iOS开发之视频压缩

基于AVAssetExportSession的视频质量压缩

参考 Unclefeng iOS视频压缩处理

AVAssetExportSession属于<AVFoundation/AVFoundation.h> 这个类, 官方API 是这样解释说明的, AVAssetExportSession 是对AVAsset对象内容进行转码, 并输出到制定的路径;

• (nullable instancetype)initWithAsset:(AVAsset *)asset presetName:(NSString *)presetName NS_DESIGNATED_INITIALIZER; 初始化方法 asset, 参数为要转码的asset 对象, presetName, 该参数为要进行转码的方式名称, 为字符串类型, 系统有给定的类型值,

视频质量类型

- AVAssetExportPresetLowQuality
- AVAssetExportPresetMediumQuality
- AVAssetExportPresetHighestQualitAy 
- AVAssetExportPreset640x480
- AVAssetExportPreset1280x720

outputURL , 为输出内容的URL, (指定一个文件路径, 而后根据路径初始化一个URL, 赋给, outputURL) outputFileType, 为输出压缩后视频内容的格式类型

//  Created by iOS-Developer on 16/2/19.
//  Copyright © 2016年 iOS-Jessonliu. All rights reserved.
//

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


#define CompressionVideoPaht [NSHomeDirectory() stringByAppendingFormat:@"/Documents/CompressionVideoField"]

@interface JFCompressionVideo ()
@end

@implementation JFCompressionVideo

+ (void)compressedVideoOtherMethodWithURL:(NSURL *)url compressionType:(NSString *)compressionType compressionResultPath:(CompressionSuccessBlock)resultPathBlock {
    
    NSString *resultPath;
    NSData *data = [NSData dataWithContentsOfURL:url];
    CGFloat totalSize = (float)data.length / 1024 / 1024;
    AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:url options:nil];
    NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:avAsset];
    // 所支持的压缩格式中是否有 所选的压缩格式
    if ([compatiblePresets containsObject:compressionType]) {
        
        // 用时间, 给文件从新命名, 防止视频存储覆盖,
        NSDateFormatter *formater = [[NSDateFormatter alloc] init];
        [formater setDateFormat:@"yyyy-MM-dd-HH:mm:ss"];
        
        NSFileManager *manager = [NSFileManager defaultManager];
        BOOL isExists = [manager fileExistsAtPath:CompressionVideoPaht];
        if (!isExists) {
            [manager createDirectoryAtPath:CompressionVideoPaht withIntermediateDirectories:YES attributes:nil error:nil];
        }
        resultPath = [CompressionVideoPaht stringByAppendingPathComponent:[NSString stringWithFormat:@"outputJFVideo-%@.mov", [formater stringFromDate:[NSDate date]]]];
        NSLog(@"resultPath = %@",resultPath);

        AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:avAsset presetName:compressionType];
        exportSession.outputURL = [NSURL fileURLWithPath:resultPath];
        exportSession.outputFileType = AVFileTypeMPEG4;
        exportSession.shouldOptimizeForNetworkUse = YES;
        [exportSession exportAsynchronouslyWithCompletionHandler:^(void) {
             if (exportSession.status == AVAssetExportSessionStatusCompleted) {
                 
                 NSData *data = [NSData dataWithContentsOfFile:resultPath];
                 float memorySize = (float)data.length / 1024 / 1024;
                 NSLog(@"视频压缩后大小 %f", memorySize);
                 resultPathBlock (resultPath, memorySize);
             } else {
                 
                 NSLog(@"压缩失败");
             }
         }];
    } else {
        NSLog(@"不支持 %@ 格式的压缩", compressionType);
    }
}

/**
*  清楚沙盒文件中, 压缩后的视频全部, 在使用过压缩文件后, 不进行再次使用时, 可调用该方法, 进行删除 
 */
+ (void)removeCompressedVideoFromDocuments {
    NSFileManager *manager = [NSFileManager defaultManager];
    if ([manager fileExistsAtPath:CompressionVideoPaht]) {
        [[NSFileManager defaultManager] removeItemAtPath:CompressionVideoPaht error:nil];
    }
}
@end