FFmpeg export / import problem - bitrate.


Hey People: I’ve had a problem for some time …
Namely, since the x64 version of the program was released, exporting edited * .MP4 files to AAC completely does not keep the set bit-rate! For example: in version 3.0.2 (x86) I could easily export the edited clip at 192 kbps … while in newer versions - e.g. 3.0.5-64bit the bitrate set is completely pointless - at random it goes beyond 400 … Reinstalled and checked it a couple of times - what the hell happened to that ?!
I warn you of any doubts: I have the FFmpeg export / import libraries correctly installed!

There is a bug logged on the Audacity bug tracker that says that the bit-rate slider for AAC export, has not been working correctly since Audacity 2.3.3.
Are you sure that it was working for you in Audacity 3.0.2?

I think I know … where is the problem - since version 2.3.2 I use libraries compiled on May 22, 2014:

FFmpeg version: 2.2.2
libavutil 52. 66.100 / 52. 66.100
libavcodec 55. 52.102 / 55. 52.102
libavformat 55. 33.100 / 55. 33.100
libavdevice 55. 10.100 / 55. 10.100
libavfilter 4. 2.100 / 4. 2.100
libswscale 2. 5.102 / 2. 5.102
libswresample 0. 18.100 / 0. 18.100
libpostproc 52. 3.100 / 52. 3.100

and in all subsequent Audacity-x86 I installed them manually (from a .zip file), while with the latter - x64 - I used the installer and probably some newer package of libraries … And that’s why (yet) there was no problem on 3.0.2 - I always check the resulting files via MediaInfo.

Testing on W10 with 3.0.5 and 3.1.0 alpha

a) The File Export command remembers my previous setting

b) I confirm that the slider setting appears to have no bearing on the actual rate of the exported M4A file

@Steve: where is this loggedL: Bugzilla or GitHub ?


This is a bug that you logged previously, though I’m not sure exactly what issue you were describing (it’s different on my Linux system)

Looks to be pretty similar to what I was experiencing today - but then I was just just testing with mono…

I’ll look into this some more - and I’ll probably end up logging this on GitHub.

When I made all my AAC files:

  1. I exported from Audacity as 16-bit PCM WAV
  2. I imported that WAV into iTunes
  3. I used iTunes to convert to AAC (Apple had a kosher paid-for FFmpeg license)

And note that if I told iTunes to make it 256 then the AAC file jolly well came out as 256.


Logged asP2 (marginal P1) on GitHub as issue 1818

The slider setting value for AAC/MP4 export is not honored by Audacity

I also noted that it’s darn hard (perhaps impossible) to set “standard” kbps values for say 256 and 192 with the slier - I certainly couldn’t do that.

Thanks for the “nudge” Chris_71 :sunglasses:


Well, it would be worth … if someone could adjust some “slightly better” libraries for Audacity-x64. I assume that the 64-bit program will work more efficiently and more stable, and M4A is very convenient for me for later editing tracks in, for example, Pinnacle Studio. Thanks for your interest in my case. Regards. :slight_smile:

I THINK somebody is working on an FFmpeg update for Audacity. There is a newer FFmpeg library but it hasn’t been tweaked for Audacity yet. FFmpeg is now at version 4.4 and Audacity is still using 2.2.2.

But, I don’t know if this will fix the issue or if something in Audacity has to be fixed.

But, I don’t know if this will fix the issue or if something in Audacity has to be fixed.

It is very possible that this is a bit of both …
On these libraries:
in version 3.0.2 I was able to easily set the values of 192/256 kbps, but for example lower values did not work anymore. However, for Audacity-x64, there is another compilation and in this case the setup doesn’t work at all.

I have been advised of an undocumented “Easter Egg”

It appears you can fine tune your slider position with the left and right arrows :ugeek: :sunglasses:

Give it a try Chris …


It would be pretty cool … :wink:
But unfortunately that doesn’t work - the only thing that can be done is to get the range: 425-441 kbps on the resulting file.

OK so now for the upcoming 3.1.0 I have revealed this Easter-Egg in a tip div:
{{tip:You can use the keyboard left and right arrows to move or fine-tune your slider position.}}

See: https://alphamanual.audacityteam.org/man/AAC_Export_Options#Format_Options


Works-for-me, else I wouldn’t have documented it :sunglasses:
when I say “works-for-me” I mean setting the slider - Audacity still ignores the setting you make there and does its own thing - that is still a live logged issue in GitHub for the developers to look at.

It’s okay - I generally know that you can use the arrows additionally - similarly in various other settings. But in audacity-win-3.0.5-64bit, it doesn’t affect the bit-rate of the resulting file … and that’s right - that’s the heart of the matter. Well … unless in version 3.1.0 it will be possible and if there is, say, build-alpha somewhere, then I can test … or just wait for the official release. :slight_smile:

I suspect it might not get fixed for 3.1.0 as that is a little close (a couple of planned weeks away) - but I’ll see what I can do to exert a little pressure.


Until this issue gets fixed there is a workaround - using iTunes to make the AAC conversion:

  1. download iTunes

  2. make your required AAC quality settings for import and conversion

  3. Record in Audacity

  4. Export from Audacity as a 16-bit PCM WAV file (default)

In iTunes:
4) import the WAV file in iTunes
5) select the file in iTunes
6) File > Convert
7) copy or move the file from iTunes

You will also need to delete the WAV file in iTunes as it retains the WAV and makes the AAC as a copy.

I did this for all my AAC files for my iPod when I was converting my LP and tape collection some years ago - I figured at the time that Apple’s AAC FFmpeg converter was likely to be better than Audacity’s as AAC is their native format - plus Apple had a pukka paid for license for FFmpeg that they purchased from Steinberg.


It does not necessarily have to be “better” - as a curiosity - a screenshot of information about the file after export from version 3.0.2 … - but of course - any solution that helps and makes something easier is OK :slight_smile:

My mine criterion was what the AAC sounded like on my Sennheiser cans and latterly my B&W cans on mi iPod - but I did also audition some of the AACs on my hi-fi rig with my QUAD ELS-57 electrostatic speakers :wink:

But I do realize my ears are getting older now - along with the rest of me …


I admire the original approach to listening! But I am also happy with my Monitor Audio Platinum PL300 II … But by the nature of things I focus more on some sound editing … And I think that is what Audacity is all about, and unfortunately we all get old. :wink: