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• Can't read video using VideoCapture in Opencv

  8 mai 2018, par batuman

  I have installed Opencv 2.4.13.6 at my Ubuntu 16.04 OS.
  I have ffmpeg and during Opencv installation I made WITH_FFMPEG ON.
  My ffmpeg is working.
  If I type ffmpeg at command window, I have

  ffmpeg version N-90982-gb995ec0 Copyright (c) 2000-2018 the FFmpeg developers
  
  
  
    built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.9) 20160609
  
    configuration: --prefix=/home/nyan/ffmpeg_build --enable-shared --extra-cflags=-I/home/nyan/ffmpeg_build/include --extra-ldflags=-L/home/nyan/ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/home/nyan/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
  
    libavutil      56. 18.100 / 56. 18.100
  
    libavcodec     58. 19.100 / 58. 19.100
  
    libavformat    58. 13.101 / 58. 13.101
  
    libavdevice    58.  4.100 / 58.  4.100
  
    libavfilter     7. 21.100 /  7. 21.100
  
    libswscale      5.  2.100 /  5.  2.100
  
    libswresample   3.  2.100 /  3.  2.100
  
    libpostproc    55.  2.100 / 55.  2.100
  
  Hyper fast Audio and Video encoder
  
  usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

  Then I have put ffmpeg paths to .bashrc as

  export PATH=/home/bin${PATH:+:${PATH}}
  
  export PATH=/home/ffmpeg_build${PATH:+:${PATH}}
  
  export PATH=/home/ffmpeg_build/include${PATH:+:${PATH}}
  
  export LD_LIBRARY_PATH=/home/ffmpeg_build/lib${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}

  In my Opencv libraries I have libopencv_video.so. So video input/output should be fine.

  My following program gives me "can't read video". What could be the reason ?

  I tried VideoCapture cap(0); gives me same error. What is wrong ?

  #include <opencv2></opencv2>opencv.hpp>
  
  using namespace cv;
  
  using namespace std;
  
  
  
  int main(void){
  
  
  
      VideoCapture cap("IMG_5715.MOV"); // open the default camera
  
      if(!cap.isOpened())  // check if we succeeded
  
      {
  
          cout &lt;&lt; "can't read video"&lt;&lt; endl;
  
          return -1;
  
      }
  
  
  
      while(1){ 
  
      Mat frame;
  
      // Capture frame-by-frame
  
      cap >> frame;
  
          imshow( "Frame", frame );
  
          waitKey(1);
  
      // If the frame is empty, break immediately
  
      if (frame.empty())
  
         break; 
  
      }
  
  
  
      cap.release();
  
      return 0;
  
  }

• FFMPEG : Loop multiple videos indefinitely

  4 mai 2018, par stevendesu

  I’ve got an interesting setup. I have four videos which are all identical in duration, identical frame rate, and have identical PTS timestamps. I wish to stream these four videos to an RTMP server but keep them synchronized so that someone switching between the streams will not jump forward or back in time, but instead pick up right where they left off.

  Here’s the command I’m currently using :

  ffmpeg \
  
      -re -stream_loop -1 -fflags +genpts -i 01.mp4 \
  
      -re -stream_loop -1 -fflags +genpts -i 02.mp4 \
  
      -re -stream_loop -1 -fflags +genpts -i 03.mp4 \
  
      -re -stream_loop -1 -fflags +genpts -i 04.mp4 \
  
      -map 0:v -map 0:a \
  
          -c:a speex -ar 16000 -ac 1 \
  
          -c:v libx264 -preset ultrafast \
  
          -b:v 500k -b:a 32k \
  
          -f flv rtmp://output/01 \
  
      -map 1:v -map 1:a \
  
          -c:a speex -ar 16000 -ac 1 \
  
          -c:v libx264 -preset ultrafast \
  
          -b:v 500k -b:a 32k \
  
          -f flv rtmp://output/02 \
  
      -map 2:v -map 2:a \
  
          -c:a speex -ar 16000 -ac 1 \
  
          -c:v libx264 -preset ultrafast \
  
          -b:v 500k -b:a 32k \
  
          -f flv rtmp://output/03 \
  
      -map 3:v -map 3:a \
  
          -c:a speex -ar 16000 -ac 1 \
  
          -c:v libx264 -preset ultrafast \
  
          -b:v 500k -b:a 32k \
  
          -f flv rtmp://output/04

  This command properly synchronizes the streams and broadcasts all four, however the moment the video ends so does the stream. Due to the -stream_loop -1 I would expect the video to keep looping indefinitely. This is the output to stdout when the stream dies :

  [flv @ 0x2392d40] Failed to update header with correct duration.
  
