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• C++ Parse data from FFMPEG pipe output

  5 janvier 2017, par Simon

  I want to play around with data coming from an RTSP stream (e.g., do motion detection). Instead of using the cumbersome ffmpeg C API for decoding the stream, I decided to try something different. FFmpeg offers the possibility to pipe its output to stdout. Therefore, I wrote a C++ program which calls popen() to make an external call to ffmpeg and grabs the output. My aim is now to extract the YUV images from the resulting stream. As a first test, I decoded an h264 video file and wrote the stdout output coming from the ffmpeg call to a file.

  #include <iostream>
  
  #include <fstream>
  
  #include 
  
  
  
  using namespace std;
  
  
  
  int main()
  
  {
  
    FILE *in;
  
    char buff[512];
  
  
  
    if(!(in = popen("ffmpeg -i input.mp4 -c:v rawvideo -an -r 1 -f rawvideo pipe:1", "r")))
  
    {
  
      return 1;
  
    }
  
  
  
    ofstream outputFile("output.yuv");
  
    while(fgets(buff, sizeof(buff), in) != NULL)
  
    {
  
      outputFile &lt;&lt; buff;
  
    }
  
  
  
    outputFile.close();
  
    pclose(in);
  
    return 0;
  
  }
  
  </fstream></iostream>

  The resulting raw video can be played with vlc afterwards :

  vlc --rawvid-fps 1 --rawvid-width 1280 --rawvid-height 544 --rawvid-chroma I420 output.yuv

  Here, I chose the width and height from the video (a trailer of the Simpsons movie from http://www.dvdloc8.com/clip.php?movieid=12167&clipid=3). This first test worked very well. The resulting file is the same as when calling the ffmpeg binary directly with

  ffmpeg -i input.mp4 -c:v rawvideo -an -f output_ffmpeg.yuv

  Now I want to do some processing with the images coming from the ffmpeg output instead of dumping it to a file. My question is : Is there a clever way of parsing the stdout data from ffmpeg ? Ideally, I want to parse the stream into a sequence of instances of a YUVImage class (for example).

• Can't use dshow devices with nodejs fluent-ffmpeg

  18 janvier 2017, par vivien anglesio

  I’m working on windows with electron on a program that stream raw-video+desktop captured audio via ffmpeg (using fluent-ffmpeg).

  I’m having trouble when I try to use dshow capture device as audio input, ffmpeg tell me that it doesn’t find this device. But when i run exactly the same command directly via command line it works...

  dump using ffmpeg-fluent :

  started : ffmpeg -vcodec rawvideo -f rawvideo -pix_fmt rgb32 -framerate 30 -s 1280x720 -rtbufsize 1500M -vsync 0 -fflags genpts -i pipe:0 -f dshow -i audio="virtual-audio-capturer" -acodec aac -b:a 128k -ac 1 -vcodec h264_nvenc -r 30 -preset fast -pix_fmt yuv420p -crf 20 -maxrate 4000k -bufsize 8000k -g 30 -flvflags no_duration_filesize -f mpegts udp://127.0.0.1:8888
  
  Stderr output: ffmpeg version N-82966-g6993bb4 Copyright (c) 2000-2016 the FFmpeg developers
  
  Stderr output:   built with gcc 5.4.0 (GCC)
  
  Stderr output:   configuration: --enable-gpl --enable-version3 --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
  Stderr output:   libavutil      55. 43.100 / 55. 43.100
  
  Stderr output:   libavcodec     57. 70.100 / 57. 70.100
  
  Stderr output:   libavformat    57. 61.100 / 57. 61.100
  
  Stderr output:   libavdevice    57.  2.100 / 57.  2.100
  
  Stderr output:   libavfilter     6. 68.100 /  6. 68.100
  
  Stderr output:   libswscale      4.  3.101 /  4.  3.101
  
  Stderr output:   libswresample   2.  4.100 /  2.  4.100
  
  Stderr output:   libpostproc    54.  2.100 / 54.  2.100
  
  Stderr output: Input #0, rawvideo, from 'pipe:0':
  
  Stderr output:   Duration: N/A, start: 0.000000, bitrate: 884736 kb/s
  
  Stderr output:     Stream #0:0: Video: rawvideo (BGRA / 0x41524742), bgra, 1280x720, 884736 kb/s, 30 tbr, 30 tbn, 30 tbc
  
  Stderr output: [dshow @ 000000000070ac20] Could not find audio only device with name ["virtual-audio-capturer"] among source devices of type audio.
  
  Stderr output: [dshow @ 000000000070ac20] Searching for audio device within video devices for "virtual-audio-capturer"
  
  Stderr output: [dshow @ 000000000070ac20] Could not find audio only device with name ["virtual-audio-capturer"] among source devices of type video.
  
