[Flac] technical questions about FLAC

Brian Willoughby brianw at sounds.wa.com
Thu Apr 16 05:58:14 PDT 2009

Sorry, those should be 255 kHz and 655,350 Hz.  I was off by one,  
forgetting that 0 Hz is not allowed in FLAC.

On Apr 16, 2009, at 05:53, Brian Willoughby wrote:
> On Apr 14, 2009, at 02:05, Casey wrote:
>> 4. Why was 655,350 Hz chosen to be the maximum supported sample  
>> rate?  I noticed it's not a power of 2.  Also, this is an  
>> unimaginably fast frequency, doesn't it exceed the limit for most  
>> channels?
> 20-bit frequency in the stream header should allow for up to  
> 1,048,576 Hz, but the documentation points out that there are  
> limitations in the block headers.  The block header has a 4-bit  
> code to select among a few common frequencies, then has breakout  
> codes for 8-bit kHz, 16-bit Hz, or 16-bit dHz (d- for deca-).  In  
> other words, frequency can be specified in ones, tens, and  
> thousands.  When specified in thousands, you only get 8 bits, so  
> the maximum frequency with that code is 256*1000 or 256 kHz.  When  
> specified in tens, you can reach 65,536*10 Hz or 655,360 Hz.  The  
> reason these limits are not powers of 2 is because the  
> specification allowed for human factors such as tens and  
> thousands.  You'll note that 655,536 is a product of a power of 2  
> and a power of 10.

Brian Willoughby
Sound Consulting

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