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

  26 juin 2012, par Agzam

  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 :

• How can I acheive the best overall FLV quality with FFMPEG ?

  14 novembre 2013, par dcolumbus

  First of all, FFMPEG has the worst documentation of all time, and secondly, the syntax is so trivial that it's often hard to understand what some lines are doing.

  What I'm looking to accomplish would be the best quality FLV with the lowest file size. After all, isn't that everyone's goal ? These videos will be streamed if that makes any difference.

  Do any of you have some command lines that could do this ?

  For now, my video(s) are no wider than 320px, and some are widescreen, so their heights are a little smaller than 240px. As it stands, the quality of the converted FLVs is quite poor.

  Current command :

  > ffmpeg -i video.mov -ar 22050 -ab 32 -f flv -s 320x240 -aspect 4:3 video.flv

• Presenting more then 2 videos using FFmpeg

  9 décembre 2012, par Radagskar

  i found this answer for combining 2 videos using Ffmpeg

  ffmpeg.exe -i LeftInput.mp4 -vf "[in] scale=iw/2:ih/2, pad=2*iw:ih [left]; 
  
      movie=RightInput.mp4, scale=iw/3:ih/3, fade=out:300:30:alpha=1 [right]; 
  
      [left][right] overlay=main_w/2:0 [out]" -b:v 768k Output.mp4

  Is there a way to combine more then 2 ? i tried adding [bottom] and [upper] but i'm failing to understand how the overlay works and where do i put more videos.
  Thanks