On 1/15/23 22:32, Laurent Pinchart wrote:
Hi Marek,
On Fri, Jan 13, 2023 at 02:03:33AM +0100, Marek Vasut wrote:
On 1/13/23 00:15, Laurent Pinchart wrote:
On Tue, Jan 10, 2023 at 08:53:31PM +0100, Marek Vasut wrote:
The Cypress EZUSB FX3 UVC example can be configured to report pixel
format "e436eb7e-524f-11ce-9f53-0020af0ba770". This is its GUID for
BGRA/X 8:8:8:8.
The UVC 1.5 spec [1] only defines GUIDs for YUY2, NV12, M420 and I420.
This seems to be an extension documented in the Microsoft Windows Media
Format SDK[2]. This Media Format SDK defines this GUID as corresponding
to `MEDIASUBTYPE_RGB32`.
Note that in my case, the FX3 UVC can output either channel order,
BGR or RGB or any other mix for that matter. Since Linux commit
1b8dc32286a1a ("[media] uvcvideo: Add GUID for BGR 8:8:8")
defined a GUID for `MEDIASUBTYPE_RGB24` channel order as BGR, keep
this change consistent and define `MEDIASUBTYPE_RGB32` as BGR as well.
I'd like to see documentation of the MEDIASUBTYPE_RGB32 format that
indicates the components order precisely. While there's a high chance it
maps to a BGR (in the V4L2 nomenclature) format, there would still be
two different options for the A or X component.
Maybe this ?
https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src/DirectShow/uncompressed-rgb-video-subtypes.md
"
Remarks
...
For RGB 32, every pixel is an RGBQUAD. Each color is one byte, with a
value from 0 to 255, inclusive. The memory layout is:
Byte 0 1 2 3
Value Blue Green Red Alpha or Don't Care
"
Maps to
drivers/media/v4l2-core/v4l2-ioctl.c: case V4L2_PIX_FMT_BGR32:
descr = "32-bit BGRA/X 8-8-8-8"; break;
Thank you for digging it up. Looks good to me, except that
V4L2_PIX_FMT_BGR32 is deprecated (see
https://linuxtv.org/downloads/v4l-dvb-apis/userspace-api/v4l/pixfmt-rgb.html#deprecated-rgb-formats).
You should use V4L2_PIX_FMT_BGRA32 or V4L2_PIX_FMT_BGRX32 instead.
V4L2_PIX_FMT_XBGR32 , right ?
