[Mesa-dev] [PATCH] st/va: enable vbr rate control for vaapi encode

[Andy Furniss]

Zhang, Boyuan wrote:
> Hi Andy,
>
> For the VBR target/max bit-rate, yes, this is gstreamer-vaapi's
> current design. User typed bit-rate is actually the max bit-rate not
> the actual bit-rate, which is a bit confused.

Fair enough on the bitrate, though I am still a bit confused on the VBR
being constrained as both va.h and gstreamer vaapi have vbr and
vbr_constrained.

Any thoughts on my other questions?

> For the overflow concern, unsigned int can handle about 4294Mbit/s,
> which we thought is big enough for real life cases, right?

Yea, but it gets x 100 and my vce can do at least 2160p so for baseline
higher than 42.94 mbit is not that extreme.

Anyway Christian acked my v2 patch -

https://patchwork.freedesktop.org/patch/112161/



> Regards, Boyuan
>
> -----Original Message----- From: Andy Furniss
> [mailto:adf.lists at gmail.com] Sent: September-25-16 6:46 AM To: Liu,
> Leo; Christian König; Zhang, Boyuan; mesa-dev at lists.freedesktop.org
> Subject: Re: [Mesa-dev] [PATCH] st/va: enable vbr rate control for
> vaapi encode
>
> Leo Liu wrote:
>>
>>
>> On 09/07/2016 03:02 AM, Christian König wrote:
>>> Am 06.09.2016 um 22:39 schrieb boyuan.zhang at amd.com:
>>>> From: Boyuan Zhang <boyuan.zhang at amd.com>
>>>>
>>>> This patch enables variable bit-rate for vaapi encoding.
>>>> According to va.h, target bit-rate equals to maximum bit-rate
>>>> multiplies by target_percentage.
>>>>
>>>> Signed-off-by: Boyuan Zhang <boyuan.zhang at amd.com>
>>>
>>> That was astonishing simple to fix :)
>
> Bit late on this but I am not sure this is VBR as it's constrained
> and that has it's own setting.
>
> Maybe I am taking too much notice of what libx264/broadcast encoders
> do, but it would be good if VCE could throw way more bits at IDR
> frames as they really need it to avoid pulsing with default gop 30.
>
> Of course I don't know how things work/what's possible.
>
> The names help of course but not always eg. what is -
>
> peak_bits_picture_fraction seems to be always 0.
>
> and
>
> rate_ctrl.vbv_buf_lv 0 or 48 is this some level in a spec, or is it
> initial buffer fullness for vbv?
>
> One issue I found and sent a patch for is the bitrate calc can
> overflow.
>
> Generally as a user asking for a rate and getting 70% seems a bit
> strange anyway but maybe that's a different discussion.
>
> https://patchwork.freedesktop.org/patch/112040/
>
>>>
>>> Patch is Reviewed-by: Christian König
>>> <christian.koenig at amd.com>.
>>>
>>> Leo do you want to push it or should I take care of this?
>>
>> I will take care of it.
>>
>> Regards, Leo
>>
>>>
>>> Regards, Christian.
>>>
>>>> --- src/gallium/state_trackers/va/config.c  | 2 +-
>>>> src/gallium/state_trackers/va/picture.c | 2 +- 2 files changed,
>>>> 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/src/gallium/state_trackers/va/config.c
>>>> b/src/gallium/state_trackers/va/config.c index 84bf913..4052316
>>>> 100644 --- a/src/gallium/state_trackers/va/config.c +++
>>>> b/src/gallium/state_trackers/va/config.c @@ -120,7 +120,7 @@
>>>> vlVaGetConfigAttributes(VADriverContextP ctx, VAProfile
>>>> profile, VAEntrypoint en value = VA_RT_FORMAT_YUV420; break;
>>>> case VAConfigAttribRateControl: -         value = VA_RC_CQP |
>>>> VA_RC_CBR; +         value = VA_RC_CQP | VA_RC_CBR |
>>>> VA_RC_VBR; break; default: value = VA_ATTRIB_NOT_SUPPORTED;
>>>> diff --git a/src/gallium/state_trackers/va/picture.c
>>>> b/src/gallium/state_trackers/va/picture.c index
>>>> a283e83..7f3d96d 100644 ---
>>>> a/src/gallium/state_trackers/va/picture.c +++
>>>> b/src/gallium/state_trackers/va/picture.c @@ -322,7 +322,7 @@
>>>> handleVAEncMiscParameterTypeRateControl(vlVaContext *context,
>>>> VAEncMiscParameter PIPE_H264_ENC_RATE_CONTROL_METHOD_CONSTANT)
>>>> context->desc.h264enc.rate_ctrl.target_bitrate =
>>>> rc->bits_per_second; else -
>>>> context->desc.h264enc.rate_ctrl.target_bitrate =
>>>> rc->bits_per_second * rc->target_percentage; +
>>>> context->desc.h264enc.rate_ctrl.target_bitrate =
>>>> rc->bits_per_second * rc->target_percentage / 100;
>>>> context->desc.h264enc.rate_ctrl.peak_bitrate =
>>>> rc->bits_per_second; if
>>>> (context->desc.h264enc.rate_ctrl.target_bitrate < 2000000)
>>>> context->desc.h264enc.rate_ctrl.vbv_buffer_size =
>>>> MIN2((context->desc.h264enc.rate_ctrl.target_bitrate * 2.75),
>>>> 2000000);
>>>
>>>
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>>
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