16-bit textures memory allocation

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16-bit textures memory allocation

(8 posts) (4 voices)

Started 2 years ago by Jonathan
Latest reply from gaminghorror

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Jonathan
Member

Hello everyone,

I need to load quite a few big animations (sprite sheets 1024*1024) so to save on memory I decided (as said in the best practice) to use 16-bit textures (RGBA4444 since I need transparency for fading in and out).

To do so, first I converted my sprite sheets with DamageControl using 444+4 mode

And putting the following line before loading each sprite sheet:

[Texture2D setDefaultAlphaPixelFormat:kTexture2DPixelFormat_RGBA4444];

Seeing that this did not change the memory consumption at all (from the 32-bit textures), I looked in my code and found this:

[[Director sharedDirector] setPixelFormat:kPixelFormatRGBA8888];

Which apparently sets the buffer size. So I wanted to change the value to RGBA4444.
But the possible values are only RGBA_8888 or RGB_565

I tried using RGB_565 since it is a 16 bit format (hoping that there would be no verification on the buffer content) but there was no change.

Looking on around I found that there is a bug converting 32bit texture to 16bit:
http://code.google.com/p/cocos2d-iphone/issues/detail?id=410
But I am using 16bit textures.

Is this also a bug or is there something I am doing wrong?

Thank you for any help

Jonathan

Cocos2d Version 0.8.2
Xcode Version 3.2.1
iPhoneSDK 3.1.2

Posted 2 years ago #
gaminghorror
Member

I would like to bump this thread, i have similar questions.

Currently i'm loading 150 images which are all 32-bit PNGs. They take up maybe 5 MB on disk but when i load them in memory they take around 35 MB. Of course i get memory warnings. I tried to set the Director's PixelFormat as mentioned above to RGB_565 just to see if memory usage would decrease - but it didn't.

Then after i read about this issue mentioned above i simply set Texture2D default format to RGBA_4444 in code but that didn't change memory usage either.

Would i save memory (not: app size) if i converted all my PNGs to 16-bit or even 8-bit, or would they take up the same memory because it really only depends on the texture PixelFormat?

Posted 2 years ago #
gaminghorror
Member

Uhm ... i just converted all my PNGs to 8bit and i still get the memory warning. So memory consumption doesn't change even if you use 8bit textures???

PS: my PNGs take up 35 MB in memory + maybe 5 mb at most for other stuff. With 8bit textures my app should consume way less than the memory warning threshold.

Posted 2 years ago #

gaminghorror
Member

Oh my ... this is from CCTexture2D ... it looks like all textures use the same memory, except for A8. :(

switch(pixelFormat) {
	case kTexture2DPixelFormat_RGBA8888:
	case kTexture2DPixelFormat_RGBA4444:
	case kTexture2DPixelFormat_RGB5A1:
		colorSpace = CGColorSpaceCreateDeviceRGB();
		data = malloc(height * width * 4);
		context = CGBitmapContextCreate(data, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
		CGColorSpaceRelease(colorSpace);
		break;
	case kTexture2DPixelFormat_RGB565:
		colorSpace = CGColorSpaceCreateDeviceRGB();
		data = malloc(height * width * 4);
		context = CGBitmapContextCreate(data, width, height, 8, 4 * width, colorSpace, kCGImageAlphaNoneSkipLast | kCGBitmapByteOrder32Big);
		CGColorSpaceRelease(colorSpace);
		break;
	case kTexture2DPixelFormat_A8:
		data = malloc(height * width);
		context = CGBitmapContextCreate(data, width, height, 8, width, NULL, kCGImageAlphaOnly);
		break;
	default:
		[NSException raise:NSInternalInconsistencyException format:@"Invalid pixel format"];
}

Shouldn't it be more like this, to take account for the 16-bit textures using only the memory they need?

case kTexture2DPixelFormat_RGBA4444:
case kTexture2DPixelFormat_RGB565:
	colorSpace = CGColorSpaceCreateDeviceRGB();
	// why not just allocate 16 bit data??
	data = malloc(height * width * 2);
	context = CGBitmapContextCreate(data, width, height, 8, 4 * width, colorSpace, kCGImageAlphaNoneSkipLast | kCGBitmapByteOrder16Big);

Posted 2 years ago #

riq
Key Master

perhaps this post might help:
http://www.cocos2d-iphone.org/archives/61

Posted 2 years ago #
Karl
Member
Look just under that code in Texture2D.m. It first loads the image using 32bpp, and then converts it to the pixel format you specified.

Actually, it's worse than that. First, the shared texture manager loads the PNG file (I'm assuming 1024x1024 here) using Apple's SDK, eating some memory (4MB? Not sure how much Apple SDK takes). That UIImage then gets passed to Texture2D, which mallocs another 4MB so that it can get a copy of the pixel data from the UIImage in RGB8888 format. If you specify a 16-bit pixel format, it will then malloc ANOTHER 2MB so that it can copy pixels from the first 4MB malloc, converting to 16bpp (Texture2D.m line 271).

Once the conversion is done, the 4MB malloc'd data is freed, and the UIImage gets autoreleased once control leaves your event handler.

So if you want to load a 1024x1024 image into a 16-bit texture, expect it to eat 10MB and then free 8MB of that.

And there's another gotcha here: If you do a lot of texture allocations within a single event handler (like init or onEnterTransitionDidFinish), the UIImage objects will NOT get released until control LEAVES the event handler! So if you're doing a bunch of 1024x1024 textures, it'll work as follows:

Control enters your method. Total allocated = 0.

Create texture 1: SDK takes 4MB, Texture2D takes 4MB + 2MB. Total allocated = 10MB.
Finish creating texture 1: Texture2D frees 4MB. Total allocated = 6MB.

Create texture 2: SDK takes 4MB, Texture2D takes 4MB + 2MB. Total allocated = 16MB.
Finish creating texture 2: Texture2D frees 4MB. Total allocated = 12MB.

Create texture 3: SDK takes 4MB, Texture2D takes 4MB + 2MB. Total allocated = 22MB.
Finish creating texture 3: Texture2D frees 4MB. Total allocated = 18MB.

Control leaves your method and bubbles up: Autorelease pool releases 3 UIImage objects. Total allocated = 6MB.

Actually Riq, maybe instead of doing this in TextureMgr.m line 186:
```
tex = [ [Texture2D alloc] initWithImage: [UIImage imageWithContentsOfFile: fullpath ] ];
```
You could do this:
```
UIImage image = [ [UIImage alloc] initWithContentsOfFile: fullpath ];
tex = [ [Texture2D alloc] initWithImage: image ];
[image release];
```
In doing so, we can avoid the accumulation of UIImages when lots of textures are loaded within a single event.
Posted 2 years ago #
riq
Key Master

@Karl: good idea.
fixed on r1581

Posted 2 years ago #
gaminghorror
Member

Hey thanks! Yes that helps. I didn't know i could specify the texture format, since i have quite a few black/white images that should help reduce the size.

But i can save around 10 megs by putting the PNGs into 1024x1024 sprite atlases. Most images are just above the 128x128 limit (eg. 150x170) so they take up unnecessary space without using an atlas for them.

Posted 2 years ago #

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