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• Performance issue in streaming desktop out of a Raspberry with FFMPEG

  30 avril 2021, par skynet

  I'm quite a newbie in FFMPEG and I apologize in advance for any inaccuracy I may write.

  


  My goal is to stream over UDP a Full HD (1920x1080) desktop connected to a Raspberry PI 4 - 4 GB RAM.

  


  I made many attempts, and currently this the setup with better performance I found (I used the knowledge in https://www.willusher.io/general/2020/11/15/hw-accel-encoding-rpi4).

  


  

  1. I installed the 64-bit Raspbian OS on the PI from this link : https://www.raspberrypi.org/forums/viewtopic.php?t=275370

  


  


  This because the HW H264 encoder (h264_v4l2m2m) is faster than the 32-bit encoder h264_omx

  


  

  2. I downloaded and installed FFMPEG 4.4, using this configuration
./configure —prefix="$HOME/ffmpeg_build" —pkg-config-flags="pkg-config —static" —extra-cflags="-I$HOME/ffmpeg_build/include" —extra-ldflags="-L$HOME/ffmpeg_build/lib" —extra-libs="-lpthread -lm" —bindir="$HOME/bin" —enable-gpl —enable-gnutls —disable-libaom —enable-libass —enable-libfdk-aac —enable-libfreetype —enable-libmp3lame —enable-libopus —enable-libvorbis —enable-libvpx —enable-libx264 —disable-libx265 —enable-nonfree —arch=aarch64 —disable-libxml2 —enable-libwebp—enable-libdrm

  


  


  I used FFMPEG 4.4 because of compatibility issues with h264_v4l2m2m of the shipped FFMPEG version 4.1.4

  


  


  3. I use this command

     


     ffmpeg -f x11grab -probesize 42M -s 1920x1080 -i :0.0 -c:a copy -c:v h264_v4l2m2m -num_output_buffers 32 -num_capture_buffers 16 -b:v 8M -minrate 8M -maxrate 8M -pix_fmt rgb24 -f mpegts udp ://239.255.90.60:5004 ?pkt_size=1316

     


  


  


  The -pix_fmt rgb24 flag is needed because x11grab in 64 bit OS use BGR0 chroma subsampling... which means red and blue colours are inverted !

  


  This is the output :

  


  ffmpeg version 4.4 Copyright (c) 2000-2021 the FFmpeg developers  
  built with gcc 8 (Debian 8.3.0-6)  
  configuration: --prefix=/home/pi/ffmpeg_build --pkg-config-flags='pkg-config --static' --extra-cflags=-I/home/pi/ffmpeg_build/include --extra-ldflags=-L/home/pi/ffmpeg_build/lib --extra-libs='-lpthread -lm' --enable-gpl --enable-gnutls --disable-libaom --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --disable-libx265 --enable-nonfree --arch=aarch64 --disable-libxml2 --enable-libwebp --enable-libdrm  
  libavutil      56. 70.100 / 56. 70.100  
  libavcodec     58.134.100 / 58.134.100  
  libavformat    58. 76.100 / 58. 76.100  
  libavdevice    58. 13.100 / 58. 13.100  
  libavfilter     7.110.100 /  7.110.100  
  libswscale      5.  9.100 /  5.  9.100  
  libswresample   3.  9.100 /  3.  9.100  
  libpostproc    55.  9.100 / 55.  9.100  
Input #0, x11grab, from ':0.0':  
  Duration: N/A, start: 1619778505.990981, bitrate: 1988667 kb/s  
  Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1920x1080, 1988667 kb/s, 29.97 fps, 56   tbr, 1000k tbn, 1000k tbc  
Stream mapping:  
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (h264_v4l2m2m))  
Press [q] to stop, [?] for help  
[h264_v4l2m2m @ 0x5598d14070] Using device /dev/video11  
[h264_v4l2m2m @ 0x5598d14070] driver 'bcm2835-codec' on card 'bcm2835-codec-encode' in mplane mode  
[h264_v4l2m2m @ 0x5598d14070] requesting formats: output=RGB3 capture=H264  
[h264_v4l2m2m @ 0x5598d14070] Failed to set gop size: Invalid argument  
Output #0, mpegts, to 'udp://239.255.90.60:5004?pkt_size=1316':  
  Metadata:  
    encoder         : Lavf58.76.100  
  Stream #0:0: Video: h264, rgb24(pc, progressive), 1920x1080, q=2-31, 8000 kb/s, 56 fps, 90k tbn  
    Metadata:  
      encoder         : Lavc58.134.100 h264_v4l2m2m  
[mpegts @ 0x5598d12c10] Non-monotonous DTS in output stream 0:0; previous: 0, current: 0; changing   to 1. This may result in incorrect timestamps in the output file.  
frame=  799 fps= 16 q=-0.0 size=   16180kB time=00:00:49.19 bitrate=2694.2kbits/s speed=   1x 


  


  As you can see my issue is that the fps value is about 15 when streaming an HD video with VLC in full-screen mode (the fps value depends on what is displayed on screen, which I find odd being the encoding process should be done in HW).

  


  So the question is : any hope I can get close to 25 fps, so to have a smooth display on the receiver ? Either using a better FFMPEG command or tweaking the Raspberry ?

  


  Thanks for any help !

