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• ffmpeg - compilation problem with g++

  22 août 2014, par Sun

  I am trying to run a program which uses ffmpeg libraries to decode a mp3 file. I am using following options for compiling the program :

  g++ -c play.cpp -o play.o
  
  g++ -o play play.o -L/usr/local/lib -lavutil -lavcodec -lavformat -lavdevice \
  
                     -lavfilter -ldl -lasound -L/usr/lib -lSDL -lpthread -lz -lswscale -lm

  But while linking I am gettign following errors :

  play.cpp:(.text+0x49): undefined reference to `av_dup_packet(AVPacket*)'
  
  play.cpp:(.text+0x66): undefined reference to `av_malloc(unsigned int)'
  
  play.cpp:(.text+0x324): undefined reference to `avcodec_decode_audio3(AVCodecContext*, short*, int*, AVPacket*)'
  
  play.cpp:(.text+0x387): undefined reference to `av_free_packet(AVPacket*)'

  and so on...
  These reported functions are available in the libavcodec.a etc. which i have already specified with the link options.
  Can anyone please tell me what could be wrong here or suggest how to approach debugging this ?

• Problem about get the video from webcam in julia

  12 août 2020, par Wendy Chen

  I used this code to get the video from webcam in julia, but it was unstable when I setting the time exceed 4 and one half minutes(ex. -t 00:05:00). Why is that so ? And what should I do ?
Thanks.

  


  using  PyCall
run(`$(PyCall.python) -m pip install ffmpy`)
ffmpy = pyimport("ffmpy")
ff=ffmpy.FFmpeg(
     inputs=Dict("rtsp://......@....."=>nothing),
     outputs=Dict("./Video.mp4"=>"-t 00:01:00"))
println(ff.cmd)
ENV["PATH"]="PATH/TO/ffmpeg.executable;"*ENV["PATH"]
ff.run()


  


• FFMPEG to create an MPEG-DASH stream with VP8

  24 avril 2017, par Kenneth Worden

  I’m trying to use FFMPEG to stream a live video feed from my webcam /dev/video0. Following scattered tutorials and scarce documentation (is this a known problem for the encoding community ?) I arrived at the following bash script :

  #!/bin/bash
  
  
  
  ffmpeg \
  
      -y \
  
      -f v4l2 \
  
          -i /dev/video0 \
  
          -s 640x480 \
  
          -input_format mjpeg \
  
          -r 24 \
  
      -map 0:0 \
  
      -pix_fmt yuv420p \
  
      -codec:v libvpx \
  
          -s 640x480 \
  
          -threads 4 \
  
          -b:v 50k \
  
          -tile-columns 4 \
  
          -frame-parallel 1 \
  
          -keyint_min 24 -g 24 \
  
      -f webm_chunk \
  
          -header "stream.hdr" \
  
          -chunk_start_index 1 \
  
      stream_%d.chk &
  
  
  
  sleep 2
  
  
  
  ffmpeg \
  
      -f webm_dash_manifest -live 1 \
  
      -i stream.hdr \
  
      -c copy \
  
      -map 0 \
  
      -f webm_dash_manifest -live 1 \
  
          -adaptation_sets "id=0,streams=0" \
  
          -chunk_start_index 1 \
  
          -chunk_duration_ms 1000 \
  
          -time_shift_buffer_depth 30000 \
  
          -minimum_update_period 60000 \
  
      stream_manifest.mpd

  When I run this script, my webcam light turns on, the stream.hdr and stream_manifest.mpd files are written, and chunks start to be created (i.e. stream_1.chk, stream_2.chk, etc...). However, FFMPEG throws the following error :

  Could not write header for output file #0 (incorrect codec parameters
   ?) : Invalid data found when processing input

  I will explain what I think I am doing with this script, and hopefully this will expose any errors in my thinking.

  First, we invoke FFMPEG to use Video for Linux 2 (v4l2) to read from my webcam (/dev/video0) of a resolution 640x480. The input format is mjpeg with a framerate of 24fps.

  I then declare that FFMPEG should "map" (copy) the video stream output by v4l2 to a file. I specify the pixel format (YUV420P) and use libvpx (VP8 encoding) to encode the video stream. I set the size to be 640x480, use 4 threads, set the bitrate to be 50kbps, do some magic with tile-columns and frame-parallel options, and set the I-frames to be 24 frames apart.

