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• stream usb webcam via http using vlc without transcoding using mjpeg signal from webcam

  10 novembre 2020, par Peter Nußreiner

  I wanna stream my (Microsoft live) USB webcam using vlc from a raspberry.
While it works perfectely fine with transcoding my raspberry does not have enough power.

  


  So I checked the output formats of my webcam using :

  


  ffmpeg -f v4l2 -list_formats all -i /dev/video0


  


  wich gives me the following output :

  


  [video4linux2,v4l2 @ 0x559d5aee36c0] Raw       :     yuyv422 :           YUYV 4:2:2 : 640x480 1280x720 960x544 800x448 640x360 424x240 352x288 320x240 800x600 176x144 160x120 1280x800
[video4linux2,v4l2 @ 0x559d5aee36c0] Compressed:       mjpeg :          Motion-JPEG : 640x480 1280x720 960x544 800x448 640x360 800x600 416x240 352x288 176x144 320x240 160x120
/dev/video0: Immediate exit requested


  


  when running my streaming command :

  


  cvlc v4l2:///dev/video0:chroma=h264:width=1280:height=720 --sout '#standard{access=http,mux=ts,dst=192.168.178.27:8080,name=stream,mime=video/ts}' -vvv


  


  I get the following error :

  


  mux_ts mux warning: rejecting stream with unsupported codec YUY2
main mux error: cannot add this stream
main decoder error: cannot create packetizer output (YUY2)


  


  along with many other lines of information.
As far as I can interpret the error, vlc wants to use the YUY2 RAW signal of my webcam.
Is there any way I can force vlc to use the mjpg output of my camera ?

  


  I've already tried to use 'chroma=mjpg' without success.
Transcoding is not an alternative as my raspi has by far not enough power.

  


  I've also read about using ffmpeg for streaming, maybe someone has an alternative solution since I'm very new to the whole topic of websites and stuff

  


  It will (or should) be used as a live webcam for a windsurfing spot.
Therefore I need a fluent video with at least 10fps to judge the situation. A delay of a minute or so is no problem.
The basic idea was to stream the video to a webserver and embed the image in a website. I've got good internet connection at the spot.

  


  But for now I want to try it locally on my pc.

  


• FFMPEG encoding 16bit video data results in 10bit

  12 mars 2023, par Jl arto

  I want to compress a depth map that has 16 bits of information per pixel. In general, such depth maps can be stored in different ways, e.g. p016le, gray16le, yuv420p16le, yuv444p16le, ... but for simplicity, let's assume the depth map is a yuv420p16le (where the y-channel contains the depth).

  


  For some reason when encoding with hevc_nvenc (I use an NVIDIA GTX 1660 Ti GPU), ffmpeg (the command line tool) changes the pixel format to a 10 or 12 bit variant (p010le, gray12le, yuv420p10le, yuv444p12le, ...), but I would like to keep the full 16 bits, since this affects the quality of the depth stored.

  


  For example :

  


  ffmpeg.exe -s:v 1920x1080 -r 30 -pix_fmt yuv420p16le -i depth_yuv420p16le.yuv -c:v hevc_nvenc -pix_fmt yuv444p16le output.mp4


  


  If I use ffprobe on the output.mp4, it tells me that the underlying pixel format is actually yuv444p10le. (Decoding and looking at the raw pixel data, I can confirm that the precision has decreased from 16 bits to 10 bits).

  


  I hope 16 bit compression is possible, since according to

  


  ffmpeg -h encoder=hevc_nvenc


  


  the supported pixel formats are :

  


  hevc_nvenc: yuv420p nv12 p010le yuv444p p016le yuv444p16le bgr0 rgb0 cuda d3d11


  


  But p016le results in a p010le output, and yuv444p16le in yuv444p10le.

  


  Does anyone know where the problem could lie ? Should I re-install ffmpeg (version 4.3.2-2021-02-27-essentials_build-www.gyan.dev) ? Is it because of Windows 10 having limited encoding/decoding capabilities ? Will buying the HEVC Video Extensions help solve this problem ?

  


  Additional info : using libx256 does not look like it will work for this purpose, since the supported pixel formats are :

  


  libx256 : yuv420p yuvj420p yuv422p yuvj422p yuv444p yuvj444p gbrp yuv420p10le yuv422p10le yuv444p10le gbrp10le yuv420p12le yuv422p12le yuv444p12le gbrp12le gray gray10le gray12le


  


  Any help would be greatly appreciated.

  


• FFMPEG Failure - Extracting frames on large file

  25 avril 2018, par Marian Montagnino

  Calling the ffmpeg command :

  ffmpeg -y -ss "00:00:02" -i 5ccaea226acfc1b4b75ccd1a9f09512c.mxf -frames 30 -f image2 -vf "fps=1/1.25,scale='min(420,iw)':-1" video%04d.jpg

  Causes a failure :

  ffmpeg failed: ffmpeg version N-85692-g78a5fc4 Copyright (c) 2000-2017 the FFmpeg developers
  
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-11)
  
  configuration: --prefix=/tmp/gm-ffmpeg-1.0.4/BUILD/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/tmp/gm-ffmpeg-1.0.4/BUILD/ffmpeg_build/include --extra-ldflags=-L/tmp/gm-ffmpeg-1.0.4/BUILD/ffmpeg_build/lib --bindir=/tmp/gm-ffmpeg-1.0.4/BUILDROOT/gm-ffmpeg-1.0.4-1.el7.centos.x86_64/opt/graymeta/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 55. 61.100 / 55. 61.100
  
  libavcodec 57. 93.100 / 57. 93.100
  
  libavformat 57. 72.101 / 57. 72.101
  
  libavdevice 57. 7.100 / 57. 7.100
  
  libavfilter 6. 87.100 / 6. 87.100
  
  libswscale 4. 7.101 / 4. 7.101
  
  libswresample 2. 8.100 / 2. 8.100
  
  libpostproc 54. 6.100 / 54. 6.100
  
  [mxf @ 0x2c6da60] broken or empty index
  
  Input #0, mxf, from '/alloc/5ccaea226acfc1b4b75ccd1a9f09512c.mxf':
  
  Metadata:
  
  uid : 27b07007-2dc8-4305-a78a-81a612d78b94
  
  generation_uid : ef5ae870-4075-4513-ea1f-39c0ed197267
  
  company_name : Colorfront
  
  product_name : Transkoder
  
  product_uid : 3a4fe380-0d01-11e4-869f-3cd92b5c1dfc
  
  product_version : 2.7.3.20150121
  
  application_platform: Microsoft Windows 7 Professional Service Pack 1 (Build 7601)
  
  modification_date: 2016-09-09T11:29:39.000000Z
  
  material_package_umid: 0x060A2B340101010501010F20130000008991E1DCEA584837149E72E7F9F0E09D
  
  timecode : 00:00:17;12
  
  Duration: 00:11:58.92, start: 0.000000, bitrate: 150802 kb/s
  
  Stream #0:0: Video: jpeg2000, yuv422p10le(progressive), 3840x2160, SAR 1:1 DAR 16:9, 59.94 fps, 59.94 tbr, 59.94 tbn, 59.94 tbc
  
  Metadata:
  
  file_package_umid: 0x060A2B340101010501010F2013000000F8B3B48BE8044408DDD6303A6D43F566
  
  track_name : Picture
  
  Stream mapping:
  
  Stream #0:0 -> #0:0 (jpeg2000 (native) -> mjpeg (native))
  
  Press [q] to stop, [?] for help
  
  : signal: killed

  I’m not sure how to interpret this error message and why it actually failed. This file is about 90GB large and shot in 4K resolution but 11 seconds long.