Mac: in AAC export, setting the bit rate quality by typing fails to work (previous setting is used)

[petersampsonaudacity]

Bug description

On Mac in the MP4(AAC) export dialog setting the bit rate quality by typing fails to work (previous setting is used)
a) if I use the up/down arrows to set the required bit-rate Audacity uses that bit-rate
b) if I type a number into the bit-rate field, the Audacity ignores that "setting" and instead uses the previously used setting

The worst of this is, is that the user is extremely likely to be opaquely unaware of this inappropriate, unwanted, export quality setting.

This does NOT happen on Windows, only on Mac (I do not know the behavior on Linux)

Steps to reproduce

1. get a 3 minute stereo song
2. File > Export > Export Audio
3. choose M4A(AAC)... in the Save as Type field
4. Change the bit rate to 200 kbps by using the up/down arrows
5. Export the AAC file
6. Observe: the exported file is exported at 202kbps (I use iTunes to assess this)
7. File > Export > Export Audio
8. AAC is still active
9. change the bit rate to 320 kbps by typing "320"
10. Export the AAC file
11. Observe: the file is exported at 202 kbps not 320/321

Expected behavior

As with Windows the user's typed numerical bit rate should be used by Audacity for the export.

Actual behavior

When the user changes the bit rate by typing a value, Audacity ignores this and instead uses the last previously used value.

Audacity Version

3.2.4 and 3.3.0 latest alpha

Operating system

macOS 12.6.3 Monterey

Additional context

Discovered while testing #4309

[Ryan-Miller-Audacity]

I can reproduce this issue as described on MacOS, not on windows as mentioned in the summary. The previous setting is being used when a bit rate is typed into the field on the export dialog screen for AAC export.

[petersampsonaudacity]

@chinakov @dozzzzer @LWinterberg

Testing on macOS 12.6.8 Monterey with latest 3.4.0 alpha: audacity-macOS-3.4.0-alpha-20230823+2dd7948-x86_64

This no longer appears to be an issue:
a) at steps 5-6 the requested 200kbps file exports as 197kbps
b) at steps10-11 the requested 320kbps file exports as 263kbps

This indicates that the issue reported in this ticket is no longer extant in the latest master 3.4.0 alpha as the over-typing at step 9 is "honored" by Audacity as it exports at a higher bitrate than the previous bitrate.

I suspect that this isl most likely due to the new Export dialog changes that @vsverchinsky worked on recently and are now in the 3.4.0 alpha builds.

Accordingly I think that this issue can be closed.

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Residual issue

BUT from observing the two results one can see that there remains the residual issue that the user's requested bitrate is not actually honored for the AAC export.

See: M4A(AAC) Export does not honor the user's quality settings for bit rates below 196kbps in the export dialog #4309

I have not re-tested #4309 - but it now looks like the 320kbps request is no longer honored either.

[petersampsonaudacity]

And see also this old (now closed) issue:

The slider setting value for AAC/MP4 export is not honored by Audacity - and the slider cannot make precise settings #1818