[FFmpeg-user] ffmpeg and two (2) logitech 920 webcams

[DopeLabs]

you could try using the alternate names.. examples are shown here

https://www.ffmpeg.org/ffmpeg-devices.html#dshow


is it always that specific camera?

if you connect the one that isnt working first so that its listed as #1, will it work?

have you tried connecting the 2nd camera to a separate USB bus?

you can use the following tool to get usb bus info on your system

https://github.com/Microsoft/Windows-driver-samples/tree/master/usb/usbview



> On May 22, 2018, at 9:35 03AM, Frank Belson <frankbelson2 at gmail.com> wrote:
> 
> The following is the output from ffmpeg -list_devices true -f dshow -i dummy
> 
> ffmpeg version N-87353-g183fd30 Copyright (c) 2000-2017 the FFmpeg
> developers
>  built with gcc 7.2.0 (GCC)
>  configuration: --enable-gpl --enable-version3 --enable-cuda
> --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx
> --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig
> --enable-frei0r --enable-gnutls --enable-iconv --enable-libass
> --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype
> --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug
> --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb
> --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp
> --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora
> --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc
> --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp
> --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid
> --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib
>  libavutil      55. 76.100 / 55. 76.100
>  libavcodec     57.106.101 / 57.106.101
>  libavformat    57. 82.101 / 57. 82.101
>  libavdevice    57.  8.101 / 57.  8.101
>  libavfilter     6.105.100 /  6.105.100
>  libswscale      4.  7.103 /  4.  7.103
>  libswresample   2.  8.100 /  2.  8.100
>  libpostproc    54.  6.100 / 54.  6.100
> [dshow @ 00000000002f6c00] DirectShow video devices (some may be both video
> and audio devices)
> [dshow @ 00000000002f6c00]  "Logitech Cam#1"
> [dshow @ 00000000002f6c00]     Alternative name
> "@device_pnp_\\?\usb#vid_046d&pid_082d&mi_00#6&10047afe&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\{bbefb6c7-2fc4-4139-bb8b-a58bba724083}"
> [dshow @ 00000000002f6c00]  "Logitech Cam#2"
> [dshow @ 00000000002f6c00]     Alternative name
> "@device_pnp_\\?\usb#vid_046d&pid_082d&mi_00#6&3a78d907&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
> [dshow @ 00000000002f6c00]  "Kodak S101 Webcam"
> [dshow @ 00000000002f6c00]     Alternative name
> "@device_pnp_\\?\usb#vid_0979&pid_0206&mi_00#6&2455fd16&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
> [dshow @ 00000000002f6c00] DirectShow audio devices
> [dshow @ 00000000002f6c00]  "Microphone (4- Kodak S101 Micro"
> [dshow @ 00000000002f6c00]     Alternative name
> "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\Microphone (4- Kodak
> S101 Micro"
> [dshow @ 00000000002f6c00]  "Line (WsAudio_Device)"
> [dshow @ 00000000002f6c00]     Alternative name
> "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\Line (WsAudio_Device)"
> [dshow @ 00000000002f6c00]  "Microphone (2- HD Pro Webcam C9"
> [dshow @ 00000000002f6c00]     Alternative name
> "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\Microphone (2- HD Pro
> Webcam C9"
> [dshow @ 00000000002f6c00]  "Microphone (HD Pro Webcam C920)"
> [dshow @ 00000000002f6c00]     Alternative name
> "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\Microphone (HD Pro
> Webcam C920)"
> dummy: Immediate exit requested
> 
> 
> On Tue, May 22, 2018 at 6:59 AM, DopeLabs <dopelabs at dubstep.fm> wrote:
> 
>> what is the output of
>> 
>> $ ffmpeg -list_devices true -f dshow -i dummy
>> 
>> 
>> if you have multiple entries of a webcam named "Logitech Cam", you can
>> specify which using -video_device_number
>> 
>> the following would select the 2nd identical device (as numbers for
>> devices start at 0)
>> 
>> $ ffmpeg -f dshow -video_device_number 1 -i video="Logitech Cam"
>> 
>> 
>> im also curious.. would this work? video="Logitech Cam#0"
>> 
>> (please include complete uncut console output)
>> 
>> running the latest version of ffmpeg?
>> 
>> 
>>> On May 19, 2018, at 3:34 17PM, Brenda Spinner <brendaspinner at gmail.com>
>> wrote:
>>> 
>>> I am using the following line to preview my webcam:
>>> 
>>> ffmpeg -s 1280x720 -framerate 30 -pix_fmt yuv420p -rtbufsize 100MB -f
>> dshow
>>> -i video="Logitech Cam#1" -c:v copy -an -f sdl "WebCAM Preview"
>>> 
>>> this line works fine with cam #1, however when try it with cam #2, I get
>>> the error:
>>> 
>>> [dshow @ 00000000002d8920] Could not set video options video=Logitech
>>> Cam#2: I/O error
>>> 
>>> Can anyone tell me why this is happening. I would like to able to preview
>>> both webcams at the same time?
>>> 
>>> Thanks, Frank
>>> 
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