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• Artifacts in ffmpeg fifo, low fps, stream ends

  11 août 2020, par Ben Gardner

  I'm using a Raspberry Pi 3B and 4 for this, neither works.

  


  I'm trying to both pass my capture card's input (/dev/video0) through a fifo file so I can play it on the screen via omxplayer (1080p/30fps), and also grab frames of /dev/video0 out to a series of jpgs (1920x1080 right now, but I'd like it to be 640x480) so I can do analysis on it while it's being played. The input to the capture card is television via HDMI.

  


  This is the command I use to make the stream go to the fifo and jpgs.

  


  ffmpeg -y -f v4l2 -input_format mjpeg -framerate 30 -video_size 1920x1080 \
-thread_queue_size 16384 -i /dev/video0 -f alsa -ac 1 \
-thread_queue_size 16384 -i hw:CARD=U0x534d0x2109,DEV=0 \
-c:v copy -b:v 32000k -preset faster -x264opts keyint=50 \
-g 25 -pix_fmt yuvj422p -c:a aac -b:a 128k -codec:v copy -f tee \
-map 0:v -map 1:a "fifo.mkv|output_%3d.jpg"


  


  Here is my output, which gives me 30fps originally, sometimes dipping into 29-28 fps, and then skipping (both audio and video) and artifacts in the video after around 5-10 minutes with the severity eventually increasing until it stops :

  


  [mjpeg @ 0x1504490] EOI missing, emulating
Input #0, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start: 27151.039849, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1920x1080, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
Guessed Channel Layout for Input Stream #1.0 : mono
Input #1, alsa, from 'hw:CARD=U0x534d0x2109,DEV=0':
  Duration: N/A, start: 1596773777.825328, bitrate: 1536 kb/s
    Stream #1:0: Audio: pcm_s16le, 96000 Hz, mono, s16, 1536 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (native))
Press [q] to stop, [?] for help
Output #0, tee, to 'fifo.mkv|output_%3d.jpg':
  Metadata:
    encoder         : Lavf58.20.100
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1920x1080, q=2-31, 32000 kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
    Stream #0:1: Audio: aac (LC), 96000 Hz, mono, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc58.35.100 aac
[alsa @ 0x1507300] Thread message queue blocking; consider raising the thread_queue_size option (current value: 16384)
[alsa @ 0x1507300] ALSA buffer xrun.time=00:13:55.89 bitrate=N/A speed=0.972x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:14:16.02 bitrate=N/A speed=0.974x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:14:27.25 bitrate=N/A speed=0.972x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:14:33.35 bitrate=N/A speed=0.97x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:14:44.71 bitrate=N/A speed=0.969x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:14:49.71 bitrate=N/A speed=0.97x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:15:01.51 bitrate=N/A speed=0.967x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:15:07.78 bitrate=N/A speed=0.969x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:15:14.27 bitrate=N/A speed=0.962x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:15:26.44 bitrate=N/A speed=0.96x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:15:32.40 bitrate=N/A speed=0.96x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:15:38.63 bitrate=N/A speed=0.963x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:15:45.60 bitrate=N/A speed=0.959x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:15:50.93 bitrate=N/A speed=0.957x
    Last message repeated 1 times
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:00.79 bitrate=N/A speed=0.951x
    Last message repeated 1 times
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:05.29 bitrate=N/A speed=0.949x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:07.19 bitrate=N/A speed=0.949x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:11.72 bitrate=N/A speed=0.945x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:16.02 bitrate=N/A speed=0.944x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:26.39 bitrate=N/A speed=0.953x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:30.22 bitrate=N/A speed=0.938x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:30.98 bitrate=N/A speed=0.937x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:37.66 bitrate=N/A speed=0.941x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:41.28 bitrate=N/A speed=0.935x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:42.95 bitrate=N/A speed=0.934x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:45.82 bitrate=N/A speed=0.933x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:46.76 bitrate=N/A speed=0.932x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:47.05 bitrate=N/A speed=0.931x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:50.74 bitrate=N/A speed=0.927x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:57.05 bitrate=N/A speed=0.927x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:16:58.91 bitrate=N/A speed=0.927x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:17:09.41 bitrate=N/A speed=0.92x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:17:12.04 bitrate=N/A speed=0.917x
[alsa @ 0x1507300] ALSA buffer xrun.time=00:17:12.61 bitrate=N/A speed=0.916x
Killed31579 fps= 28 q=-1.0 size=N/A time=00:17:32.56 bitrate=N/A speed=0.919x


  


  I also occasionally get this error :

  


  [tee @ 0x17001c0] Non-monotonous DTS in output stream 0:1; previous: 99251754, current: 99247503; changing to 99251755. This may result in incorrect timestamps in the output file.


