Not the correct "Bitrate"

Reporting a bug!?

Audacity version number: 3.1.3 (64 bit)

computer info:
Edition: Windows 10 Pro
Version: 21H2
Operating System Build: 19044.1826
Experience: Windows Feature Experience Pack 120.2212.4180.0

Device: Lenovo ThinkPad E15 Gen. 2
Processor: AMD Ryzen 7 4700U with Radeon Graphics 2.00 GHz
Installed RAM: 16.0 GB (15.2 GB available)
System type: 64-bit OS, x64 processor

AMD HD Audio device version number:
Realtek Audio version number: 6.0.9354.1

My question/notice of the “Bug” is, when exporting the audio to m4a (FFMPEG) the Output “Bitrate” is not the correct value that is set. Example: set is 320 Kbps and the actual output varies between 200 and 500 Kbps per audio file. How is this possible?
Of course, the correct library (FFMPEG 64 bit) is installed from the link on the Audacity homepage.

The problem/challenge is consistent.
Here is the exact sequence of events from the launch of Audacity.

Open any audio file, in this example, mp3 (but it doesn’t matter if you take audio with the well-known extensions like “WAV”, “M4A”, “WMA” “MP3” or “FLAC”). Perform the audio editing such as cutting and deleting the silences at the beginning and end, select the audio, then export selected audio, save to edit, edit file name, change format options to m4a (FFMPEG), change quality to eg 320 Kbps, Save, Edit Metadata Tags, OK, file has been saved and in this case is 480 Kbps, Exit Audacity without saving the project.

Thank you kindly in advance for the answer.
Sincerely, Jack Radio.

Thanks for the report. Yes it’s a bug: The slider setting value for AAC/MP4 export is not honored by Audacity - and the slider cannot make precise settings · Issue #1818 · audacity/audacity · GitHub
Near the bottom of the comments, I gave a workaround: The slider setting value for AAC/MP4 export is not honored by Audacity - and the slider cannot make precise settings · Issue #1818 · audacity/audacity · GitHub

Hi, thanks for your reply, but this is different from what you described.

Okay, I’m a “Longterm User” of Audacity. Okay I know that Audacity is a so-called “Open Source” project and that’s partly why I noticed in the past that this issue has apparently been addressed before (I thought with version 2.3.3), because there was a fixed “bitrate” setting of up to 192 Kbps. Later in version 3.0.2, it was adjusted to max 320 Kbps which gave an output of about 320 Kbps (315-323 Kbps). Now the “known” problem/challenge has resurfaced, only much worse!
So this is a different “Bug” than what is described from what you gave me. Your solution/workaround is indeed not very user friendly. Would it be much better to use the fixed/most common “bitrate” with buttons?

And again,
Thank you kindly in advance for the answer.
Sincerely, Jack Radio.

Unfortunately the logged bug conflates two issues:

1. The slider setting value for AAC/MP4 export is not honored by Audacity
This appears to be the issue that you are reporting.

2. the slider cannot make precise settings
This issue has been improved since the bug was logged, but (testing on Linux) it’s still not very good as the slider is very small.

The bug is still open and has a high priority rating (“P2”).

What I said, I’m happy with what it was! First 192 Kbps and later about 320 Kbps.
Now it’s different, at interval it’s worse.

That it is, what I’m talking about: It’s a new issue in the bug!


When I converted my vinyl and tapes to digibits I exported as WAVs and then used iTunes to convert the WAVS to MP3 and latterly AAC/MP4 for my iTunes libraries. That gave me good control over the setup I wanted, including bitrates, for the MP3s and AACs

Partly I did that because at the time Apple held a legitimate license from Steinberg - and because I use the WAVs on my hi-fi “jukebox”.


A long time ago I heard that in the future “m4a” audio will replace “mp3” audio, because it would be of better quality, and would be more compatible with other devices, so more universal! This was the reason for me that I made that choice to choose m4a instead of mp3.

But when I’m dealing with a (very good) audio editer, to export m4a, which unfortunately has a variable “bitrate” with its own will, to per interval that is sometimes as high as possible, then the choice is quick made to fall back on mp3 anyway.
Perhaps also a reason, after almost ten years, to look for another “converter/editor” that would work better, or to switch to mp3 again!

Sincerely, Jack Radio.

It never happened.
The LAME (MP3) encoder got better, MP3 patent restrictions expired, and the MP3 format had already become so widely used that Apple’s “better” format, (which was still encumbered by patents) never gained much traction (compared to MP3) outside of the Apple universe.

Okay, but still, why is m4a still popular outside of Apple environments? And is it still possible to use m4a (which I do), in audio editors?
In terms of users perhaps a little less, but that does not take away from continuing to support m4a well, which also happens with other audio coders/extensions!
New coders/extensions are designed every time, which of course must remain compatible with other devices either by means of converters/editors. Older, longer existing coders/extensions are also permanently supported.

After this post I will stop contributing, I see that I have to wait and see with that “P2”!


AAC/MP4 works fine and dandy on
a) my Samsung Galaxy phone
b) my Cocktail Audio X30 - hi-fi “jukebox”
c) various players on my Windows PC


I’m’ waiting for this to happen too - I really think it should be fixed, it’s just plain sloppy the way it is - I will add a nudge to the bug thread.