问iOS Swift -合并和转换.wav文件为.mp3
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Stack Overflow用户

提问于 2015-07-16 18:54:47

回答 2查看 11.4K关注 0票数 20

我想合并两个或多个.wav文件为一个，然后将其转换为.mp3，这我想在Swift中完成(或至少有选项将其包括到快速项目中)。

在swift中合并两个.wav文件不成问题。Here is my example现在我不知道如何将lame库添加到swift项目中，以及如何使用它(如何更改objective C语言代码使用语法以在swift中使用它)。

我坚持使用.mp3，所以我用Objective C尝试了Lame库，我发现了将.caf转换为swift的示例代码，所以我尝试了一下。下面是我尝试过的：

- (void) toMp3
{
    NSString *cafFilePath = [[NSBundle mainBundle] pathForResource:@"sound" ofType:@"caf"];

    NSString *mp3FileName = @"Mp3File";
    mp3FileName = [mp3FileName stringByAppendingString:@".mp3"];
    NSString *mp3FilePath = [[NSHomeDirectory() stringByAppendingFormat:@"/Documents/"] stringByAppendingPathComponent:mp3FileName];

    NSLog(@"%@", mp3FilePath);

    @try {
        int read, write;

        FILE *pcm = fopen([cafFilePath cStringUsingEncoding:1], "rb");  //source
        fseek(pcm, 4*1024, SEEK_CUR);                                   //skip file header
        FILE *mp3 = fopen([mp3FilePath cStringUsingEncoding:1], "wb");  //output

        const int PCM_SIZE = 8192;
        const int MP3_SIZE = 8192;
        short int pcm_buffer[PCM_SIZE*2];
        unsigned char mp3_buffer[MP3_SIZE];

        lame_t lame = lame_init();
        lame_set_in_samplerate(lame, 44100);
        lame_set_VBR(lame, vbr_default);
        lame_init_params(lame);

        do {
            read = fread(pcm_buffer, 2*sizeof(short int), PCM_SIZE, pcm);
            if (read == 0)
                write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
            else
                write = lame_encode_buffer_interleaved(lame, pcm_buffer, read, mp3_buffer, MP3_SIZE);

            fwrite(mp3_buffer, write, 1, mp3);

        } while (read != 0);

        lame_close(lame);
        fclose(mp3);
        fclose(pcm);
    }
    @catch (NSException *exception) {
        NSLog(@"%@",[exception description]);
    }
    @finally {
        [self performSelectorOnMainThread:@selector(convertMp3Finish)
                               withObject:nil
                            waitUntilDone:YES];
    }
}

- (void) convertMp3Finish
{
}

但这样做的结果就是带有噪声的.mp3。

所以我需要解决我的三个问题：

在Objective C中从caf创建正确的文件
更改代码以将其用于wav文件
并将其更改为能够在Swift

中使用

我知道在iOS中有很多关于编码和转换mp3的问题，但我找不到使用Swift example的问题，也找不到使用Objective C代码的示例(就是上面的代码)。感谢你的帮助

ios

swift

audio

mp3

lame

回答 2

Stack Overflow用户

回答已采纳

发布于 2015-08-27 22:06:45

我想发布我的工作解决方案，因为我得到了太多人竖起大拇指，naresh的回答对我没有太大帮助。

我已经从这个项目中生成了wav库，并将库添加到了我的Swift项目中(Build Phases https://github.com/wuqiong/mp3lame-for-iOS

I've Link Binary With Libraries)

I've创建了包装器，用于在Objective C中使用c函数，并通过桥接标头来在Swift中使用它。

用于连接wav文件我使用AVAssetExportSession -> Swift

现在是源代码。所以第一个包装器。它是用于将.wav文件转换为.mp3的类。可能会有很多更改(可能是输出文件的参数和其他选项)，但我认为每个人都可以更改它。我想这可以重写成Swift，但我不确定该怎么做。所以它是Objective C类：

#import "AudioWrapper.h"
#import "lame/lame.h"

@implementation AudioWrapper

+ (void)convertFromWavToMp3:(NSString *)filePath {


    NSString *mp3FileName = @"Mp3File";
    mp3FileName = [mp3FileName stringByAppendingString:@".mp3"];
    NSString *mp3FilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:mp3FileName];

    NSLog(@"%@", mp3FilePath);

