iOS 下Opus 压缩PCM音频数据方法

我上篇文章有交大家如何编译Opus库

不多说直接贴代码了

opusCodec.h

#import <Foundation/Foundation.h>
@interface opusCodec : NSObject

-(void)opusInit;

-(NSData*)encodePCMData:(NSData*)data;

-(NSData*)decodeOpusData:(NSData*)data;

-(void)destroy;

@end

opusCodec.m

#import "opusCodec.h"

#import "opus.h"

#define kDefaultSampleRate 8000

#define WB_FRAME_SIZE  320

@implementation opusCodec

{

OpusEncoder *enc;

OpusDecoder *dec;

unsigned char opus_data_encoder[40];

}

-(void)opusInit

{

int error;

enc = opus_encoder_create(kDefaultSampleRate, 1, OPUS_APPLICATION_VOIP, &error);//(采样率，声道数,,)

dec = opus_decoder_create(kDefaultSampleRate, 1, &error);

opus_encoder_ctl(enc, OPUS_SET_BITRATE(kDefaultSampleRate));//比特率

opus_encoder_ctl(enc, OPUS_SET_BANDWIDTH(OPUS_AUTO));//OPUS_BANDWIDTH_NARROWBAND 宽带窄带

opus_encoder_ctl(enc, OPUS_SET_VBR(0));

opus_encoder_ctl(enc, OPUS_SET_VBR_CONSTRAINT(1));

opus_encoder_ctl(enc, OPUS_SET_COMPLEXITY(8));//录制质量 1-10

opus_encoder_ctl(enc, OPUS_SET_PACKET_LOSS_PERC(0));

opus_encoder_ctl(enc, OPUS_SET_SIGNAL(OPUS_SIGNAL_VOICE));//信号

}

- (NSData *)encode:(short *)pcmBuffer length:(NSInteger)lengthOfShorts

{

//    NSLog(@"--->>lengthOfShorts = %ld  size -= %lu",(long)lengthOfShorts,sizeof(short));

int frame_size = (int)lengthOfShorts / sizeof(short);//WB_FRAME_SIZE;

short input_frame[frame_size];

opus_int32 max_data_bytes = 2 * WB_FRAME_SIZE ;//随便设大,此时为原始PCM大小

memcpy(input_frame, pcmBuffer, lengthOfShorts );//frame_size * sizeof(short)

int encodeBack = opus_encode(enc, input_frame, frame_size, opus_data_encoder, max_data_bytes);

//    NSLog(@"encodeBack===%d",encodeBack);

if (encodeBack > 0)

{

NSData *decodedData = [NSData dataWithBytes:opus_data_encoder length:encodeBack];

return decodedData;

}

else

{

return nil;

}

}

//int decode(unsigned char* in_data, int len, short* out_data, int* out_len) {

-(int)decode:(unsigned char *)encodedBytes length:(int)lengthOfBytes output:(short *)decoded

{

int frame_size = WB_FRAME_SIZE;

unsigned char cbits[frame_size*2];

memcpy(cbits, encodedBytes, lengthOfBytes);

int pcm_num = opus_decode(dec, cbits, lengthOfBytes, decoded, frame_size, 0);

//    NSLog(@"解压后长度=%d",pcm_num);

return frame_size;

}

-(NSData *)encodePCMData:(NSData*)data

{

//    NSLog(@"原始数据长度--->>%lu",(unsigned long)data.length);

return  [self encode:(short *)[data bytes] length:[data length]];

}

-(NSData *)decodeOpusData:(NSData*)data

{

int len = (int)[data length];

Byte *byteData = (Byte*)malloc(len);

memcpy(byteData, [data bytes], len);

int frame_size = WB_FRAME_SIZE;

short decodedBuffer[frame_size ];

int nDecodedByte = sizeof(short) * [self decode:byteData length:len output:decodedBuffer];

NSData *PCMData = [NSData dataWithBytes:(Byte *)decodedBuffer length:nDecodedByte];

return PCMData;

}

-(void)destroy

{

opus_encoder_destroy(enc);

opus_decoder_destroy(dec);

}

@end

使用方法

1. 首先 使用audioqueue 来录制音频数据 生成NSdata 类型的数据流
   注意：使用audioqueue录制音频的大小最好设置为320
   然后使用我上面的方法 opusInit 初始化 opus 编码器

2. 使用-(NSData)encodePCMData:(NSData)data;
   编码数据流
   然后通过socket 上传服务器 通过服务器分发到手机上

3. 手机收到服务器分发的数据使用
   -(NSData)decodeOpusData:(NSData)data;
   解码数据流
   得到 可以播放的音频数据流
   然后使用audio queue 来播放

4. 使用完以后记得使用-(void)destroy 来销毁