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• h264 inside AVI, MP4 and "Raw" h264 streams. Different format of NAL units (or ffmpeg bug)

  24 octobre 2019, par bukkojot

  TL ;DR : I want to read raw h264 streams from AVI/MP4 files, even broken/incomplete.

  Almost every document about h264 tells me that it consists of NAL packets. Okay. Almost everywhere told to me that the packet should start with a signature like 00 00 01 or 00 00 00 01. For example, https://stackoverflow.com/a/18638298/8167678, https://stackoverflow.com/a/17625537/8167678

  The format of H.264 is that it’s made up of NAL Units, each starting
  with a start prefix of three bytes with the values 0x00, 0x00, 0x01
  and each unit has a different type depending on the value of the 4th
  byte right after these 3 starting bytes. One NAL Unit IS NOT one frame
  in the video, each frame is made up of a number of NAL Units.

  Okay.

  I downloaded random_youtube_video.mp4 and strip out one frame from it :

  ffmpeg -ss 10 -i random_youtube_video.mp4 -frames 1 -c copy pic.avi

  And got :
  
  Red part - this is part of AVI container, other - actual data.
  As you can see, here I have 00 00 24 A9 instead of 00 00 00 01

  This AVI file plays perfectly

  I do same for mp4 container :
  

  As you can see, here exact same bytes.
  This MP4 file plays perfectly

  I try to strip out raw data :
  ffmpeg -i pic.avi -c copy pic.h264
  

  This file can’t play in VLC or even ffmpeg, which produced this file, can’t parse it :
  

  I downloaded mp4 stream analyzer and got :
  

  MP4Box tells me :

   Cannot find H264 start code
  
   Error importing pic.h264: BitStream Not Compliant

  It very hard to learn internals of h264, when nothing works.

  So, I have questions :

  1. What actual data inside mp4 ?
  2. What I must read to decode that data (I mean different annex-es)
  3. How to read stream and get decoded image (even with ffmpeg) from this "broken" raw stream ?

  UPDATE :

  It seems bug in ffmpeg :

  When I do double conversion :

           ffmpeg -ss 10 -i random_youtube_video.mp4 -frames 1 -c copy pic.mp4
  
           ffmpeg pic.mp4 -c copy pic.h264

  

  But when I convert file directly :

  ffmpeg -ss 10 -i random_youtube_video.mp4 -frames 1 -c copy pic.h264
  

  I have NALs signatures and one extra NAL unit. Other bytes are same (selected).

  This is bug ?

  UPDATE

  Not, this is not bug, U must use option -bsf h264_mp4toannexb to save stream as "Annex B" format (with prefixes)

• ffmpeg azure function consumption plan low CPU availability for high volume requests

  27 novembre 2017, par The Lemon

  I am running an azure queue function on a consumption plan ; my function starts an FFMpeg process and accordingly is very CPU intensive. When I run the function with less than 100 items in the queue at once it works perfectly, azure scales up and gives me plenty of servers and all of the tasks complete very quickly. My problem is once I start doing more than 300 or 400 items at once, it starts fine but after a while the CPU slowly goes from 80% utilisation to only around 10% utilisation - my functions cant finish in time with only 10% CPU. This can be seen in the image shown below.
  Does anyone know why the CPU useage is going lower the more instances my function creates ? Thanks in advance Cuan

  edit : the function is set to only run one at a time per instance, but the problem exists when set to 2 or 3 concurrent processes per instance in the host.json

  edit : the CPU drops get noticeable at 15-20 servers, and start causing failures at around 60. After that the CPU bottoms out at an average of 8-10% with individuals reaching 0-3%, and the server count seems to increase without limit (which would be more helpful if I got some CPU with the servers)

  Thanks again, Cuan.

  I’ve also added the function code to the bottom of this post in case it helps.

