Re: [Audacity-devel] Opus format

[Martyn S. <mar...@gm...>]

Hi

I am thinking that we should add opusenc.exe and opusdec.exe to our 
'libraries' (in prefs) and then add 'Opus' to our 'Files of type:' on 
import and 'Save as type:' on export (if we have the 
importer/exporter).  Obviously we would need a custom 'Options' 
dialog, as we have for MP3, FFmpeg etc., and we would need to decide 
what options to expose to the user.

The only down-side I can see to this is that opusenc.exe appears to 
take a 16-bit wav file as an input, not a 32-bit float, so there may 
be a minor degradation in quality compared to the native calls to a 
fully integrated library.  But I may have misread that.

I am assuming that the command-line options for opusenc will remain 
constant across versions so we won't have to change with any updates, 
which would be a great advantage compared to FFMpeg.

We could add the encoder and decoder to the win installer or offer it 
as a download from somewhere, I don't know about other platforms.

I've had a successful attempt at compiling opusenc.exe and 
opusdec.exe, which was good but probably not the way to go for us.  We 
should rely on others doing that, such as 
http://opus-codec.org/downloads/ in the opus-tools package.

For the record, to compile opusenc.exe and opusdec.exe I had to:

*	Install 'Microsoft Visual Studio Express 2012 for Windows Desktop'
*	Install Git http://git-scm.com/download/win using the instructions 
at https://help.github.com/articles/set-up-git (but not the 'Download 
our native app instead' one, it didn't work for me).
*	Get various things with Git:
		opus
		opus-tools
	following
	http://opus-codec.org/development/

*	Add in libogg to the mix.
and then compile the various sources in the right order.

TTFN
Martyn

On 31/10/2012 21:46, Vaughan Johnson wrote:
> On 10/30/2012 6:08 PM, Martyn Shaw wrote:
>> Hi
>>
>> The fact is that it doesn't matter what we, individually, think of the
>> sound quality.  Opus has been adopted by the IETF, so we should be
>> supporting it, I feel.
>
> +1.
>
>
>> [...]
>> Some executable files are available for various operating systems and
>> the reference source is available in RFC6716.  To my mind, we just
>> have to decide how to make it available for import/export in Audacity,
>> then do that.  But things are never as easy as they appear :-).
>
> Seems easiest to run it by command line, so a good start, although we'll
> probably want to integrate it fully, eventually.
>
>
>>
>> The 1.0.0 and 1.0.1 releases don't appear to be available in a
>> compiled form http://www.opus-codec.org/downloads/ so I think I'll
>> have a go at compiling 1.0.0.  But my machine is currently trying to
>> catch up with my brain.
>
> Why 1.0.0 instead of 1.0.1?
>
>
>>
>> TTFN
>> Martyn
>> PS that leaves the libavcodec vulnerabilities an open question, and we
>> have gone OT.
>
> At least the subject line changed. :-)
>
> Thanks,
> V
>
>
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