AVFoundation – 将多个媒体合并(二) – 一个轨道多个视频无缝衔接

AVFoundation – 将多个媒体合并(二) - 一个轨道多个视频无缝衔接


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一.前言


1.AVAsset

Assets  可以来自一个文件或用户的相册,可以理解为多媒体资源,通过 URL 作为一个 asset 对象的标识. 这个 URL 可以是本地文件路径或网络流;


2.AVAssetTrack

AVAsset 包含很多轨道 AVAssetTrack的结合,如 audio, video, text, closed captions, subtitles…


3.AVComposition / AVMutableComposition

使用  AVMutableComposition  类可以增删 AVAsset 来将单个或者多个 AVAsset 集合到一起,用来合成新视频。除此之外,若想将集合到一起的视听资源以自定义的方式进行播放,需要使用 AVMutableAudioMix 和 AVMutableVideoComposition 类对其中的资源进行协调管理;


4.AVMutableVideoComposition

AVFoundation 类 API 中最核心的类是 AVVideoComposition / AVMutableVideoComposition 。

AVVideoComposition / AVMutableVideoComposition 对两个或多个视频轨道组合在一起的方法给出了一个总体描述。它由一组时间范围和描述组合行为的介绍内容组成。这些信息出现在组合资源内的任意时间点。

AVVideoComposition / AVMutableVideoComposition 管理所有视频轨道,可以决定最终视频的尺寸,裁剪需要在这里进行;


5.AVMutableCompositionTrack

AVMutableCompositionTrack多个 AVAsset 集合到一起合成新视频中轨道信息,有音频轨、视频轨等,里面可以插入各种对应的素材(画中画,水印等);


6.AVMutableVideoCompositionLayerInstruction

AVMutableVideoCompositionLayerInstruction 主要用于对视频轨道中的一个视频处理缩放、模糊、裁剪、旋转等;


7.AVMutableVideoCompositionInstruction

表示一个指令,决定一个 timeRange 内每个轨道的状态,每一个指令包含多个 AVMutableVideoCompositionLayerInstruction ;而 AVVideoComposition 由多个 AVVideoCompositionInstruction 构成;

AVVideoCompositionInstruction 所提供的最关键的一段数据是组合对象时间轴内的时间范围信息。这一时间范围是在某一组合形式出现时的时间范围。要执行的组全特质是通过其 AVMutableVideoCompositionLayerInstruction 集合定义的。


8.AVAssetExportSession

AVAssetExportSession 主要用于导出视频;


9.AVAssetTrackSegment

AVAssetTrackSegment 不可变轨道片段;


10.AVCompositionTrackSegment

AVCompositionTrackSegment 可变轨道片段,继承自 AVAssetTrackSegment;


二.多个视频合并流程简介

AVComposition 继承自 AVAsset,将来自多个基于源文件的媒体数据组合在一起显示,或处理来自多个源媒体数据;

AVMutableComposition *mutableComposition = [AVMutableComposition composition];

//进行添加资源等操作
//1.添加媒体1的视频轨道
//2.添加媒体1的音频轨道
//3.添加媒体2的视频轨道
//4.添加媒体2的音频轨道
//.....


//使用可变的 composition 生成一个不可变的 composition 以供使用
AVComposition *composition = [myMutableComposition copy];
AVPlayerItem *playerItem = [[AVPlayerItem alloc] initWithAsset:composition];

三.多个视频合并流程

为了避免导出失败,解决方案是提取视频资源 AVURLAsset 音频轨道和视频轨道,重新构建 AVComposition ,然后在使用 AVAssetExportSession 导出;

其中将多个 AVURLAsset 重新构建 AVComposition 时,可以有两种思路:


1.每个 AVURLAsset 单独使用一个音频或者视频轨道;


2.所有 AVURLAsset 共用一个音频或者视频轨道;

所有 AVURLAsset 共用一个音频或者视频轨道,示例代码如下:

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:AVFoundation – 将多个媒体合并(二) - 一个轨道多个视频无缝衔接
//@Time:2021/08/21 07:30
//@Motto:不积跬步无以至千里,不积小流无以成江海,程序人生的精彩需要坚持不懈地积累!
/******************************************************************************************/

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>




@interface ViewController ()
{
    
    
}


@end

@implementation ViewController


- (void)viewDidLoad
{
    [super viewDidLoad];
    
    
    int width = self.view.bounds.size.width;
    int heigt = self.view.bounds.size.height;
    
//    [self exportMove];
    [self exportMove];
    
