iOS-视频帧处理优化_Ios_Optimization_Mpmovieplayercontroller_Video Processing

iOS-视频帧处理优化

ios optimization

iOS-视频帧处理优化,ios,optimization,mpmovieplayercontroller,video-processing,Ios,Optimization,Mpmovieplayercontroller,Video Processing,在我的项目中，我需要将视频每帧的一块复制到一个唯一的结果图像上捕获视频帧不是什么大事。可能是这样的： // duration is the movie lenght in s. // frameDuration is 1/fps. (or 24fps, frameDuration = 1/24) // player is a MPMoviePlayerController for (NSTimeInterval i=0; i < duration; i += frameDuration)

在我的项目中，我需要将视频每帧的一块复制到一个唯一的结果图像上

捕获视频帧不是什么大事。可能是这样的：

// duration is the movie lenght in s.
// frameDuration is 1/fps. (or 24fps, frameDuration = 1/24)
// player is a MPMoviePlayerController
for (NSTimeInterval i=0; i < duration; i += frameDuration) {
    UIImage * image = [player thumbnailImageAtTime:i timeOption:MPMovieTimeOptionExact];

    CGRect destinationRect = [self getDestinationRect:i];
    [self drawImage:image inRect:destinationRect fromRect:originRect];

    // UI feedback
    [self performSelectorOnMainThread:@selector(setProgressValue:) withObject:[NSNumber numberWithFloat:x/totalFrames] waitUntilDone:NO];
}

//持续时间是以秒为单位的电影长度。
//帧持续时间为1/fps。（或24fps，帧持续时间=1/24）
//玩家是MPMoviePlayerController
对于（NSTimeInterval i=0；i


当我尝试实现drawImage:inRect:fromRect:
方法时，问题就出现了。

我试过了，这是：
使用视频帧中的CGImageCreateWithImageInRect
创建新的CGImage，以提取图像块
在ImageContext上制作CGContextDrawImage以绘制区块
但当视频播放到12-14秒时，我的iphone4s发布了第三次内存警告并崩溃。我用泄漏工具分析了应用程序，它没有发现任何泄漏
我在石英方面不是很强。有没有更好的优化方法来实现这一点？
最后，我保留了代码中的石英部分，并改变了检索图像的方式
现在我使用AVFoundation，这是一个更快的解决方案
// Creating the tools : 1/ the video asset, 2/ the image generator, 3/ the composition, which helps to retrieve video properties.
AVURLAsset *asset = [[[AVURLAsset alloc] initWithURL:moviePathURL
                                             options:[NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], AVURLAssetPreferPreciseDurationAndTimingKey, nil]] autorelease];
AVAssetImageGenerator *generator = [[[AVAssetImageGenerator alloc] initWithAsset:asset] autorelease];
generator.appliesPreferredTrackTransform = YES; // if I omit this, the frames are rotated 90° (didn't try in landscape)
AVVideoComposition * composition = [AVVideoComposition videoCompositionWithPropertiesOfAsset:asset];

// Retrieving the video properties
NSTimeInterval duration = CMTimeGetSeconds(asset.duration);
frameDuration = CMTimeGetSeconds(composition.frameDuration);
CGSize renderSize = composition.renderSize;
CGFloat totalFrames = round(duration/frameDuration);

// Selecting each frame we want to extract : all of them.
NSMutableArray * times = [NSMutableArray arrayWithCapacity:round(duration/frameDuration)];
for (int i=0; i<totalFrames; i++) {
    NSValue *time = [NSValue valueWithCMTime:CMTimeMakeWithSeconds(i*frameDuration, composition.frameDuration.timescale)];
    [times addObject:time];
}

__block int i = 0;
AVAssetImageGeneratorCompletionHandler handler = ^(CMTime requestedTime, CGImageRef im, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error){
    if (result == AVAssetImageGeneratorSucceeded) {
        int x = round(CMTimeGetSeconds(requestedTime)/frameDuration);
        CGRect destinationStrip = CGRectMake(x, 0, 1, renderSize.height);
        [self drawImage:im inRect:destinationStrip fromRect:originStrip inContext:context];
    }
    else
        NSLog(@"Ouch: %@", error.description);
    i++;
    [self performSelectorOnMainThread:@selector(setProgressValue:) withObject:[NSNumber numberWithFloat:i/totalFrames] waitUntilDone:NO];
    if(i == totalFrames) {
        [self performSelectorOnMainThread:@selector(performVideoDidFinish) withObject:nil waitUntilDone:NO];
    }
};

// Launching the process...
generator.requestedTimeToleranceBefore = kCMTimeZero;
generator.requestedTimeToleranceAfter = kCMTimeZero;
generator.maximumSize = renderSize;
[generator generateCGImagesAsynchronouslyForTimes:times completionHandler:handler];

