基于AVAssetExportSession的视频质量压缩

参考 Unclefeng

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, 然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 
    
     #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, 给文件重新命名, 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, 压缩后的视频所有, 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