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• Why is one ffmpeg webm dash stream much larger than the others ?

  5 janvier 2017, par ranvel

  Over the summer, I worked on putting together a script which took a x264 video/mp3 stream and broke it up into the different streams so that it would work via MSE-DASH. (Based heavily on the instructions on the webmproject.org website) Those same scripts have ceased to work, turning a 6GB video into several 25 Gb videos. I kept up with updates of ffmpeg and so I don’t know when it stopped working, but I am guessing it was due to the way that their DASH Webm implementation was updated.

  I found new method which works better, but still has a major problem with one stream. I was hoping someone could explain how this encoding works so that I could understand the underlying cause.

  #!/bin/bash
  
  COMMON_OPTS="-map 0:0 -an -threads 11 -cpu-used 4 -cmp chroma"
  
  WEBM_OPTS="-f webm -c:v vp9 -keyint_min 50 -g 50 -dash 1"
  
  
  
  ffmpeg -i $1 -vn -acodec libvorbis -ab 128k audio.webm &
  
  ffmpeg -i $1 $COMMON_OPTS $WEBM_OPTS -b:v 500k -vf scale=1280:720 -y vid-500k.webm &
  
  ffmpeg -i $1 $COMMON_OPTS $WEBM_OPTS -b:v 700k -vf scale=1280:720 -y vid-700k.webm & 
  
  ffmpeg -i $1 $COMMON_OPTS $WEBM_OPTS -b:v 1000k -vf scale=1280:720 -y vid-1000k.webm &
  
  ffmpeg -i $1 $COMMON_OPTS $WEBM_OPTS -b:v 1500k -vf scale=1280:720 -y vid-1500k.webm  

  The transcode is not yet complete, but you can see where this is headed :

  -rw-r--r--  1 user  staff    87M Jan  4 23:27 audio.webm
  
  -rw-r--r--  1 user  staff    27M Jan  4 23:42 vid-1000k.webm
  
  -rw-r--r--  1 user  staff   285M Jan  4 23:42 vid-1500k.webm
  
  -rw-r--r--  1 user  staff    15M Jan  4 23:42 vid-500k.webm
  
  -rw-r--r--  1 user  staff    20M Jan  4 23:42 vid-700k.webm

  The 1500k variant is disproportionately larger than the other streams.

  The other problem is that when I use a shorter video, lets say eight or nine minutes, the above configuration runs as expected and everything is perfect. I don’t know where the limit for this is since each test costs a lot of processing power and time, but if it’s less than ten minutes, it works and if its longer than an hour, it produces massive files.

• TypeError : Cannot read property 'url' of undefined - ws

  28 juillet 2021, par Bawantha Rathnayaka

  I am trying to get URL starts with '/rtmp/', and extract the target RTMP URL.

  


  Uncaught TypeError : Cannot read property 'url' of undefined

  


  this is my server.js

  


    let match
  if (!(match = req.url.match(/^\/rtmp\/(.*)$/))) {
    ws.terminate() // No match, reject the connection.
    return
  }

  


  


• avformat/mov : add option max_stts_delta

  27 novembre 2021, par Gyan Doshi

  avformat/mov : add option max_stts_delta
  Very high stts sample deltas may occasionally be intended but usually
  
  they are written in error or used to store a negative value for dts correction
  
  when treated as signed 32-bit integers.
  This option lets the user set an upper limit, beyond which the delta is clamped to 1.
  
  Values greater than the limit if negative when cast to int32 are used to adjust onward dts.
  Unit is the track time scale. Default is UINT_MAX - 48000*10 which
  
  allows upto a 10 second dts correction for 48 kHz audio streams while
  
  accommodating 99.9% of uint32 range.
  Signed-off-by : Gyan Doshi <ffmpeg@gyani.pro>
  
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] doc/demuxers.texi
  • [DH] libavformat/isom.h
  • [DH] libavformat/mov.c