视频在后台合并 iOS

Video merging in background iOS

任务:将传单图像合并到传单视频中。

案例:

案例 1

案例2

FAIL = Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo=0x17266d40 {NSLocalizedDescription=The operation could not be completed, NSUnderlyingError=0x172b3920 "The operation couldn’t be completed. (OSStatus error -16980.)", NSLocalizedFailureReason=An unknown error occurred (-16980)}

代码:

- (void)modifyVideo:(NSURL *)src destination:(NSURL *)dest crop:(CGRect)crop
              scale:(CGFloat)scale overlay:(UIImage *)image
         completion:(void (^)(NSInteger, NSError *))callback {

    // Get a pointer to the asset
    AVURLAsset* firstAsset = [AVURLAsset URLAssetWithURL:src options:nil];

    // Make an instance of avmutablecomposition so that we can edit this asset:
    AVMutableComposition* mixComposition = [AVMutableComposition composition];

    // Add tracks to this composition
    AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];

    // Audio track
    AVMutableCompositionTrack *audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

    // Image video is always 30 seconds. So we use that unless the background video is smaller.
    CMTime inTime = CMTimeMake( MAX_VIDEO_LENGTH * VIDEOFRAME, VIDEOFRAME );
    if ( CMTimeCompare( firstAsset.duration, inTime ) < 0 ) {
        inTime = firstAsset.duration;
    }

    // Add to the video track.
    NSArray *videos = [firstAsset tracksWithMediaType:AVMediaTypeVideo];
    CGAffineTransform transform;
    if ( videos.count > 0 ) {
        AVAssetTrack *track = [videos objectAtIndex:0];
        [videoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, inTime) ofTrack:track atTime:kCMTimeZero error:nil];
        transform = track.preferredTransform;
        videoTrack.preferredTransform = transform;
    }

    // Add the audio track.
    NSArray *audios = [firstAsset tracksWithMediaType:AVMediaTypeAudio];
    if ( audios.count > 0 ) {
        [audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, inTime) ofTrack:[audios objectAtIndex:0] atTime:kCMTimeZero error:nil];
    }

    NSLog(@"Natural size: %.2f x %.2f", videoTrack.naturalSize.width, videoTrack.naturalSize.height);

    // Set the mix composition size.
    mixComposition.naturalSize = crop.size;

    // Set up the composition parameters.
    AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
    videoComposition.frameDuration = CMTimeMake(1, VIDEOFRAME );
    videoComposition.renderSize = crop.size;
    videoComposition.renderScale = 1.0;

    // Pass through parameters for animation.
    AVMutableVideoCompositionInstruction *passThroughInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    passThroughInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, inTime);

    // Layer instructions
    AVMutableVideoCompositionLayerInstruction *passThroughLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];

    // Set the transform to maintain orientation
    if ( scale != 1.0 ) {
        CGAffineTransform scaleTransform = CGAffineTransformMakeScale( scale, scale);
        CGAffineTransform translateTransform = CGAffineTransformTranslate( CGAffineTransformIdentity,
                                                                          -crop.origin.x,
                                                                          -crop.origin.y);
        transform = CGAffineTransformConcat( transform, scaleTransform );
        transform = CGAffineTransformConcat( transform, translateTransform);
    }

    [passThroughLayer setTransform:transform atTime:kCMTimeZero];

    passThroughInstruction.layerInstructions = @[ passThroughLayer ];
    videoComposition.instructions = @[passThroughInstruction];

    // If an image is given, then put that in the animation.
    if ( image != nil ) {

        // Layer that merges the video and image
        CALayer *parentLayer = [CALayer layer];
        parentLayer.frame = CGRectMake( 0, 0, crop.size.width, crop.size.height);

        // Layer that renders the video.
        CALayer *videoLayer = [CALayer layer];
        videoLayer.frame = CGRectMake(0, 0, crop.size.width, crop.size.height );
        [parentLayer addSublayer:videoLayer];

        // Layer that renders flyerly image.
        CALayer *imageLayer = [CALayer layer];
        imageLayer.frame = CGRectMake(0, 0, crop.size.width, crop.size.height );
        imageLayer.contents = (id)image.CGImage;
        [imageLayer setMasksToBounds:YES];

        [parentLayer addSublayer:imageLayer];

        // Setup the animation tool
        videoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
    }

    // Now export the movie
    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
    exportSession.videoComposition = videoComposition;

    // Export the URL
    exportSession.outputURL = dest;
    exportSession.outputFileType = AVFileTypeQuickTimeMovie;
    exportSession.shouldOptimizeForNetworkUse = YES;
    [exportSession exportAsynchronouslyWithCompletionHandler:^{
        callback( exportSession.status, exportSession.error );
    }];
}

我从 AppDelegate.m

调用这个函数
- (void)applicationDidEnterBackground:(UIApplication *)application
{
    bgTask = [application beginBackgroundTaskWithName:@"MyTask" expirationHandler:^{
        // Clean up any unfinished task business by marking where you
        // stopped or ending the task outright.
        [application endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    }];

    // Start the long-running task and return immediately.
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        // Do the work associated with the task, preferably in chunks.
         [self goingToBg];

        [application endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    });

    NSLog(@"backgroundTimeRemaining: %f", [[UIApplication sharedApplication] backgroundTimeRemaining]);
}

在这个问题上做了很多 RND,没有找到解决方案。

想分享几个链接希望它能帮助堆栈社区,如果他们遇到同样的问题[要求]。

链接 1:AVExportSession to run in background

与问题相关的引用[从上面链接1复制]

Sadly, since AVAssetExportSession uses the gpu to do some of it's work, it cannot run in the background if you are using an AVVideoComposition.

链接 2:Starting AVAssetExportSession in the Background

与问题相关的引用[从上面链接2复制]

You can start AVAssetExportSession in background. The only limitations in AVFoundation to performing work in the background, are using AVVideoCompositions or AVMutableVideoCompositions. AVVideoCompositions are using the GPU, and the GPU cannot be used in the background

Url(s) 用于后台任务:

APPLE DEV URL

RAYWENDERLICH URL

Stack question

如果您更新项目功能中的 "Background Modes" 设置以包含音频,参加派对就太晚了。它将允许导出。

这是为了在后台播放音乐。

对我有用。