队列中的Lame编码iOS

Question

我正在尝试使用LAME将一个WAV文件转换为MP3文件。

我正在使用这个代码。我想在后台(或队列中)这样做。由于输入文件很大，可以对其进行完整的控制，直至完成。有人能帮我吗？

int read, write;
FILE *pcm = fopen([mergeFile 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);
    NSLog(@"");
    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);

} while (read != 0);

lame_close(lame);
fclose(mp3);
fclose(pcm);

Answer 1

我会使用串行NSOperationQueue进行编码。

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
queue.maxConcurrentOperationCount = 1;
#ifdef __IPHONE_8_0
queue.qualityOfService = /* a NSQualityOfService */;
#endif

您可以添加这样的作业：

[queue addOperationWithBlock:^{

    /* Encoding code goes here */

    dispatch_async(dispatch_get_main_queue(), ^{

        /* Report operation status on completion (delegate, notification, etc...)

    }];

}];