[Mesa-dev] [PATCH] st/va encode handle ntsc framerate rate control

[Andy Furniss]

Mark Thompson wrote:
> On 26/01/17 18:26, Andy Furniss wrote:
>> Tested with ffmpeg and gst-vaapi. Without this bits per
>> frame is set way too low.
>>
>> Signed-off-by: Andy Furniss <adf.lists at gmail.com>
>> ---
>>   src/gallium/state_trackers/va/picture.c | 32 ++++++++++++++++++++++++--------
>>   1 file changed, 24 insertions(+), 8 deletions(-)
>>
>> diff --git a/src/gallium/state_trackers/va/picture.c b/src/gallium/state_trackers/va/picture.c
>> index 82584ea..a024437 100644
>> --- a/src/gallium/state_trackers/va/picture.c
>> +++ b/src/gallium/state_trackers/va/picture.c
>> @@ -119,14 +119,30 @@ getEncParamPreset(vlVaContext *context)
>>      context->desc.h264enc.rate_ctrl.fill_data_enable = 1;
>>      context->desc.h264enc.rate_ctrl.enforce_hrd = 1;
>>      context->desc.h264enc.enable_vui = false;
>> -   if (context->desc.h264enc.rate_ctrl.frame_rate_num == 0)
>> -      context->desc.h264enc.rate_ctrl.frame_rate_num = 30;
>> -   context->desc.h264enc.rate_ctrl.target_bits_picture =
>> -      context->desc.h264enc.rate_ctrl.target_bitrate / context->desc.h264enc.rate_ctrl.frame_rate_num;
>> -   context->desc.h264enc.rate_ctrl.peak_bits_picture_integer =
>> -      context->desc.h264enc.rate_ctrl.peak_bitrate / context->desc.h264enc.rate_ctrl.frame_rate_num;
>> -   context->desc.h264enc.rate_ctrl.peak_bits_picture_fraction = 0;
>> +   if (context->desc.h264enc.rate_ctrl.frame_rate_num == 0 ||
>> +       context->desc.h264enc.rate_ctrl.frame_rate_den == 0) {
>> +         context->desc.h264enc.rate_ctrl.frame_rate_num = 30;
>> +         context->desc.h264enc.rate_ctrl.frame_rate_den = 1;
>> +   }
>> +   if (context->desc.h264enc.rate_ctrl.frame_rate_den > 1) {
>> +      context->desc.h264enc.rate_ctrl.target_bits_picture =
>> +         context->desc.h264enc.rate_ctrl.target_bitrate /
>> +         (context->desc.h264enc.rate_ctrl.frame_rate_num /
>> +         context->desc.h264enc.rate_ctrl.frame_rate_den + 1);
>
> This is still doing more rounding than necessary?  (Consider 0.5fps as 1/2, say.)  Don't you want:

Hmm, sub 1 fps is going to be treated as 1 fps with my code but -

>
> context->desc.h264enc.rate_ctrl.target_bits_picture =
>      (context->desc.h264enc.rate_ctrl.target_bitrate *
>       context->desc.h264enc.rate_ctrl.frame_rate_den) /
>      context->desc.h264enc.rate_ctrl.frame_rate_num;
>
> (And no need for any extra +1 or conditional, because you've already made sure that neither of them are zero.)

This will overflow, with high bitrate plus ntsc denom = 1001

Could use floats I guess like I did here.

https://cgit.freedesktop.org/mesa/mesa/commit/?id=a5993022275c20061ac025d9adc26c5f9d02afee

I don't know what the preference is between float and int.

>> +      context->desc.h264enc.rate_ctrl.peak_bits_picture_integer =
>> +         context->desc.h264enc.rate_ctrl.peak_bitrate /
>> +         (context->desc.h264enc.rate_ctrl.frame_rate_num /
>> +         context->desc.h264enc.rate_ctrl.frame_rate_den + 1);
>
> Similarly this one.
>
>> +   } else {
>> +      context->desc.h264enc.rate_ctrl.target_bits_picture =
>> +         context->desc.h264enc.rate_ctrl.target_bitrate /
>> +         context->desc.h264enc.rate_ctrl.frame_rate_num;
>> +      context->desc.h264enc.rate_ctrl.peak_bits_picture_integer =
>> +         context->desc.h264enc.rate_ctrl.peak_bitrate /
>> +         context->desc.h264enc.rate_ctrl.frame_rate_num;
>> +   }
>
> Doing that would also avoid needing the if at all.
>
>>
>> +   context->desc.h264enc.rate_ctrl.peak_bits_picture_fraction = 0;
>>      context->desc.h264enc.ref_pic_mode = 0x00000201;
>>   }
>>
>> @@ -362,7 +378,7 @@ handleVAEncSequenceParameterBufferType(vlVaDriver *drv, vlVaContext *context, vl
>>         context->gop_coeff = VL_VA_ENC_GOP_COEFF;
>>      context->desc.h264enc.gop_size = h264->intra_idr_period * context->gop_coeff;
>>      context->desc.h264enc.rate_ctrl.frame_rate_num = h264->time_scale / 2;
>> -   context->desc.h264enc.rate_ctrl.frame_rate_den = 1;
>> +   context->desc.h264enc.rate_ctrl.frame_rate_den = h264->num_units_in_tick;
>>      return VA_STATUS_SUCCESS;
>>   }
>
> Otherwise LGTM :)

Thanks.

>
> Thanks,
>
> - Mark
>