[mythtv-users] Recording from input video on demand, no tuner; update: troubles capturing video using RPI4

[Dan Wilga]

On 2/28/23 2:39 PM, Jay Harbeston wrote:
> I am trying to keep processing down to a minimal amount since I am 
> trying to use a Raspberry Pi 4b with 4GB ram running mythbackend to 
> capture the video stream.
>
> If I try to use any mpeg2 or mp4 transcoding, I get in trouble with 
> using too much cpu. Any ideas as to what I can try to capture with 
> little or no transcoding effort on the RPI 4b? Or am I asking too much 
> from the RPI4 to capture it.

I'd suggest using the mkv codec. Various people have done comparison 
charts that show the tradeoff between compression speed, file size and 
quality when using the different presets. Here is one example:

https://write.corbpie.com/ffmpeg-preset-comparison-x264-2019-encode-speed-and-file-size/

Watch the frame rate as it's encoding. If the FPS drops below the rate 
of the material being recorded for more than a short time, you know 
you're overtaxing the CPU.