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

[Mark Thompson]

On 27/01/17 22:06, Andy Furniss wrote:
> 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

Urgh, yes, so it will.  Apologies for missing that.

> 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.

I think float is fine here?  I don't know what the preference is either...  (uint64_t would also be big enough, I think.)

As an alternative source of inspiration, <https://cgit.freedesktop.org/vaapi/intel-driver/tree/src/gen6_mfc_common.c#n93> is full of doubles ;)

>>> +      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
>>
>