linux-kernel - Re: [PATCH] media: doc: pixfmt-yuv: Fix 4:4:4 subsampling info

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Message-ID: <7f650d51-d419-53cc-0ad1-b241a10ab801@collabora.com>
Date:   Mon, 25 Jan 2021 10:57:15 -0300
From:   Helen Koike <helen.koike@...labora.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     linux-media@...r.kernel.org, hverkuil@...all.nl,
        hans.verkuil@...co.com, kernel@...labora.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: doc: pixfmt-yuv: Fix 4:4:4 subsampling info



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@...labora.com>
>> ---
>>  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.
> 
> 
> Maybe the text could be reflowed ?
> 

Ack.

I'll submit v2 updating the text.

Thanks,
Helen