I'm taking hi-res screencasts of googleearth sim sessions with fffmpeg, typical code:

ffmpeg -thread_queue_size 1024 -y -r 30 -f x11grab -s 1509x1080 -i :0.0+91,0 -c:v libx264rgb -crf 0 -preset:v ultrafast 0-capture-crf0.mkv

I might watermark with a transparent image like so:

ffmpeg -i c3237vs.mkv -i img4.png -c:v libx264rgb -preset veryslow -qp 0 -filter_complex "overlay=0:0:enable='between(t,36,41)'" d3641vs.mkv

Problem is that the playback with VLC sometimes shows 'artifacts'(?)

machines are asus g73 and amd-8-core with nvidia, these artifacts appear almost exclusively on videos that I have made as above and less frequently if i inject images with '-preset ultrafast' (but I haven't really been able to nail it).


According to some experts underclocking the gpu might be the answer, if so, how would i do that & why would my vids require it more than others?

oh yeah, greets!

[blinking around 48n66w]

Are you sure the artifacts are happening on "playback", and they're not actually GPU corruption that's happening during capture and then getting accurately recorded?

not qualified to know

i think maybe not on account of that when a video watermarked using 'veryslow' plays artifacts and i then repeat the exercise with 'ultrafast' then the artifacts might vanish. I've also seen them appear only after so many plays, i'm beginning to think gpu overheat over time but i'm really at the very beginning of the hunt. Done about 50 in the last few days & i never ever saw stuff like this in my life.

another clue is that when i reload a badly grimacing 5 gigger into brakehandle it will let me produce a clean and much smaller mv4 file that shows no corruption at all. I don't imaginse this would be possible with an original corrupted at the source file level.

Would it be possible for such home spun hires vids to so overload a gpu? Such should be impossible, but searching on the net i see lotsa complaints.

Welcome to the forum.
Please be aware that this forum is for introductions only, not asking technical questions. See info.
http://www.linuxquestions.org/questi...se-read-81010/

You would probably get a better response to your question by starting a new thread in the appropriate forum

You should watch one of the videos on some other machine, to eliminate the possibility that it the artifacts are in the file and not the hardware. Also, try a different player (mpv or mplayer and ffplay and xine instead of VLC) to see if the behaviour is different.

I do not believe your GPU would be overheating from media playback, but I guess there's the possibility. I would suspect caching issues; do you have enough RAM to create a ramdisk and then play the media file back from that? I'd be interested in hearing if that behaved differently on the current hardware.

I did the ramdisk thing, still artifacting. Since the problem is on both boxes, although perhaps not necessarily equally, it could be more than just hardware.

I'll repost somewhere else

I suppose you're right, I'm outta here :-)

+1

Welcome to the forum

Because of what offgridguy mentioned above, I have requested that a moderator move this thread.

EDIT: I just now noticed your post above and the new thread you created. The moderator will need to decide which thread to close or move, etc.

Regards...