On 9/5/19 1:42 PM, Philipp Zabel wrote:
> To explain why num_ref_idx_active_override_flag is not part of the API,
> describe how the num_ref_idx_l[01]_active_minus1 fields and the
> num_ref_idx_l[01]_default_active_minus1 fields are used, depending on
> whether the decoder parses slice headers itself or not.
>
> Signed-off-by: Philipp Zabel <p.za...@pengutronix.de>
> ---
> Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> index bc5dd8e76567..b9834625a939 100644
> --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> @@ -1630,10 +1630,10 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
> -
> * - __u8
> - ``num_ref_idx_l0_default_active_minus1``
> - -
> + - This field is only used by decoders that parse slices themselves.
How do you know that the decoder does this?
> * - __u8
> - ``num_ref_idx_l1_default_active_minus1``
> - -
> + - This field is only used by decoders that parse slices themselves.
> * - __u8
> - ``weighted_bipred_idc``
> -
> @@ -1820,10 +1820,14 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
> -
> * - __u8
> - ``num_ref_idx_l0_active_minus1``
> - -
> + - This field is used by decoders that do not parse slices themselves.
> + If num_ref_idx_active_override_flag is not set, this field must be
> + set to the value of num_ref_idx_l0_default_active_minus1.
I don't think you can know if the decoder parses the slices.
Wouldn't it be better to just delete the 'This field is only used by decoders
that parse slices themselves.' sentence? Drivers for HW that handle this can
just ignore these fields.
Regards,
Hans
> * - __u8
> - ``num_ref_idx_l1_active_minus1``
> - -
> + - This field is used by decoders that do not parse slices themselves.
> + If num_ref_idx_active_override_flag is not set, this field must be
> + set to the value of num_ref_idx_l1_default_active_minus1.
> * - __u32
> - ``slice_group_change_cycle``
> -
>
