stream>
  
  
  
  # ffmpeg command line
  
  ffmpeg -f rawvideo -s 640x480 -i /dev/zero -vb 100000  http://vsodo.vi-server.org:8090/feed1.ffm
  
  
  
  # video element
  
  <video controls="controls" autoplay="autoplay">
  
      <source src="http://vsodo.vi-server.org:8090/feed1.webm" type="video/webm"></source>
  
      Your browser does not support the video tag.
  
  </video> 

  But it works only in few cases :

  • luakit - works (uses GStreamer) ;
  • uzbl - works ;
  • Firefox - fails (at least in versions 17, 24 and 26 and 31) ;
  • Chromium 31.0.1650.63 - fails ;
  • Google Chrome 27.0.1453.93 - fails ;
  • Built-in browser in Android 2.3 - fails.

  Failing browsers usually show the video length and the fact that there’s no audio track, but the video area stays black, not green as expected.

  This page lists "Partial support" or "Supported" for webm and video element. Usual players like VLC or mplayer work if specify http://vsodo.vi-server.org:8090/feed1.webm to them. Example video page also works (except of on Android 2.3).

  Why it can fail ? How do I troubleshoot browser-specific the <video></video> problems ?