Output #0, video4linux2,v4l2, to '/dev/video1':
While ffmpeg starts cloning the stream without any warnings or errors, it is still outputting in yuv420p instead: ffmpeg -f v4l2 -i /dev/video0 -codec copy -f v4l2 -pix_fmt yuv422p /dev/video1įfmpeg version 4.2.2-1ubuntu1 Copyright (c) 2000-2019 the FFmpeg developersĬonfiguration: -prefix=/usr -extra-version=1ubuntu1 -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-opencl -enable-opengl -enable-sdl2 -enable-libdc1394 -enable-libdrm -enable-libiec61883 -enable-nvenc -enable-chromaprint -enable-frei0r -enable-libx264 -enable-shared
I thought that this would be a simple task that can easily be handled by presenting ffmpeg with an additional -pix_fmt argument on the output device like so: ffmpeg -f v4l2 -i /dev/video0 -codec copy -f v4l2 -pix_fmt yuv422p /dev/video1 Next I'd like to convert the pixel format of the dummy device as the application that is accessing the dummy device can only handle yuv422p or RGB whereas my source device /dev/video0 provides yuv420p. Note: To make this work you need to ensure that the v4l2loopback device kernel module is enabled: modprobe v4l2loopback devices=1 I am able to successfully access /dev/video1 which presents the same feed as /dev/video0. To achieve this, I simply clone to a v4l2 loop back device: ffmpeg -f v4l2 -i /dev/video0 -codec copy -f v4l2 /dev/video1 :554/udp/av0_1 -preset veryfast -c:a copy -c:v copy -f hls -pix_fmt yuv420p -hls_time 1 -hls_list_size 10 -start_number 0 -hls_allow_cache 0 -hls_flags +delete_segments+omit_endlist /dev/shm/streams/ //s.m3u8 -update 1 -r 1 -s 640x360 /dev/shm/streams/ //s.jpg -y -map 0:a -acodec pcm_s16le -f s16le -ac 1 -ar 16000 pipe:6 -r 2 -s 640x360 -an -c:v pam -pix_fmt gray -f image2pipe pipe:3 -pix_fmt yuv420p -movflags +faststart -preset veryfast -crf 20 -r 5 -c:a copy -c:v libx264 -f hls -tune zerolatency -g 1 -hls_time 2 -hls_list_size 10 -start_number 0 -live_start_index -3 -hls_allow_cache 0 -hls_flags +delete_segments+omit_endlist /dev/shm/streams/ //detectorStream.I am using ffmpeg 4.2.2 on an Ubuntu 20.04 machine to clone the video stream of a USB webcam so that multiple applications can use the same feed. usr/local/bin/ffmpeg -loglevel warning -r 5 -progress pipe:5 -use_wallclock_as_timestamps 1 -analyzeduration 5000000 -probesize 5000000 -rtsp_transport udp -err_detect aggressive -fflags discardcorrupt -i rtsp://. from my system, see "-preset veryfast" right after the rtsp:***. This leads to the situation where if previously preset is not set, the ffmpeg process will die because there will be no option (veryfast/ultrafast/etc.) after -preset.Į.g. Shinobi will generate a ffmpeg command line that contains unnecessary -preset parameter even though the stream and recorders are both set to copy the RTSP video stream and the AAC audio stream directly.
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