  Stderr output: audio="virtual-audio-capturer": I/O error

  Dump using cmd.exe :

  ffmpeg -vcodec rawvideo -f rawvideo -pix_fmt rgb32 -framerate 30 -s 1280x720 -rtbufsize 1500M -vsync 0 -fflags genpts -i pipe:0 -f dshow -i audio="virtual-audio-capturer" -acodec aac -b:a 128k -ac 1 -vcodec h264_nvenc -r 30 -preset fast -pix_fmt yuv420p -crf 20 -maxrate 4000k -bufsize 8000k -g 30 -flvflags no_duration_filesize -f mpegts udp://127.0.0.1:8888
  
  ffmpeg version N-82966-g6993bb4 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.4.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 43.100 / 55. 43.100
  
    libavcodec     57. 70.100 / 57. 70.100
  
    libavformat    57. 61.100 / 57. 61.100
  
    libavdevice    57.  2.100 / 57.  2.100
  
    libavfilter     6. 68.100 /  6. 68.100
  
    libswscale      4.  3.101 /  4.  3.101
  
    libswresample   2.  4.100 /  2.  4.100
  
    libpostproc    54.  2.100 / 54.  2.100
  
  Input #0, rawvideo, from 'pipe:0':
  
    Duration: N/A, bitrate: 884736 kb/s
  
      Stream #0:0: Video: rawvideo (BGRA / 0x41524742), bgra, 1280x720, 884736 kb/s, 30 tbr, 30 tbn, 30 tbc
  
  Guessed Channel Layout for Input Stream #1.0 : stereo
  
  Input #1, dshow, from 'audio=virtual-audio-capturer':
  
    Duration: N/A, bitrate: N/A
  
      Stream #1:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
  
  Using -vsync 0 and -r can produce invalid output files
  
  Codec AVOption crf (Select the quality for constant quality mode) specified for output file #0 (udp://127.0.0.1:8888) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
  
  Output #0, mpegts, to 'udp://127.0.0.1:8888':
  
    Metadata:
  
      encoder         : Lavf57.61.100
  
      Stream #0:0: Video: h264 (h264_nvenc) (Main), yuv420p, 1280x720, q=-1--1, 2000 kb/s, 30 fps, 90k tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc57.70.100 h264_nvenc
  
      Side data:
  
        cpb: bitrate max/min/avg: 4000000/0/2000000 buffer size: 8000000 vbv_delay: -1
  
      Stream #0:1: Audio: aac (LC), 48000 Hz, mono, fltp, 128 kb/s
  
      Metadata:
  
        encoder         : Lavc57.70.100 aac
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (h264_nvenc))
  
    Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (native))
  
  frame=    0 fps=0.0 q=0.0 Lsize=       0kB time=00:00:00.00 bitrate=N/A speed=N/A

  If anybody has an idea of what’s happening. It could be great !

  Thanks

• ffmpeg webm encode for low powered devices

  21 février 2017, par Max Tkachenko

  I want to play transparent video into my app using built-in player over phone’s camera capture. I try to encode my video with alpha channel for android device :

  ffmpeg -i "Comp.avi" -c:v libvpx -pix_fmt yuva420p -metadata:s:v:0 alpha_mode="1" output.webm

  The result is pretty good, but I have lags (freezing video from time to time) while playing it on my android phone. Is it any options to improve decode performance ?

  Some console output :

  D:\SOFT\ffmpeg-20160207-git-9ee4c89-win64-static\bin>ffmpeg -i "d:\temp\cherti\Comp 1.avi" -c:v libvpx -pix_fmt yuva420p -metadata:s:v:0 alpha_mode="1" d:\temp\cherti\output.webm
  
  ffmpeg version N-80386-g5f5a97d Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.4.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmfx --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 24.100 / 55. 24.100
  
    libavcodec     57. 46.100 / 57. 46.100
  
    libavformat    57. 38.100 / 57. 38.100
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 46.101 /  6. 46.101
  
    libswscale      4.  1.100 /  4.  1.100
  
    libswresample   2.  1.100 /  2.  1.100
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, avi, from 'd:\temp\cherti\Comp 1.avi':
  
    Metadata:
  
      date            : 2017-02-18T14:10:42.00916
  
      encoder         : Adobe After Effects CC 2015 (Windows)
  
    Duration: 00:00:05.00, start: 0.000000, bitrate: 1592542 kb/s
  
      Stream #0:0: Video: rawvideo, bgra, 1080x1920, 1605907 kb/s, 24 fps, 24 tbr, 24 tbn, 24 tbc
  
  File 'd:\temp\cherti\output.webm' already exists. Overwrite ? [y/N] y
  
  [libvpx @ 0000000002593640] v1.5.0
  
  [webm @ 00000000025a54e0] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
  
  Output #0, webm, to 'd:\temp\cherti\output.webm':
  
    Metadata:
  
      date            : 2017-02-18T14:10:42.00916
  
      encoder         : Lavf57.38.100
  
      Stream #0:0: Video: vp8 (libvpx), yuva420p, 1080x1920, q=-1--1, 200 kb/s, 24 fps, 1k tbn, 24 tbc
  
      Metadata:
  
        alpha_mode      : 1
  
        encoder         : Lavc57.46.100 libvpx
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> vp8 (libvpx))