我有一个视觉上相当复杂的应用程序,它有一个基本的 UIViewController 和几个 UIViews(由我子类化和扩展)。我会定期抛出 UIAlertViews 和 UIPopOverControllers。
我正在努力开发一种视频录制解决方案,以便在用户使用该应用程序时,它会记录正在发生的事情以供日后汇报。
我有一个部分有效的解决方案,但它非常慢(每秒不能超过 1 帧),有一些问题(图像当前旋转和倾斜,但我想我可以解决这个问题)这不是我认为的理想解决方案。
我跳出了那个思路,开始实现一个使用 UIGetImageFromCurrentImageContext() 的解决方案,但它一直给我 nil
图像,即使是从 drawRect:
中调用时也是如此>.
不过,我突然想到,我不想一直调用 drawRect:
只是为了截屏!我不想实际启动任何额外的绘图,只是捕捉屏幕上的内容。
我很高兴发布我正在使用的代码,但它还没有真正起作用。有谁知道一个好的解决方案来做我正在寻找的事情?
我找到的一个解决方案并不完全适合我,因为它似乎从未捕获 UIAlertViews 和其他重叠 View 。
有什么帮助吗?
谢谢!
颠簸
最佳答案
我无法进行全尺寸实时视频编码。但是,作为替代方案,请考虑这一点。
不记录帧,而是记录发生的 Action (带有时间戳)。然后,当你想回放时,只需重放 Action 即可。您已经有了代码,因为您在“现实生活”中执行了它。
您所做的就是及时重播这些相同的 Action 。
编辑
如果你想尝试录音,这就是我所做的(注意,我放弃了它......这是一个正在进行的实验,所以就拿它作为我如何接近它的例子......没有什么是生产 -准备好)。我能够以 640x360 的分辨率录制实时音频/视频,但分辨率对我来说太低了。在 iPad 上看起来不错,但当我将视频移到我的 Mac 上观看时就很糟糕了。
我在使用更高的分辨率时遇到了问题。我从 RosyWriter 示例项目中改编了大部分代码。以下是设置 Assets 编写器、开始录制以及将 UIImage 添加到视频流的主要例程。
祝你好运。
CGSize const VIDEO_SIZE = { 640, 360 };
- (void) startRecording
{
dispatch_async(movieWritingQueue, ^{
NSLog(@"startRecording called in state 0x%04x", state);
if (state != STATE_IDLE) return;
state = STATE_STARTING_RECORDING;
NSLog(@"startRecording changed state to 0x%04x", state);
NSError *error;
//assetWriter = [[AVAssetWriter alloc] initWithURL:movieURL fileType:AVFileTypeQuickTimeMovie error:&error];
assetWriter = [[AVAssetWriter alloc] initWithURL:movieURL fileType:AVFileTypeMPEG4 error:&error];
if (error) {
[self showError:error];
}
[self removeFile:movieURL];
[self resumeCaptureSession];
[self.delegate recordingWillStart];
});
}
// TODO: this is where we write an image into the movie stream...
- (void) writeImage:(UIImage*)inImage
{
static CFTimeInterval const minInterval = 1.0 / 10.0;
static CFAbsoluteTime lastFrameWrittenWallClockTime;
CFAbsoluteTime thisFrameWallClockTime = CFAbsoluteTimeGetCurrent();
CFTimeInterval timeBetweenFrames = thisFrameWallClockTime - lastFrameWrittenWallClockTime;
if (timeBetweenFrames < minInterval) return;
// Not really accurate, but we just want to limit the rate we try to write frames...
lastFrameWrittenWallClockTime = thisFrameWallClockTime;
dispatch_async(movieWritingQueue, ^{
if ( !assetWriter ) return;
if ((state & STATE_STARTING_RECORDING) && !(state & STATE_MASK_VIDEO_READY)) {
if ([self setupAssetWriterImageInput:inImage]) {
[self videoIsReady];
}
}
if (state != STATE_RECORDING) return;
if (assetWriter.status != AVAssetWriterStatusWriting) return;
CGImageRef cgImage = CGImageCreateCopy([inImage CGImage]);
if (assetWriterVideoIn.readyForMoreMediaData) {
CVPixelBufferRef pixelBuffer = NULL;
// Resize the original image...
