Home / ubuntu / Questions

Questions[gphoto2](ubuntu)

Martin Hope
minder
Asked: 2020-06-18 05:51:29 +0800 CST
  • 1

I tried adding my Canon EOS M50 as a webcam using v4l2 loopback like this:

gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0

It works but the picture is 512x288.

On the other hand SparkoCam on a Windows box can squeeze 1080p liveview out of it with decent fps and full control over ISO etc. The picture is very sharp and does not look upscaled (although I didn't do a pixel by pixel analysis yet). Anyway: how can I achieve the same or similar results with gphoto2?

gphoto2
Martin Hope
Jamie Hutber
Asked: 2020-04-26 15:29:31 +0800 CST
  • 1

I have a Nikon D7000 which is supported by gphoto2 and can successfully take a photo.

However I cannot get this camera to work as a webcam as I thought I would be able to. Please see below:

hutber@hutber:~$ gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video2
ffmpeg version N-49161-g50e194e6e1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
  libavutil      56. 30.100 / 56. 30.100
  libavcodec     58. 53.101 / 58. 53.101
  libavformat    58. 28.101 / 58. 28.101
  libavdevice    58.  7.100 / 58.  7.100
  libavfilter     7. 55.100 /  7. 55.100
  libswscale      5.  4.101 /  5.  4.101
  libswresample   3.  4.100 /  3.  4.100
  libpostproc    55.  4.100 / 55.  4.100
Capturing preview frames as movie to 'stdout'. Press Ctrl-C to abort.
[mjpeg @ 0x7389940] Format mjpeg detected only with low score of 25, misdetection possible!
Input #0, mjpeg, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg (Baseline), yuvj422p(pc, bt470bg/unknown/unknown), 640x426, 25 tbr, 1200k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> rawvideo (native))
[swscaler @ 0x73b4040] deprecated pixel format used, make sure you did set range correctly
[video4linux2,v4l2 @ 0x7392700] Unable to open V4L2 device '/dev/video2'
Could not write header for output file #0 (incorrect codec parameters ?): No such file or directory
Error initializing output stream 0:0 -- 
Conversion failed!

More information:

hutber@hutber:~$ v4l2-ctl --list-devices
HD Pro Webcam C920 (usb-0000:05:00.0-1.2.3):
    /dev/video0
    /dev/video1
usb webcam ffmpeg gphoto2
Martin Hope
Valentin H.
Asked: 2020-04-10 07:18:35 +0800 CST
  • 2

I am trying to set up my nikon d7000 dslr as a video device for Ubuntu 18.04, as shown in this article.

When I try to start the video stream/device with 

gphoto2 --capture-movie --stdout | ffmpeg -loglevel verbose -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0

The Error I get:

:~$ gphoto2 --capture-movie --stdout | ffmpeg -loglevel verbose -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0
ffmpeg version 3.4.6-0ubuntu0.18.04.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.3.0-16ubuntu3)
  configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Capturing preview frames as movie to 'stdout'. Press Ctrl-C to abort.

[mjpeg @ 0x5556d09cd9c0] Format mjpeg detected only with low score of 25, misdetection possible!
Input #0, mjpeg, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg, 1 reference frame, yuvj422p(pc, bt470bg/unknown/unknown, center), 640x426, 25 tbr, 1200k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> rawvideo (native))
[graph 0 input from stream 0:0 @ 0x5556d09e0cc0] w:640 h:426 pixfmt:yuvj422p tb:1/1200000 fr:25/1 sar:0/1 sws_param:flags=2
[auto_scaler_0 @ 0x5556d09e88e0] w:iw h:ih flags:'bicubic' interl:0
[format @ 0x5556d09e5e60] auto-inserting filter 'auto_scaler_0' between the filter 'Parsed_null_0' and the filter 'format'
[swscaler @ 0x5556d09e99c0] deprecated pixel format used, make sure you did set range correctly
[auto_scaler_0 @ 0x5556d09e88e0] w:640 h:426 fmt:yuvj422p sar:0/1 -> w:640 h:426 fmt:yuv420p sar:0/1 flags:0x4
[v4l2 @ 0x5556d09d7980] ioctl(VIDIOC_G_FMT): Invalid argument
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:0 --
Conversion failed!

