视频的录制、保存、压缩以及base64转码

这里没有主要是说下和视频相关的小技术点,都是一些相对比较基本的,但是对于没有怎么和视频打交道的人而言,找一些资料还不是很方便,所以今天就没事白这些东西给稍微整理了一下。
先看看视频的录制,这里主要说的是使用系统的UIImagePickerController这个类进行视频的录制。注意:导入这个框架才能录制视频#import<MobileCoreServices/MobileCoreServices.h>这个框架后才能播放进入系统的录制视频界面。

 //1、判断照相机是否可用  不可用就直接return  一般都是这样
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        return;
    }
    //2.初始化
    UIImagePickerController *picker = [UIImagePickerController new];
    //3.设置类型
    picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    //通常4和5是一块设置的
    //4.设置媒体类型  默认是拍照
    picker.mediaTypes = @[(NSString *)kUTTypeMovie];
    //注意:如果是UIImagePickerControllerSourceTypePhotoLibrary设置下面的两句会崩溃
  //5.设置摄像机模式
  picker.cameraCaptureMode = UIImagePickerControllerCameraCaptureModeVideo; //6.设置视频质量
//    picker.videoQuality = UIImagePickerControllerQualityTypeHigh;
    //7.设置代理
    picker.delegate = self;
    //8.模态弹出
    [self presentViewController:picker animated:YES completion:nil];

再看一下录制的视频如何保存到本地。注意:保存视频到本地 需要这个资源库<AssetsLibrary/AssetsLibrary.h>

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info{
    //1.判断是否是视频的媒体类型
    NSString *mediaType = info[UIImagePickerControllerMediaType];
    //2.保存视频到本地   需要这个资源库<AssetsLibrary/AssetsLibrary.h>
    //必须做这个判断
   if (picker.sourceType == UIImagePickerControllerSourceTypeCamera) {
      //这个已经过期了  iOS9需要换成PHPhotoLibrary
      //2.1创建ALAssetsLibrary对象
      ALAssetsLibrary *assetsLibrary = [ALAssetsLibrary new];
      //2.2 这个url是指要保存的视频的url 
       [assetsLibrary writeVideoAtPathToSavedPhotosAlbum:url completionBlock:^(NSURL *assetURL, NSError *error) {           
      }];
  }
    [picker dismissViewControllerAnimated:YES completion:nil];
}

下面是视频的压缩的一个类方法,以及删除压缩后视频的方法。代码内部有十分详细的注释。说明一下第一个方法中传入的sourceVideoPathString是这样获取的。在(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info这个方法中,通过
self.videoPathString = (NSString *)([info[@"UIImagePickerControllerMediaURL"] path]);这样的形式获取到路径。

+ (void)compressVideoWithSourceVideoPathString:(NSString *)sourceVideoPathString
                                  CompressType:(NSString *)compressType
                          CompressSuccessBlock:(SuccessBlock)compressSuccessBlock
                           CompressFailedBlock:(FailedBlock)compressFailedBlock
                       CompressNotSupportBlock:(NotSupportBlock)compressNotSupportBlock {
    
    // 源视频路径
    NSURL *sourceVideoPathUrl = [NSURL fileURLWithPath:sourceVideoPathString];
    // 利用源视频路径将源视频转化为 AVAsset 多媒体载体对象
    AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:sourceVideoPathUrl options:nil];
    
    // 源视频载体对象支持的压缩格式
    NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:avAsset];
    // 源视频载体对象支持的压缩格式中是否包含我们选择的压缩格式
    if ([compatiblePresets containsObject:compressType]) {
        
        // 存放压缩视频的文件夹
        NSFileManager *fileManager = [NSFileManager defaultManager];
        NSString *compressVideoFolder = [NSHomeDirectory() stringByAppendingPathComponent:@"/Documents/compressVideoFolder"];
        if (![fileManager fileExistsAtPath:compressVideoFolder]) {
            
            [fileManager createDirectoryAtPath:compressVideoFolder withIntermediateDirectories:YES attributes:nil error:nil];
        }
        // 用当前系统时间给文件命名, 避免因名字重复而覆盖存储
        NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
        [formatter setDateFormat:@"yyyy-MM-dd-HH:mm:ss"];
        NSString *currentDateString = [formatter stringFromDate:[NSDate date]];
        
        /**
         *  第一个参数 : 要压缩的 AVAsset 对象
            第二个参数 : 我们选择的压缩方式
         */
        AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:avAsset presetName:compressType];
        // 压缩视频的输出路径
        NSString *compressVideoPathString = [compressVideoFolder stringByAppendingPathComponent:[NSString stringWithFormat:@"compressVideo-%@.mp4", currentDateString]];
        NSURL *compressFilePathUrl = [NSURL fileURLWithPath:compressVideoPathString];
        exportSession.outputURL = compressFilePathUrl;
        // 压缩文件的输出格式
        exportSession.outputFileType = AVFileTypeMPEG4;
        // 压缩文件应保证优化网络使用
        exportSession.shouldOptimizeForNetworkUse = YES;
        // 开始压缩
        [exportSession exportAsynchronouslyWithCompletionHandler:^(void) {
            
            if (exportSession.status == AVAssetExportSessionStatusCompleted) {
                
                compressSuccessBlock(compressVideoPathString);
            }else {
                
                compressFailedBlock();
            }
        }];
    }else {
        
        compressNotSupportBlock();
    }
}
//删除压缩后视频的方法
+ (void)deleteCompressVideoFromPath:(NSString *)compressVideoPathString {
    
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *compressVideoFolder = [NSHomeDirectory() stringByAppendingPathComponent:@"/Documents/compressVideoFolder"];
    if ([fileManager fileExistsAtPath:compressVideoFolder]) {
        
        [fileManager removeItemAtPath:compressVideoFolder error:nil];
    }
}

视频的base64转码,转码成功后将返回一堆字符串。

// 编码
+ (void)base64StringFromString:(NSString *)filePathString
                    SuccessBlock:(SuccessBlock)success
                     FailedBlock:(FailedBlock)failed {
    
    // 获取文件的二进制数据 data
    NSData *data = [NSData dataWithContentsOfFile:filePathString];
    
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        
        // 转码 --> 码文
        NSString *base64String = [data base64EncodedStringWithOptions:0];
        
        if (base64String) {
            
            dispatch_async(dispatch_get_main_queue(), ^{
                
                success(base64String);
            });
        }else {
            
            dispatch_async(dispatch_get_main_queue(), ^{
                
                failed();
            });
        }
    });
}

//外部的调用形式
[ZWBase64EncodeTools base64StringFromString:self.filePathString SuccessBlock:^(NSString *string) {
            //转码成功后返回一堆字符串
            self.base64StringTextView.text = string;
            self.navigationItem.title = [NSString stringWithFormat:@"压缩data的Base64码, %.2fM", string.length / 1024.0 / 1024.0];
        } FailedBlock:^{
            
            self.navigationItem.title = @"转码失败了!";
  }];

说道这里就顺便说一下图片的base64转码了。下面方法中fileData是图片的二进制文件。

+ (void)base64StringFromData:(NSData *)fileData
                      SuccessBlock:(SuccessBlock)success
                   FailedBlock:(FailedBlock)failed {
    
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        
        // 转码 --> 码文
        NSString *base64String = [fileData base64EncodedStringWithOptions:0];
        
        if (base64String) {
            
            dispatch_async(dispatch_get_main_queue(), ^{
                
                success(base64String);
            });
        }else {
            
            dispatch_async(dispatch_get_main_queue(), ^{
                
                failed();
            });
        }
    });
}

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