On 2019-10-31 11:20, Boris Brezillon wrote:
> On Tue, 29 Oct 2019 01:26:01 +0000
> Jonas Karlman <jonas@xxxxxxxxx> wrote:
>
>> Add DPB entry flags to help indicate when a reference frame is a field picture
>> and how the DPB entry is referenced, top or bottom field or full frame.
>>
>> Signed-off-by: Jonas Karlman <jonas@xxxxxxxxx>
>> ---
>> Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 12 ++++++++++++
>> include/media/h264-ctrls.h | 4 ++++
>> 2 files changed, 16 insertions(+)
>>
>> diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
>> index 28313c0f4e7c..d472a54d1c4d 100644
>> --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
>> +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
>> @@ -2028,6 +2028,18 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
>> * - ``V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM``
>> - 0x00000004
>> - The DPB entry is a long term reference frame
>> + * - ``V4L2_H264_DPB_ENTRY_FLAG_FIELD_PICTURE``
>> + - 0x00000008
>> + - The DPB entry is a field picture
>> + * - ``V4L2_H264_DPB_ENTRY_FLAG_REF_TOP``
>> + - 0x00000010
>> + - The DPB entry is a top field reference
>> + * - ``V4L2_H264_DPB_ENTRY_FLAG_REF_BOTTOM``
>> + - 0x00000020
>> + - The DPB entry is a bottom field reference
>> + * - ``V4L2_H264_DPB_ENTRY_FLAG_REF_FRAME``
>> + - 0x00000030
>> + - The DPB entry is a reference frame
>>
>> ``V4L2_CID_MPEG_VIDEO_H264_DECODE_MODE (enum)``
>> Specifies the decoding mode to use. Currently exposes slice-based and
>> diff --git a/include/media/h264-ctrls.h b/include/media/h264-ctrls.h
>> index e877bf1d537c..76020ebd1e6c 100644
>> --- a/include/media/h264-ctrls.h
>> +++ b/include/media/h264-ctrls.h
>> @@ -185,6 +185,10 @@ struct v4l2_ctrl_h264_slice_params {
>> #define V4L2_H264_DPB_ENTRY_FLAG_VALID 0x01
>> #define V4L2_H264_DPB_ENTRY_FLAG_ACTIVE 0x02
>> #define V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM 0x04
>> +#define V4L2_H264_DPB_ENTRY_FLAG_FIELD_PICTURE 0x08
>> +#define V4L2_H264_DPB_ENTRY_FLAG_REF_TOP 0x10
>> +#define V4L2_H264_DPB_ENTRY_FLAG_REF_BOTTOM 0x20
>> +#define V4L2_H264_DPB_ENTRY_FLAG_REF_FRAME 0x30
> I don't remember all the details, but do we really need 3 flags?
> Maybe I'm wrong, but it looks like the following combination doesn't
> make sense:
>
> - FIELD_PICTURE + REF_FRAME: if it's a full frame ref it should
> contain both top and bottom fields right, so it's no longer a
> FIELD_PICTURE, is it?
>
> Can't we just have 2 flags?
>
> FIELD_PICTURE 0x08
> FIELD_REF_TOP 0x10 (meaning that FIELD_REF_BOTTOM is
> 0x00)
>
> and then have the following combinations:
>
> top field ref => FIELD_PICTURE | FIELD_REF_TOP
> bottom field ref => FIELD_PICTURE
> full frame ref => 0x0
I am not sure and will need to look closer at spec and what ffmpeg is doing.
These flags was mostly inspired by the information ffmpeg stores in
H264Picture->reference and H264Picture->field_picture.
I also believe that the new FLAG_REF_TOP/BOTTOM may make FLAG_ACTIVE obsolete.
active => flags & FLAG_REF_FRAME
Hopefully I will have some time to rework and respin this at the end of next week.
Regards,
Jonas
>
>>
>> struct v4l2_h264_dpb_entry {
>> __u64 reference_ts;
