How could save the CMSampleBuffer to a CFArrayRef (or other container) that from didOutputSampleBuffer

Question

I tried to save the CMSampleBuffer from didOutputSampleBuffer, as the iOS developer docs, I copy it in CFArrayRetainCallBack like blow:

static const void * ObjectRetainCallBack(CFAllocatorRef allocator, const void *value) {

    CMSampleBufferRef buffer = (CMSampleBufferRef)value;
    if (buffer) {

        CMSampleBufferRef new = NULL;
        OSStatus status = CMSampleBufferCreateCopy(kCFAllocatorDefault, buffer, &new);
        if (status == noErr) {
            return new;
        }
        return NULL;

    }
    return NULL;
}

static void ObjectReleaseCallBack(CFAllocatorRef allocator, const void *value) {
    if (value) {
        CFRelease(value);
    }
}

CFMutableArrayRef CreateDispatchHoldingArray() {
    CFArrayCallBacks callBacks = {
        0,
        ObjectRetainCallBack,
        ObjectReleaseCallBack,
        NULL,
        NULL
    };
    return CFArrayCreateMutable(kCFAllocatorDefault, 0, &callBacks);
}

I use the array like below:

- (void) captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
     CFArrayAppendValue(_pixelArray, sampleBuffer);
}

Somebody has better way to do this or any suggestion?

Thanks a lot.

Answer 1

CMSampleBufferCreateCopy is shallow copy, according to the answer from how to deep copy pixelbuffer

recreate the samplebuffer with a new pixelbuffer. then I could cache sample buffers.

But this way cost resource, I can't hold too many CMSampleBufferRefs in memory(each of them takes about 3MB), and the process of deep copy is waste of time.