[Libav-user] could not open camera use qtkit on the macOS

[Thilo Borgmann]

Hi,

> I am getting these messages when I exec "ffmpeg -f qtkit -i "0" out.mpg" on the terminal:
> 
> Mac-mini-2:~ infowarelab-macmini$ ffmpeg -f qtkit -i "0" out.mpg
> 
> ffmpeg version 3.1.2 Copyright (c) 2000-2016 the FFmpeg developers
> 
>   built with Apple LLVM version 7.3.0 (clang-703.0.31)
> 
>   configuration: --enable-shared --disable-yasm
> 
>   libavutil      55. 28.100 / 55. 28.100
> 
>   libavcodec     57. 48.101 / 57. 48.101
> 
>   libavformat    57. 41.100 / 57. 41.100
> 
>   libavdevice    57.  0.101 / 57.  0.101
> 
>   libavfilter     6. 47.100 /  6. 47.100
> 
>   libswscale      4.  1.100 /  4.  1.100
> 
>   libswresample   2.  1.100 /  2.  1.100
> 
> [qtkit @ 0x7fc35f000000] Could not find codec parameters for stream 0 (Unknown: none): unknown codec
> 
> Consider increasing the value for the 'analyzeduration' and 'probesize' options
> 
> Input #0, qtkit, from '0':
> 
>   Duration: N/A, start: 2.020000, bitrate: N/A
> 
>     Stream #0:0: Unknown: none
> 
> Output #0, mpeg, to 'out.mpg':
> 
> Output file #0 does not contain any stream
> 
> The macOS version is 10.12.

on 10.12 you should consider using the avfoundation device instead of qtkit.

Also the output of "-list_devices true" could be helpful if the problem still exists with avfoundation or you have to stick to qtkit for some reason.

-Thilo