}



#pragma mark - 获取视频角度
- (int)degressFromVideoFileWithAsset:(AVAsset *)asset {
    int degress = 0;
    NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
    if([tracks count] > 0) {
        AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
        CGAffineTransform t = videoTrack.preferredTransform;
        if(t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0){
            // Portrait
            degress = 90;
        } else if(t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0){
            // PortraitUpsideDown
            degress = 270;
        } else if(t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0){
            // LandscapeRight
            degress = 0;
        } else if(t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0){
            // LandscapeLeft
            degress = 180;
        }
    }
    return degress;
}

#pragma mark - 导出
- (void)startExportMP4VideoWithVideoAssets:(NSArray *)videoArrays presetName:(NSString *)presetName success:(void (^)(NSString *outputPath))success failure:(void (^)(NSString *errorMessage, NSError *error))failure {
    
    AVMutableComposition *composition = [AVMutableComposition composition];
    
    __block CMTime insertTime = kCMTimeZero;
    __block AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    __block AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    
    [videoArrays enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        
        AVURLAsset* videoAsset = [videoArrays objectAtIndex:idx];
        
        
        
        AVAssetTrack *sourceVideoTrack = [videoAsset tracksWithMediaType:AVMediaTypeVideo].firstObject;
        AVAssetTrack *sourceAudioTrack = [videoAsset tracksWithMediaType:AVMediaTypeAudio].firstObject;
        
        [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:sourceVideoTrack atTime:insertTime error:nil];
        [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:sourceAudioTrack atTime:insertTime error:nil];
        
        insertTime = CMTimeAdd(insertTime, videoAsset.duration);
    }];
    
    
    NSArray *presets = [AVAssetExportSession exportPresetsCompatibleWithAsset:composition];
    
    if ([presets containsObject:presetName]) {
        AVAssetExportSession *session = [[AVAssetExportSession alloc] initWithAsset:composition presetName:presetName];
        // 输出地址
        NSDateFormatter *formater = [[NSDateFormatter alloc] init];
        [formater setDateFormat:@"yyyy-MM-dd-HH:mm:ss-SSS"];
        NSString *outputPath = [NSHomeDirectory() stringByAppendingFormat:@"/tmp/video-%@.mp4", [formater stringFromDate:[NSDate date]]];
        session.outputURL = [NSURL fileURLWithPath:outputPath];
        // 优化
        session.shouldOptimizeForNetworkUse = YES;
        
        NSArray *supportedTypeArray = session.supportedFileTypes;
        if ([supportedTypeArray containsObject:AVFileTypeMPEG4]) {
            session.outputFileType = AVFileTypeMPEG4;
        } else if (supportedTypeArray.count == 0) {
            if (failure) {
                failure(@"该视频类型暂不支持导出", nil);
            }
            NSLog(@"No supported file types 视频类型暂不支持导出");
            return;
        } else {
            session.outputFileType = [supportedTypeArray objectAtIndex:0];
        }
        
        if (![[NSFileManager defaultManager] fileExistsAtPath:[NSHomeDirectory() stringByAppendingFormat:@"/tmp"]]) {
            [[NSFileManager defaultManager] createDirectoryAtPath:[NSHomeDirectory() stringByAppendingFormat:@"/tmp"] withIntermediateDirectories:YES attributes:nil error:nil];
        }
        
        //旋转角度相关
        AVMutableVideoComposition *videoComposition = [self fixedCompositionWithAsset:videoArrays];
        if (videoComposition.renderSize.width) {
            // 修正视频转向
            session.videoComposition = videoComposition;
        }
        
        // 合成完毕
        [session exportAsynchronouslyWithCompletionHandler:^{
            dispatch_async(dispatch_get_main_queue(), ^{
                switch (session.status) {
                    case AVAssetExportSessionStatusUnknown: {
                        NSLog(@"AVAssetExportSessionStatusUnknown");
                    }  break;
                    case AVAssetExportSessionStatusWaiting: {
                        NSLog(@"AVAssetExportSessionStatusWaiting");
                    }  break;
                    case AVAssetExportSessionStatusExporting: {
                        NSLog(@"AVAssetExportSessionStatusExporting");
                    }  break;
                    case AVAssetExportSessionStatusCompleted: {
                        NSLog(@"AVAssetExportSessionStatusCompleted");
                        if (success) {
                            success(outputPath);
                        }
                    }  break;
                    case AVAssetExportSessionStatusFailed: {
                        NSLog(@"AVAssetExportSessionStatusFailed");
                        if (failure) {
                            failure(@"视频导出失败", session.error);
                        }
                    }  break;
                    case AVAssetExportSessionStatusCancelled: {
                        NSLog(@"AVAssetExportSessionStatusCancelled");
                        if (failure) {
                            failure(@"导出任务已被取消", nil);
                        }
                    }  break;
                    default: break;
                }
            });
        }];
    } else {
        if (failure) {
            NSString *errorMessage = [NSString stringWithFormat:@"当前设备不支持该预设:%@", presetName];
            failure(errorMessage, nil);
        }
    }
}


