ios - AVAssetWriterInputPixelBufferAdaptor 返回空像素缓冲池

Question

我确定我的缓冲区属性有问题，但我不清楚是什么 -- 没有很好地记录应该去那里的内容，所以我猜测基于 CVPixelBufferPoolCreate -- Core Foundation 对我来说几乎是一本合上的书。

    // "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

Answer 1

当 pixelBufferPool 返回 null 时，检查以下内容:

1. AVAssetsWriter 的输出文件不存在。

2. 在 AVAssetsWriter 上调用 startSessionAtTime: 后使用像素缓冲区。

3. AVAssetWriterInput 和 AVAssetWriterInputPixelBufferAdaptor 设置正确。

4.appendPixelBuffer的当前使用次数不一样。