  

  

  using System.Net;
  
  using System;
  
  using System.Diagnostics;
  
  using System.ComponentModel;
  
  
  
  public static void Run(string myQueueItem, TraceWriter log)
  
  {
  
      log.Info($"C# Queue trigger function processed a request: {myQueueItem}");
  
      //Basic Parameters
  
          string ffmpegFile = @"D:\home\site\wwwroot\CommonResources\ffmpeg.exe";
  
          string outputpath = @"D:\home\site\wwwroot\queue-ffmpeg-test\output\";
  
          string reloutputpath = "output/";
  
          string relinputpath = "input/";
  
          string outputfile = "video2.mp4";
  
          string dir =  @"D:\home\site\wwwroot\queue-ffmpeg-test\";
  
  
  
      //Special Parameters
  
  
  
          string videoFile = "1 minute basic.mp4";
  
          string sub = "1 minute sub.ass";
  
      //guid tmp files
  
  
  
          // Guid g1=Guid.NewGuid();
  
          // Guid g2=Guid.NewGuid();
  
          // string f1 = g1 + ".mp4";
  
          // string f2 = g2 + ".ass";
  
          string f1 = videoFile;
  
          string f2 = sub;
  
      //guid output - we will now do this at the caller level
  
          string g3 = myQueueItem;
  
          string outputGuid = g3+".mp4";
  
      //get input files
  
      //argument
  
          string tmp = subArg(f1, f2, outputGuid );
  
      //String.Format("-i \"" + @"input/tmp.mp4" + "\" -vf \"ass = '" + sub + "'\" \"" + reloutputpath +outputfile + "\" -y");
  
      log.Info("ffmpeg argument is: "+tmp);
  
  
  
  
  
      //startprocess parameters
  
      Process process = new Process();
  
      process.StartInfo.FileName = ffmpegFile;
  
      process.StartInfo.Arguments =  tmp;
  
      process.StartInfo.UseShellExecute = false;
  
      process.StartInfo.RedirectStandardOutput = true;
  
      process.StartInfo.RedirectStandardError = true;
  
      process.StartInfo.WorkingDirectory = dir;
  
      //output handler
  
  
  
      process.OutputDataReceived += new DataReceivedEventHandler(
  
          (s, e) => 
  
          { 
  
              log.Info("O: "+e.Data);
  
          }
  
      );
  
      process.ErrorDataReceived += new DataReceivedEventHandler(
  
          (s, e) => 
  
          { 
  
              log.Info("E: "+e.Data);
  
          }
  
      );
  
      //start process
  
      process.Start();
  
      log.Info("process started");
  
      process.BeginOutputReadLine();
  
      process.BeginErrorReadLine();
  
      process.WaitForExit();
  
  }
  
  public static void getFile(string link, string fileName, string dir, string relInputPath){
  
      using (var client = new WebClient()){
  
          client.DownloadFile(link, dir + relInputPath+ fileName);
  
          }
  
  
  
  }
  
  public static string subArg(string input1, string input2, string output1){
  
      return String.Format("-i \"" + @"input/" +input1+ "\" -vf \"ass = '" + @"input/"+input2 + "'\" \"" + @"output/" +output1 + "\" -y");
  
  
  
  }

• Macports, ffpmeg, mpv on High Sierra [on hold]

  21 novembre 2017, par chris

  Has anyone seen this error on macports ?

  I’ve already installed Xcode and agreed license.

  Checked the logs and appears there’s an issue with audiotoolbox :

  :info:configure ERROR: audiotoolbox requested but not found

  Best, Chris

  Chris-MacBookAir:apps chrisbridges$ sudo port install mpv
  
  Password:
  
  --->  Computing dependencies for mpv
  
  The following dependencies will be installed: 
  
   ffmpeg
  
   libcddb
  
   libcdio
  
   libcdio-paranoia
  
   libdvdcss
  
   libdvdnav
  
   libdvdread
  
   lua52
  
   popt
  
   rubberband
  
   youtube-dl
  
  Continue? [Y/n]: Y
  
  --->  Configuring ffmpeg
  
  Error: Failed to configure ffmpeg: configure failure: command execution failed
  
  Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_multimedia_ffmpeg/ffmpeg/main.log for details.
  
  Error: Follow https://guide.macports.org/#project.tickets to report a bug.
  
  Error: Processing of port mpv failed
  
  Chris-MacBookAir:apps chrisbridges$