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Question

尝试通过 AVAssetWriter 和 AVAssetWriterInput 方法将多个视频连接成一个时。在第 3 个视频之后，我收到来自 AVAssetWriter.error 的“无法编码”错误。

此外，我可以通过控制台看到成功读取缓冲区，但只有最后一次成功读取的视频才会出现在串联的 mov 中。对其中一个或两个问题的任何见解表示赞赏，来源和日志如下。谢谢

+(void)doWriteWithVideoWriter:(AVAssetWriter *)videoWriter withIndex:(int)index withWriterInputArray:(NSMutableArray *)writersArray withInstance:(VideoCombinerManager *)theInstance{
if ([writersArray count] > 0)
{
    int newIndex = index+1;

    NSError *readerError;
    NSDictionary *videoOptions = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange] forKey:(id)kCVPixelBufferPixelFormatTypeKey];

    AVAsset *sourceAsset = [theInstance.loadedAssetsForCompilationDictionary objectForKey:[theInstance.sortedKeysArray objectAtIndex:index]];
    AVAssetTrack *videoTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    AVAssetReaderTrackOutput *currentReaderTrackOutput = [[AVAssetReaderTrackOutput alloc] initWithTrack:videoTrack outputSettings:videoOptions];
    AVAssetReader *currentReader = [[AVAssetReader alloc] initWithAsset:sourceAsset error:&readerError];
    [currentReader addOutput:currentReaderTrackOutput];
    [currentReader startReading];

    AVAssetWriterInput *writerInput = [[writersArray objectAtIndex:0] retain];

    dispatch_queue_t _processingQueue = dispatch_queue_create("asdf", NULL);
    [writerInput requestMediaDataWhenReadyOnQueue:_processingQueue usingBlock:^{
    if ([writerInput isReadyForMoreMediaData])
    {
        CMSampleBufferRef nextSampleBuffer;

        if ([currentReader status] == AVAssetReaderStatusReading &&
        (nextSampleBuffer = [currentReaderTrackOutput copyNextSampleBuffer])) {

        if (nextSampleBuffer)
        {
            BOOL result = [writerInput appendSampleBuffer:nextSampleBuffer];
            if (!result)
            {
            NSLog(@"videoWriter.error.userInfo: %@", videoWriter.error.userInfo);
            }
            CFRelease(nextSampleBuffer);
        }
        }
        else
        {
        NSLog(@"writer done: %d", index);
        dispatch_release(_processingQueue);

        [writersArray removeObjectAtIndex:0];

        [writerInput markAsFinished];
        [writerInput release];

        [currentReader release];
        [currentReaderTrackOutput release];

        [VideoCombinerManager doWriteWithVideoWriter:videoWriter withIndex:newIndex withWriterInputArray:writersArray withInstance:theInstance];
        }
    }
    }];
}
else
    [videoWriter finishWriting];

}

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videoWriter.error.userInfo: {
    NSLocalizedDescription = "Cannot Encode";
    NSLocalizedFailureReason = "The encoder required for this media is busy.";
    NSLocalizedRecoverySuggestion = "Stop any other actions that encode media and try again.";
    NSUnderlyingError = "Error Domain=NSOSStatusErrorDomain Code=-12915 \"The operation couldn\U2019t be completed. (OSStatus error -12915.)\"";
}

videoWriter.error.userInfo: {
    NSLocalizedDescription = "Cannot Encode";
    NSLocalizedFailureReason = "The encoder required for this media is busy.";
    NSLocalizedRecoverySuggestion = "Stop any other actions that encode media and try again.";
    NSUnderlyingError = "Error Domain=NSOSStatusErrorDomain Code=-12915 \"The operation couldn\U2019t be completed. (OSStatus error -12915.)\"";
}

Answer 1

至于 Cannot Encode 错误，您同时存在的 writer 和/或 writerInputs 太多。当我遇到同样的错误时，我意识到我必须释放所有以前使用的 writer 和 writerInputs 才能摆脱它。由于您确实释放了它们，您的问题可能是您同时拥有许多它们。