//
//  NSURL+TransferFileFormat.m
//  VQU
//
//  Created by CY on 2021/4/27.
//  Copyright © 2021 leo. All rights reserved.
//

#import "NSURL+TransferFileFormat.h"
#import "lame.h"

@implementation NSURL (TransferFileFormat)

- (NSURL *)transformCAFToMP3{
    // 输入路径
    NSString *inPath = [self resourceSpecifier];
    
    // 输出路径
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *outPath =  [[NSURL URLWithString:[path stringByAppendingPathComponent:@"audioVerify.mp3"]] resourceSpecifier];
    @try {
        size_t read, write;
        
        FILE *pcm = fopen([inPath UTF8String], "rb");  //source 被转换的音频文件位置
        fseek(pcm, 4*1024, SEEK_CUR);                                   //skip file header
        FILE *mp3 = fopen([outPath UTF8String], "wb");  //output 输出生成的Mp3文件位置
        
        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();
        int rateKey = 44100;
        int numOfChannelsKey = 2;
        lame_set_in_samplerate(lame, rateKey);
        lame_set_VBR(lame, vbr_default);
        lame_set_num_channels(lame, numOfChannelsKey);//设置1为单通道，默认为2双通道
        lame_set_quality(lame, 0); /* 2=high 5 = medium 7=low 音质*/
        lame_init_params(lame);
        
        do {
            size_t size = (size_t)(2 * sizeof(short int));
            read = fread(pcm_buffer, size, PCM_SIZE, pcm);
            if (read == 0)
                write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
            else
                write = lame_encode_buffer_interleaved(lame, pcm_buffer, (int)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 {
        NSLog(@"MP3生成成功:");
    }
    return [NSURL fileURLWithPath:outPath];
}






@end