AvassetWriterInputPixelBufferadaptor返回null像素缓冲区池
https://stackoverflow.com/questions/5810984
-
25-10-2019 - |
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我敢肯定我的缓冲区属性有问题，但是我不清楚什么 - 没有很好的记录，所以我猜是基于 CVPixelBufferPoolCreate - 核心基金会对我来说几乎是一本封闭的书。
// "width" and "height" are const ints
CFNumberRef cfWidth = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &width);
CFNumberRef cfHeight = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &height);
CFStringRef keys[] = {
kCVPixelBufferWidthKey,
kCVPixelBufferHeightKey,
kCVPixelBufferCGImageCompatibilityKey
};
CFTypeRef values[] = {
cfWidth,
cfHeight,
kCFBooleanTrue
};
int numValues = sizeof(keys) / sizeof(keys[0]);
CFDictionaryRef bufferAttributes = CFDictionaryCreate(kCFAllocatorDefault,
(const void **)&keys,
(const void **)&values,
numValues,
&kCFTypeDictionaryKeyCallBacks,
&kCFTypeDictionaryValueCallBacks
);
AVAssetWriterInputPixelBufferAdaptor *adaptor = [[AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
sourcePixelBufferAttributes:(NSDictionary*)bufferAttributes] retain];
CVPixelBufferPoolRef bufferPool = adaptor.pixelBufferPool;
NSParameterAssert(bufferPool != NULL); // fails
解决方案
当PixelBufferPool返回null时，请检查以下内容：
- 1.不存在Avassetswriter的输出文件。
- 2.致电startessessionatime：在avassetswriter上使用PixelBuffer。
- 3. AvassetWriterInput和AvassetWriterInitputPixelBufferadaptor的设置是正确的。
- 4.附录pixelbuffer使用的当前时间不相同。
其他提示
我有同样的问题，我认为这可能是因为您尚未配置 AVAssetWriterInput 正确。我这样做后，我的游泳池开始工作。特别是，除非我提供了数据，否则池不会给我像素缓冲区 AVVideoCompressionPropertiesKey. 。首先，创建并完全配置 AVAssetWriter （ 在看 /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk/System/Library/Frameworks/AVFoundation.framework/Headers/AVVideoSettings.h 对于钥匙和值 outputSettings 和 compressionSettings):
NSError * err = 0;
AVAssetWriter * outputWriter = [AVAssetWriter
assetWriterWithURL: [NSURL fileURLWithPath:outputPath]
fileType: AVFileTypeAppleM4V
error: & err];
NSMutableDictionary * outputSettings
= [[NSMutableDictionary alloc] init];
[outputSettings setObject: AVVideoCodecH264
forKey: AVVideoCodecKey];
[outputSettings setObject: [NSNumber numberWithInt: width_]
forKey: AVVideoWidthKey];
[outputSettings setObject: [NSNumber numberWithInt: height_]
forKey: AVVideoHeightKey];
NSMutableDictionary * compressionProperties
= [[NSMutableDictionary alloc] init];
[compressionProperties setObject: [NSNumber numberWithInt: 1000000]
forKey: AVVideoAverageBitRateKey];
[compressionProperties setObject: [NSNumber numberWithInt: 16]
forKey: AVVideoMaxKeyFrameIntervalKey];
[compressionProperties setObject: AVVideoProfileLevelH264Main31
forKey: AVVideoProfileLevelKey];
[outputSettings setObject: compressionProperties
forKey: AVVideoCompressionPropertiesKey];
AVAssetWriterInput * writerInput = [AVAssetWriterInput
assetWriterInputWithMediaType: AVMediaTypeVideo
outputSettings: outputSettings];
[compressionProperties release];
[outputSettings release];
创建像素缓冲区适配器：
NSMutableDictionary * pixBufSettings = [[NSMutableDictionary alloc] init];
[pixBufSettings setObject: [NSNumber numberWithInt: kCVPixelFormatType_32BGRA]
forKey: (NSString *) kCVPixelBufferPixelFormatTypeKey];
[pixBufSettings setObject: [NSNumber numberWithInt: width_]
forKey: (NSString *) kCVPixelBufferWidthKey];
[pixBufSettings setObject: [NSNumber numberWithInt: height_]
forKey: (NSString *) kCVPixelBufferHeightKey];
AVAssetWriterInputPixelBufferAdaptor * outputPBA =
[AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput: outputInput
sourcePixelBufferAttributes: nil];
然后使用以下方式从其池中检索像素缓冲区
CVReturn res = CVPixelBufferPoolCreatePixelBuffer (NULL
, [outputPBA pixelBufferPool]
, & outputFrame);
根据文档：
“此属性在第一次打电话给Startessessatemime之前是无效的：在关联的AvassetWriter对象上。”
因此，如果您试图过早访问游泳池，那将是无效的。我自己只是自己学习这些东西，所以目前我无法真正详细说明。
对于仍在寻找解决方案的每个人：首先，请确保您的AvassetWriter通过检查其状态正常工作。我遇到了这个问题，在检查状态后，尽管我打电话给“开始”，但作者还没有开始。它像魅力一样工作）
我明白了！将选项字典设置为兼容性，他们说可以使用缓冲池，这是工作示例和代码在没有缓冲区的情况下编写，但这是一个很好的起点。
这是示例代码 关联
这是您需要的代码：
- (void) testCompressionSession
{
CGSize size = CGSizeMake(480, 320);
NSString *betaCompressionDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Movie.m4v"];
NSError *error = nil;
unlink([betaCompressionDirectory UTF8String]);
//----initialize compression engine
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:[NSURL fileURLWithPath:betaCompressionDirectory]
fileType:AVFileTypeQuickTimeMovie
error:&error];
NSParameterAssert(videoWriter);
if(error)
NSLog(@"error = %@", [error localizedDescription]);
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:size.width], AVVideoWidthKey,
[NSNumber numberWithInt:size.height], AVVideoHeightKey, nil];
AVAssetWriterInput *writerInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary];
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
if ([videoWriter canAddInput:writerInput])
NSLog(@"I can add this input");
else
NSLog(@"i can't add this input");
[videoWriter addInput:writerInput];
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
//---
// insert demo debugging code to write the same image repeated as a movie
CGImageRef theImage = [[UIImage imageNamed:@"Lotus.png"] CGImage];
dispatch_queue_t dispatchQueue = dispatch_queue_create("mediaInputQueue", NULL);
int __block frame = 0;
[writerInput requestMediaDataWhenReadyOnQueue:dispatchQueue usingBlock:^{
while ([writerInput isReadyForMoreMediaData])
{
if(++frame >= 120)
{
[writerInput markAsFinished];
[videoWriter finishWriting];
[videoWriter release];
break;
}
CVPixelBufferRef buffer = (CVPixelBufferRef)[self pixelBufferFromCGImage:theImage size:size];
if (buffer)
{
if(![adaptor appendPixelBuffer:buffer withPresentationTime:CMTimeMake(frame, 20)])
NSLog(@"FAIL");
else
NSLog(@"Success:%d", frame);
CFRelease(buffer);
}
}
}];
NSLog(@"outside for loop");
}
- (CVPixelBufferRef )pixelBufferFromCGImage:(CGImageRef)image size:(CGSize)size
{
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey, nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, size.width, size.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options, &pxbuffer);
// CVReturn status = CVPixelBufferPoolCreatePixelBuffer(NULL, adaptor.pixelBufferPool, &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, kCGImageAlphaPremultipliedFirst);
NSParameterAssert(context);
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image), CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}
当没有文件时，它可以工作 outputURL 为了 AVAssetWriter.
extension FileManager {
func removeItemIfExist(at url: URL) {
do {
if FileManager.default.fileExists(atPath: url.path) {
try FileManager.default.removeItem(at: url)
}
} catch {
fatalError("\(error)")
}
}
}
用法
let assetWriter = try? AVAssetWriter(outputURL: outputURL, fileType: .mov)
FileManager.default.removeItemIfExist(at: outputURL)
// do something
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