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• Can't synchronize frame from two webcam streams side by side using ffmpeg

  15 juin 2019, par Peppe

  i’m trying to stream two webcam in sbs mode using ffmpeg websocket.

  It works but there is a delay of some second between the two scene.

  Here is what I do :

  ffmpeg -f v4l2   -framerate 30 -video_size 1280x720 -input_format mjpeg 
  
  -i /dev/video1 -f v4l2 -framerate 30  -input_format mjpeg 
  
  -video_size 1280x720 -i /dev/video0 -filter_complex "
  
  [0:v][1:v]hstack [left+right]" -map [left+right] -r 30 -fflags nobuffer 
  
  -f mpegts -codec:v mpeg1video -s 2560x720 -b:v 800k -bf 0 http://localhost:8081/secretsecret

  And this is the output :

  ffmpeg version 4.1.3-0ubuntu1 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with gcc 8 (Ubuntu 8.3.0-6ubuntu1)
  
    configuration: --prefix=/usr --extra-version=0ubuntu1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable- libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  
    libavutil      56. 22.100 / 56. 22.100
  
    libavcodec     58. 35.100 / 58. 35.100
  
    libavformat    58. 20.100 / 58. 20.100
  
    libavdevice    58.  5.100 / 58.  5.100
  
    libavfilter     7. 40.101 /  7. 40.101
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  3.100 /  5.  3.100
  
    libswresample   3.  3.100 /  3.  3.100
  
    libpostproc    55.  3.100 / 55.  3.100
  
  Input #0, video4linux2,v4l2, from '/dev/video2':
  
      Duration: N/A, start: 9539.835119, bitrate: N/A
  
      Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, 25 fps, 25 tbr, 1000k tbn, 1000k tbc
  
  Input #1, video4linux2,v4l2, from '/dev/video4':
  
    Duration: N/A, start: 9541.474622, bitrate: N/A
  
      Stream #1:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, 25 fps, 25 tbr, 1000k tbn, 1000k tbc
  
  Stream mapping:
  
    Stream #0:0 (mjpeg) -> hstack:input0
  
    Stream #1:0 (mjpeg) -> hstack:input1
  
    hstack -> Stream #0:0 (mpeg1video)
  
  Press [q] to stop, [?] for help
  
  [swscaler @ 0x55aa2c266f00] deprecated pixel format used, make sure you did set range correctly
  
  Output #0, mpegts, to 'http://localhost:8081/supersecret':
  
    Metadata:
  
  encoder         : Lavf58.20.100
  
  Stream #0:0: Video: mpeg1video, yuv420p, 2560x720, q=2-31, 800 kb/s, 25 fps, 90k tbn, 25 tbc (default)
  
  Metadata:
  
    encoder         : Lavc58.35.100 mpeg1video
  
  Side data:
  
    cpb: bitrate max/min/avg: 0/0/800000 buffer size: 0 vbv_delay: -1
  
  [video4linux2,v4l2 @ 0x55aa2c1d4e40] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)

  It works but there is a delay of 1 second between the two screens.

  also tried with :

  ffmpeg -f v4l2 -framerate 25 -video_size 1280x720 -input_format mjpeg -i \
  
  /dev/video2 -f v4l2 -framerate 25  -input_format mjpeg -video_size 1280x720 \
  
  -i /dev/video4 -filter_complex " \
  
  nullsrc=size=2560x720 [background]; \
  
  [0:v] setpts=PTS-STARTPTS, scale=1280x720 [left]; \
  
  [1:v] setpts=PTS-STARTPTS, scale=1280x720 [right]; \
  
  [background][left]       overlay=shortest=1       [background+left]; \
  
  [background+left][right] overlay=shortest=1:x=1280 [left+right] \
  
  " -map [left+right] -f mpegts -codec:v mpeg1video -s 2560x720 -b:v 800k -bf 0     http://localhost:8081/supersecret

  but same problem....
  How can I fix ?

• How can I merge 2 videos side by side whose have different resolutions, using FFmpeg ?

  14 juillet 2019, par Miri Yusifli

  I have 2 video files whose resolutions are 1600x900 and 640x480. How can I merge them side by side using FFmpeg ? Resolution of output video should be 1920*1080. Is that possible without stretching ?

  ffmpeg -i 1.mp4 -i 2.webm -filter_complex \
  
         "[0][1]scale2ref='oh*mdar':'if(lt(main_h,ih),ih,main_h)'[0s][1s]; \
  
          [1s][0s]scale2ref='oh*mdar':'if(lt(main_h,ih),ih,main_h)'[1s][0s]; \
  
          [0s][1s]hstack,setsar=1" \
  
          -vcodec libx264 \
  
          -acodec aac \
  
          -r 15 \
  
          output.mp4

  This command merges them but how can I achieve specific resolution for the output video ?

  This is the layout I want

• avformat/dashenc : update stream extradata from packet side data

  30 juillet 2019, par James Almer

  avformat/dashenc : update stream extradata from packet side data
  codecpar->extradata is not going to change between packets. New extradata
  
  is instead propagated using packet side data.
  Use ff_alloc_extradata() as well.
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavformat/dashenc.c