Info about the Camera:

:~$ gphoto2 --auto-detect
Model                          Port                                            
----------------------------------------------------------
Nikon DSC D7000 (PTP mode)     usb:001,005    
:~$ gphoto2 --summary
Camera summary:                                                                
Manufacturer: Nikon Corporation
Model: D7000
  Version: V1.03
  Serial Number:
Vendor Extension ID: 0xa (1.0)
Vendor Extension Description: microsoft.com: 1.0

Capture Formats: JPEG Undefined Type
Display Formats: JPEG, Undefined Type, Association/Directory, DPOF, Script, Apple Quicktime

Device Capabilities:
        File Download, File Deletion, File Upload
        Generic Image Capture, No Open Capture, Nikon Capture 1, Nikon Capture 2, Nikon Capture 3
[...]

I spent some time in the man pages of these commands, without luck. I am still not sure where the problem is exactly. The camera appears to be sending a stream, at least the mirror goes up and when I try the command without the ffmpeg stuff I get a Terminal full of Garbage, witch is Image data in Text form, I presume.

Maybe I set the v4l2 device up wrong?

How can I check what is working and what is not? Maybe I have to tell the v4l2 exactly what it should do?

Can anybody help me with gphoto + ffmpeg + video4linux or point me in the right direction?

video webcam ffmpeg gphoto2 video4linux
Martin Hope
Mehran
Asked: 2020-01-05 17:04:09 +0800 CST
  • 3

I followed this other post and managed to turn my DSLR into a webcam successfully. To test it, I can see the live video in applications like guvcview and my DSLR is recognized as Dummy video device (0x0000).

But the same device can not be found in Chrome when I try to use it as a webcam. For the record, this is how I initialize the process:

gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video1

[UPDATE]

Thanks to @llogan, I tested with FireFox and it works there! So my problem is only with Chrome.

This is what I'm getting by running the given command:

$ gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video1
Capturing preview frames as movie to 'stdout'. Press Ctrl-C to abort.
ffmpeg version 3.4.6-0ubuntu0.18.04.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.3.0-16ubuntu3)
  configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
[mjpeg @ 0x5653c54659c0] Format mjpeg detected only with low score of 25, misdetection possible!
Input #0, mjpeg, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 960x640, 25 tbr, 1200k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> rawvideo (native))
[swscaler @ 0x5653c54bb000] deprecated pixel format used, make sure you did set range correctly
Output #0, v4l2, to '/dev/video1':
  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 960x640, q=2-31, 184320 kb/s, 25 fps, 25 tbn, 25 tbc
    Metadata:
      encoder         : Lavc57.107.100 rawvideo
frame=  551 fps= 23 q=-0.0 size=N/A time=00:00:22.04 bitrate=N/A speed=0.905x

[UPDATE]

As suggested by @llogan, I tested this other command:

$ gphoto2 --stdout --capture-movie | ffmpeg -i - -c copy -f v4l2 /dev/video1
Capturing preview frames as movie to 'stdout'. Press Ctrl-C to abort.
ffmpeg version 3.4.6-0ubuntu0.18.04.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.3.0-16ubuntu3)
  configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
[mjpeg @ 0x55eaeabdd900] Format mjpeg detected only with low score of 25, misdetection possible!
Input #0, mjpeg, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 960x640, 25 tbr, 1200k tbn, 25 tbc
[v4l2 @ 0x55eaeabe78c0] V4L2 output device supports only a single raw video stream
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
    Last message repeated 1 times

As you can see it did not even initialize the webcam. And to be clear about what I mean when I say it doe not work in Chrome, the webcam menu only shows my other webcam and there's no trace of my DSLR. While in FireFox, I have two webcams to select from. I also opened the developer tools in Chrome and there's no errors/warnings to help understand anything about this issue.

browser webcam ffmpeg gphoto2
Martin Hope
haxpor
Asked: 2019-04-27 02:55:31 +0800 CST
  • 4

I have Nikon D3300 camera and want to feed video output into my computer as part of live streaming with OBS.

I successfully installed v4l2loopback as well as gphoto2 on my Ubuntu 18.04. I already had ffmpeg installed. (Their all version information can be found at the bottom)

Then I execute the command gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video2. I tested to see video output via guvcview and OBS. It shows video output properly but with one issue. It looks greenish like this (captured from OBS).

enter image description here

I also asked in v4l2loopback on github and developer pin-points that the problem is with the parameters feeding the program i.e. gphoto2 (or need some adjustment of parameters in ffmpeg too or not I'm not sure).

So do you know whether I use the right parameters? or else what's the right ones to solve this greenish video output.

ffmpeg v4l gphoto2