Forums

Sampling rate conversion

Started by Ting Liu June 22, 2004
Hi experts:

Does any one know an easy way to convert the following two formats
back and forth.

mono 16bits sampling rate 44100hz PCM 
mono 16bits sampling rate 8000hz PCM

I have used ACM stream API to perform the conversion, but it produced
poor sound quality (Alias occurred). I guess Microsoft's codecs are
not good enough. :-(

Is there any easy and fast way to accomplish this on Microsoft OS
other than interpolation + filtering + decimation. Any free source
code samples will be greatly appreciated.

Any suggestions or comments are welcomed. Thank you in advance.


Ting
Ting Liu wrote:

> Hi experts: > > Does any one know an easy way to convert the following two formats > back and forth. > > mono 16bits sampling rate 44100hz PCM > mono 16bits sampling rate 8000hz PCM > Is there any easy and fast way to accomplish this on Microsoft OS > other than interpolation + filtering + decimation. Any free source > code samples will be greatly appreciated.
Has SOX been ported? Also, you may wish to try gooleing for "secret rabbit code" - dont ask! It is a SRC package that I think has a windows port? Regards, Dan. -- And on the evening of the first day, the lord said.... LX1, Go! And there was light. The email address *IS* valid, do not remove the spamblock.
go to http://osalp.sourceforge.net

Under the class hierarchy look for the class aflibConverter, this class can
be used for samplerate conversion by _real_ factors, and offers 3
quality/performance levels of doing so.  Although, the code is written for
unix, not all classes have platform dependent code (this class being one of
them).  The documentation pretty much explains how to use the class but if
you have questions, i can help as i've used it in a project recently.

David

ps, i think you have to download the entire library but can add only the
needed source files to your project


"Ting Liu" <tl_163@hotmail.com> wrote in message
news:ae45a9be.0406221042.466a1073@posting.google.com...
> Hi experts: > > Does any one know an easy way to convert the following two formats > back and forth. > > mono 16bits sampling rate 44100hz PCM > mono 16bits sampling rate 8000hz PCM > > I have used ACM stream API to perform the conversion, but it produced > poor sound quality (Alias occurred). I guess Microsoft's codecs are > not good enough. :-( > > Is there any easy and fast way to accomplish this on Microsoft OS > other than interpolation + filtering + decimation. Any free source > code samples will be greatly appreciated. > > Any suggestions or comments are welcomed. Thank you in advance. > > > Ting
Dan Mills wrote:
> > Has SOX been ported?
SoX runs on everything.
> Also, you may wish to try gooleing for "secret rabbit code" - dont ask! It > is a SRC package
Very good advice [1]
> that I think has a windows port?
Its not really a port. The same source code compiles and runs on Linux, MacOSX and win32. Erik [1] I'm the author. -- +-----------------------------------------------------------+ Erik de Castro Lopo nospam@mega-nerd.com (Yes it's valid) +-----------------------------------------------------------+ "The power of accurate observation is commonly called cynicism by those who don't have it." -- George Bernard Shaw
The best (free) audio tool I've found is called BeSweet and you can download
it for free here:

http://dspguru.doom9.net/

It does audio transcoding of many kinds of audio (mp2, mp3, ogg vorbis, wav,
ac3).  During the transcoding process you can do sample-rate conversion.

Brad

"Ting Liu" <tl_163@hotmail.com> wrote in message
news:ae45a9be.0406221042.466a1073@posting.google.com...
> Hi experts: > > Does any one know an easy way to convert the following two formats > back and forth. > > mono 16bits sampling rate 44100hz PCM > mono 16bits sampling rate 8000hz PCM > > I have used ACM stream API to perform the conversion, but it produced > poor sound quality (Alias occurred). I guess Microsoft's codecs are > not good enough. :-( > > Is there any easy and fast way to accomplish this on Microsoft OS > other than interpolation + filtering + decimation. Any free source > code samples will be greatly appreciated. > > Any suggestions or comments are welcomed. Thank you in advance. > > > Ting
Thank you all your suggestions, I will check them out.

Ting


tl_163@hotmail.com (Ting Liu) wrote in message news:<ae45a9be.0406221042.466a1073@posting.google.com>...
> Hi experts: > > Does any one know an easy way to convert the following two formats > back and forth. > > mono 16bits sampling rate 44100hz PCM > mono 16bits sampling rate 8000hz PCM > > I have used ACM stream API to perform the conversion, but it produced > poor sound quality (Alias occurred). I guess Microsoft's codecs are > not good enough. :-( > > Is there any easy and fast way to accomplish this on Microsoft OS > other than interpolation + filtering + decimation. Any free source > code samples will be greatly appreciated. > > Any suggestions or comments are welcomed. Thank you in advance. > > > Ting