iphone - CFDataGetBytes(image, CRangeMake(0, CFDataGetLength(image)), destPixels) 崩溃；

Question

我正在制作屏幕视频，但在这条线上崩溃。

 CFDataGetBytes(image, CFRangeMake(0, CFDataGetLength(image)), destPixels);  

注意：如果像素缓冲区是连续的并且具有与输入数据相同的 bytesPerRow ，它将起作用

Answer 1

所以我提供了从相机中抓取帧的代码 - 也许它会有所帮助 在抓取数据后，我将它放在队列中以进行进一步处理。我不得不删除一些代码，因为它与你无关——所以你在这里看到的部分应该是你可以使用的。

- (void)captureOutput:(AVCaptureVideoDataOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    @autoreleasepool {
        CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
        //NSLog(@"PE: value=%lld timeScale=%d flags=%x", prStamp.value, prStamp.timescale, prStamp.flags);

        /*Lock the image buffer*/
        CVPixelBufferLockBaseAddress(imageBuffer,0); 

        NSRange captureRange;

        /*Get information about the image*/
        uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer); 
        size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); 
        size_t width = CVPixelBufferGetWidth(imageBuffer); 

        // Note Apple sample code cheats big time - the phone is big endian so this reverses the "apparent" order of bytes
        CGContextRef newContext = CGBitmapContextCreate(NULL, width, captureRange.length, 8, bytesPerRow, colorSpace, kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Little); // Video in ARGB format

assert(newContext);

        uint8_t *newPtr = (uint8_t *)CGBitmapContextGetData(newContext);
        size_t offset   = captureRange.location * bytesPerRow;

        memcpy(newPtr, baseAddress + offset, captureRange.length * bytesPerRow);

        CVPixelBufferUnlockBaseAddress(imageBuffer, 0);

        CMTime prStamp = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);      // when it was taken?
        //CMTime deStamp = CMSampleBufferGetDecodeTimeStamp(sampleBuffer);          // now?

        NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
            [NSValue valueWithBytes:&saveState objCType:@encode(saveImages)], kState,
            [NSValue valueWithNonretainedObject:(__bridge id)newContext], kImageContext,
            [NSValue valueWithBytes:&prStamp objCType:@encode(CMTime)], kPresTime,
            nil ];
        dispatch_async(imageQueue, ^
            {
                // could be on any thread now
                OSAtomicDecrement32(&queueDepth);

                if(!isCancelled) {
                    saveImages state; [(NSValue *)[dict objectForKey:kState] getValue:&state];
                    CGContextRef context; [(NSValue *)[dict objectForKey:kImageContext] getValue:&context];
                    CMTime stamp; [(NSValue *)[dict objectForKey:kPresTime] getValue:&stamp];

                    CGImageRef newImageRef = CGBitmapContextCreateImage(context); 
                    CGContextRelease(context);
                    UIImageOrientation orient = state == saveOne ? UIImageOrientationLeft : UIImageOrientationUp;
                    UIImage *image = [UIImage imageWithCGImage:newImageRef scale:1.0 orientation:orient]; // imageWithCGImage:  UIImageOrientationUp  UIImageOrientationLeft
                    CGImageRelease(newImageRef);
                    NSData *data = UIImagePNGRepresentation(image);

                    // NSLog(@"STATE:[%d]: value=%lld timeScale=%d flags=%x", state, stamp.value, stamp.timescale, stamp.flags);

                    {
                        NSString *name = [NSString stringWithFormat:@"%d.png", num];
                        NSString *path = [[wlAppDelegate snippetsDirectory] stringByAppendingPathComponent:name];
                        BOOL ret = [data writeToFile:path atomically:NO];
//NSLog(@"WROTE %d err=%d w/time %f path:%@", num, ret, (double)stamp.value/(double)stamp.timescale, path);
                        if(!ret) {
                            ++errors;
                        } else {
                            dispatch_async(dispatch_get_main_queue(), ^
                                {
                                    if(num) [delegate progress:(CGFloat)num/(CGFloat)(MORE_THAN_ONE_REV * SNAPS_PER_SEC) file:path];
                                } );
                        }
                        ++num;
                    }
                } else NSLog(@"CANCELLED");

            } );
    }
}