  [flv @ 0x2392d40] Failed to update header with correct filesize.
  
  [flv @ 0x229b980] Failed to update header with correct duration.
  
  [flv @ 0x229b980] Failed to update header with correct filesize.
  
  [flv @ 0x22f3bc0] Failed to update header with correct duration.
  
  [flv @ 0x22f3bc0] Failed to update header with correct filesize.
  
  [flv @ 0x23a4240] Failed to update header with correct duration.
  
  [flv @ 0x23a4240] Failed to update header with correct filesize.
  
  [libx264 @ 0x25ebd00] frame I:236   Avg QP:29.17  size: 20892
  
  [libx264 @ 0x25ebd00] frame P:5412  Avg QP:32.33  size:  1892
  
  [libx264 @ 0x25ebd00] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x25ebd00] mb P  I16..4:  0.2%  0.0%  0.0%  P16..4: 18.5%  0.0%  0.0%  0.0%  0.0%    skip:81.3%
  
  [libx264 @ 0x25ebd00] final ratefactor: 31.62
  
  [libx264 @ 0x25ebd00] coded y,uvDC,uvAC intra: 68.8% 62.8% 34.6% inter: 8.8% 1.8% 0.0%
  
  [libx264 @ 0x25ebd00] i16 v,h,dc,p: 38% 25% 19% 18%
  
  [libx264 @ 0x25ebd00] i8c dc,h,v,p: 40% 22% 27% 11%
  
  [libx264 @ 0x25ebd00] kb/s:515.11
  
  [libspeex @ 0x2537580] 1 frames left in the queue on closing
  
  [libx264 @ 0x2531d00] frame I:236   Avg QP:31.85  size: 15843
  
  [libx264 @ 0x2531d00] frame P:5412  Avg QP:34.95  size:  2086
  
  [libx264 @ 0x2531d00] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x2531d00] mb P  I16..4:  2.8%  0.0%  0.0%  P16..4: 37.8%  0.0%  0.0%  0.0%  0.0%    skip:59.4%
  
  [libx264 @ 0x2531d00] final ratefactor: 32.38
  
  [libx264 @ 0x2531d00] coded y,uvDC,uvAC intra: 48.4% 40.8% 13.5% inter: 12.1% 4.0% 0.0%
  
  [libx264 @ 0x2531d00] i16 v,h,dc,p: 41% 21% 26% 13%
  
  [libx264 @ 0x2531d00] i8c dc,h,v,p: 48% 20% 24%  8%
  
  [libx264 @ 0x2531d00] kb/s:510.33
  
  [libspeex @ 0x2533080] 1 frames left in the queue on closing
  
  [libx264 @ 0x22da600] frame I:236   Avg QP:26.11  size: 13705
  
  [libx264 @ 0x22da600] frame P:5412  Avg QP:29.17  size:  2185
  
  [libx264 @ 0x22da600] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x22da600] mb P  I16..4:  4.5%  0.0%  0.0%  P16..4: 35.2%  0.0%  0.0%  0.0%  0.0%    skip:60.3%
  
  [libx264 @ 0x22da600] final ratefactor: 28.44
  
  [libx264 @ 0x22da600] coded y,uvDC,uvAC intra: 37.1% 40.1% 10.4% inter: 12.3% 6.2% 0.1%
  
  [libx264 @ 0x22da600] i16 v,h,dc,p: 40% 21% 22% 17%
  
  [libx264 @ 0x22da600] i8c dc,h,v,p: 43% 18% 28% 11%
  
  [libx264 @ 0x22da600] kb/s:511.43
  
  [libspeex @ 0x22db080] 1 frames left in the queue on closing
  
  [libx264 @ 0x22d7a00] frame I:236   Avg QP:30.31  size: 13811
  
  [libx264 @ 0x22d7a00] frame P:5412  Avg QP:33.28  size:  2209
  
  [libx264 @ 0x22d7a00] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x22d7a00] mb P  I16..4:  5.4%  0.0%  0.0%  P16..4: 37.4%  0.0%  0.0%  0.0%  0.0%    skip:57.2%
  
  [libx264 @ 0x22d7a00] final ratefactor: 31.52
  
  [libx264 @ 0x22d7a00] coded y,uvDC,uvAC intra: 37.9% 36.7% 9.5% inter: 11.4% 5.0% 0.1%
  
  [libx264 @ 0x22d7a00] i16 v,h,dc,p: 41% 23% 21% 16%
  
  [libx264 @ 0x22d7a00] i8c dc,h,v,p: 45% 19% 27%  9%
  
  [libx264 @ 0x22d7a00] kb/s:516.78
  
  [libspeex @ 0x22d8d80] 1 frames left in the queue on closing

  My FFMPEG version :

  $ ffmpeg -version
  
  ffmpeg version N-90065-g8a8d0b3 Copyright (c) 2000-2018 the FFmpeg developers
  
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.5) 20160609
  
  configuration: --prefix=/home/sbarnett/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/sbarnett/ffmpeg_build/include --extra-ldflags=-L/home/sbarnett/ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/home/sbarnett/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libspeex --enable-nonfree
  
  libavutil      56.  7.101 / 56.  7.101
  
  libavcodec     58. 11.101 / 58. 11.101
  
  libavformat    58.  9.100 / 58.  9.100
  
  libavdevice    58.  1.100 / 58.  1.100
  
  libavfilter     7. 12.100 /  7. 12.100
  
  libswscale      5.  0.101 /  5.  0.101
  
  libswresample   3.  0.101 /  3.  0.101
  
  libpostproc    55.  0.100 / 55.  0.100

  How do I get the video to loop indefinitely ? Why is -stream_loop -1 not working ?

  Update (Edited with new error)

  Following @Gyan’s advice, I attempted to use filter_complex with the movie filter, however I may be doing it incorrectly :

  ffmpeg \
  
      -stream_loop -1 \
  
      -re -i 01.mp4 \
  
      -re -i 02.mp4 \
  
      -re -i 03.mp4 \
  
      -re -i 04.mp4 \
  
      -filter_complex \
  
          "movie=01.mp4:loop=0[v1];[v1]setpts=N/FRAME_RATE/TB[v1];
  
           amovie=01.mp4:loop=0[a1];[a1]asetpts=N/SR/TB[a1];
  
           movie=02.mp4:loop=0[v2];[v2]setpts=N/FRAME_RATE/TB[v2];
  
           amovie=02.mp4:loop=0[a2];[a2]asetpts=N/SR/TB[a2];
  
           movie=03.mp4:loop=0[v3];[v3]setpts=N/FRAME_RATE/TB[v3];
  
           amovie=03.mp4:loop=0[a3];[a3]asetpts=N/SR/TB[a3];
  
           movie=04.mp4:loop=0[v4];[v4]setpts=N/FRAME_RATE/TB[v4];
  
           amovie=04.mp4:loop=0[a4];[a4]asetpts=N/SR/TB[a4]" \
  
      -map "[v1]" -map "[a1]" \
  
          -c:a speex -ar 16000 -ac 1 \
  
          -c:v libx264 -preset ultrafast \
  
          -b:v 500k -b:a 32k \
  
          -f flv rtmp://output/01 \
  
      -map "[v2]" -map "[a2]" \
  
          -c:a speex -ar 16000 -ac 1 \
  
          -c:v libx264 -preset ultrafast \
  
          -b:v 500k -b:a 32k \
  
          -f flv rtmp://output/02 \
  
      -map "[v3]" -map "[a3]" \
  
          -c:a speex -ar 16000 -ac 1 \
  
          -c:v libx264 -preset ultrafast \
  
          -b:v 500k -b:a 32k \
  
          -f flv rtmp://output/03 \
  
      -map "[v4]" -map "[a4]" \
  
          -c:a speex -ar 16000 -ac 1 \
  
          -c:v libx264 -preset ultrafast \
  
          -b:v 500k -b:a 32k \
  
          -f flv rtmp://output/04

  This threw the following error :

  [libspeex @ 0x23f4d80] nb_samples (325) != frame_size (320) (avcodec_encode_audio2)

• Bewildering issue - FFmpeg segment filter desyncs video

  14 mai 2018, par r_jei

  I need to segment a large (72GB) Prores video file and merge the segments to get a file identical to the original.