  


  I'm assuming this has something to do with the audio getting routed to the jpg. I've tried [select=\'v\'] in front of the jpg, which doesn't change the behavior as well as [map=\'1\:a\'] in front of the mkv, which says [matroska @ 0xe446f0] Unknown option 'map'.

  


  I should also disclaim that I don't have much of an idea of what this command is doing compression-wise, I basically just copy/pasted that part.

  


  What edits do I need to make to get this into a fifo and series of jpgs at the same time ?

  


• ffmpeg video&audio streaming from webcam

  23 février 2016, par johncarrie

  I am new to ffmpeg and I want to stream webcam video&audio by using ffmpeg and ffserver.

  ffserver config is the following :

  <stream>
  
  Feed feed1.ffm
  
  Format avi
  
  VideoSize 176x128
  
  VideoFrameRate 15
  
  VideoBufferSize 40
  
  VideoBitRate 64
  
  AudioBitRate 32
  
  AudioChannels 1
  
  AudioSampleRate 11025
  
  VideoQMin 1
  
  VideoQMax 20
  
  NoDefaults
  
  </stream>

  ffmpeg process is the following :

  ffmpeg -vcodec mjpeg -v verbose -r 15 -s 176x128 -f video4linux2 -i /dev/video0 -f
  
   alsa -ac 1 -i hw:0 http://localhost:8090/feed1.ffm
  
  ffmpeg version N-77547-g2893dbf Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04)
  
    configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
  
    libavutil      55. 11.100 / 55. 11.100
  
    libavcodec     57. 20.100 / 57. 20.100
  
    libavformat    57. 21.100 / 57. 21.100
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 22.100 /  6. 22.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [video4linux2,v4l2 @ 0xa6133a0] fd:3 capabilities:84000001
  
  [video4linux2,v4l2 @ 0xa6133a0] The V4L2 driver changed the video from 176x128 to 1280x720
  
  [mjpeg @ 0xa613ec0] Changing bps to 8
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
    Duration: N/A, start: 77139.395765, bitrate: N/A
  
  Stream #0:0: Video: mjpeg, 1 reference frame, yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, -2 kb/s, 15 fps, 15 tbr, 1000k tbn, 1000k tbc
  
  Guessed Channel Layout for  Input Stream #1.0 : mono
  
  Input #1, alsa, from 'hw:0':
  
    Duration: N/A, start: 1456086923.213492, bitrate: 768 kb/s
  
  Stream #1:0: Audio: pcm_s16le, 48000 Hz, 1 channels, s16, 768 kb/s
  
  [tcp @ 0xa622000] Connection to tcp://localhost:8090 failed (Connection refused), trying next address
  
  [tcp @ 0xa61e140] Connection to tcp://localhost:8090 failed (Connection refused), trying next address
  
  [graph 0 input from stream 1:0 @ 0xa613220] tb:1/48000 samplefmt:s16 samplerate:48000 chlayout:0x4
  
  [audio format for output stream 0:0 @ 0xa62a620] auto-inserting filter 'auto-inserted resampler 0' between the filter 'Parsed_anull_0' and the filter 'audio format for output stream 0:0'
  
  [auto-inserted resampler 0 @ 0xa6229c0] ch:1 chl:mono fmt:s16 r:48000Hz -> ch:1 chl:mono fmt:s32p r:11025Hz
  
  [graph 1 input from stream 0:0 @ 0xa6244c0] w:1280 h:720 pixfmt:yuvj422p tb:1/15 fr:15/1 sar:0/1 sws_param:flags=2
  
