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• ffmpeg to generate dash and HLS - best practise

  8 septembre 2017, par LaborC

  Looking for the correct way to encode a given input video in multiple bitrates and then package it for dash and HLS. I thought this is a basic task, but for me it was quite a challenge. So the way I do it is as follows :

  First I split my video (mp4) into video and audio (I encode the audio, because I need to make sure that the output codec is aac, which is a requirement for web I think).

  ffmpeg -c:v copy -an video_na.mp4 -i source_input.mp4
  
  ffmpeg -c:a aac -ac 2 -async 1 -vn audio.mp4 -i source_input.mp4

  Then I encode the video with the following commands :

      ffmpeg.exe -i video_na.mp4 -an -c:v libx264 -crf 18 \
  
  -preset fast -profile:v high -level 4.2 -b:v 2000k -minrate 2000k \
  
  -maxrate 2000k -bufsize 4000k -g 96 -keyint_min 96 -sc_threshold 0 \
  
  -filter:v "scale='trunc(oh*a/2)*2:576'" -movflags +faststart \
  
  -pix_fmt yuv420p -threads 4 -f mp4 video-2000k.mp4
  
  
  
      ffmpeg.exe -i video_na.mp4 -an -c:v libx264 -crf 18 \
  
  -preset fast -profile:v high -level 4.2 -b:v 1500k -minrate 1500k \
  
  -maxrate 1500k -bufsize 3000k -g 96 -keyint_min 96 -sc_threshold 0 \
  
  -filter:v "scale='trunc(oh*a/2)*2:480'" -movflags +faststart \
  
  -pix_fmt yuv420p -threads 4 -f mp4 video-1500k.mp4

  After that I fragment the videos (I used the parameter —timescale 10000 but then the result was out of sync).
  Sidenote : the -g parameter is 4 times 24 (frames). this is important because the fragmentation is 4000 (4 seconds)

  mp4fragment --fragment-duration 4000 video-2000k.mp4 \
  
  video-2000k-f.mp4
  
  
  
  mp4fragment --fragment-duration 4000 video-1500k.mp4 \
  
  video-1500k-f.mp4

  And finally package everything together again for dash (I used to use —use-segment-timeline but then again the result was out-of-sync).
  I use mp4dash and not mp4box because I want to be able to encrypt everything later on for DRM.

  mp4dash --media-prefix=out  \
  
        video-2000k-f.mp4  \
  
        video-1500k-f.mp4  \
  
       --out dash

  The result works in Firefox, Chrome, IE Edge via a webserver and via Cloudfront AWS Streaming also on older browsers.

  So for me there are still 2 tasks to accomplish.
  First I need to generate a HLS package for Apple Phone, IPad Users.
  And second : I need to encrypt everything.

  So far my HLS command is :

  ffmpeg -y -loglevel info ^
  
          -i video-2000k.mp4 \
  
          -i video-1500k.mp4 \
  
          -i audio.mp4 \
  
          -profile:v baseline -start_number 0 -hls_time 10 \
  
          -flags -global_header -hls_list_size 0 -f hls hls/master.m3u8

  This basically works, but generates only 1 bandwith without the posibility of multi-streams.
  I am not certain about that statement, but it looks that way.
  Has anyone an idea on what I am doing wrong ?

• Ffmpeg error with output file not specified on linux when executing from dockerized new process in .net-core

  29 août 2017, par DutchGuy

  Some time back i created a small program in full .net framework that could rip mp3 and then add meta-info and a thumbnail to it. For innovation sake i started porting the application to .net core. After that i thought it would be cool to run this in docker on Linux. It took some time but i got it working. Now i’m running into the issue where i can rip the mp3 from the video file but when i try to combine the meta-info, thumbnail and mp3 ffmpeg tells me "At least one output file must be specified"

  I added some checks so the program can run on Linux and Windows (to switch paths etc)

  What i tried :

  • running same argument structure on windows (works)
  • Manualy starting the encode on linux (works)
  • Simplifying the names, paths and titles used in the command
  • replacing extra spaces and special characters, only "-" and single spaces allowed

  Below i have an example of the command that does work when i execute it manually but produces the earlier mentioned error when my program executes it. Also keep in mind that ripping the mp3 from the video does result in the desired outputfile.

