Pixel formats, CVPixelBufferRefs and glReadPixels

Question

I\'m using glReadPixels to read data into a CVPixelBufferRef. I use the CVPixelBufferRef as the input into an AVAssetWriter

Answer 1

Regarding the bit manipulation, you can get a pointer to the pixel buffer's raw data:

CVPixelBufferLockBaseAddress(buffer, 0);
size_t stride = CVPixelBufferGetBytesPerRow(buffer);
char *data = (char *)CVPixelBufferGetBaseAddress(buffer);
for (size_t y = 0; y < CVPixelBufferGetHeight(buffer); ++y) {
    uint32_t *pixels = (uint32_t *)(data + stride * y);
    for (size_t x = 0; x < CVPixelBufferGetWidth(buffer); ++x)
        pixels[x] = (pixels[x] >> 8) | (pixels[x] << 24);
}
CVPixelBufferUnlockBaseAddress(buffer, 0);