Thanks for the information. I will see if I can find out what algorithm 
Adobe Audition uses for downsampling.

Regards,
Mike

----- Original Message ----- 
From: "Erik de Castro Lopo" 
To: 
Sent: Saturday, April 26, 2008 7:28 PM
Subject: [Csnd] Re: Re: request for advice: mastering for CD


> Denis Crowdy wrote:
>
>> On Thu, Apr 24, 2008 at 11:22 PM, Dave Seidel  
>> wrote:
>> > Thanks, Mike.
>> >
>> >  As I mentioned, I normally render to 96/24, and that's what I play in 
>> > a
>> > concert situation.  I'm guessing that you recommend 88.2K rather than 
>> > 96K
>> > because dithering it down to 441.1K is simpler (just a divide by 2),
>> > correct?
>>
>> I'm pretty sure the answer to this is no - it is by no means a simple
>> divide by 2.  The author of libsamplerate (Erik de Castro Lopo) gives
>> a series of lectures to my audio engineering students
>
> I really enjoyed that Denis. Thanks.
>
>> and demonstrates
>> how important the filtering and conversion process is so that aliasing
>> artefacts don't appear after the conversion,
>
> To expand on this a bit, there are two basic categories of doing sample
> rate conversion
>
>  - algorithmically naive and computationally cheap ways
>  - good algorithms
>
> When using the first method, yes, downsampling by 2 is better/easier
> than downsampling by 960/441.
>
> However, when using good algorithms (ie the SRC_SINC_* in libsamplerate
> and similar converters in other libraires and applications) the
> difference in quality between downsampling by 2 over downsampling by
> 960/441 is unlikely to be measurable.
>
>> (similar to those at http://src.infinitewave.ca/) to demonstrate this.
>
> Excellent web site. For a little more on what these spectral plots
> mean and how they are obtained, see my blog post:
>
> 
> http://www.mega-nerd.com/erikd/Blog/CodeHacking/SecretRabbitCode/src_compare.html
>
> A later post
>
> 
> http://www.mega-nerd.com/erikd/Blog/CodeHacking/SecretRabbitCode/progress.html
> 
> http://www.mega-nerd.com/erikd/Blog/CodeHacking/SecretRabbitCode/rel_0_1_3.html
>
> describes a reworking of the converters I did just recently which put
> the best of the libsamplerate converters (with a SNR of 145dB)
> extremely close to the best of the commercial converters (160dB SNR or
> better). Personally, I think 145dB SNR should be more than sufficient
> for any audio application.
>
> Cheers,
> Erik
> -- 
> -----------------------------------------------------------------
> Erik de Castro Lopo
> -----------------------------------------------------------------
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