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Message-ID: <eb410d2c-9650-2251-cff8-4306663f41f9@xs4all.nl>
Date: Tue, 16 Feb 2021 09:58:35 +0100
From: Hans Verkuil <hverkuil-cisco@...all.nl>
To: Stanimir Varbanov <stanimir.varbanov@...aro.org>,
linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 1/2] v4l2-ctrl: Add decoder conceal color control
On 16/02/2021 09:56, Stanimir Varbanov wrote:
>
>
> On 2/15/21 1:57 PM, Hans Verkuil wrote:
>> On 15/02/2021 12:32, Stanimir Varbanov wrote:
>>>
>>>
>>> On 2/9/21 1:05 PM, Hans Verkuil wrote:
>>>> On 09/02/2021 10:45, Stanimir Varbanov wrote:
>>>>> Add decoder v4l2 control to set conceal color.
>>>>>
>>>>> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@...aro.org>
>>>>> ---
>>>>> .../media/v4l/ext-ctrls-codec.rst | 20 +++++++++++++++++++
>>>>> drivers/media/v4l2-core/v4l2-ctrls.c | 9 +++++++++
>>>>> include/uapi/linux/v4l2-controls.h | 1 +
>>>>> 3 files changed, 30 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
>>>>> index 00944e97d638..994650052333 100644
>>>>> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
>>>>> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
>>>>> @@ -674,6 +674,26 @@ enum v4l2_mpeg_video_frame_skip_mode -
>>>>> is currently displayed (decoded). This value is reset to 0 whenever
>>>>> the decoder is started.
>>>>>
>>>>> +``V4L2_CID_MPEG_VIDEO_DEC_CONCEAL_COLOR (integer64)``
>>>>> + This control sets conceal color in YUV color space. It describes the
>>>>> + client preference of error conceal color in case of error where
>>>>> + reference frame is missing. The decoder would paint the reference
>>>>> + buffer with preferred color and use it for future decoding.
>>>>> + Applicable to decoders.
>>>>
>>>> You should mention explicitly that this is using 16-bit color components
>>>> and expects Limited Range.
>>>
>>> I don't want to limit the client to Limited range only. I'll mention in
>>> the description that both ranges are valid.
>>
>> OK, but then you need to describe what the color format depends on. See more
>> below.
>>
>>>
>>>>
>>>>> +
>>>>> +.. flat-table::
>>>>> + :header-rows: 0
>>>>> + :stub-columns: 0
>>>>> +
>>>>> + * - Bit 0:15
>>>>> + - Y luminance
>>>>> + * - Bit 16:31
>>>>> + - Cb chrominance
>>>>> + * - Bit 32:47
>>>>> + - Cr chrominance
>>>>> + * - Bit 48:63
>>>>> + - Must be zero
>>>>> +
>
> The table how the bits are spread into int64.
>
>>>>> ``V4L2_CID_MPEG_VIDEO_DECODER_SLICE_INTERFACE (boolean)``
>>>>> If enabled the decoder expects to receive a single slice per buffer,
>>>>> otherwise the decoder expects a single frame in per buffer.
>>>>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
>>>>> index 016cf6204cbb..a3b9d28a00b7 100644
>>>>> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
>>>>> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
>>>>> @@ -945,6 +945,7 @@ const char *v4l2_ctrl_get_name(u32 id)
>>>>> case V4L2_CID_MPEG_VIDEO_VBV_SIZE: return "VBV Buffer Size";
>>>>> case V4L2_CID_MPEG_VIDEO_DEC_PTS: return "Video Decoder PTS";
>>>>> case V4L2_CID_MPEG_VIDEO_DEC_FRAME: return "Video Decoder Frame Count";
>>>>> + case V4L2_CID_MPEG_VIDEO_DEC_CONCEAL_COLOR: return "Video Decoder Conceal Color";
>>>>> case V4L2_CID_MPEG_VIDEO_VBV_DELAY: return "Initial Delay for VBV Control";
>>>>> case V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE: return "Horizontal MV Search Range";
>>>>> case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE: return "Vertical MV Search Range";
>>>>> @@ -1430,6 +1431,14 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>>>>> *max = 0x7fffffffffffffffLL;
>>>>> *step = 1;
>>>>> break;
>>>>> + case V4L2_CID_MPEG_VIDEO_DEC_CONCEAL_COLOR:
>>>>> + *type = V4L2_CTRL_TYPE_INTEGER64;
>>>>> + *min = 0;
>>>>> + /* default for 8bit black, luma is 16, chroma is 128 */
>>>>
>>>> Since this is 16 bit the actual default luma value for black is 4096 and for chroma use
>>>> 32768 (i.e. both values are times 256).
>>>
>>> If we follow this for pixel format with 10bit per channel we have to
>>> multiply by 64?
>>
>> No, you multiply by 4. 12 bit depth will multiple by 16, and 16 bit depth by 256.
>>
>> But how do you format this? Using bits 29-0? Or use 9-0 for one color component,
>> 25-16 for another and 41-32 for the last component?
>
> I described this in the table above:
>
> Bit 0:15 - Y luminance
> Bit 16:31 - Cb chrominance
> Bit 32:47 - Cr chrominance
> Bit 48:63 - Must be zero
>
> So depending on the bit depth of the current pixel format:
>
> 8bit - 0:7 Y', 16:23 Cb, 32:39 Cr
> 10bit - 0:9 Y', 16:25 Cb, 32:41 Cr
> 12bit - 0:11 Y', 16:27 Cb, 32:43 Cr
Apologies, I missed that table!
Regards,
Hans
>
>>
>> Also missing is an explanation of which bits are for Y', which for Cb and which for Cr.
>>
>> It is surprisingly hard to provide an unambiguous description of this :-)
>>
>> Regards,
>>
>> Hans
>>
>>>
>>>>
>>>>> + *def = 0x8000800010LL;
>>>>> + *max = 0xffffffffffffLL;
>>>>> + *step = 1;
>>>>> + break;
>>>>> case V4L2_CID_PIXEL_RATE:
>>>>> *type = V4L2_CTRL_TYPE_INTEGER64;
>>>>> *flags |= V4L2_CTRL_FLAG_READ_ONLY;
>>>>> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
>>>>> index 039c0d7add1b..5e5a3068be2d 100644
>>>>> --- a/include/uapi/linux/v4l2-controls.h
>>>>> +++ b/include/uapi/linux/v4l2-controls.h
>>>>> @@ -428,6 +428,7 @@ enum v4l2_mpeg_video_multi_slice_mode {
>>>>> #define V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (V4L2_CID_CODEC_BASE+228)
>>>>> #define V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME (V4L2_CID_CODEC_BASE+229)
>>>>> #define V4L2_CID_MPEG_VIDEO_BASELAYER_PRIORITY_ID (V4L2_CID_CODEC_BASE+230)
>>>>> +#define V4L2_CID_MPEG_VIDEO_DEC_CONCEAL_COLOR (V4L2_CID_CODEC_BASE+231)
>>>>>
>>>>> /* CIDs for the MPEG-2 Part 2 (H.262) codec */
>>>>> #define V4L2_CID_MPEG_VIDEO_MPEG2_LEVEL (V4L2_CID_CODEC_BASE+270)
>>>>>
>>>>
>>>> Regards,
>>>>
>>>> Hans
>>>>
>>>
>>
>
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