#pragma mark - 获取优化后的视频转向信息
- (AVMutableVideoComposition *)fixedCompositionWithAsset:(NSArray *)videoAssets  {
    AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
    
    __block NSMutableArray* instructions = [NSMutableArray array];
    [videoAssets enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
       
        AVAsset *videoAsset = [videoAssets objectAtIndex:idx];
        int degrees = [self degressFromVideoFileWithAsset:videoAsset];
        if (degrees != 0) {
            CGAffineTransform translateToCenter;
            CGAffineTransform mixedTransform;
            videoComposition.frameDuration = CMTimeMake(1, 30);
            
            NSArray *tracks = [videoAsset tracksWithMediaType:AVMediaTypeVideo];
            AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
            
            AVMutableVideoCompositionInstruction *roateInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
            roateInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, [videoAsset duration]);
            AVMutableVideoCompositionLayerInstruction *roateLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
            
            if (degrees == 90) {
                // 顺时针旋转90°
                translateToCenter = CGAffineTransformMakeTranslation(videoTrack.naturalSize.height, 0.0);
                mixedTransform = CGAffineTransformRotate(translateToCenter,M_PI_2);
                videoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.height,videoTrack.naturalSize.width);
                [roateLayerInstruction setTransform:mixedTransform atTime:kCMTimeZero];
            } else if(degrees == 180){
                // 顺时针旋转180°
                translateToCenter = CGAffineTransformMakeTranslation(videoTrack.naturalSize.width, videoTrack.naturalSize.height);
                mixedTransform = CGAffineTransformRotate(translateToCenter,M_PI);
                videoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.width,videoTrack.naturalSize.height);
                [roateLayerInstruction setTransform:mixedTransform atTime:kCMTimeZero];
            } else if(degrees == 270){
                // 顺时针旋转270°
                translateToCenter = CGAffineTransformMakeTranslation(0.0, videoTrack.naturalSize.width);
                mixedTransform = CGAffineTransformRotate(translateToCenter,M_PI_2*3.0);
                videoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.height,videoTrack.naturalSize.width);
                [roateLayerInstruction setTransform:mixedTransform atTime:kCMTimeZero];
            }
            
            roateInstruction.layerInstructions = @[roateLayerInstruction];
            [instructions addObject:roateInstruction];
    }
    }];
    
    
        // 加入视频方向信息
        videoComposition.instructions = instructions;
    
    return videoComposition;
}



#pragma mark - 导出函数
-(BOOL)exportMove
{
    //加载媒体
    NSURL* srcVideo = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"789.MP4" ofType:nil]];
    AVURLAsset* videoAsset = [[AVURLAsset alloc] initWithURL:srcVideo options:nil];
    
//    NSURL* srcVideo1 = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"123.MOV" ofType:nil]];
//    AVURLAsset* videoAsset1 = [[AVURLAsset alloc] initWithURL:srcVideo1 options:nil];
    
    NSArray* videoArrays = [[NSArray alloc] initWithObjects:videoAsset,videoAsset, nil];
    
    // 查找当前媒体支持的presetName
    NSArray *presets = [AVAssetExportSession exportPresetsCompatibleWithAsset:videoAsset];
    NSLog(@"%@",presets);
    if ([presets containsObject:AVAssetExportPreset640x480])
    {
        //导出视频文件到沙盒目录
        [self startExportMP4VideoWithVideoAssets:videoArrays presetName:AVAssetExportPreset640x480 success:^(NSString *outputPath) {
            NSLog(@" startExportMP4VideoWithVideoAssets  success,path:%@",outputPath);
        } failure:^(NSString *errorMessage, NSError *error) {
            NSLog(@"startExportMP4VideoWithVideoAssets fail");
        }];
        
    }
    else
    {
        NSLog(@"exportMove fail");
    }
    
    return YES;
}

@end

遗留bug:如果是两个分辨率比例不同的视频会提示导出失败;

温馨提示:上面工程源码可通过网站右上角立即购买获取下载地址即可!


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