[FFmpeg-devel] [PATCH 3/6] vaapi_encode_h265: Don't require uniform_spacing_flag

[Mark Thompson]

On 29/07/2020 04:13, Xiang, Haihao wrote:
> On Tue, 2020-07-28 at 23:50 +0100, Mark Thompson wrote:
>> Though still use it if the tile arrangement matches.  Also try to keep the
>> fields in the same order as the standard.
>> ---
>>   libavcodec/vaapi_encode_h265.c | 39 ++++++++++++++++++++++++----------
>>   1 file changed, 28 insertions(+), 11 deletions(-)
>>
>> diff --git a/libavcodec/vaapi_encode_h265.c b/libavcodec/vaapi_encode_h265.c
>> index 04bd2bef1d..a7230a676c 100644
>> --- a/libavcodec/vaapi_encode_h265.c
>> +++ b/libavcodec/vaapi_encode_h265.c
>> @@ -555,23 +555,40 @@ static int
>> vaapi_encode_h265_init_sequence_params(AVCodecContext *avctx)
>>       pps->cu_qp_delta_enabled_flag = (ctx->va_rc_mode != VA_RC_CQP);
>>       pps->diff_cu_qp_delta_depth   = 0;
>>   
>> -    pps->pps_loop_filter_across_slices_enabled_flag = 1;
>> -
>>       if (ctx->tile_rows && ctx->tile_cols) {
>> -        pps->tiles_enabled_flag         = 1;
>> -        pps->uniform_spacing_flag       = 1;
>> -
>> -        pps->num_tile_rows_minus1       = ctx->tile_rows - 1;
>> -        pps->num_tile_columns_minus1    = ctx->tile_cols - 1;
>> -
>> -        pps->loop_filter_across_tiles_enabled_flag = 1;
>> +        int uniform_spacing;
>> +
>> +        pps->tiles_enabled_flag      = 1;
>> +        pps->num_tile_columns_minus1 = ctx->tile_cols - 1;
>> +        pps->num_tile_rows_minus1    = ctx->tile_rows - 1;
>> +
>> +        // Test whether the spacing provided matches the H.265 uniform
>> +        // spacing, and set the flag if it does.
>> +        uniform_spacing = 1;
>> +        for (i = 0; i <= pps->num_tile_columns_minus1; i++) {
> 
> Better to use 'i <= pps->num_tile_columns_minus1 && uniform_spacing' to allow
> early-exiting the loop if uniform_spacing has been 0

I weakly think that a minor optimisation like this in a cold path doesn't seem like a particularly good tradeoff against having the code cleanly match the standard.

But whatever, changed as you suggest.

>> +            if (ctx->col_width[i] !=
>> +                (i + 1) * ctx->slice_block_cols / ctx->tile_cols -
>> +                 i      * ctx->slice_block_cols / ctx->tile_cols)
>> +                uniform_spacing = 0;
>> +        }
>> +        for (i = 0; i <= pps->num_tile_rows_minus1; i++) {
> 
> Same as above.
> 
>> +            if (ctx->row_height[i] !=
>> +                (i + 1) * ctx->slice_block_rows / ctx->tile_rows -
>> +                 i      * ctx->slice_block_rows / ctx->tile_rows)
>> +                uniform_spacing = 0;
>> +        }
>> +        pps->uniform_spacing_flag = uniform_spacing;
>>   
>> -        for (i = 0; i <= pps->num_tile_rows_minus1; i++)
>> -            pps->row_height_minus1[i]   = ctx->row_height[i] - 1;
>>           for (i = 0; i <= pps->num_tile_columns_minus1; i++)
>>               pps->column_width_minus1[i] = ctx->col_width[i] - 1;
>> +        for (i = 0; i <= pps->num_tile_rows_minus1; i++)
>> +            pps->row_height_minus1[i]   = ctx->row_height[i] - 1;
>> +
>> +        pps->loop_filter_across_tiles_enabled_flag = 1;
>>       }
>>   
>> +    pps->pps_loop_filter_across_slices_enabled_flag = 1;
>> +
>>       // Fill VAAPI parameter buffers.
>>   

Applied with that.

Thanks,

- Mark