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• avformat/matroskadec : Don't discard valid packets

  25 mars 2020, par Andreas Rheinhardt

  avformat/matroskadec : Don't discard valid packets
  A Block (meaning both a Block in a BlockGroup as well as a SimpleBlock)
  
  must have at least three bytes after the field containing the encoded
  
  TrackNumber. So if there are <= 3 bytes, the Matroska demuxer would
  
  skip this block, believing it to be an empty, but valid Block.
  This might discard valid nonempty Blocks, namely if the track uses header
  
  stripping. And certain definitely spec-incompliant Blocks don't raise
  
  errors : Those with two or less bytes left after the encoded TrackNumber
  
  and those with three bytes left, but with flags indicating that the Block
  
  uses lacing as then there has to be further data describing the lacing.
  Furthermore, zero-sized packets were still possible because only the
  
  size of the last entry of a lace was checked.
  This commit fixes this. All spec-compliant Blocks that contain data
  
  (even if side data only) are now returned to the caller ; spec-compliant
  
  Blocks that don't contain anything are not returned.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskadec.c

• Live video feed from ffmpeg to html with minimum latency

  11 juin 2020, par XPModder

  I am currently working on a project that requires me to get live video from a raspberry pi camera and stream it to a html page. At the moment I am using ffmpeg to create *.m3u8 and *.ts files and stream the video that way. In the html page I have hls.js running that receives the video and displays it through a video tag. This does work pretty good, but the latenca is a problem... The video in the browser is always between a few seconds and multiple minutes late. This is not really acceptable.

  



  I am currently using the following command to run ffmpeg :

  



  ffmpeg -loglevel quiet -y -i - -c:v copy -preset veryfast -hls_wrap 2 -hls_time 1 -g 1 stream.m3u8

  



  I have also tried other values for -hls_time and -g including values between 0 and 1.

  



  I am now searching for an alternative solution, that does not have this problem, or a way to reduce the latency to at least 2 seconds max. The video itself is transferred in to ffmpeg as h264. The html webpage is hosted on the same raspberry pi using apache2.

  



  Is there a way to accomplish that without installing a seperate streaming server on the pi ?

  



  Also this all has to work without a internet connection. Meaning the pi and the smartphone/computer that is viewing the html page are on the same wifi, but that wifi does not always have a connection to the internet and does not need to have one.

  



  So basically I want to have h264 video into ffmpeg and then somehow into html tag. The stream should also be accessable in another way, as I have a button on the page that should start and stop the recording of the stream to an mp4 file. This recording is also done using ffmpeg at the moment.

  



  I am asking this here and not on the raspberry pi stackexchange forum, because it is a general problem and the problem itself does not have anythingto do with the raspberry pi.

  


• To convert from avi file to mp4 file by ffmpeg command in php

  12 septembre 2018, par user27240

  The ffmpeg command in php below creates mp4 file from avi file without deleting the original avi file meaning that,for example,
  there are two files, 1221222.avi and 1221222.mp4 exist in the directry after all.

  (’for i in /xxxxx/xxxxxx/*.avi ; do ffmpeg -i "$i" -frames:v 1 "/xxxxx/xxxxxx/$(basename "$i" .avi).mp4" ; done’)

  I’d like to delete this 1221222.avi file right after the command created 1221222.mp4 file.

  Is there any command that converts the file from avi to mp4 by replacing it ? Or do I have to add delete command after the command above ?

  I would appreciate if anyone could help me out for the command.

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  Even though the php script below can upload avi file from local drive to application I’m currently developping, the avi will not be played at html.
  So, I’m trying to convert from the avi file to mp4 file which is working fine by using ffmpeg command in php. This ffmpeg command creates mp4, but the html still do not play it. Is it because the original avi file still exists in the directory ?

  //php
  
  case "video/x-msvideo":
  
  
  
  if($header){
  
      header("Content-Type: video/x-msvideo");
  
  
  
   $dst_im = copy($path, $dst_file);
  
   return "";
  
   }else{ 
  
  
  
   $dst_file = $dst_file . ".avi";
  
   shell_exec('for i in  /xxxxxx/xxxxxx/*.avi; do ffmpeg -i "$i" - frames:v 1 "/xxxxxx/xxxxxx/$(basename "$i"  .avi).mp4"; done');      
  
  
  
   $dst_im = copy($path, $dst_file);
  
   }
  
   unlink($dst_im);
  
   break; 
  
  
  
  
  
  //html
  
  <video width="500" height="250" poster="video.jpg" controls="controls" preload="auto" autoplay="autoplay">
  
  <source type="video/mp4" src="xxxxxxxxxxxxxxxxxxxxx.mp4"></source>
  
  </video>