    @try {
        int read, write;

        FILE *pcm = fopen([filePath cStringUsingEncoding:1], "rb");  //source
        fseek(pcm, 4*1024, SEEK_CUR);                                   //skip file header
        FILE *mp3 = fopen([mp3FilePath cStringUsingEncoding:1], "wb");  //output

        const int PCM_SIZE = 8192;
        const int MP3_SIZE = 8192;
        short int pcm_buffer[PCM_SIZE*2];
        unsigned char mp3_buffer[MP3_SIZE];

        lame_t lame = lame_init();
        lame_set_in_samplerate(lame, 44100);
        lame_set_VBR(lame, vbr_default);
        lame_init_params(lame);

        do {
            read = fread(pcm_buffer, 2*sizeof(short int), PCM_SIZE, pcm);
            if (read == 0)
                write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
            else
                write = lame_encode_buffer_interleaved(lame, pcm_buffer, read, mp3_buffer, MP3_SIZE);

            fwrite(mp3_buffer, write, 1, mp3);

        } while (read != 0);

        lame_close(lame);
        fclose(mp3);
        fclose(pcm);
    }
    @catch (NSException *exception) {
        NSLog(@"%@",[exception description]);
    }
    @finally {
        [self performSelectorOnMainThread:@selector(convertMp3Finish)
                               withObject:nil
                            waitUntilDone:YES];
    }
}

连接音频文件的Swift AudioHelper类和将.wav文件转换为.mp3的调用方法：

import UIKit
import AVFoundation


protocol AudioHelperDelegate {
    func assetExportSessionDidFinishExport(session: AVAssetExportSession, outputUrl: NSURL)
}

class AudioHelper: NSObject {

    var delegate: AudioHelperDelegate?

    func concatenate(audioUrls: [NSURL]) {

        //Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
        var composition = AVMutableComposition()
        var compositionAudioTrack:AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())

        //create new file to receive data
        var documentDirectoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first! as! NSURL
        var fileDestinationUrl = NSURL(fileURLWithPath: NSTemporaryDirectory().stringByAppendingPathComponent("resultmerge.wav"))
        println(fileDestinationUrl)

        StorageManager.sharedInstance.deleteFileAtPath(NSTemporaryDirectory().stringByAppendingPathComponent("resultmerge.wav"))

        var avAssets: [AVURLAsset] = []
        var assetTracks: [AVAssetTrack] = []
        var durations: [CMTime] = []
        var timeRanges: [CMTimeRange] = []

        var insertTime = kCMTimeZero

        for audioUrl in audioUrls {
            let avAsset = AVURLAsset(URL: audioUrl, options: nil)
            avAssets.append(avAsset)

            let assetTrack = avAsset.tracksWithMediaType(AVMediaTypeAudio)[0] as! AVAssetTrack
            assetTracks.append(assetTrack)

            let duration = assetTrack.timeRange.duration
            durations.append(duration)

            let timeRange = CMTimeRangeMake(kCMTimeZero, duration)
            timeRanges.append(timeRange)

            compositionAudioTrack.insertTimeRange(timeRange, ofTrack: assetTrack, atTime: insertTime, error: nil)
            insertTime = CMTimeAdd(insertTime, duration)
        }

        //AVAssetExportPresetPassthrough => concatenation
        var assetExport = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetPassthrough)
        assetExport.outputFileType = AVFileTypeWAVE
        assetExport.outputURL = fileDestinationUrl
        assetExport.exportAsynchronouslyWithCompletionHandler({
            self.delegate?.assetExportSessionDidFinishExport(assetExport, outputUrl: fileDestinationUrl!)
        })
    }

    func exportTempWavAsMp3() {

        let wavFilePath = NSTemporaryDirectory().stringByAppendingPathComponent("resultmerge.wav")
        AudioWrapper.convertFromWavToMp3(wavFilePath)
    }
}

桥接报头包含：

#import "lame/lame.h"
#import "AudioWrapper.h"

票数 13

Stack Overflow用户

发布于 2015-07-24 14:34:56

我们有专门的类来读/写媒体文件，它们是AVAssetReader和AVAssetWriter，在AVAssetExportSession的帮助下，你可以将其导出为mp3文件。或者，您可以使用https://github.com/michaeltyson/TPAACAudioConverter

票数 6

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/31452202

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