  I then create a stream.hdr file. The starting index is 1. This command continues to run infinitely until I kill it, grabbing new video from my webcam and outputting it into chunks.

  I then sleep for 2 seconds to give the previous command time to generate a header file.

  And that’s really it. The next invocation of FFMPEG simply creates the MPEG-DASH manifest file given the header generated in the previous step.

  So what’s going on ? Why can I not view the video in a web browser (I’m using Dash.js) ? I serve the manifest, header, and chunks on a Node.js server so that trivial issue is not the problem.

  ---

  Edit : Here is my full console output.

  ffmpeg version 3.0.7-0ubuntu0.16.10.1 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 6.2.0 (Ubuntu 6.2.0-5ubuntu12) 20161005
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.16.10.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librubberband --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-chromaprint --enable-libx264
  
    libavutil      55. 17.103 / 55. 17.103
  
    libavcodec     57. 24.102 / 57. 24.102
  
    libavformat    57. 25.100 / 57. 25.100
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 31.100 /  6. 31.100
  
    libavresample   3.  0.  0 /  3.  0.  0
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [video4linux2,v4l2 @ 0x55847e244ea0] The driver changed the time per frame from 1/24 to 1/30
  
  [mjpeg @ 0x55847e245c00] Changing bps to 8
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
    Duration: N/A, start: 64305.102081, bitrate: N/A
  
      Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 640x480, -5 kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
  
  Codec AVOption frame-parallel (Enable frame parallel decodability features) specified for output file #0 (stream_%d.chk) 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.
  
  Codec AVOption tile-columns (Number of tile columns to use, log2) specified for output file #0 (stream_%d.chk) 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.
  
  [swscaler @ 0x55847e24b720] deprecated pixel format used, make sure you did set range correctly
  
  [libvpx @ 0x55847e248a20] v1.5.0
  
  Output #0, webm_chunk, to 'stream_%d.chk':
  
    Metadata:
  
      encoder         : Lavf57.25.100
  
      Stream #0:0: Video: vp8 (libvpx), yuv420p, 640x480, q=-1--1, 50 kb/s, 30 fps, 30 tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc57.24.102 libvpx
  
      Side data:
  
        unknown side data type 10 (24 bytes)
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mjpeg (native) -> vp8 (libvpx))
  
  Press [q] to stop, [?] for help
  
  frame=   21 fps=0.0 q=0.0 size=N/A time=00:00:00.70 bitrate=N/A dup=5 drop=frame=   36 fps= 35 q=0.0 size=N/A time=00:00:01.20 bitrate=N/A dup=5 drop=frame=   51 fps= 33 q=0.0 size=N/A time=00:00:01.70 bitrate=N/A dup=5 drop=ffmpeg version 3.0.7-0ubuntu0.16.10.1 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 6.2.0 (Ubuntu 6.2.0-5ubuntu12) 20161005
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.16.10.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librubberband --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-chromaprint --enable-libx264
  
    libavutil      55. 17.103 / 55. 17.103
  
    libavcodec     57. 24.102 / 57. 24.102
  
    libavformat    57. 25.100 / 57. 25.100
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 31.100 /  6. 31.100
  
    libavresample   3.  0.  0 /  3.  0.  0
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, webm_dash_manifest, from 'stream.hdr':
  
    Metadata:
  
      encoder         : Lavf57.25.100
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        webm_dash_manifest_file_name: stream.hdr
  
        webm_dash_manifest_track_number: 1
  
  Output #0, webm_dash_manifest, to 'stream_manifest.mpd':
  
    Metadata:
  
      encoder         : Lavf57.25.100
  
      Stream #0:0: Video: vp8, yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        webm_dash_manifest_file_name: stream.hdr
  
        webm_dash_manifest_track_number: 1
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid data found when processing input
  
  frame=   67 fps= 33 q=0.0 size
  
  frame=   82 fps= 32 q=0.0 size=N/A time=00:00:02.73 bitrate=N/A dup=5 drop=
  
  frame=   97 fps= 32 q=0.0 size=N/A time=00:00:03.23 bitrate=N/A dup=5 drop=
  
  frame=  112 fps= 32 q=0.0 size=N/A time=00:00:03.73 bitrate=N/A dup=5 ...