AW: YUV buffer pstride and rstride clarification needed

[Thornton, Keith]

I think pstride is probably the scanning stride. I.e. it takes all of the Luma pixel data and every second Chroma pixel byte both horizontally and vertically. This probably doesn’t say anything about the stride in the buffer.
The increase in buffer size is because NV12 encoder often need width and height to be multiples of 16. i.e. 720 * 576. Whereby you can ignore the data in the additional added lines.

Von: gstreamer-devel <gstreamer-devel-bounces at lists.freedesktop.org> Im Auftrag von Neil Young
Gesendet: Montag, 15. Juli 2019 23:45
An: gstreamer-devel at lists.freedesktop.org
Betreff: YUV buffer pstride and rstride clarification needed

Hi,


I'm referring to this documentation


https://gstreamer.freedesktop.org/documentation/additional/design/mediatype-video-raw.html?gi-language=c


Up to now I received namely I420 buffers with a size of 1.5*width*height, as expected default YUV size.


Caps:


video/x-raw, format=(string)I420, width=(int)720, height=(int)540, interlace-mode=(string)progressive, multiview-mode=(string)mono, multiview-flags=(GstVideoMultiviewFlagsSet)0:ffffffff:/right-view-first/left-flipped/left-flopped/right-flipped/right-flopped/half-aspect/mixed-mono, pixel-aspect-ratio=(fraction)1/1, chroma-site=(string)jpeg, colorimetry=(string)bt601, framerate=(fraction)0/1;


Frame buffer size is 583200 byte.


Today for the first time I got this:


Caps:


video/x-raw(memory:VASurface), format=(string)NV12, width=(int)720, height=(int)540, interlace-mode=(string)progressive, multiview-mode=(string)mono, multiview-flags=(GstVideoMultiviewFlagsSet)0:ffffffff:/right-view-first/left-flipped/left-flopped/right-flipped/right-flopped/half-aspect/mixed-mono, pixel-aspect-ratio=(fraction)1/1, framerate=(fraction)0/1


with a frame buffer size of 622080 byte, which is more than 1.5 * width * height.


Now I'm wondering, how to understand the values of rstride and pstride in the above document. Could somebody help please?


TIA
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