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• Http Live Streaming EXT-X-STREAM-INF, Calculating BANDWITH

  4 octobre 2023, par iLemming

  Initially I've tried to find possible ways to do HLS segmenting on other non-Mac platforms.

  



  Segmenting videos for HLS involves the following steps :

  



  1) Splitting the encoded video into segments

  



  2) Creating playlist (.m3u8) file that simply contains list of segments for the current rendition, including duration in seconds for each segment

  



  3) Creating a variant playlist that contains relative paths to all playlists of all renditions with the information about BANDWITH which according to HTTP Live streaming protocol is :

  



  The value is a decimal-integer of bits per second. It MUST be an upper bound of the overall bitrate of each media segment (calculated to include container overhead) that appears or will appear in the Playlist.

  



  Latest version of ffmpeg includes possibilities of splitting videos. However ffmpeg can’t create m3u8 files. Creating simple playlist not a problem. But creating variant playlist might be :

  



  So variantplaylistcreator on Mac creates those, calculates somehow bitrates and puts value based on that into BANDWITH tag.

  



  I’ve tried many different ways but yet I couldn’t get exactly the same numbers that variantplaylistcreator does, and at this point I can’t find any information how exactly it calculates those values and what algorithm it uses.
My numbers are close, but still slightly different.

  



  In theory it should not be a problem, but the point is - I don’t know that for sure. 
Maybe the BANDWITH information should be precise for flawless video playing, maybe it doesn’t have to.

  



  Anyway I'm really curious how exactly variantplaylistcreator calculates them :

  


• avfilter/buffersrc : promote unspecified color metadata

  12 janvier 2024, par Niklas Haas

  avfilter/buffersrc : promote unspecified color metadata
  Currently, this only affects untagged RGB/XYZ/Gray, which get forced to
  
  their corresponding metadata before entering the filter graph. The main
  
  justification for this change, however, is the planned ability to add
  
  automatic promotion of unspecified yuv to mpeg range yuv.
  Notably, this change will never allow accidentally cross-promoting
  
  unspecified to jpeg or to a specific YUV matrix, since that is still
  
  bound by the constraints of YUV range negotiation as set up by
  
  query_formats.
  

  • [DH] libavfilter/buffersrc.c
  • [DH] tests/ref/fate/rgb24-mkv

• Live Streaming WebM with Wowza Server

  2 décembre 2010, par noreply@blogger.com (John Luther)

  Guest blogger Charlie Good is CTO and co-founder of Wowza Media Systems

  As a company, we at Wowza move fast and like to tinker. When WebM was announced in May, we saw it as a promising new approach to HTML5 video and decided to do an experiment with live WebM streaming over http.

  Adding WebM VP8 video and Vorbis audio to the other encoding formats that our server supported was easy (we designed the Wowza server to be codec-agnostic). We then created a WebMfile and implemented WebM HTTP streaming.

  We originally created the demo as a proof-of-concept for the IBC show in September, 2010 but have made it available to watch on our web site.

  The file is streamed live (more precisely, "pseudo-live") over http using the Wowza server-side publishing API (PDF). The result is very impressive ; playback starts fast and the VP8 image quality is fantastic.

  You will need a WebM-enabled browser or VLC media player 1.1.5 to view the live stream.

  If you’re interested in keeping up with Wowza’s WebM progress, visit Wowza Labs or drop us a note at info@wowzamedia.com.