  [scaler for output stream 0:1 @ 0xa623fc0] w:176 h:128 flags:'bicubic' interl:0
  
  [graph 1 input from stream 0:0 @ 0xa6244c0] TB:0.066667 FRAME_RATE:15.000000 SAMPLE_RATE:nan
  
  [swscaler @ 0xa63fe40] deprecated pixel format used, make sure you did set range correctly
  
  [scaler for output stream 0:1 @ 0xa623fc0] w:1280 h:720 fmt:yuvj422p sar:0/1 -> w:176 h:128 fmt:yuv420p sar:0/1 flags:0x4
  
  [mpeg4 @ 0xa626260] Either both buffer size and max rate or neither must be specified
  
  Output #0, ffm, to 'http://localhost:8090/feed1.ffm':
  
    Metadata:
  
      creation_time   : 2016-02-22 03:35:23
  
      Stream #0:0: Audio: mp3 (libmp3lame), 11025 Hz, mono, s32p, 32 kb/s
  
      Metadata:
  
        encoder         : Lavc57.20.100 libmp3lame
  
      Stream #0:1: Video: mpeg4, 1 reference frame, none, 176x128 (0x0), q=1-20, 64 kb/s, 15 fps, 15 tbc
  
      Metadata:
  
        encoder         : Lavc57.20.100 mpeg4
  
  Stream mapping:
  
    Stream #1:0 -> #0:0 (pcm_s16le (native) -> mp3 (libmp3lame))
  
    Stream #0:0 -> #0:1 (mjpeg (native) -> mpeg4 (native))
  
  Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height

  I am using a FEBON168 UVC HDMI GRABBER CARD as Webcam.
  USB UVC output is the following :
  1. MJPEG 1280x720 up to 30fps (full screen)
  2. YUV 1280x720 up to 10fps (full screen)

  How can I fix it ? What am I doing wrong ?

• HTML Video Exporting Using MediaRecorder vs ffmpeg.js

  3 octobre 2020, par Owen Ovadoz

  TLDR

  


  Imagine I have one video and one image. I want to create another video that overlays the image (e.g. watermark) at the center for 2 seconds in the beginning of the video and export it as the final video. I need to do this on the client-side only. Is it possible to use MediaRecorder + Canvas or should I resort to using ffmpeg.js ?

  


  Context

  


  I am making a browser-based video editor where the user can upload videos and images and combine them. So far, I implemented this by embedding the video and images inside a canvas element appropriately. The data representation looks somewhat like this :

  


  video: {
  url: 'https://archive.com/video.mp4',
  duration: 34,
},
images: [{
  url: 'https://archive.com/img1.jpg',
  start_time: 0,
  end_time: 2,
  top: 30,
  left: 20,
  width: 50,
  height: 50,
}]


  


  Attempts

  


  

  1. I play the video and show/hide images in the canvas. Then, I can use the MediaRecorder to capture the canvas' stream and export it as a data blob at the end. The final output is as expected, but the problem with this approach is I need to play the video from the beginning to the end for me to capture the stream from the canvas. If the video is 60 seconds, exporting it also takes 60 seconds.

  


  


  


  


  function record(canvas) {
  return new Promise(function (res, rej) {
    const stream = canvas.captureStream();
    const mediaRecorder = new MediaRecorder(stream);
    const recordedData = [];

    // Register recorder events
    mediaRecorder.ondataavailable = function (event) {
      recordedData.push(event.data);
    };
    mediaRecorder.onstop = function (event) {
      var blob = new Blob(recordedData, {
        type: "video/webm",
      });
      var url = URL.createObjectURL(blob);
      res(url);
    };

    // Start the video and start recording
    videoRef.current.currentTime = 0;
    videoRef.current.addEventListener(
      "play",
      (e) => {
        mediaRecorder.start();
      },
      {
        once: true,
      }
    );
    videoRef.current.addEventListener(
      "ended",
      (e) => {
        mediaRecorder.stop();
      },
      {
        once: true,
      }
    );
    videoRef.current.play();
  });
}

  


  


  



  

  2. I can use ffmpeg.js to encode the video. I haven't tried this method yet as I will have to convert my image representation into ffmpeg args (I wonder how much work that is).