[FFmpeg-user] Recording From Video4Linux Device When Resolution Changes Midstream

Carl Eugen Hoyos ceffmpeg at gmail.com
Fri May 24 00:25:28 EEST 2019

Am Do., 23. Mai 2019 um 20:34 Uhr schrieb Ide, Bruce (Contractor)
<Bruce_Ide at comcast.com>:

> This might be a better question for ffmpeg-developers, but I thought I’d ask here, first.

If you send a patch, please do not send it here but to the development
mailing list.

> I have a magewell HDMI capture card that provides a video4linux driver, and am
> recording the output of a digital set top box to a webm file with this command:
> ffmpeg -thread_queue_size 4096 -f v4l2 -i /dev/video0 \
>        -thread_queue_size 4096 -f alsa -i hdmi_audio_0 -ac 2 -ar 48000 \
>        -f webm \
>        -c:v libvpx -threads 4 -speed 6 -r 15 -b:v 512 \
>        -c:a libopus -ac 2 -threads 4 -ar 48000  \
>        /tmp/video0.webm

(Complete, uncut console output missing.)

> While doing this, I navigate to the settings menu on the digital set top box and change
> the resolution from 720p to 1080p. The magewell driver and video4linux both detect the
> resolution change immediately, but the resolution of the video I’m recording never changes.

ffmpeg (the application) does not support changing output resolutions.

Carl Eugen

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