if (!CGSizeEqualToSize(inImage.size, VIDEO_SIZE)) {
// Build a context that's the same dimensions as the new size
CGRect newRect = CGRectIntegral(CGRectMake(0, 0, VIDEO_SIZE.width, VIDEO_SIZE.height));
CGContextRef bitmap = CGBitmapContextCreate(NULL,
newRect.size.width,
newRect.size.height,
CGImageGetBitsPerComponent(cgImage),
0,
CGImageGetColorSpace(cgImage),
CGImageGetBitmapInfo(cgImage));
// Rotate and/or flip the image if required by its orientation
//CGContextConcatCTM(bitmap, transform);
// Set the quality level to use when rescaling
CGContextSetInterpolationQuality(bitmap, kCGInterpolationHigh);
// Draw into the context; this scales the image
//CGContextDrawImage(bitmap, transpose ? transposedRect : newRect, imageRef);
CGContextDrawImage(bitmap, newRect, cgImage);
// Get the resized image from the context and a UIImage
CGImageRef newImageRef = CGBitmapContextCreateImage(bitmap);
CGContextRelease(bitmap);
CGImageRelease(cgImage);
cgImage = newImageRef;
}
CFDataRef image = CGDataProviderCopyData(CGImageGetDataProvider(cgImage));
int status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, self.assetWriterPixelBufferAdaptor.pixelBufferPool, &pixelBuffer);
if(status != 0){
//could not get a buffer from the pool
NSLog(@"Error creating pixel buffer: status=%d", status);
}
// set image data into pixel buffer
CVPixelBufferLockBaseAddress( pixelBuffer, 0 );
uint8_t* destPixels = CVPixelBufferGetBaseAddress(pixelBuffer);
// Danger, Will Robinson!!!!! USE_BLOCK_IN_FRAME warning...
CFDataGetBytes(image, CFRangeMake(0, CFDataGetLength(image)), destPixels);
if(status == 0){
//CFAbsoluteTime thisFrameWallClockTime = CFAbsoluteTimeGetCurrent();
CFTimeInterval elapsedTime = thisFrameWallClockTime - firstFrameWallClockTime;
CMTime presentationTime = CMTimeAdd(firstBufferTimeStamp, CMTimeMake(elapsedTime * TIME_SCALE, TIME_SCALE));
BOOL success = [self.assetWriterPixelBufferAdaptor appendPixelBuffer:pixelBuffer withPresentationTime:presentationTime];
if (!success)
NSLog(@"Warning: Unable to write buffer to video");
}
//clean up
CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );
CVPixelBufferRelease( pixelBuffer );
CFRelease(image);
CGImageRelease(cgImage);
} else {
NSLog(@"Not ready for video data");
}
});
}
-(BOOL) setupAssetWriterImageInput:(UIImage*)image
{
NSDictionary* videoCompressionProps = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithDouble:1024.0*1024.0], AVVideoAverageBitRateKey,
nil ];
NSDictionary* videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
//[NSNumber numberWithInt:image.size.width], AVVideoWidthKey,
//[NSNumber numberWithInt:image.size.height], AVVideoHeightKey,
[NSNumber numberWithInt:VIDEO_SIZE.width], AVVideoWidthKey,
[NSNumber numberWithInt:VIDEO_SIZE.height], AVVideoHeightKey,
videoCompressionProps, AVVideoCompressionPropertiesKey,
nil];
NSLog(@"videoSettings: %@", videoSettings);
assetWriterVideoIn = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
NSParameterAssert(assetWriterVideoIn);
assetWriterVideoIn.expectsMediaDataInRealTime = YES;
NSDictionary* bufferAttributes = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil];
self.assetWriterPixelBufferAdaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:assetWriterVideoIn sourcePixelBufferAttributes:bufferAttributes];
//add input
if ([assetWriter canAddInput:assetWriterVideoIn]) {
[assetWriter addInput:assetWriterVideoIn];
}
else {
NSLog(@"Couldn't add asset writer video input.");
return NO;
}
return YES;
}
关于iOS 截图/App 录制技巧,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9823242/