Compress Dynamics problem: plugin stops working

I have a problem with the Compress Dynamics plugin - it has suddenly stopped working.

I have successfully used Chris’s Compress Dynamics 1.2.6 for over a year, processing seminars, church sermons, and audio books. It is so-o-o good at what it does! But for the last couple of days, I will process 2 or 3 files, and then it suddenly stops working.

Sequence: After I open an audio MP3 file, I start Compress Dynamics. The parameter settings window appears, but as soon as I click on OK, that window closes, and no processing takes place. I try again, but the same happens - no processing.

I restarted my PC (Windows 10 Pro with 8 cores, 16 Gb memory, and 90 Gb free disk space) but the same thing happens again: it sometimes works once or twice, but then it stops working.

I checked for latest updates on Audacity, and updated it today to v2.2.2, but I still get the same problem.

Can anyone help? Have you any ideas please?

I’m not sure if this applies to Chris’s compressor, but some Nyquist plug-ins have to load the entire track into the first 32-bit addressable RAM (the first 2GB of machine RAM). This usually works out at about 45 minutes for a track with a sampling rate of 44100 Hz. If tracks are too long, plug-ins with this limitation will usually fail in the manner that you describe. The workaround in this case is to select no more than about 45 minutes at a time (about half an hour of audio is usually a good safe bet).

Hello friends,
Whoops! It seems that I had a string of defective MP3 files to process.
I had downloaded a set of seminar MP4 files from Facebook. Then I wanted to convert them into MP3s ready to process them and listen on my mobile phone.
I used a free MP4 conversion application – but it obviously has a bugette.
The fix was to do a basic process on my dodgy MP3s in Audacity – such as export it as an MP3 file. Then close it. Then reopen the processed file, and Compress Dynamics now works perfectly! :wink:
All the best, and thanks for looking.

WOW! . . . I just discovered that Audacity can process MP4 files directly into MP3! Now that took maybe an hour of hunting round the internet for better apps to do this for me, before I discovered this!
AUDACITY DEVELOPERS! – Is there a way to make this more obvious to users? It’s not in the Windows 10 File Explorer > right-click options for MP4 files. I had to dig for it, and create the link myself!
What else can Audacity do that could be in a > right-click option?
Don’t let’s hide a good feature!
Best wishes, and thanks for creating Audacity.

Not exactly.
Audacity does not process files directly. Audacity copies the audio data from files into the Audacity project. Editing and processing is applied to the audio data in the project, and then the audio data may be exported as a new audio file.

If you have FFmpeg installed for Audacity (which you clearly have), then Audacity can import and export many additional file types. See: FAQ:Installation, Startup and Plugins - Audacity Manual

Hi Steve,
OK, that may be the way it does it in the background, but to the user (people like me), I now have it on my *.mp4 > right-click > Open with > Audacity. I only want the Audio from it. I have wasted hours over the last week or so in processing MP4s the hard way . . . I just didn’t have a clue that Audacity could do it so cleanly.
If you were to include it in the standard right-click options, I would have found it very quickly.
How about it? Everyone knows Audacity is for Audio; they won’t expect to process the video. And you could include any other video file types that Audacity can work with.
While I think of it, if I want to set the MP3 tags, I use a free application called MP3tag (see This is accessible from the first level of the right-click in File Explorer:
right-click > Mp3tag.
But Audacity is on the next level down:
right-click > Open with > Audacity.
Would it be possible to enhance this to operate from the first level, instead of having to drill down to it? Please?
(As for FFmpeg, I don’t know if or when I might have added this (as a plugin?) – I’ve used it for years!)
Thank you for your interest and your answers.
God bless you.

Associating files of a particular type with an application is an operating system (Windows) option.

When Audacity is first installed, you are asked if you want to associate Audacity project files (.AUP files) with Audacity.
Audacity “Project” files are the only file type that Audacity actually opens. Other media types may be “imported” into an Audacity project, but usually they are associated with a media player, so that when you “open” a media file, it plays (which most will agree is the correct behaviour).

I rarely use Windows, but I believe it has an option to “always open with…” so that you can associate files of a particular type with the application of your choice. If, for example, you tell Windows to always open WAV files with Audacity, then the default behaviour when double clicking on a WAV file will be to launch Audacity (if it is not already running), and import the WAV file into the Audacity project.

While this option is available in Windows, it is not generally recommended because it interferes with being able to double click on a file to play it in a media player.

I simply drag a downloaded MP4 video out of Win File Manager (or Explorer) and drop in into Audacity where is opens lickety-split. From there you can edit it or Export to MP3 right away. This instead of using the context menu in Explorer.


Good idea, Ed, I’ll try and remember that. Fortunately, I have dual monitors!
● Just to apply the “Think User” rule for a moment: Is there some way you can tell your users that they can use Audacity to extract audio tracks from movie files? I wasted so many hours doing it the hard way, and only came across using Audacity by accident after several exhausting searches on Google for MP4 to MP3 converters…
● Perhaps a “Tips and Tricks” popup, or mailer? As I always thought of Audacity as something that processed existing audio files, it just didn’t occur to me that it would extract audio from MP4 videos.
● Another possible: How about a SEO-optimised “convert_mp4_to_mp3.php” page on your web site? Judging by the 218,000 pages in Google already covering this topic, it’s a popular one!
Over to you!
Best wishes, Ed, and God bless you.
Philip Tory, Gloucester, England.

On the website “About > Features > Export and Import” it says:

Import and export AC3, M4A/M4R (AAC) and WMA with the optional FFmpeg library (this also supports import of audio from video files).

