Blackmagic Forum

Is anyone able to provide some basic example code on how to use the

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IBlackmagicRawClipResolutions

Interface?

Thanks in advance!

All good, worked it out, thanks to this thread.

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IBlackmagicRawClipResolutions *clipResolutions;
clip->QueryInterface(IID_IBlackmagicRawClipResolutions, (void**)&clipResolutions);

This should probably be added to the SDK Documentation?

Interestingly though, that when I feed it really low width and height (i.e. 112x63), the `requestUpsideDown` isn't properly respected? For example, I expect:

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bool requestUpsideDown = true;
clipResolutions->GetClosestScaleForResolution(destinationWidth, destinationHeight, requestUpsideDown, &resolutionScale);


...to always return `blackmagicRawResolutionScaleFullUpsideDown`, `blackmagicRawResolutionScaleHalfUpsideDown`, `blackmagicRawResolutionScaleQuarterUpsideDown` or `blackmagicRawResolutionScaleEighthUpsideDown` - because I've set `requestUpsideDown` to `true`?

Am I misunderstanding something?

I've modified the ProcessClipMetal sample, to explain my issue.

Specifically:

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IBlackmagicRawClipResolutions *clipResolutions;
clip->QueryInterface(IID_IBlackmagicRawClipResolutions, (void**)&clipResolutions);

uint32_t decodeQuality;

//
// NOTE: Feeding `GetClosestScaleForResolution` with 1920x1080 and `requestUpsideDown` as `true` gives upside down image,
//       however, feeding it 112x63 and `requestUpsideDown` as `true` gives a right-side-up image?!?
//
uint32_t destinationWidth   = 112; //1920;
uint32_t destinationHeight  = 63;  //1080;
bool requestUpsideDown      = true;

clipResolutions->GetClosestScaleForResolution(destinationWidth, destinationHeight, requestUpsideDown, &decodeQuality);

Here's the full code:

https://gist.github.com/latenitefilms/2 ... 54a5544128

Feeding it 1920x1080 and requestUpsideDown as true gives an upside down image, which is correct.

Feeding it 112x63 and requestUpsideDown as true gives a right-side-up image, which I believe is incorrect.

Am I missing something CaptainHook? Is this a bug or a misunderstanding on my part?

Alternatively, you could maybe use GetClosestResolutionForScale to look for the best scale possible

Thanks for the fast reply Antoine!

Dumb question... If I did use GetClosestScaleForResolution, what do I then do with the resolutionWidthPixels, and resolutionHeightPixels? I couldn't see any API for setting a specific output resolution?

If you use GetClosestScaleForResolution you get Scale in output from Resolution in input (what you initially wanted). With GetClosestResolutionForScale you would do the opposite, you would iterate all the scales (in input) until you get a resolution (in output) that would fit best (or least worst ) you for what you're trying to do

Thanks Antoine!

It sounds like this is a bug - will hopefully get confirmation tomorrow.

For anyone playing along at home... Blackmagic has confirmed this is a bug, and will be hopefully addressed in the future. Thanks team!

This post is no longer relevant with the v3.0 SDK.

Yeah the new SDK has plenty of new info there to get and set, it's good. Chris did you use it already and does it work for what you're trying to do ?

Sorry for the delayed reply - just noticed this! Yes, the new SDK solves the issues I was having.

Hope all is well in your world!