原生音视频编码  

 

基于 AVFoundation 进行音频录制

@interface ViewController ()
     
      {    AVAudioRecorder *recorder;    AVAudioPlayer *player;}@property (weak, nonatomic) IBOutlet UILabel *label; @end- (IBAction)record:(id)sender {        if (recorder == nil) {//        路径拼接        NSString *filePath =        [NSString stringWithFormat:@"%@/rec_audio.caf", [self documentsDirectory]];//        构建URL        NSURL *fileUrl = [NSURL fileURLWithPath:filePath];                NSError *error = nil;//        AVAudioSession类提供了Audio Session服务，Audio Session是指定应用于音频系统如何交互。AVAudioSession通过指定一个音频类别实现的，音频类别描述了应用使用音频的方式//        下面是设置音频回话类别//        AVAudioSessionCategoryRecord代表只能输入音频，即录制音频，其效果是停止其他音频播放，开始录制音频，         AVAudioSessionCategoryPlayback代表只能输出音频，即进行音频播放。        [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryRecord                                               error:&error];//        设置是否“活跃”，这会把系统的任何声音关闭        [[AVAudioSession sharedInstance] setActive:YES error:&error];//        设置settings参数        NSMutableDictionary *settings = [NSMutableDictionary dictionary];//        AVFormatIDKey键是设置录制音频编码格式，kAudioFormatLinearPCM代表线性PCM编码格式，PCM（pulse code modulation）线性脉冲编码调制，它是一种非压缩格式。//        注意：编码格式与文件格式不同，例如WAV是音频文件格式，它采用线性PCM音频编码        [settings setValue:[NSNumber numberWithInt:kAudioFormatLinearPCM]                    forKey:AVFormatIDKey];//        AVSampleRateKey键是设置音频采样频率，44100.0是音频CD，VCD，SVCD和MP3所用的采样频率。        [settings setValue:[NSNumber numberWithFloat:44100.0]                    forKey:AVSampleRateKey];//        AVNumberOfChannelsKey设置声道数量，值为1或者2        [settings setValue:[NSNumber numberWithInt:1]                    forKey:AVNumberOfChannelsKey];//        AVLinearPCMBitDepthKey这是采样位数，取值为8，16，24，32，16是默认值        [settings setValue:[NSNumber numberWithInt:16]                    forKey:AVLinearPCMBitDepthKey];//        AVLinearPCMIsBigEndianKey设置音频解码是大字节序还是小字节序，大字节序，YES，否则为NO        [settings setValue:[NSNumber numberWithBool:NO]                    forKey:AVLinearPCMIsBigEndianKey];//        AVLinearPCMIsFloatKey设置音频解码是否为浮点数，如果是则设置为YES，否则为NO        [settings setValue:[NSNumber numberWithBool:NO]                    forKey:AVLinearPCMIsFloatKey];//        实例化recorder对象        recorder = [[AVAudioRecorder alloc]                    initWithURL:fileUrl                    settings:settings                    error:&error];//        设置代理        recorder.delegate = self;    }    //    如果正在录制，return    if(recorder.isRecording) {        return;    }//如果正在播放，停止    if(player && player.isPlaying) {        [player stop];    }//    开始录制    [recorder record];        self.label.text = @"录制中...";}- (IBAction)stop:(id)sender {    self.label.text = @"停止...";//    是否正在录制    if(recorder.isRecording) {        [recorder stop];//停止        recorder.delegate = nil;        recorder = nil;    }    if(player.isPlaying) {        [player stop];    }}- (IBAction)play:(id)sender {        if(recorder.isRecording) {        [recorder stop];        recorder.delegate = nil;        recorder = nil;    }    if(player.isPlaying) {        [player stop];    }        NSString *filePath =    [NSString stringWithFormat:@"%@/rec_audio.caf", [self documentsDirectory]];    NSURL *fileUrl = [NSURL fileURLWithPath:filePath];        NSError *error = nil;    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback                                           error:&error];    [[AVAudioSession sharedInstance] setActive:YES error:&error];    player = [[AVAudioPlayer alloc] initWithContentsOfURL:fileUrl error:&error];        if(error) {        NSLog(@"%@",[error description]);    } else {        [player play];        self.label.text = @"播放...";    }    }-(NSString *)documentsDirectory{    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,                                                         NSUserDomainMask, YES);    return [paths objectAtIndex:0];}#pragma mark--实现AVAudioRecorderDelegate协议方法- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)recorder successfully:(BOOL)flag{       NSLog(@"录制完成。");}- (void)audioRecorderEncodeErrorDidOccur:(AVAudioRecorder *)recorder error:(NSError *)error{    NSLog(@"录制错误发生: %@", [error localizedDescription]);}- (void)audioRecorderBeginInterruption:(AVAudioRecorder *)recorder{    NSLog(@"播放中断。");}- (void)audioRecorderEndInterruption:(AVAudioRecorder *)recorder withOptions:(NSUInteger)flags{    NSLog(@"中断返回。");}