Saving/Loading CCRenderTexture data

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Saving/Loading CCRenderTexture data

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Started 1 year ago by abitofcode
Latest reply from MrLucky

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monte
Member

@renderplace Turns out I was just making silly mistakes. It works now...

Get the Flash Video

...but I haven't had a chance to optimize it so every time I grab a frame there's a very slight stutter.

After I refactor it I'll let you know how the CVPixelBufferPools impact performance.

Do you know if there's a way to write the movie file directly to the photo album? I'm writing it to the documents directory, then using ALAssetsLibrary to copy to the album, then deleting the file from the documents dir. Seems like I'm making extra steps. More research for tomorrow :)

(by the way, the app actually runs at about 3x the frame rate you see in the video above)

Posted 1 year ago #
renderplace
Member

@monte great, it looks pretty cool FPS to me! ~20FPS?

Regarding saving the movie, don't know if you can actually specify movie url pointing directly to the library while initialize the AVAssetWriter, thus I'm doing the same: remove local file first, create new one via AVAssetWriter init; save the local one to the library via UISaveVideoAtPathToSavedPhotosAlbum().

As said, glReadPixels() is probably the slowest part, encoder itself can handle 30FPS without problems.
Let me know if you'll find some optimization hacks ;)

Posted 1 year ago #
monte
Member
@render

hey i found another way to flip the video *without* flipping the buffer obtained from glReadPixels. really curious if you've seen it and if it gives you a speed improvement!

immediately after making your AVAssetWriterInput, do this to it...
```
writerInput.transform = CGAffineTransformMakeScale(1.0, -1.0);
```
...i think maybe it can hardware/gpu accelerate the flipping done this way?

anyway i was using lots of transforms in another project and saw the transform property on AVAssetWriterInput and it works and i was able to get rid of the separate buffer i had been using for flipping.

hope this helps!
Posted 1 year ago #
renderplace
Member

@monte great finding, will try it out for sure. Tnx!

Posted 1 year ago #
nitin_daviet88
Member

hey @renderplace

i m implementing the same thing in my app.
when i capture the screen using glreadpixel() and flip it accordingly . now what i want to do is to rotate the captured data (Image) by 90" how can i do so...?

Also i tried using transform property of the AVAssetWriterInput but the output file saved in the iphone photo library does not have desired orientation . thats why i was trying to rotate the captured data instead..?

Posted 10 months ago #
renderplace
Member

@nitin_daviet88 never tried it though, but you may want to search for CGAffineTransformMakeRotation() examples.

Posted 10 months ago #

tim.shi
Member

@renderplace @monte

I tried same approach as the one mentioned in this thread, and glreadpixel works for the RGBA pixel format. But for BGRA pixel format all the entry in the output buffer is 0. The code below is how I logged out the content of the buffer.

GLint native_format;
    GLint native_type;

    glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES, &native_format);
    glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE_OES, &native_type);

    NSLog(@"native_format: 0x%04X", native_format);
    NSLog(@"native_type: 0x%04X", native_type);

    //screen size
    CGSize s = [[CCDirector sharedDirector] winSize];
    int tx = s.width;
    int ty = s.height;

    int bitsPerPixel=32;				

    int bytesPerRow = (bitsPerPixel/8) * tx;
    NSInteger myDataLength = bytesPerRow * ty;

    GLubyte *buffer	= malloc(sizeof(GLubyte)*myDataLength);

    [target begin];
    glReadPixels(0,0,tx,ty,native_format,native_type, buffer);
    [target end];

    int x,y;
    for(y = 0; y <ty; y++) {
        for(x = 0; x <tx * 4; x++) {
            CCLOG(@"pixel is %04X", buffer[y * 4 * tx + x]);
        }
    }

I tried this setting the EAGLView's buffer to kEAGLColorFormatRGBA8 as below but it didn't make any difference

EAGLView *glView = [EAGLView viewWithFrame:[window bounds]
pixelFormat:kEAGLColorFormatRGBA8
depthFormat:0];

Is there anything else that's required to get glreadpixel working with BGRA?

Posted 9 months ago #

tim.shi
Member

When I do glgeterror() after the glreadpixel call, I get the error code 1280 (0x0500), which should only be returned when not using the GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES/ GL_IMPLEMENTATION_COLOR_READ_TYPE_OES pair, but I am definitely using the pair. Has anyone encountered this problem?

Posted 9 months ago #
tim.shi
Member

I figured it out, it was because it was called after [target begin] where target is a render texture, the method itself includes some opengl calls.

A somewhat related question, if there's multiple layers on the screen (i.e. a render texture on top of a cclayer), is it possible to only capture the pixels in the render texture?

Also, if the app keeps on getting frames from the video and adding it to AVAssetWriter's buffer, would it eventually run into memory problems? And what's the best practice to dealing with that?

Posted 9 months ago #
MrLucky
Member

Nice thread!

I managed to make a screen capture with a similar approach, but the app recieves memory warnings and crashes after about 1 min videocapture for iPad and 2 min for iPhone. Did you guys do anything spesific to be able to make a longer video?

Posted 5 months ago #

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