AVAssetWriterInputPixelBufferAdaptor pixelBufferPool在一段时间后变为NULL

Question

我在AVAssetWriterInputPixelBufferAdaptor中使用pixelBufferPool来创建像素缓冲区以与append方法一起使用.创建4个缓冲区后,pixelBufferPool属性变为NULL;

我设置了我的编写器,输入和适配器,如下所示:

- (BOOL) setupRecorder {
    NSError *error = nil;
    if([[NSFileManager defaultManager] fileExistsAtPath:[[self tempFileURL] path]])
        [[NSFileManager defaultManager] removeItemAtURL:[self tempFileURL] error:&error];


    assetWriter = [[AVAssetWriter alloc] initWithURL: [self tempFileURL] 
                                            fileType:AVFileTypeQuickTimeMovie
                                               error:&error]; 
    if (error) {
        NSLog(@"Error creating asset writer: %@", error);
        [assetWriter release];
        return NO;
    }
    // writer

    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   AVVideoCodecH264, AVVideoCodecKey, 
                                   [NSNumber numberWithInt:videoWidth], AVVideoWidthKey, 
                                   [NSNumber numberWithInt:videoHeight], AVVideoHeightKey,
                                   nil];

    assetWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo 
                                                      outputSettings:videoSettings];

    NSDictionary *bufferAttributes = [NSDictionary dictionaryWithObjectsAndKeys: 
                                      [NSNumber numberWithInt:kCVPixelFormatType_32BGRA], kCVPixelBufferPixelFormatTypeKey, 
                                      nil];

    adaptor = [[AVAssetWriterInputPixelBufferAdaptor alloc] initWithAssetWriterInput:assetWriterInput sourcePixelBufferAttributes:bufferAttributes];  
    [adaptor retain];
    assetWriterInput.expectsMediaDataInRealTime = YES;
    [assetWriter addInput:assetWriterInput];

    return YES;
}

然后用这个分配像素缓冲区:

- (CVPixelBufferRef) createPixelBufferRef {
    CVPixelBufferPoolRef pixelBufferPool = adaptor.pixelBufferPool;
    CVPixelBufferRef pixelBuffer = NULL;
    CVReturn cvReturn = CVPixelBufferPoolCreatePixelBuffer(NULL, pixelBufferPool, &pixelBuffer);
    if(cvReturn != kCVReturnSuccess)
        NSLog(@"CVPixelBuffePoolCreatePixelBuffer: %d", cvReturn);
    bufferCreatedCount++;
    return pixelBuffer;
}

当我完成将像素缓冲区传递给appendPixelBuffer时,我使用CVPixelBufferRelease释放像素缓冲区.在此之前的任何时候,我都不会调用markAsFinished,endSessionAtSourceTime或finishWriting.此外,适配器本身不会为NULL.

我读过的大多数帖子都谈到由于配置错误配置而导致池从一开始就缺席,但是我的存在,但只是很短的时间.其他人看到过这种行为吗？

Answer 1

我有同样的问题.正如我所知,如果CMTime您投入的某些内容相同,就会发生这种情况appendPixelBuffer:withPresentationTime:.例如,如果您使用CMTimeMakeWithSeconds过于粗略的时间刻度,就会发生这种情况.

Answer 2

如果像素缓冲区适配器出现错误，则可能会发生这种情况。由于帧被乱序推送或具有相同的呈现时间，像素缓冲区适配器可能会进入错误状态。