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• Play MJPEG stream to v4l2loopback device

  28 juillet 2020, par ahoffer

  I have a RaspberryPi with a V1 camera.

  


  I want to use it as my camera for Zoom, Teams, and other virtual meetings.

  


  I have the RaspberryPi streaming motion JPEG over http using the application named "Motion".

  


  I created a v4l2 dummy device on my linux laptop as a virtual camera.

  


  However, I can't get the mjpeg stream to play to the v4l2 dummy device with the simple command :

  


  ffmpeg  -i "http://milan.local:8081" -map 0:v  -f v4l2 /dev/video4

  


  The result is :

  


  Input #0, mpjpeg, from 'http://milan.local:8081':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 640x480 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> rawvideo (native))
Press [q] to stop, [?] for help
[v4l2 @ 0x55a04567bbe0] Unknown V4L2 pixel format equivalent for yuvj420p
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:0 --


  


  ---

  


  What options am I missing from my ffmpeg command ?

  


• how to make ffmpeg transcoding from mjpeg to h264 in real time ?

  3 août 2020, par SolskGaer

  I have a mjpeg stream which output picture 10FPS(cellphone screenshot), and I use the following command to trancode it to a h264 stream and play it on my laptop

  


  ffmpeg -f mjpeg -r 20 -y -i http://127.0.0.1:53293/  -vcodec libx264 -preset veryfast -profile:v baseline -b:v 1024k -r 10 -f h264 pipe:1 | ffplay -i pipe:0


  


  but the output stream is a few seconds behind the cellphone screen. Here is the output of ffmpeg

  


  ffplay version 4.3.1 Copyright (c) 2003-2020 the FFmpeg developers
  built with Apple clang version 11.0.3 (clang-1103.0.32.62)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 11.0.3 (clang-1103.0.32.62)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, mjpeg, from 'http://127.0.0.1:53293/':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/unknown), 750x1334 [SAR 144:144 DAR 375:667], 20 tbr, 1200k tbn, 20 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0x7f8f2900da00] using SAR=1/1
[libx264 @ 0x7f8f2900da00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x7f8f2900da00] profile Constrained Baseline, level 3.2, 4:2:0, 8-bit
Output #0, h264, to 'pipe:1':
  Metadata:
    encoder         : Lavf58.45.100
    Stream #0:0: Video: h264 (libx264), yuvj420p(pc), 750x1334 [SAR 144:144 DAR 375:667], q=-1--1, 1024 kb/s, 10 fps, 10 tbn, 10 tbc
    Metadata:
      encoder         : Lavc58.91.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/1024000 buffer size: 0 vbv_delay: N/A
frame=   30 fps=5.2 q=29.0 size=      97kB time=00:00:00.10 bitrate=7911.0kbits/s dup=0 drop=26 speed=0.0172
frame=   33 fps=5.2 q=41.0 size=     190kB time=00:00:00.40 bitrate=3888.2kbits/s dup=0 drop=29 speed=0.0633
frame=   35 fps=5.1 q=40.0 size=     253kB time=00:00:00.60 bitrate=3457.8kbits/s dup=0 drop=31 speed=0.0874
frame=   38 fps=5.1 q=40.0 size=     330kB time=00:00:00.90 bitrate=3006.1kbits/s dup=0 drop=34 speed=0.122x
frame=   40 fps=5.1 q=40.0 size=     381kB time=00:00:01.10 bitrate=2838.3kbits/s dup=0 drop=36 speed=0.139x
frame=   43 fps=5.1 q=39.0 size=     460kB time=00:00:01.40 bitrate=2691.3kbits/s dup=0 drop=39 speed=0.166x
frame=   45 fps=5.0 q=39.0 size=     505kB time=00:00:01.60 bitrate=2585.9kbits/s dup=0 drop=41 speed=0.178x
frame=   48 fps=5.0 q=38.0 size=     552kB time=00:00:01.90 bitrate=2381.0kbits/s dup=0 drop=44 speed= 0.2x 
frame=   50 fps=5.0 q=33.0 size=     562kB time=00:00:02.10 bitrate=2190.7kbits/s dup=0 drop=46 speed=0.209x
frame=   53 fps=5.0 q=37.0 size=     572kB time=00:00:02.40 bitrate=1951.2kbits/s dup=0 drop=49 speed=0.227x
frame=   55 fps=5.0 q=37.0 size=     581kB time=00:00:02.60 bitrate=1830.0kbits/s dup=0 drop=51 speed=0.234x
frame=   58 fps=5.0 q=36.0 size=     591kB time=00:00:02.90 bitrate=1670.8kbits/s dup=0 drop=54 speed=0.25x 
frame=   60 fps=4.9 q=35.0 size=     598kB time=00:00:03.10 bitrate=1580.2kbits/s dup=0 drop=56 speed=0.255x
frame=   63 fps=5.0 q=35.0 size=     608kB time=00:00:03.40 bitrate=1465.2kbits/s dup=0 drop=59 speed=0.268x
frame=   65 fps=4.9 q=34.0 size=     613kB time=00:00:03.60 bitrate=1395.7kbits/s dup=0 drop=61 speed=0.273x
frame=   68 fps=5.0 q=34.0 size=     659kB time=00:00:03.90 bitrate=1384.5kbits/s dup=0 drop=64 speed=0.284x
frame=   70 fps=4.9 q=34.0 size=     682kB time=00:00:04.10 bitrate=1363.2kbits/s dup=0 drop=66 speed=0.288x
frame=   73 fps=4.9 q=35.0 size=     720kB time=00:00:04.40 bitrate=1340.1kbits/s dup=0 drop=69 speed=0.298x
frame=   75 fps=4.9 q=35.0 size=     746kB time=00:00:04.60 bitrate=1329.1kbits/s dup=0 drop=71 speed=0.301x
frame=   78 fps=4.9 q=36.0 size=     786kB time=00:00:04.90 bitrate=1314.6kbits/s dup=0 drop=74 speed=0.31x 
frame=   80 fps=4.9 q=36.0 size=     811kB time=00:00:05.10 bitrate=1303.3kbits/s dup=0 drop=76 speed=0.312x


