iOS開發之視頻壓縮

基於AVAssetExportSession的視頻質量壓縮

參考 Unclefeng iOS視頻壓縮處理

AVAssetExportSession屬於<AVFoundation/AVFoundation.h> 這個類, 官方API 是這樣解釋說明的, AVAssetExportSession 是對AVAsset對象內容進行轉碼, 並輸出到制定的路徑;

• (nullable instancetype)initWithAsset:(AVAsset *)asset presetName:(NSString *)presetName NS_DESIGNATED_INITIALIZER; 初始化方法 asset, 參數爲要轉碼的asset 對象, presetName, 該參數爲要進行轉碼的方式名稱, 爲字符串類型, 系統有給定的類型值,

視頻質量類型

- AVAssetExportPresetLowQuality
- AVAssetExportPresetMediumQuality
- AVAssetExportPresetHighestQualitAy 
- AVAssetExportPreset640x480
- AVAssetExportPreset1280x720

outputURL , 爲輸出內容的URL, (指定一個文件路徑, 而後根據路徑初始化一個URL, 賦給, outputURL) outputFileType, 爲輸出壓縮後視頻內容的格式類型

//  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];
    // 所支持的壓縮格式中是否有 所選的壓縮格式
    if ([compatiblePresets containsObject:compressionType]) {
        
        // 用時間, 給文件從新命名, 防止視頻存儲覆蓋,
        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(@"視頻壓縮後大小 %f", memorySize);
                 resultPathBlock (resultPath, memorySize);
             } else {
                 
                 NSLog(@"壓縮失敗");
             }
         }];
    } else {
        NSLog(@"不支持 %@ 格式的壓縮", compressionType);
    }
}

/**
*  清楚沙盒文件中, 壓縮後的視頻全部, 在使用過壓縮文件後, 不進行再次使用時, 可調用該方法, 進行刪除 
 */
+ (void)removeCompressedVideoFromDocuments {
    NSFileManager *manager = [NSFileManager defaultManager];
    if ([manager fileExistsAtPath:CompressionVideoPaht]) {
        [[NSFileManager defaultManager] removeItemAtPath:CompressionVideoPaht error:nil];
    }
}
@end