首先,我想展示通过Lame库将源.wav文件转换为.mp3的方法:
- (void)convertFromWav:(NSString *)sourceFilePath ToMp3:(NSString *)resultName {
NSString *mp3FileName = [resultName stringByAppendingString:@".mp3"];
NSString *mp3FilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:mp3FileName];
@try {
int read, write;
FILE *pcm = fopen([sourceFilePath UTF8String], "rb"); //source
if (pcm == NULL) {
perror("fopen");
return;
}
fseek(pcm, 4*1024, SEEK_CUR); //skip file header
FILE *mp3 = fopen([mp3FilePath cStringUsingEncoding:1], "wb"); //output
const int sampleRate = 44100;
const int bitsPerSample = 16;
const int numberOfChannels = 2;
const int PCM_SIZE = 8192*2;
const int MP3_SIZE = 8192*2;
short int pcm_buffer[PCM_SIZE*2];
unsigned char mp3_buffer[MP3_SIZE];
lame_t lame = lame_init();
lame_set_in_samplerate(lame, sampleRate);
lame_set_VBR(lame, vbr_default);
lame_init_params(lame);
lame_get_num_samples(lame);
long long fileSize = [[[[NSFileManager defaultManager] attributesOfItemAtPath:sourceFilePath error:nil] objectForKey:NSFileSize] longLongValue];
long duration = fileSize / (sampleRate * numberOfChannels * bitsPerSample / 8);//(fileSize * 8.0f) / (sampleRate * 2);
lame_set_num_samples(lame, (duration * sampleRate));
lame_get_num_samples(lame);
float percent = 0.0;
int totalframes = lame_get_totalframes(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);
int frameNum = lame_get_frameNum(lame);
if (frameNum < totalframes)
percent = (100. * frameNum / totalframes + 0.5);
else
percent = 100;
if ([_delegate respondsToSelector:@selector(convertingProgressChangedWithPercent:)])
{
[_delegate convertingProgressChangedWithPercent:percent];
}
} while (read != 0);
lame_close(lame);
fclose(mp3);
fclose(pcm);
}
@catch (NSException *exception) {
NSLog(@"%@",[exception description]);
}
@finally {
if ([_delegate respondsToSelector:@selector(convertingDidFinish:)])
{
[_delegate convertingDidFinish:mp3FilePath];
}
}
}
没关系,它正在工作。结果,我的.mp3每秒具有152000位。但我想使其每秒320000位。我该如何更改?我对这些东西理论上不太好,所以我不知道哪个价值观变成了什么。谢谢。
最佳答案
您要使用lame_set_VBR (lame_t, vbr_off);
,然后可以使用lame_set_brate
来设置所需的比特率。使用vbr_off
可为您提供CBR模式,如文档中所确认(请参阅 headers.h ):
****************************************************** *******************
VBR控制
****************************************************** ********************** / * VBR的类型。默认值= vbr_off = CBR * / int CDECL
lame_set_VBR(lame_global_flags *,vbr_mode); vbr_mode CDECL
lame_get_VBR(const lame_global_flags *);
试试这个 :
//# for constants of settings
const int sampleRate = 44100;
const int bitsPerSample = 16;
const int numberOfChannels = 2;
const int myBitRate = 320;
//# for Lame settings
lame_t lame = lame_init();
lame_set_in_samplerate (lame_t, sampleRate); //is 44100
lame_set_VBR (lame_t, vbr_off); //force CBR mode
lame_set_brate (lame_t, myBitRate); //is 320
lame_init_params (lame_t);
您也可以像这样设置Lame:
lame_t lame = lame_init();
变成这样:lame_t = lame_init();
只是说,如果您定义了lame_t
,那么我期望它在其余设置中要求使用该名称。您知道像lame_init_params (lame_t);
等。关于ios - me脚-将比特率提高到320,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/35151284/