  


• ffmpeg : segmenting webcam video output on windows (dshow)

  2 mai 2021, par Arthur Hebert-Ryan

  I want to do exactly what is described in the post linked below, except on Windows using dshow instead of v4l2 :

  


  FFMPEG : Create contiguous videos from webcam

  


  My attempts all result in a single output file as though the segment options are being ignored. Here is my most basic command to try to get a series of 30s video files from my webcam :

  


  ffmpeg -f dshow -video_pin_name 1 -i video="USB Camera" -copyinkf -vcodec copy -f segment -segment_time 30 video_segment_%03d.mp4


  


  Command output :

  


  D:\videos>ffmpeg -f dshow -video_pin_name 1 -i video="USB Camera" -copyinkf -vcodec copy -f segment -segment_time 30 video_segment_%03d.mp4
ffmpeg version 4.3.2-2021-02-27-essentials_build-www.gyan.dev Copyright (c) 2000-2021 the FFmpeg developers
built with gcc 10.2.0 (Rev6, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-sdl2 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libgme --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libtheora --enable-libvo-amrwbenc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-librubberband
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
libswscale      5.  7.100 /  5.  7.100
libswresample   3.  7.100 /  3.  7.100
libpostproc    55.  7.100 / 55.  7.100
Input #0, dshow, from 'video=USB Camera':
Duration: N/A, start: 869580.415000, bitrate: N/A
    Stream #0:0: Video: h264 (Main) (H264 / 0x34363248), yuv420p, 1920x1080, 30 fps, 30 tbr, 10000k tbn, 20000k tbc
[segment @ 000001e814655640] Opening 'video_segment_000.mp4' for writing
Output #0, segment, to 'video_segment_%03d.mp4':
Metadata:
    encoder         : Lavf58.45.100
    Stream #0:0: Video: h264 (Main) (H264 / 0x34363248), yuv420p, 1920x1080, q=2-31, 30 fps, 30 tbr, 10000k tbn, 10000k tbc
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=  171 fps= 34 q=-1.0 size=N/A time=00:00:05.26 bitrate=N/A speed=1.04x


  


  I've tried :

  


  

  • using ssegment instead of segment

  


  • different output containers (.mp4, .h264, .avi, .mkv)

  


  • adding -map 0 and -an options

  


  • verifying that I'm getting keyframes from the output every second using the ffprobe command described here

  


  • adding -g 60

  


  


  But I get only one output file, which grows indefinitely. How do I capture from my webcam continuously into files of equal duration ?

  


  Here is a log of the same command using the -report option during 2+ minutes of capture (the log too big to paste into SO).

  


• Image generated by System.Drawing.Image is 10x larger than original file

  13 mai 2021, par Ninbura

  I've written a Powershell script that extracts one frame from a dshow capture device using FFmpeg, and then copies the output image from a file to my clipboard :

  


  $screenshot = [System.Drawing.Image]::FromFile((Get-Item -Path $outputFilePath))
[System.Windows.Forms.Clipboard]::SetImage($screenshot)
$screenshot.Dispose()


  


  The original file is a 1MB JPEG, but the image in my clipboard is an 11MB PNG. When I go to paste this file into something like Discord the file size is too large, unless you have Discord Nitro.

  


  Is there any way to avoid this file size inflation while using [System.Drawing.Image]::FromFile() ?

  


  Here's an easy test template :

  


  Add-Type -AssemblyName System.Drawing
Add-Type -AssemblyName System.Windows.Forms

$screenshot = [System.Drawing.Image]::FromFile((Get-Item -Path "Path to picture"))
[System.Windows.Forms.Clipboard]::SetImage($screenshot)
$screenshot.Dispose()


  


  Edit 2021/05/13 :

  


  Interestingly, it's starting to seem like this is a limitation of copying an image to a clipboard. I decided to dig deeper and see if the image size was increasing when I drew the image with System.Drawing.Image or when I pushed it in my clipboard with System.Windwos.Forms.Clipboard. If I save the image before putting it my clipboard like so, it retains the original file size, even if I change the extension to png :

  


  Add-Type -AssemblyName System.Drawing
Add-Type -AssemblyName System.Windows.Forms

$screenshot = [System.Drawing.Image]::FromFile((Get-Item -Path "C:\Users\gabri\Pictures\FFScreenshots\2021-05-12 19-04-26.845.jpeg"))
$screenshot.Save("C:\Users\gabri\Pictures\FFScreenshots\test.jpeg") # test.png makes no difference
$screenshot.Dispose()


  


  So it would seem that the image grows exponentially in size specifically when I push it to my clipboard. I verified this by simply uploading an image to Discord, copying it to my clipboard (click image > Open original > right click and copy result), and uploading it again. Sure enough, the new image pasted from my clipboard was around 10x the size of the original image (1MB vs 12MB). I wondered if this was a "limitation" of Windows so I ran the same test on Ubuntu 20.04. Uploaded an image to Discord, copied the image to my clipboard, and uploaded it again. Once again the image was about 10x larger, though slightly smaller than then when I uploaded the image from my clipboard on my Windows machine (11.4MB VS 12MB). Just to make sure this wasn't limited to Discord, I ran the same test with Gmail in-browser on both operating systems, same result.

  


  Alas, there appears to be something happening when you copy an image to a clipboard that drastically increases file size. One thing's for sure, whatever's happening is definitely over my head.