的OpenGL ES glReadPixels EXC_BAD_ACCESS

Question

我试图创建使用OpenGL ES和ffmpeg的从图像的视频，但在iPad（4.3）我有glReadPixels

-(NSData *) glToUIImage { 

    int numberOfComponents = NUMBER_OF_COMPONENTS; //4 
    int width = PICTURE_WIDTH; 
    int height = PICTURE_HEIGHT; 

    NSInteger myDataLength = width * height * numberOfComponents; 

    NSMutableData * buffer= [NSMutableData dataWithLength :myDataLength];  

    [self checkForGLError]; 

    GLenum type = NUMBER_OF_COMPONENTS == 3 ? GL_RGB : GL_RGBA; //RGBA 
    glReadPixels(0, 0, width, height, type, GL_UNSIGNED_BYTE, [buffer mutableBytes]); //EXC_BAD_ACCESS here 

    return buffer; 
} 

它正在开发iPhone 4（4.3）崩溃和iPod Touch，但在iPhone 3G（3.0）和iPad（4.3）上存在问题。你能帮我解决这个问题吗？

同样在iPhone 3G（3.0）和iPad（4.3）上我有视频问题 - 首先5-20帧视频有垃圾。也许问题与优化？还是建筑？

EDITED 堆栈：

#0 0x33be3964 in void BlockNxN<64ul, 16ul, 1, BLOCK_CONVERTER_NULL_32>(unsigned long, int, int, unsigned long, int, int, unsigned int, unsigned int, unsigned int, unsigned int)() 
#1 0x33be1c76 in glrBIFDetile() 
#2 0x33b586b2 in sgxGetImage(SGXImageReadParams const*)() 
#3 0x33b50d38 in gldReadPixels() 
#4 0x31813e16 in glReadPixels_Exec() 
#5 0x31e3c518 in glReadPixels() 

Answer 1

我已经想通了！

我已解决这个问题约两周。

必须调用glReadPixels()前[(EAGLView *)eagleView presentFramebuffer];

所以你必须绑定colorRenderbuffer之前，你会读出像素。 最后的方法列表：

int numberOfComponents = NUMBER_OF_COMPONENTS; 
int width = PICTURE_WIDTH; 
int height = PICTURE_HEIGHT; 

NSInteger myDataLength = width * height * numberOfComponents; 


NSMutableData * buffer= [NSMutableData dataWithLength :myDataLength]; 
glBindRenderbuffer(GL_RENDERBUFFER_OES, [((EAGLView *)eagleView) colorRenderbuffer]); 
[self checkForGLError]; 
glPixelStorei(GL_PACK_ALIGNMENT, 4); // force 4 byte alignment 

glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, [buffer mutableBytes]); 
return buffer;