[英]Duration of an amr audio file
我想找到类型为“ amr”的音频文件的持续时间,而不用任何方式将其转换为其他音频格式?
阿克
我已经在Objective-C中编写了以下代码,以获取电影的播放时间。 同样可以使用它来获取音频的持续时间:
-(double)durationOfMovieAtPath:(NSString*)inMoviePath
{
double durationToReturn = -1;
NSFileManager *fm = [NSFileManager defaultManager];
if ([fm fileExistsAtPath:inMoviePath])
{
av_register_all();
AVFormatContext *inMovieFormat = NULL;
inMovieFormat = avformat_alloc_context();
int errorCode = av_open_input_file(&inMovieFormat, [inMoviePath UTF8String], NULL, 0, NULL);
//double durationToReturn = (double)inMovieFormat->duration / AV_TIME_BASE;
if (0==errorCode)
{
// only on success
int numberOfStreams = inMovieFormat->nb_streams;
AVStream *videoStream = NULL;
for (int i=0; i<numberOfStreams; i++)
{
AVStream *st = inMovieFormat->streams[i];
if (st->codec->codec_type == CODEC_TYPE_VIDEO)
{
videoStream = st;
break;
}
}
double divideFactor;
// The duraion in AVStream is set in accordance with the time_base of AVStream, so we need to fetch back the duration using this factor
divideFactor = (double)1/rationalToDouble(videoStream->time_base);
if (NULL!=videoStream)
durationToReturn = (double)videoStream->duration / divideFactor;
//DEBUGLOG (@"Duration of movie at path: %@ = %0.3f", inMoviePath, durationToReturn);
}
else
{
DEBUGLOG (@"avformat_alloc_context error code = %d", errorCode);
}
if (nil!=inMovieFormat)
{
av_close_input_file(inMovieFormat);
//av_free(inMovieFormat);
}
}
return durationToReturn;
}
将CODEC_TYPE_VIDEO
更改为CODEC_TYPE_AUDIO
,我认为它应该对您CODEC_TYPE_AUDIO
。
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