  


  I don't think the CPU of my laptop is the bottleneck of this process, here is the spec of my laptop

  


  
      Model Name: MacBook Pro
      Model Identifier: MacBookPro16,1
      Processor Name: 6-Core Intel Core i7
      Processor Speed: 2.6 GHz
      Number of Processors: 1
      Total Number of Cores: 6
      L2 Cache (per Core): 256 KB
      L3 Cache: 12 MB
      Hyper-Threading Technology: Enabled
      Memory: 16 GB


  


  but I can't track the reason why this happened. What can I make the output stream be real time ? Any suggestion would be appreciated.

  


• What is the recommended settings for video editing using ffmpeg ?

  19 août 2020, par Moustafa Mahmoud

  I am quite new for using FFmpeg, and I am using FFmpeg in screen recording. I checked the online documentation in this link ffmpeg documentation "Capturing your Desktop / Screen Recording", but I didn't find sufficient information.

  


  I have a 4k laptop with invidia GPU, and I am using the below command to screencast the video (4k, 60 f/s), and audio from my laptop.

  


  ffmpeg -video_size 3840x2160 \
 -framerate 60 \
 -f x11grab -i :1 -f pulse -ac 2 -i default \
 -c:v libx264 \
 -crf 0 \
 -qp 0 \
 -preset ultrafast videoname.mp4


  


  I have some problems in these settings as following :

  


  

  1. The output video is too large, and I need to reduce the size without touch the quality at all.

  


  2. The output video seems to be not a row video, and it takes too much time in video editing decoding and encoding. I am not sure if there is a recommended setting for video editing. As I did some search and found the above is advised, but in practice perspective, it is not efficient.

  


  


  Below is my Linux distro information :

  


  Distributor ID: Ubuntu
Description   : Ubuntu 20.04.1 LTS
Release       : 20.04
Codename      : focal