YUV buffer pstride and rstride clarification needed

[David Ing]

I hope someone can correct me if I am wrong, but I am guessing that

   - pstride = pixel stride (i.e. the number of bytes per pixel)
   - rstride = row stride (i.e. the number of bytes per row of pixels)

Suppose I want to find the pixel (row=y, column=x), then I should look at
the following location within the byte array:

   - y * rstride + x * pstride

Keep in mind that I am a complete novice ... this is just a guess.

On Mon, Jul 15, 2019 at 2:45 PM Neil Young <foreverneilyoung at googlemail.com>
wrote:

> 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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