Question

我想将两个或多个.wav文件合并为一个，然后将其转换为.mp3，我想在Swift中完成（或者至少可以选择将它包含在swift项目中）。

在swift中合并两个.wav文件没问题。 Here is my example现在我不知道如何将lame库添加到swift项目以及如何使用它（如何更改客观的蹩脚代码使用语法以便在swift中使用它）。

我陷入了swift，所以我尝试了使用Objective C的Lame库。我找到了将.caf转换为.mp3的示例代码，所以我试了一下。这是我尝试过的：

- (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
{
}

但结果只是带有噪音的.mp3。

所以我需要解决我的三个问题：

在Objective C
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，但是我找不到一个使用Swift示例的例子，我找不到使用Objective C代码的例子（只是上面的代码）。谢谢你的帮助

Answer 1

我想发布我的工作解决方案，因为我得到了很多赞许，而来自naresh的回答对我帮助不大。

我已从此项目生成lame.framework库https://github.com/wuqiong/mp3lame-for-iOS
我已将库添加到我的Swift项目中（构建阶段 - >使用库链接二进制文件）
我已经创建了在Objective C中使用c函数的包装器，以及通过桥接头我在Swift中使用它。
对于连接wav文件，我使用AVAssetExportSession和Swift

现在是源代码。所以首先包装。它是将.wav文件转换为.mp3的类。可能会有很多变化（可能是输出文件和其他选项的参数），但我认为每个人都可以改变它。我想这可以改写为Swift，但我不知道该怎么做。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];
    }
}

用于连接音频文件的Swift AudioHelper类和用于将.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)
    }
}

桥接标题包含：

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

Answer 2

我们有专门的类来从/向AVAssetReader和AVAssetWriter文件读取/写入媒体，并且在AVAssetExportSession的帮助下，您可以将其导出为mp3文件。或者你可以使用https://github.com/michaeltyson/TPAACAudioConverter

iOS Swift - 将.wav文件合并并转换为.mp3

2 个答案: