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• variable video bitrate calculator [closed]

  8 mars 2013, par Meraman

  I am thinking to calculate bitrate of video every second.

  I am thinking if I know size of encoded frames, I can calculate bitrate. If suppose video is 24 fps, then calculating size of these 24 frames will give me size in bits per second, if I am not wrong.

  How can I accomplish this using libraries like FFmpeg and Java.

  Thanks in advance

• BASH : how to make timecode calculations

  31 décembre 2014, par Roger

  I wish to know how to calculate the difference among two video timecodes tha are in frames (in this case, a second equals 30 frames).

  Let say the point A is 600 (00:00:02) and the point B is 120 (00:00:04).

  How can I calculate the difference among pont A and B and echo the result in the 00:00:00.00 format (h:m:s) using bash ?

  ---

  UPDATE :

  This is perfection : http://www.1728.com/angle.htm

• how to convert HLS to RTMP with DISCONTINUITY tag

  21 août 2018, par bekks8

  We have software that produces concatenated HLS files. This concatenation is basically just playlist manipulation. We replace some parts of the manifest by other parts. To make the HLS valid we add a #EXT-X-DISCONTINUITY tag before and after the change :

  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-TARGETDURATION:5
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXT-X-PLAYLIST-TYPE:VOD
  
  #EXTINF:4.0000,
  
  http://host/stream/1
  
  #EXT-X-DISCONTINUITY
  
  #EXTINF:4.0000,
  
  http://host/stream/2
  
  #EXTINF:4.0000,
  
  http://host/stream/3
  
  #EXTINF:4.0000,
  
  http://host/stream/4
  
  #EXTINF:4.0000,
  
  http://host/stream/5
  
  #EXTINF:4.0000,
  
  http://host/stream/6
  
  #EXTINF:0.2917,
  
  http://host/stream/7
  
  #EXT-X-DISCONTINUITY
  
  #EXTINF:4.0000,
  
  http://host/stream/8
  
  #EXT-X-ENDLIST

  In an HTML5 player above manifest will play just fine. Everything is in sync, audio and video play.

  Now, when i try and convert above to an rtmp format and stream this to a rtmp endpoint it works, but it stalls after about 4 seconds, than it continues missing 4 seconds, and runs fine after that.

  Basically, it plays part 1, skips 2, and continues with 3.

  I’ve checked the logs for ffmpeg which repeat :

  [flv @ 0x7fa696837c00] Non-monotonous DTS in output stream 0:1; previous: 3924, current: 0; changing to 3924. This may result in incorrect timestamps in the output file.
  
  [flv @ 0x7fa696837c00] Non-monotonous DTS in output stream 0:1; previous: 3924, current: 23; changing to 3924. This may result in incorrect timestamps in the output file.
  
  [flv @ 0x7fa696837c00] Non-monotonous DTS in output stream 0:1; previous: 3924, current: 46; changing to 3924. This may result in incorrect timestamps in the output file.

  After the DTS warnings ffmpeg reports that it dropped 95 frames :

  frame=  102 fps= 22 q=28.0 size=     181kB time=00:00:04.34 bitrate= 341.7kbits/s dup=0 drop=95 speed=0.958x

  This of course makes, sense, when i check with ffprobe i can see that the PTS isn’t aligned (which is expected) :

  frame|pkt_pts_time=5.316667|pkt_dts_time=5.316667|pict_type=B
  
  frame|pkt_pts_time=5.358333|pkt_dts_time=5.358333|pict_type=B
  
  frame|pkt_pts_time=5.400000|pkt_dts_time=1.400000|pict_type=P
  
  frame|pkt_pts_time=5.441667|pkt_dts_time=1.441667|pict_type=P
  
  frame|pkt_pts_time=1.483333|pkt_dts_time=1.483333|pict_type=I
  
  frame|pkt_pts_time=1.525000|pkt_dts_time=1.525000|pict_type=B
  
  frame|pkt_pts_time=1.566667|pkt_dts_time=1.566667|pict_type=B

  The 95frames, is exactly the number of frames with a PKT_PTS_TIME (and DTS) in the past.

  the ffmpeg command i use to create the RTMP stream is :

  ffmpeg -fflags +igndts -re -i http://host/manifest -c:v libx264 -force_key_frames "expr:gte(t,n_forced*2)" -c:a aac -ar 44100 -r 24 -f flv rtmp://domain/some/rtmp/endpoint

  What i’m looking for is a way to convert the HLS to a valid RTMP, without it skipping the frames with a PTS in the past. I would like it to just regenerate the PTS :
  Is there a way to tell ffmpeg to regenerate the PTS/DTS timestamps in it’s output file ?