CODEWITHSUNDEEP
iosobjective-cgpuimage
Goles
Goles

Reputation: 11799

GPUImagePicture with a GPUImageBuffer target?

I'm trying to do the following to display an image instead of trying to access video when TARGET_IPHONE_SIMULATOR is true. 

UIImage *image = [UIImage imageNamed:@"fake_camera"];

GPUImagePicture *fakeInput = [[GPUImagePicture alloc] initWithImage:image];
GPUImageBuffer *videoBuffer = [[GPUImageBuffer alloc] init];
[fakeInput processImage];
[fakeInput addTarget:videoBuffer];
[videoBuffer addTarget:self.backgroundImageView]; //backgroundImageView is a GPUImageView

This renders my backgroundImageView in black color without displaying my image.

If I send the output of fakeInput to backgroundImageView directly, I see the picture rendered normally in backgroundImageView.

What's going on here?

EDIT:

As Brad recommended I tried:

UIImage *image = [UIImage imageNamed:@"fake_camera"];

_fakeInput = [[GPUImagePicture alloc] initWithImage:image];
GPUImagePicture *secondFakeInput = [[GPUImagePicture alloc] initWithImage:image];
[_fakeInput processImage];
[secondFakeInput processImage];
[_fakeInput addTarget:_videoBuffer];
[secondFakeInput addTarget:_videoBuffer];
[_videoBuffer addTarget:_backgroundImageView];

I also tried:

UIImage *image = [UIImage imageNamed:@"fake_camera"];

_fakeInput = [[GPUImagePicture alloc] initWithImage:image];
[_fakeInput processImage];
[_fakeInput processImage];
[_fakeInput addTarget:_videoBuffer];
[_videoBuffer addTarget:_backgroundImageView];

None of this two approaches seems to work... should they?

Upvotes: 0

Views: 415

Answers (1)

Brad Larson
Brad Larson

Reputation: 170319

A GPUImageBuffer does as its name suggests, it buffers frames. If you send a still photo to it, that one image is buffered, but is not yet sent out. You'd need to send a second image into it (or use -processImage a second time) to get the default buffer of one frame deep to display your original frame.

GPUImageBuffer really doesn't serve any purpose for still images. It's intended as a frame-delaying operation for video in order to do frame-to-frame comparisons, like a low-pass filter. If you need to do frame comparisons of still images, a blend is a better way to go.

Upvotes: 1

Related Questions