  ./ffmpeg -i video.mov -codec copy -f segment -segment_time 300 -segment_list list.ffcat -reset_timestamps 1 -v error chunk_%d.mov

  Unfortunately the segments that come from running this command get out of sync after a few seconds of playback with Quicktime Player. Interestingly, seeking, rewinding or fast forwarding appears to resync the video correctly for at least a few seconds.

  The following warning appears whenever a new segment is written :

  [segment @ 0x7f87ae001200] Opening 'chunk_0.mov' for writing
  
  [mov @ 0x7f87ad807200] Valid timecode frame rate must be specified. Minimum value is 1

  Yet, setting the framerate with -r 24 doesn’t help.

  Some potentially relevant metadata :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'A004_04121423_C001.mov':
  
    Duration: 00:13:31.25, start: 0.000000, bitrate: 710117 kb/s
  
      Stream #0:0(eng): Video: prores (apch / 0x68637061), yuv422p10le(bt709, progressive), 3840x2160, 707415 kb/s, SAR 1:1 DAR 16:9, 24 fps, 24 tbr, 24 tbn, 24 tbc (default)
  
      Metadata:
  
        creation_time   : 2018-04-12T20:23:16.000000Z
  
        handler_name    : ?Apple Alias Data Handler
  
        timecode        : 14:23:16:02
  
      Stream #0:1(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
  
      Metadata:
  
        creation_time   : 2018-04-12T20:23:16.000000Z
  
        handler_name    : ?Apple Alias Data Handler
  
        timecode        : 14:23:16:02
  
      Stream #0:2(eng): Data: none (tmcd / 0x64636D74) (default)
  
      Metadata:
  
        creation_time   : 2018-04-12T20:23:16.000000Z
  
        handler_name    : ?Apple Alias Data Handler
  
        timecode        : 14:23:16:02
  
  
  
  Output #0, segment, to 'chunk_%d.mov':
  
      Stream #0:0(eng): Video: prores (apch / 0x68637061), yuv422p10le(bt709, progressive), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 707415 kb/s, 24 fps, 24 tbr, 12288 tbn, 24 tbc (default)
  
      Metadata:
  
        creation_time   : 2018-04-12T20:23:16.000000Z
  
        handler_name    : ?Apple Alias Data Handler
  
        timecode        : 14:23:16:02
  
      Stream #0:1(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
  
      Metadata:
  
        creation_time   : 2018-04-12T20:23:16.000000Z
  
        handler_name    : ?Apple Alias Data Handler
  
        timecode        : 14:23:16:02
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)

  I’m on OS X.

  Thanks so much for your time and help on this issue ! I certainly hope I’m not missing something obvious :)

  ---

  UPDATE (May 10) : Comparing the original video file with the segments, I’ve found some interesting differences. Adobe Premiere reports that the original video has the following properties :

  QuickTime Details:
  
  Movie contains 1 video track(s), 1 audio track(s), 0 closed caption track(s), **and 1 timecode track(s).**
  
  
  
  Video:
  
  There are 19470 frames with a **duration of 1/24th.**
  
  
  
  Video track 1:
  
  Duration is **0:13:31:06**
  
  
  
  Video data block #1:
  
  Frame Size = 3840 x 2160
  
  Compressor = 
  
  **Quality = Most (-2623.00)
  
  Temporal = Most (1.00)**
  
  
  
  Timecode data block #1:
  
  Start Time = 14:23:16:02
  
  Reel name = 

  On the other hand, when examining the video resulting from stitching together the segments, we find the following :

  QuickTime Details:
  
  Movie contains 1 video track(s), 1 audio track(s), 0 closed caption track(s), **and 0 timecode track(s).**
  
  
  
  Video:
  
  There are 19470 frames with a **duration of 41/1000ths.**
  
  
  
  Video track 1:
  
  Duration is **0:01:06:00**
  
  
  
  Video data block #1:
  
  Frame Size = 3840 x 2160
  
  Compressor = 
  
  **Quality = Normal (3.00)
  
  Temporal = Normal (3.00)**