On Thu, Jan 26, 2017 at 14:25:13 +0000, Andy Furniss wrote: > Maybe what Jimmy is saying is you don't need -pix_fmt h264 as you > already have -input_format h264. If removing it gives the same logging > output then it's not needed. > > As has been said, you are getting compressed h264 from the camera, but > you are using -r 20 which means you are requesting 20 fps not 30. You > should also probably use -framerate 30 rather than -r 30 - there may > be a difference in behavior.
You can also query the device (driver) to see what the camera can give you. You should probably get a result such as this: https://wiki.matthiasbock.net/index.php/Kategorie:Logitech_C920_(Webcam)#v4l2-ctl_--device.3D.2Fdev.2Fvideo1_--list-formats See the sections "VIDIOC_ENUM_FMT(n,VIDEO_CAPTURE)", n being 0,1,2. It seems there's only one H.264 format that camera can deliver, and that's what you are getting with your command. I believe you can get actual higher quality by choosing YUV 4:2:2 (it has a higher vertical chroma resolution than YUV 4:2:0), but a) it can have bandwidth (i.e. resolution or framerate) restrictions on the USB bus, and b) you need to encode it yourself. Other tools ("luvcview -L" and guvcview come to mind) will also report the natively supported resolutions and frame rates, so the driver doesn't need to make a guess at what is closest to what you request (e.g. if driver and camera support 15 & 30 fps, but you request 20). Moritz _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
