不要告诉我使用 AVAssetExportSession,谢谢。
我试过这个,但失败了。
for (int i =0; i < count; i++) {
        assetWriterInput = nil;
        assetWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
        NSParameterAssert(assetWriterInput);
        NSParameterAssert([assetWriter canAddInput:assetWriterInput]);
        [assetWriterInput setExpectsMediaDataInRealTime:YES];
        [assetWriter addInput:assetWriterInput];
}        
[assetWriter startWriting];