On Fri, 20 Dec 2024 13:36:23 +0100,
Stefan Hagen <sh+openbsd-tech@codevoid.de> wrote:
> 
> jfyi: ffplay started showing errors when playing the Logitech Webcam C270 mjpeg stream:
> ...
> [mjpeg @ 0xb22d21ed800] unable to decode APP fields: Invalid data found when processing input
> [mjpeg @ 0xb22d21ed800] unable to decode APP fields: Invalid data found when processing input
> [mjpeg @ 0xb22d21ed800] unable to decode APP fields: Invalid data found when processing input
> ...
> 
> It looks like this is not a driver issue and is simply an effect of unknown frames being forwarded now.
> This post explains that Logitech is embedding extra stuff into the mjpeg stream and ffplay finds it:
> https://stackoverflow.com/questions/55439184/getting-unable-to-decode-app-fields-while-playing-usb-webcam-stream-through-ff
>

On the contrary, this is the goal of that patch: to forward all frames to a
consumer like ffplay, even if they might be invalid for some reason, as they
may still contain useful information.

The T15g5 webcam, for example, sends more data than it should, which
prevents it from working in the first place. However, it also sends some
frames with a header length of 176 bytes, which are required to stabilize
the video and prevent it from glitching.

-- 
wbr, Kirill