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• How do I set ffmpeg pipe output ?

  5 décembre 2019, par mr_blond

  I need to read ffmpeg output as pipe.
  There is a code example :

      public static void PipeTest()
  
      {
  
          Process proc = new Process();
  
          proc.StartInfo.FileName = Path.Combine(WorkingFolder, "ffmpeg");
  
          proc.StartInfo.Arguments = String.Format("$ ffmpeg -i input.mp3 pipe:1");
  
          proc.StartInfo.UseShellExecute = false;
  
          proc.StartInfo.RedirectStandardInput = true;
  
          proc.StartInfo.RedirectStandardOutput = true;
  
          proc.Start();
  
  
  
          FileStream baseStream = proc.StandardOutput.BaseStream as FileStream;
  
          byte[] audioData;
  
          int lastRead = 0;
  
  
  
          using (MemoryStream ms = new MemoryStream())
  
          {
  
              byte[] buffer = new byte[5000];
  
              do
  
              {
  
                  lastRead = baseStream.Read(buffer, 0, buffer.Length);
  
                  ms.Write(buffer, 0, lastRead);
  
              } while (lastRead > 0);
  
  
  
              audioData = ms.ToArray();
  
          }
  
  
  
          using(FileStream s = new FileStream(Path.Combine(WorkingFolder, "pipe_output_01.mp3"), FileMode.Create))
  
          {
  
              s.Write(audioData, 0, audioData.Length);
  
          }
  
      }

  It’s log from ffmpeg, the first file is readed :

  Input #0, mp3, from ’norm.mp3’ :
  Metadata :
  encoder : Lavf58.17.103
  Duration : 00:01:36.22, start : 0.023021, bitrate : 128 kb/s
  Stream #0:0 : Audio : mp3, 48000 Hz, stereo, fltp, 128 kb/s
  Metadata :
  encoder : Lavc58.27

  Then pipe :

  [NULL @ 0x7fd58a001e00] Unable to find a suitable output format for ’$’
  $ : Invalid argument

  If I run "-i input.mp3 pipe:1", the log is :

  Unable to find a suitable output format for ’pipe:1’ pipe:1 : Invalid
  argument

  How do I set correct output ? And how should ffmpeg know what the output format is at all ?

• Stream real-time video flux in HTML video tag

  26 septembre 2018, par c.censier

  I want to stream a real-time video flux that come from udp into a HTML video tag.
  I made some research but I got a lot of informations and I struggle to have a clear overview of what I can do and what I can’t.

  The video flux use H.264 and AAC codecs, MP4 container and has a 3840x2160 (4K) resolution. I’d like to play it on Chrome (latest version).

  As I understand from now, HTML video tag can natively read H.264/AAC videos. I made it work with the video direclty on my server (I’m using Meteor JS + React).

  I learnt to use FFmpeg to stream an udp flux read by VLC player, and then I used FFserver (I know it’s deprecated) to create an HTTP flux also read by VLC but not by the HTML video tag.

  So... my question is : is HTML video can natively read video stream from HTTP ?

  I’ve seen a lot of discussions about HLS and DASH, but I didn’t understand if (and why) they’re mandatory.

  I read a post about someone creating a HLS m3u8 using only FFmpeg, is it a viable solution ?

  FFserver configuration

  HTTPPort                        8090
  
  HTTPBindAddress                 0.0.0.0
  
  MaxHTTPConnections              20
  
  MaxClients                      10
  
  MaxBandwidth                    100000
  
  
  
  <feed>
  
    File                          /tmp/feed.ffm
  
    FileMaxSize                   1g
  
    ACL allow                     127.0.0.1
  
  </feed>
  
  
  
  <stream>
  
    Feed                          feed.ffm
  
    Format                        mpeg
  
    AudioCodec                    aac
  
    AudioBitRate                  256
  
    AudioChannels                 1
  
    VideoCodec                    libx264
  
    VideoBitRate                  10000      // Total random here
  
    VideoBitRateRange             5000-15000 // And here...
  
    VideoFrameRate                30
  
    VideoQMin                     1
  
    VideoQMax                     50
  
    VideoSize                     3840x2160
  
    VideoBufferSize               20000      // Not sure either
  
    AVOptionVideo                 flags +global_header
  
  </stream>

  I had to specify QMin and QMax to avoid error message but I don’t really understand what is it.

  FFmpeg command line

  ffmpeg -re -i bbb_sunflower_2160p_30fps_normal.mp4 -strict -2 -r 30 -vcodec libx264 http://localhost:8090/feed.ffm

  This work with VLC. I’m working with a file on my computer before moving to an udp stream.

• H264/MP4 live stream from ffmpeg gets delayed

  1er octobre 2018, par paunescuionica

  I’m transcoding a MJPEG stream to H264/MP4 using ffmpeg. As client I’m using VLC.

  I use this command line :

  ffmpeg \
  
    -use_wallclock_as_timestamps 1 \
  
    -f mjpeg \
  
    -i "http://127.0.0.1:4100/getMjpegStream=L" \
  
    -f mp4 \
  
    -vcodec libx264 \
  
    -movflags frag_keyframe+empty_moov+faststart \
  
    -tune zerolatency \
  
    -crf 30 \
  
    -preset ultrafast \
  
    -g 1 \
  
    -reset_timestamps 1 \
  
    -vsync 1 \
  
    -flags global_header \
  
    -r 15 \
  
    -listen 1 \
  
    -fflags flush_packets \
  
    -avioflags direct \
  
    -flush_packets 1 \
  
    *output_URL*

  If I set the output_URL to this :

  udp://127.0.0.1:5000?pkt_size=1316

  it works just fine. I start ffmpeg, then after some time I start VLC with this URL udp://@127.0.0.1:5000, and it plays (almost) real time. The delay is 1-2 seconds, which is acceptable. And this delay is constant, it does not depend on when I start VLC. I can stop and reopen VLC and it keeps going realtime.

  But I need this stream to also be viewed in browser (in a HTML5 video), so I normally use this for output_URL :

  http://127.0.0.1:5000

  In VLC I use this URL http://127.0.0.1:5000 and it also works fine, but only if I start VLC immediately after I start ffmpeg. If there is a significant delay between the start of ffmpeg and the start of VLC, then that delay will be noticeable in the playback. Let’s say that I start ffmpeg at time T then after 10 seconds (at T+10) I start VLC. I have this behavior in VLC :

  • It starts, and it displays the frame at time T and then the stream freezes
  • After 10 seconds, the streaming resumes in VLC and it starts playing, but the image is 10 second behind ‘realtime’
  • This delays is constant, it does not recover from it

  Is there a way to solve this ?

  • Instruct ffmpeg to start transcoding only when the client connects ?
  • Instruct ffmpeg to not buffer transcoded stream until the client connects ? (with current command line, it clearly buffers because when VLC starts at T+10, the first frame displayed is from time T) ?

  Thank you !