On 9/4/2017 2:40 PM, Michael Niedermayer wrote: > On Sat, Sep 02, 2017 at 11:21:35PM +0100, Mark Thompson wrote: >> --- >> The idea here is to be able to capture the screen with little CPU >> interaction by encoding KMS scanout planes. Given X running on KMS, it can >> capture both X and virtual consoles, including transitions between them >> while recording. >> >> Unfortunately, it's rather inconvenient to use: the KMS API doesn't quite >> support the necessary set of things to work all the parameters out cleanly - >> framebuffer parameters (including the pixel format) need to be supplied by >> the user. For finding plane/CRTC IDs, the libdrm modetest program is useful >> (luckily the IDs are all global). Formats may have to be found by guessing >> until the output looks right. It also requires either DRM master or >> CAP_SYS_ADMIN to run (needed to access the framebuffer attached to the >> scanout plane). >> >> On Intel gen9 / Linux 4.12, I can capture and encode with: >> >> ./ffmpeg_g -y -framerate 60 -format bgr0 -crtc_id 26 -f kmsgrab -i - >> -init_hw_device vaapi=v:/dev/dri/renderD128 -filter_hw_device v -vf >> 'hwmap,scale_vaapi=w=1920:h=1080:format=nv12' -c:v h264_vaapi -frames:v 1000 >> out.mp4 >> >> There is some tiling going on which should need the format modifier to be >> set, but the Intel VAAPI driver is able to find it by magic so it isn't >> required for this example. On the other hand, mapping to the CPU does not >> give a sensible result because of that. >> > >> Given how tricky it is to use, I'm not really sure whether it is actually >> useful for this to be in ffmpeg. On the other hand, it does use a lot less >> CPU than xcbgrab! Thoughts welcome. > > My thought, if its less energy intensive than what we have then its > worth having. > A tiny contribution to reducing carbon emissions ...
I have to say this is a really silly reason to support implementing a new, less CPU intensive screen grabber. The real gain here is of course longer battery life on laptops. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
