ffv1 realtime capture throws out a lot of frame dropped messages! Can you help me to figure out what's going on here?

I'm trying to capture in realtime my screen and save it losslessy via ffv1 codec.



CPU usage while recording is not so much, as comparison h264 in ultrafast profile takes lot more cpu than ffv1.

Here's the command I'm using:

ffmpeg -f dshow -y -i video="screen-capture-recorder" -framerate 30 -c:v ffv1 -pix_fmt bgra -t 5 capture.mkv


I tried also adding the tuning and rtbufsize but nothing changes :\

ffmpeg -f dshow -y -i video="screen-capture-recorder" -framerate 30 -c:v ffv1 -pix_fmt bgra -t 5 -tune zerolatency -rtbufsize 2100M capture.mkv


Any suggestions? :)
I get the same result with your commands, however if I skip the pixel format conversion and use the input pixel format 'bgr0', then except for an initial frame drop, I get no further drops. Note that tune is a x264 parameter - it has no relevance for FFV1.

And if I use gdigrab (my preferred grabbing device), I get no frame drops at all, even with bgra:-

ffmpeg -y -f gdigrab -i desktop -framerate 30 -c:v ffv1 -pix_fmt bgra -t 5 capture.mkv