12
我正在嘗試使用AVAssetWriter將CGImages寫入文件以從圖像創建視頻。AVAssetWriter Woes
我已經在模擬器上以三種不同方式成功工作，但是每個方法在運行iOS 4.3的iPhone 4上都失敗。
這一切都與像素緩衝區有關。
我的第一種方法是根據需要創建像素緩衝區而不使用池。這很有效，但對設備工作而言，內存密集程度太高。
我的第二種方法是使用推薦的AVAssetWriterInputPixelBufferAdaptor，然後使用CVPixelBufferPoolCreatePixelBuffer從適配器pixelBufferPool中提取像素緩衝區。
這也適用於模擬器，但在設備上失敗，因爲適配器的像素緩衝池永遠不會被分配。我沒有收到錯誤消息。
最後，我試圖用CVPixelBufferPoolCreate創建自己的像素緩衝池。這也適用於模擬器，但在設備上，一切工作正常，直到我試圖appendPixelBuffer追加像素緩衝區，每次失敗。
我在網上發現了非常簡單的信息。我將我的代碼基於我找到的例子，但現在幾天沒有運氣。如果任何人都有成功使用AVAssetWriter的經驗，請看看並讓我知道，如果你看到任何不合適的地方。
注：您將看到註釋掉的嘗試塊。
首先，設置
- (BOOL) openVideoFile: (NSString *) path withSize:(CGSize)imageSize {
size = CGSizeMake (480.0, 320.0);//imageSize;
NSError *error = nil;
videoWriter = [[AVAssetWriter alloc] initWithURL:
[NSURL fileURLWithPath:path] fileType:AVFileTypeQuickTimeMovie
error:&error];
if (error != nil)
return NO;
NSDictionary *videoCleanApertureSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithDouble:size.width], AVVideoCleanApertureWidthKey,
[NSNumber numberWithDouble:size.height], AVVideoCleanApertureHeightKey,
[NSNumber numberWithInt:10], AVVideoCleanApertureHorizontalOffsetKey,
[NSNumber numberWithInt:10], AVVideoCleanApertureVerticalOffsetKey,
nil];
NSDictionary *videoAspectRatioSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:1], AVVideoPixelAspectRatioHorizontalSpacingKey,
[NSNumber numberWithInt:1],AVVideoPixelAspectRatioVerticalSpacingKey,
nil];
NSDictionary *codecSettings = [NSDictionary dictionaryWithObjectsAndKeys:
//[NSNumber numberWithInt:960000], AVVideoAverageBitRateKey,
// [NSNumber numberWithInt:1],AVVideoMaxKeyFrameIntervalKey,
videoCleanApertureSettings, AVVideoCleanApertureKey,
videoAspectRatioSettings, AVVideoPixelAspectRatioKey,
//AVVideoProfileLevelH264Main31, AVVideoProfileLevelKey,
nil];
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
codecSettings,AVVideoCompressionPropertiesKey,
[NSNumber numberWithDouble:size.width], AVVideoWidthKey,
[NSNumber numberWithDouble:size.height], AVVideoHeightKey,
nil];
writerInput = [[AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings] retain];
NSMutableDictionary * bufferAttributes = [[NSMutableDictionary alloc] init];
[bufferAttributes setObject: [NSNumber numberWithInt: kCVPixelFormatType_32ARGB]
forKey: (NSString *) kCVPixelBufferPixelFormatTypeKey];
[bufferAttributes setObject: [NSNumber numberWithInt: 480]
forKey: (NSString *) kCVPixelBufferWidthKey];
[bufferAttributes setObject: [NSNumber numberWithInt: 320]
forKey: (NSString *) kCVPixelBufferHeightKey];
//NSDictionary *bufferAttributes = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil];
//[bufferAttributes setObject: [NSNumber numberWithInt: 640]
// forKey: (NSString *) kCVPixelBufferWidthKey];
//[bufferAttributes setObject: [NSNumber numberWithInt: 480]
// forKey: (NSString *) kCVPixelBufferHeightKey];
adaptor = [[AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
sourcePixelBufferAttributes:nil] retain];
//CVPixelBufferPoolCreate (kCFAllocatorSystemDefault,NULL,(CFDictionaryRef)bufferAttributes,&pixelBufferPool);
//Create buffer pool
NSMutableDictionary* attributes;
attributes = [NSMutableDictionary dictionary];
int width = 480;
int height = 320;
[attributes setObject:[NSNumber numberWithInt:kCVPixelFormatType_32ARGB] forKey:(NSString*)kCVPixelBufferPixelFormatTypeKey];
[attributes setObject:[NSNumber numberWithInt:width] forKey: (NSString*)kCVPixelBufferWidthKey];
[attributes setObject:[NSNumber numberWithInt:height] forKey: (NSString*)kCVPixelBufferHeightKey];
CVReturn theError = CVPixelBufferPoolCreate(kCFAllocatorDefault, NULL, (CFDictionaryRef) attributes, &pixelBufferPool);
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];
writerInput.expectsMediaDataInRealTime = YES;
//Start a session:
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
buffer = NULL;
lastTime = kCMTimeZero;
presentTime = kCMTimeZero;
return YES;
}
接着，追加寫入器和創建像素緩衝器追加的兩種方法。
- (void) writeImageToMovie:(CGImageRef)image
{
if([writerInput isReadyForMoreMediaData])
{
// CMTime frameTime = CMTimeMake(1, 20);
// CMTime lastTime=CMTimeMake(i, 20); //i is from 0 to 24 of the loop above
// CMTime presentTime=CMTimeAdd(lastTime, frameTime);
buffer = [self pixelBufferFromCGImage:image];
BOOL success = [adaptor appendPixelBuffer:buffer withPresentationTime:presentTime];
if (!success) NSLog(@"Failed to appendPixelBuffer");
CVPixelBufferRelease(buffer);
presentTime = CMTimeAdd(lastTime, CMTimeMake(5, 1000));
lastTime = presentTime;
}
else
{
NSLog(@"error - writerInput not ready");
}
}
- (CVPixelBufferRef)pixelBufferFromCGImage:(CGImageRef)image
{
CVPixelBufferRef pxbuffer;
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
if (pixelBufferPool == NULL) NSLog(@"pixelBufferPool is null!");
CVReturn status = CVPixelBufferPoolCreatePixelBuffer (NULL, pixelBufferPool, &pxbuffer);
/*if (pxbuffer == NULL) {
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, size.width,
size.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options,
&pxbuffer);
}*/
//NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
//NSParameterAssert(pxdata != NULL);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, size.width,
size.height, 8, 4*size.width, rgbColorSpace,
kCGImageAlphaNoneSkipFirst);
//NSParameterAssert(context);
CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
CGContextDrawImage(context, CGRectMake(90, 10, CGImageGetWidth(image),
CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}
哇，這是dissapointing。沒有人有線索？ – 2011-06-02 22:25:47