Re: [Audacity-quality] Importing 16-bit AUP project into 3.0.0 set to 32-bit

[Peter S. <pet...@gm...>]

On Thu, Apr 1, 2021 at 4:21 PM Bill Wharrie <bi...@go...> wrote:

>
>
> On 2021/04/01, at 5:41 AM, Peter Sampson <pet...@gm...>
> wrote:
>
>
>
> On Wed, Mar 31, 2021 at 11:24 PM Bill Wharrie <bi...@go...> wrote:
>
>> I tried this on Mac 10.15.7 and Audacity 3.0.0
>>
>> Start 2.4.2
>> Set Quality prefs to 16-bit
>> Import some audio
>> - note that the track is labeled as 16-bit
>> Save the project
>> Quit 2.4.2
>> note the _data folder size
>>
>> Start 3.0.0
>> Set Quality prefs to 32-bit float
>> Import the previously saved 2.4.2 project
>> - note that the track is labeled as 32-bit
>> Save the project
>> - note the project size - same as the 2.4.2 project but shouldn't it be
>> twice as big?
>> Amplify the track by 20 dB
>> - since the track is 32-bit float, this should be recoverable
>> Amplify the track by -20 dB
>> - note that the track is not recovered - it appears that it is 16-bit
>> even though labeled as 32-bit
>>
>
> Testing on W10 with 2.4.2 and 3.0.1 I confirm Bill's findings.
>
> a) with 2.4.2 the AUP project was 28.5MB
> b) with 3.0.1 the AUP3 is 28.9MB throughout with Bill's steps
>
> If I than Exit Audacity and relaunch (keeping the 32-bit Quality setting
> and import the same
> audio file then indeed the project is double the 16-bit size at 56.9MB
>
> But I'm struggling to get my head around what the actual bug is here - and
> in particular
> what we would actually log in Bugzilla.
>
>
> This example does raise some interesting questions about bit-rate Quality
> settings though.
>
> In Bill's example above
> a) the user was working in 2.4.2 with a16-bit Quality setting
> b) they then upgrade to 3.x
> c) at this stage their Quality settings follow them in audacity.cfg and
> they remain at 16-bit
> d) they then take the conscious decision to upgrade their Quality to
> 32-bit ...
> Of course it could be an unconscious change by using Reset Configuration -
> or on Windows
> choosing the reset on install
>
>
> Now here's an interesting use-case
> 1) Set Quality to 16-bit
> 2) Record a short bit of audio
> 3) Observe it is 16-bit in the TCP
> 4) change Quality to 32-bit
> 5) Press Record
> 6) Observe recording continues in the 16-bit track (so is this new part
> 16-bit or 32-bit?)
> 7) Press Shift+Record
> 8) Observe: new tracks is created with 32-bit in the TCP
>
> I'm thinking that mixed bit rates call well be another of our cans o'
> worms ...
>
>
> Indeed. This is why I have occasionally advocated for a dialog to precede
> the creation of a new project where the user chooses the bit rate and bit
> depth for the project which then cannot be changed. Audio imported into the
> project is converted to the project rate and bit depth. IMO we used to
> allow mixed bit-depth or bit-rate tracks (or portions of tracks) on the
> assumption that we need to save space. With the abandonment of alias files
> we have admitted that space is not an issue.
>

I am minded to agree with these thoughts of Bill's

*This is a set of worms that could well do with being put back into a
tightly-fastened can  ...*

Peter.



> — Bill
>
>
>
> Peter.
>
>
>
>
> Importing 16-bit audio files into a 3.0.0 project with Quality prefs set
>> to 32-bit properly converts the audio to 32-bit (I tried MP3 and AIF). So
>> this appears to be an issue only when importing AUP projects.
>>
>> — Bill
>>
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