Re: [Audacity-devel] SoX resampling

[Rob S. <aq...@ya...>]

----- Original Message -----
> From: Martyn Shaw <mar...@gm...>
    
> Summary:  got it going on win, patch attached (not really 'release
> ready').
      
Great news!
      
> (1) You had 'Debug' and 'Release' Configurations which I renamed
> 'Unicode Debug' and 'Unicode Release'.  Am I right in thinking
> that there are no 'Unicode' issues that need addressing?  I've no
> idea what they might be.
        
Yes, that should be fine.
      
> (2) I am seeing 6 options in Audacity:
>     LSR best sinc
>     LSR medium sinc
>     LSR fastest sinc
>     LSR ZOH
>     LSR linear
>     SoX VHQ
> so I guess I built it correctly.
>
> but which ones correspond to which http://src.infinitewave.ca/ results?
  
The 1st 5 are libsoxr emulations of libsamplerate (LSR) so there are no exactly corresponding results to those at infinitewave; they should be similar to (or maybe slightly cleaner than) the LSR 1.3 results there. SoX VHQ should correspond to the same at infinitewave, though the background noise (but not any artefacts) will appear higher in Audacity 'cos it (and libsoxr's LSR emulation) uses float32, which gives only (but IMHO sufficient for sufficient for all but scientific purposes) 25-bits of precision (the SoX VHQ @ infinitewave is int32, 32-bit precision).
    
I had a nice graph of these things that I sent to Steve, but then lost—Steve do you still have a copy you could post to the list?
    
> don't seem to tie up.  Maybe this is a different version to 14.4?  Is there
> a method to get the version for display?
    
Yes, in both native API and LSR emulation API, there is a function to get the version—they both return the same thing i.e. the version of libsoxr, which is currently stuck at 0.0.1 (but versioning will apply henceforth).

> Just a comment: I did get the warnings below off the linker with 'Unicode
> Release', but it's not unusual to get warnings from our libraries.
> 24>warning C4744: '_soxr_rate32_cb' has different type in
> 'n:\Audacity\2_0_1Build\lib-src\libsoxr\src\rate32.c'
    
I'd suggest to disable this warning, since the run-time casting that the compiler has spotted here is intentional. 
  
All in all, good stuff!
  
Cheers,
Rob