  ffmpeg -i "temp/vid-id.mp3" -i "temp/vid-id.jpg" -map 0:0 -map 1:0 -c copy -y -id3v2_version 3 -metadata title="title" -metadata artist="artist" -metadata album="album" "completed/file - name.mp3"

  To start this from .net-core context i use the snippet below :

  using (var ffmpegProcess = new Process())
  
  {
  
    ffmpegProcess.EnableRaisingEvents = false;
  
    ffmpegProcess.StartInfo.CreateNoWindow = true;
  
    ffmpegProcess.StartInfo.UseShellExecute = false;
  
    ffmpegProcess.StartInfo.FileName = ffmpegPath(); (returns "/bin/bash")
  
  
  
    string command = "ffmpeg " + arguments;
  
  
  
    ffmpegProcess.StartInfo.Arguments = "-c \" " + command + " \"";
  
  
  
    ffmpegProcess.Start();
  
    ffmpegProcess.WaitForExit();
  
    ffmpegProcess.Dispose();
  
  }

  arguments :

  String.Format("-i \"{0}\" -i \"{1}.jpg\" -map 0:0 -map 1:0 -c copy -y -id3v2_version 3 -metadata title=\"{2}\" -metadata artist=\"{3}\" -metadata album=\"{4}\" \"{5}\"",inputFile, albumArtFile, outputTitle, artist, outputAlbum, outputFile);

  To rip the mp3 from the video file i use the same method mentioned above with the following arguments :

  -i "temp/vid-id.mp4" -vn -ab 320k -y -threads 2 "temp/vid-id.mp3"

  This works as expected.
  Arguments :

  String.Format("-i \"{0}\" -vn -ab 320k -y -threads 2 \"{1}\"", inputFile, outputFile);

  Vid-id does not contain spaces, below is and example of how it could look :

  "abcd12ef-gh34i"

  Since the initial ripping is working i cant figure out why Ffmpeg complains about the second operation. The only real difference between the two operations is that in the second one the output-file name can contain spaces. But even then, running the same command manually does work and produces the desired file in the completed dir.

  Update
  After more troubleshooting i have now narrowed the problem down to the usage of the metadata arguments. Still can’t figure out why

  Update
  The problem is with the spaces in the naming i have chosen. On linux the spaces are interpreted as end of file name. Any pointer how i can still use the naming with spaces ?

• Using FFmpeg in .net ?

  17 juin, par daniel

  So I know its a fairly big challenge but I want to write a basic movie player/converter in c# using the FFmpeg library. However, the first obstacle I need to overcome is wrapping the FFmpeg library in c#. I've downloaded ffmpeg but couldn't compile it on Windows, so I downloaded a precompiled version for me. Ok awesome. Then I started looking for C# wrappers.

  



  I have looked around and have found a few wrappers such as SharpFFmpeg (http://sourceforge.net/projects/sharpffmpeg/) and ffmpeg-sharp (http://code.google.com/p/ffmpeg-sharp/). First of all, I wanted to use ffmpeg-sharp as its LGPL and SharpFFmpeg is GPL. However, it had quite a few compile errors. Turns out it was written for the mono compiler, I tried compiling it with mono but couldn't figure out how. I then started to manually fix the compiler errors myself, but came across a few scary ones and thought I'd better leave those alone. So I gave up on ffmpeg-sharp.

  



  Then I looked at SharpFFmpeg and it looks like what I want, all the functions P/Invoked for me. However its GPL ? Both the AVCodec.cs and AVFormat.cs files look like ports of avcodec.c and avformat.c which I reckon I could port myself ? Then not have to worry about licencing.

  



  But I want to get this right before I go ahead and start coding. Should I :

  



  

  1. Write my own C++ library for interacting with ffmpeg, then have my C# program talk to the C++ library in order to play/convert videos etc.

  


  



  OR

  



  

  2. Port avcodec.h and avformat.h (is that all i need ?) to c# by using a whole lot of DllImports and write it entirely in C# ?

  


  



  First of all consider that I'm not great at C++ as I rarely use it but I know enough to get around. The reason I'm thinking #1 might be the better option is that most FFmpeg tutorials are in C++ and I'd also have more control over memory management than if I was to do it in c#.

  



  What do you think ?
Also would you happen to have any useful links (perhaps a tutorial) for using FFmpeg ?