ios - Objective -C 如何从 NSMutableArray 创建视频？

Question

我有一个 NSMutableArray 图像我需要创建一个视频并保存为 .mp4 格式我尝试了在许多地方找到的代码来从图像中生成视频。但它不起作用。它创建一个空白文件

-(void)writeImageAsMovie:(NSArray *)array toPath:(NSString*)path size:(CGSize)size duration:(int)duration
{
    NSError *error = nil;

    AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
                                  [NSURL fileURLWithPath:path] fileType:AVFileTypeQuickTimeMovie
                                                              error:&error];

    NSParameterAssert(videoWriter);

    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   AVVideoCodecH264, AVVideoCodecKey,
                                   [NSNumber numberWithInt:size.width], AVVideoWidthKey,
                                   [NSNumber numberWithInt:size.height], AVVideoHeightKey,
                                   nil];
    AVAssetWriterInput* writerInput = [AVAssetWriterInput
                                       assetWriterInputWithMediaType:AVMediaTypeVideo
                                       outputSettings:videoSettings];


    AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
                                                     assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
                                                     sourcePixelBufferAttributes:nil];

    NSParameterAssert(writerInput);
    NSParameterAssert([videoWriter canAddInput:writerInput]);
    [videoWriter addInput:writerInput];

    //Start a session:
    [videoWriter startWriting];
    [videoWriter startSessionAtSourceTime:kCMTimeZero];

    CVPixelBufferRef buffer = NULL;

    //convert uiimage to CGImage.

    for (int i = 0; i < [array count]; i++) {  //NSMutableArray
        buffer = [self pixelBufferFromCGImage:[[array objectAtIndex:i] CGImage]];
        NSLog(@"%@",[[array objectAtIndex:i] CGImage]);
    }
    [adaptor appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];

    //Write samples:


    //Finish the session:
    [writerInput markAsFinished];
}

-(CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image
{
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES],   kCVPixelBufferCGImageCompatibilityKey,
                             [NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
                             nil];
    CVPixelBufferRef pxbuffer = NULL;

    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, self.view.frame.size.width,
                                          self.view.frame.size.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options,
                                          &pxbuffer);
    NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);

    CVPixelBufferLockBaseAddress(pxbuffer, 0);
    void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
    NSParameterAssert(pxdata != NULL);

    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(pxdata, self.view.frame.size.width,
                                                 self.view.frame.size.height, 8, 4*self.view.frame.size.width, rgbColorSpace,
                                                 kCGImageAlphaNoneSkipFirst);
    NSParameterAssert(context);
    CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
    CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
                                           CGImageGetHeight(image)), image);
    CGColorSpaceRelease(rgbColorSpace);
    CGContextRelease(context);

    CVPixelBufferUnlockBaseAddress(pxbuffer, 0);

    return pxbuffer;
}

怎么了？

谁能帮我找到解决方案？

还有其他方法可以从图像创建视频吗？

Answer 1

在 [writerInput markAsFinished]; 之后使用 [videowriter finishWriting];

在 writeImageAsMovie 方法中。

在 ios7 中它被弃用了，所以使用

[videoWriter finishWritingWithCompletionHandler:^(){
    NSLog (@"finished writing");
}];

这对视频创作来说非常重要，从而解决了这个问题。

感谢大家的帮助。