//创建工具：1/视频资源，2/图像生成器，3/合成，这有助于检索视频属性。
AVURLAsset*asset=[[[AVURLAsset alloc]initWithURL:moviePathURL
选项：[NSDictionary Dictionary WithObjects and Keys:[NSNumber WithBool:YES]，AVURLASSETPREVERPRECISEDURATION AND TIMINGKEY，nil]]自动删除]；
AVAssetImageGenerator*generator=[[[AVAssetImageGenerator alloc]initWithAsset:asset]自动释放]；
generator.appliesPreferredTrackTransform=是；//如果我忽略这一点，帧将旋转90°（未尝试在横向中）
AVVideoComposition*composition=[AVVideoComposition VideoComposition WithPropertiesOSET:asset]；
//检索视频属性
NSTimeInterval duration=CMTimeGetSeconds（asset.duration）；
frameDuration=CMTimeGetSeconds（composition.frameDuration）；
CGSize renderSize=合成。renderSize；
CGFloat totalFrames=四舍五入（持续时间/帧持续时间）；
//选择要提取的每个帧：所有帧。
NSMUTABLEARRY*times=[NSMUTABLEARRY阵列容量：四舍五入（持续时间/帧持续时间）]；
对于（inti=0；i最后，我保留了代码中的石英部分，并更改了检索图像的方式
现在我使用AVFoundation，这是一个更快的解决方案
// Creating the tools : 1/ the video asset, 2/ the image generator, 3/ the composition, which helps to retrieve video properties.
AVURLAsset *asset = [[[AVURLAsset alloc] initWithURL:moviePathURL
                                             options:[NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], AVURLAssetPreferPreciseDurationAndTimingKey, nil]] autorelease];
AVAssetImageGenerator *generator = [[[AVAssetImageGenerator alloc] initWithAsset:asset] autorelease];
generator.appliesPreferredTrackTransform = YES; // if I omit this, the frames are rotated 90° (didn't try in landscape)
AVVideoComposition * composition = [AVVideoComposition videoCompositionWithPropertiesOfAsset:asset];

// Retrieving the video properties
NSTimeInterval duration = CMTimeGetSeconds(asset.duration);
frameDuration = CMTimeGetSeconds(composition.frameDuration);
CGSize renderSize = composition.renderSize;
CGFloat totalFrames = round(duration/frameDuration);

// Selecting each frame we want to extract : all of them.
NSMutableArray * times = [NSMutableArray arrayWithCapacity:round(duration/frameDuration)];
for (int i=0; i<totalFrames; i++) {
    NSValue *time = [NSValue valueWithCMTime:CMTimeMakeWithSeconds(i*frameDuration, composition.frameDuration.timescale)];
    [times addObject:time];
}

__block int i = 0;
AVAssetImageGeneratorCompletionHandler handler = ^(CMTime requestedTime, CGImageRef im, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error){
    if (result == AVAssetImageGeneratorSucceeded) {
        int x = round(CMTimeGetSeconds(requestedTime)/frameDuration);
        CGRect destinationStrip = CGRectMake(x, 0, 1, renderSize.height);
        [self drawImage:im inRect:destinationStrip fromRect:originStrip inContext:context];
    }
    else
        NSLog(@"Ouch: %@", error.description);
    i++;
    [self performSelectorOnMainThread:@selector(setProgressValue:) withObject:[NSNumber numberWithFloat:i/totalFrames] waitUntilDone:NO];
    if(i == totalFrames) {
        [self performSelectorOnMainThread:@selector(performVideoDidFinish) withObject:nil waitUntilDone:NO];
    }
};

// Launching the process...
generator.requestedTimeToleranceBefore = kCMTimeZero;
generator.requestedTimeToleranceAfter = kCMTimeZero;
generator.maximumSize = renderSize;
[generator generateCGImagesAsynchronouslyForTimes:times completionHandler:handler];

//创建工具：1/视频资源，2/图像生成器，3/合成，这有助于检索视频属性。
AVURLAsset*asset=[[[AVURLAsset alloc]initWithURL:moviePathURL
选项：[NSDictionary Dictionary WithObjects and Keys:[NSNumber WithBool:YES]，AVURLASSETPREVERPRECISEDURATION AND TIMINGKEY，nil]]自动删除]；
AVAssetImageGenerator*generator=[[[AVAssetImageGenerator alloc]initWithAsset:asset]自动释放]；
generator.appliesPreferredTrackTransform=YES；//如果忽略此项，帧将旋转90°（未尝试在横向中）
AVVideoComposition*composition=[AVVideoComposition VideoComposition WithPropertiesOSET:asset]；
//检索视频属性
NSTimeInterval duration=CMTimeGetSeconds（asset.duration）；
frameDuration=CMTimeGetSeconds（composition.frameDuration）；
CGSize renderSize=合成。renderSize；
CGFloat totalFrames=四舍五入（持续时间/帧持续时间）；
//选择要提取的每个帧：所有帧。
NSMUTABLEARRY*times=[NSMUTABLEARRY阵列容量：四舍五入（持续时间/帧持续时间）]；
对于（int i=0；i除了Martin的回答之外，我建议缩小通过该调用获得的图像的大小；也就是说，添加一个属性[generator.maximumSize=CGSizeMake（width，height）]；
使图像尽可能小，这样它们就不会占用太多内存
除了Martin的回答之外，我建议缩小通过调用获得的图像的大小；也就是说，添加一个属性[generator.maximumSize=CGSizeMake（width，height）]
使图像尽可能小，这样它们就不会占用太多内存
嗨，Martin，图像提取的方法很完美，但在应用程序中，如果视频持续时间超过30秒，则应用程序会崩溃，并带有内存警告。你有其他方法或对此进行任何更改吗？谢谢。长视频不会崩溃。检查你的代码，也许你会发现包含处理程序块中的泄漏。由于设备没有足够的内存空间，您无法将所有提取的图像保留在内存中。@iBhavik您是否找到了解决此问题的方法Hi Martin，图像提取的方法非常完美，但在应用程序中如果视频持续时间超过30秒，则应用程序会崩溃并出现内存警告。您是否有其他方法或解决方案有什么变化吗？谢谢。它不应该因为长视频而崩溃。请检查代码，可能是处理程序块中有漏洞。由于设备没有足够的内存空间，您无法在内存中保留所有提取的图像。@iBhavik您找到解决方案了吗