[linux-audio-dev] Re: Looking for fast integer resampling code

[David Cournapeau]

Olivier Guilyardi wrote:

> Hi Erik,
>
> Erik de Castro Lopo wrote:
>
>> Kjetil Svalastog Matheussen wrote:
>>
>>
>>> I recently did a lot of benchmarking between libsamplerate and mus_src
>>> in clm/sndlib. My result was quite interesting, the fastest mus_src 
>>> sinc
>>> resampler where a lot faster than the fastest libsamplerate resampler.
>>
>>
>>
>> I think most people would agree that speed is not the most important
>> aspect when measuring the quality of a sample rate converter.
>
>
> I believe libsamplerate, as a general purpose sample rate conversion 
> library, should be able to run very fast if needed. After including 
> your library into Jackbeat (http://www.xung.org/jackbeat) I was pretty 
> sad to see 40% of my 700Mhz Duron load dedicated to processing only 
> six tracks with libsamplerate's SRC_LINEAR converter.
>
> Then, I coded a trivial sample rate conversion routine by myself :
> - it sounds good, I can't hear any difference with the SRC_LINEAR 
> converter

I think the issue here is the application, and what you mean by good ? 
If the usage is purely sampling rate convertion, as a final stage before 
mastering, then linear interpolation sounds really bad, there is no 
question about it. Now, if it is used inside a processing effect, it may 
be enough (I remember having used a linear interpolation for time 
stretching processing, and the linear interpolation was certainly not 
the weak point in the processing chain).

David