[Mesa-dev] [PATCH 2/2] st/vdapu: use lanczos filter for scaling v4

[Christian König]

Am 02.09.2016 um 16:10 schrieb Leo Liu:
>
>
> On 09/02/2016 09:50 AM, Christian König wrote:
>> Am 02.09.2016 um 15:27 schrieb Leo Liu:
>>>
>>>
>>> On 09/02/2016 02:11 AM, Christian König wrote:
>>>> Am 02.09.2016 um 04:03 schrieb Michel Dänzer:
>>>>> On 02/09/16 10:17 AM, Michel Dänzer wrote:
>>>>>> On 02/09/16 12:58 AM, Leo Liu wrote:
>>>>>>> On 09/01/2016 11:54 AM, Nayan Deshmukh wrote:
>>>>>>>> I saw the code in dri3_glx.c and I could somewhat relate some 
>>>>>>>> basic
>>>>>>>> code structure to the vl_winsys_dri3.c. But I am new to this 
>>>>>>>> and not aware of the
>>>>>>>> terminology that you used about the buffers. Could you please 
>>>>>>>> explain what needs
>>>>>>>> to be done in more detail or point me to where I can read about 
>>>>>>>> it.
>>>>>>> I believe it's from loader_dri3_helper.c with "is_different_gpu"
>>>>>>> condition true, that will include back buffer and front buffer 
>>>>>>> case.
>>>>>>> you could try only back buffer case for now.
>>>>>>  From a high level, PRIME mainly affects presentation, not so 
>>>>>> much the
>>>>>> video decoding / rendering. The important thing is that the 
>>>>>> buffer used
>>>>>> for presentation via the Present extension is linear, not tiled. 
>>>>>> I'm not
>>>>>> sure whether it makes more sense to allocate a separate linear 
>>>>>> buffer
>>>>>> for this purpose, as is done for GLX, or for the vl code to make the
>>>>>> corresponding back (or front?) buffer linear in the first place.
>>>>> A separate linear buffer is probably better, actually, since it will
>>>>> also be pinned to system memory while it's being shared with 
>>>>> another GPU.
>>>>
>>>> Yes, I agree. Nayan should also work on avoiding the extra copy 
>>>> which currently occur because we can't allocate output buffers 
>>>> directly in the format needed for presentation.
>>>>
>>>> The general idea should be to to check during presentation if the 
>>>> format in the output surface is displayable directly.
>>>
>>> Also we have to consider drawable resized case.
>>
>> Actually we don't. Take a look at the VDPAU spec the output surface 
>> should be send for displaying without considering it's size.
>>
>> E.g. when the window is 256x256 pixels, but the application allocated 
>> an output surface of 1024x768 we should still send the whole surface 
>> to the X server.
>>
>> It's the job of the application to resize the output surfaces not the 
>> one of the VDPAU state tracker.
>
> I thought this get done by vl compositor from presentation, scaling up 
> or down from output surface to back buffer based on the resize.

No, that is incorrect. Take a look at the VDPAU spec:

> Applications may choose to allow resizing of the presentation queue 
> target (which may be e.g. a regular Window when using an X11-based 
> implementation).
>
> *clip_width* and *clip_height* may be used to limit the size of the 
> displayed region of a surface, in order to match the specific region 
> that was rendered to.
>
> In turn, this allows the application to allocate over-sized (e.g. 
> screen-sized) surfaces, but render to a region that matches the 
> current size of the video window.
>
> Using this technique, an application's response to window resizing may 
> simply be to render to, and display, a different region of the 
> surface, rather than de-/re-allocation of surfaces to match the 
> updated window size.
>

This means that we should send the original output surface size to X, no 
matter what size it has or what size the window has it is displayed in.

That wasn't possible with DRI2, that's why we have that workaround with 
the delayed rendering in the mixer.

But no worry it's only a minor issue and a good task for Nayan to get 
deeper into the graphics stack.

Regards,
Christian.

>
> Regards,
> Leo
>
>>
>> Regards,
>> Christian.
>>
>>>
>>> Regards,
>>> Leo
>>>
>>>> If that is the case then handle of that surface should be send 
>>>> directly to X.
>>>> If that isn't the case we reallocate the backing buffer, copy the 
>>>> content of the output surface into it and then send the new handle 
>>>> to X.
>>>>
>>>> Regards,
>>>> Christian.
>>>
>>> _______________________________________________
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>>> mesa-dev at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>>
>>
>

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