On 1/25/21 10:57 AM, Helen Koike wrote:
>
>
> On 1/23/21 6:56 AM, Laurent Pinchart wrote:
>> Hi Helen,
>>
>> Thank you for the patch.
>>
>> On Fri, Jan 22, 2021 at 03:27:23PM -0300, Helen Koike wrote:
>>> YUV 4:4:4 is not subsampled, fix this in the docs.
>>>
>>> Fixes: da785536e007 ("media: doc: pixfmt-yuv: Move all semi-planar YUV formats to common file")
>>> Signed-off-by: Helen Koike <helen.koike@xxxxxxxxxxxxx>
>>> ---
>>> Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst b/Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst
>>> index 7d4d39201a3f..bcb4ef24c334 100644
>>> --- a/Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst
>>> +++ b/Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst
>>> @@ -396,8 +396,8 @@ number of lines as the luma plane.
>>> NV24 and NV42
>>> -------------
>>>
>>> -Semi-planar YUV 4:4:4 formats. The chroma plane is subsampled by 2 in the
>>> -horizontal direction. Chroma lines contain half the number of pixels and the
>>> +Semi-planar YUV 4:4:4 formats. No sub-sampling.
>>
>> "The chroma plane is not subsampled." ?
>
> Ack.
>
>>
>>> +Chroma lines contain the same number of pixels and the
>>> same number of bytes as luma lines, and the chroma plane contains the same
>>> number of lines as the luma plane.
>>
>> That's not quite right, the chroma lines contain twice the number of
>> pixels and bytes, as there's one Cb and one Cr value in the chroma line
>> for each Y value in the luma line.
Actually, it is the same number o pixels, but twice the number o bytes.
Since a trio (YCbCr) compose a pixel.
At least this is how I understand comparing the logic of the text description
of NV16 YUV4:2:2.
Regards,
Helen
>>
>>
>> Maybe the text could be reflowed ?
>>
>
> Ack.
>
> I'll submit v2 updating the text.
>
> Thanks,
> Helen
>
