Hi Guennadi,
I'm preparing a patch series that replaces enum/g/try/s_fmt with
enum/g/try/s/_mbus_fmt in all subdevs. While doing that I stumbled on a
confusing definition of the YUV mediabus formats. Currently we have these:
V4L2_MBUS_FMT_YUYV8_2X8_LE,
V4L2_MBUS_FMT_YVYU8_2X8_LE,
V4L2_MBUS_FMT_YUYV8_2X8_BE,
V4L2_MBUS_FMT_YVYU8_2X8_BE,
The meaning of "2X8" is defined as: 'one pixel is transferred in
two 8-bit samples'.
This is confusing since you cannot really say that a Y and U pair constitutes
one pixel. And is it Y or U/V which constitutes the 'most-significant bits' in
such a 16-bit number?
In my particular case I have to translate a V4L2_PIX_FMT_UYVY to a suitable
mediabus format. I think it would map to V4L2_MBUS_FMT_YUYV8_2X8_LE, but
frankly I'm not sure.
My suggestion is to rename these mediabus formats to:
V4L2_MBUS_FMT_YUYV8_1X8,
V4L2_MBUS_FMT_YVYU8_1X8,
V4L2_MBUS_FMT_UYVY8_1X8,
V4L2_MBUS_FMT_VYUY8_1X8,
Here it is immediately clear what is going on. This scheme is also used with
the Bayer formats, so it would be consistent with that as well.
However, does V4L2_MBUS_FMT_YUYV8_2X8_LE map to V4L2_MBUS_FMT_YUYV8_1X8 or to
V4L2_MBUS_FMT_UYVY8_1X8? I still don't know.
What do you think?
Regards,
Hans
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG, part of Cisco
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