In the “Getting Started” guide in the manual
(Getting Started > Learn how to: import and play an existing audio file)
it says:

For most other cases (including audio from video files), you can install the optional FFmpeg library to import your file,

In the main Audacity manual:
Front page > Audacity Foundations (in the “Using Audacity” section) > Importing audio
it says:

Audio File Formats Supported by Audacity

The audio formats importable by Audacity as shipped are:

  • Uncompressed audio formats: most WAV and AIFF files including all PCM variants.
  • Compressed audio formats: Ogg Vorbis, FLAC, MP2 and MP3.

You can install the optional FFmpeg library to import a much larger range of audio formats including > AC3, AMR(NB), M4A, MP4 and WMA > (if the files are not DRM-protected to work only in particular software). FFmpeg will also import audio from most video files or DVDs that are not DRM-protected. On Mac only, Audacity can import M4A, MP4 and MOV files without FFmpeg.

In the FAQ, under “Opening and Saving Files”, it says:

Can Audacity import or export formats like WMA, AC3 or iTunes files (M4A/MP4)?

Hello Ed.
1: Like you said, “Getting Started > Learn how to: import and play an existing audio file”. . . But I want to process an MP4 video file, not an audio file, so I’m not going to read this.
2: “Import and export AC3, M4A/M4R (AAC) and WMA”. This doesn’t mention MP4, so I’m not going to look for it here, am I?
3: “Getting Started > Learn how to: import and play an existing audio file”. MP4 isn’t an audio file, so I’m not going to read this.
4. “Audio File Formats Supported by Audacity”. Again, I’m looking for help on video files, not audio, so I’m not going to look here.

As a former Software Product and Usability Manager, and a Technical Writer for 20+ years, one of my main adages to programmers was, “Don’t Make Me Guess!”

Recommendation: One of the biggest drawbacks of the full Audacity Manual is that it doesn’t have a full Search facility.
The Index is only a Table of Contents that lists the titles of each ‘page’; it does not index the key words in the content on each page.

In my career as a Technical Author, I created many RoboHelp online Help Guides for my clients, and these always included (a) a full Search on manually-tagged keywords, and (b) a full search for any word in the text. This provided a Search Engine for the entire Help Guide, and my Clients said this was the most useful feature for their customers. Can you imagine using the internet without search engines? The user would have to guess their way through the entire world wide web.

Can the Google search tool be appended to your Manual ( I wonder? I’ve copied across most of the main content pages, without the drill-downs, and I already have 61 pages of A4, Arial 10pt, and 25,000 words. Trying to find anything by reading every page just won’t work.

Ed, I ran Technical Writing Courses internationally, across Europe and as far from the UK as India and the USA.
You can have a free copy of my Technical Writing Course here or here . Do pass it on to whoever you think might benefit from it – I’m retired now, so it’s FREE!

I do hope this is helpful. I want this to benefit all Audacity users.

Best regards,
Philip Tory, BSc(Hons).

You could have tried:

Yes, but that ASSUMES that the user knows that Audacity processes MP4 video files! And we don’t!
As the saying goes, when you ASS|U|ME something, it makes an ASS of U and an ASS of ME!

Enjoy the tech writing course.

Philip, one learns Audacity by using it, making mistakes, reading the Help file, and having discussion in the User Forum. I’ve learned it over 3 – 4 years period, and some years before with earlier versions.

If the FFmpeg subroutine is unpacked and Audacity linked to it, you can simply Drag 'n Drop MP4 video files from Windows File Explorer into Audacity and it will quickly extract and render the audio track(s). I usually select three Flac files and drop them on Audacity and they open in separate tracks.

It doesn’t get much slicker than that. Lol


You asked if there was some way that we could inform users about MP4 support. I indicated in my previous reply, there are multiple references to MP4 support in the documentation. The documentation covers a vast range of material, and it is not possible to give priority to everything. If you can’t find the information about Audacity that you need, then we are happy to try and help - that’s why we have this support forum.

Yes, that’s long been a bugbear for us :frowning:

The irony is that we have a search function in the alpha Manual when we edit it - but the released Manual loses that for some technical reason that I can’t fathom.

_Top tip: Since the alpha manual is based heavily on the preceding released manual try searching in the alpha manual to show you where to look in the released Manual:

Alpha Manual:_

Yeah, sorry about that - it was even worse till I did a bit of work on it recently (including the blocking off into alphabetical sections). It would be a lot of hand-crafted work to expand it further - and frankly I don’t think I have enough time for that as I have to combine editing the manual with QA testing (this is my hobby not a “job”. :wink:

We did try an automated index tool a while back - but it was a bit of a disaster … :frowning:

Are there any particular terms you would like me to add :question:


There’s a twofold reason for that:

  1. The search engine that the development manual uses searches the database that drives the (MediaWiki) site. When we publish the release manual, the manual is “flattened” to plain HTML, so there is no database.

  2. The majority of users use the manual that is shipped with Audacity (and is installed locally). While there are search tools available for plain HTML sites, they all involve some sort of active scripting, but for security reasons most scripting languages are severely crippled by the operating system (Windows, macOS and Linux) when the site is running locally.

That’s not to say that it’s impossible to provide search for local HTML. In fact, most operating systems have built-in search tools that can be configured (by the user) to search the directory where the manual is installed. I tried this a while ago with a standalone document search tool, and it worked pretty well, but there’s another solution that I found even easier, and that was to use Google to search the on-line manual. The magic search terms are:

site: "thing you are searching for"

I have the same problem. I tried all the approaches which are shared, still could not solve it. Thank you.

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