Question

我尝试使用OpenGL ES和ffmpeg从图像创建视频，但在iPad（4.3）上我遇到了glReadPixels的崩溃

-(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; 
}

它适用于iPhone 4（4.3）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）上我遇到视频问题 - 首先5-20个视频帧有垃圾。也许优化问题？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!!!

我已经解决了这个问题大约两周了。

您必须在glReadPixels()

之前致电[(EAGLView *)eagleView presentFramebuffer];

因此，在读取像素之前必须绑定colorRenderbuffer。最终方法列表：

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;

OpenGL ES glReadPixels exc_bad_access

1 个答案: