[NO SOLUTION] Recorded a 2.5 hour session, and after stopping, only 39 minutes show up

We recorded a session of our podcast for about 2.5 hours, and during the recording there were waveforms. Four of us recorded in mono on separate computers with separate mics, all using Audacity.

One of our guys is pretty sure he remembers seeing his wave form when we did a clap sync about an hour and a half in, but when he stopped recording at the end to export, he discovered that it only seems to have recorded 39 minutes.

The aup3 project file size seems a little strange. At first it was 1.7 GB. My file (which is complete) was around 1.68 GB as well. However, he recorded at 192 kHz, and I recorded at 44.1 kHz. Both are about 32-bit. I did the math, and it works out to be about the same if his file is inherently going to be 4x longer.

After I downloaded the file, I observed it was 1.7 GB. I then opened the file, and looked at it. I confirmed that it only contains 39 minutes of audio. I exported the file as a wav, and then closed the aup3 project file. Then I noticed that it had become 1.82 GB (120 MB more).

Is there any way to recover the audio, or do we need to re-record completely?

I don’t know exactly what happened but WAV files have a 4GB limit (the only format I know of that has a limit). There is 32-bit file-size field in the header, which means it goes-up to 32GB.

Depending on the software, if you go over, usually the file-size rolls-over and re-starts at zero. Sometimes it continues and you get all the data but the file size is wrong and you can’t open the whole thing unless you import as raw data.

There are 8-bits in a byte, so at 32-bits that’s 4 bytes per sample. 192K samples per second works out to 2.7GB per hour so I think that’s the root of the problem.

But unfortunately, if the file isn’t larger than 4GB, it’s not all there.

The WAV file should not have come anywhere close to 4 GB. It was the aup3 project file itself that was 1.7 GB. The WAV we exported was only 220 MB. Do aup3 files have a file size maximum?

To clarify, it’s not just the exported files that have the issue, it’s the project file itself which is missing audio. The audio it contains is only the first 39 minutes.

I don’t think AUP3 projects has any artificial limits. They can be MUCH larger than 4GB.

If your AUP3 is short/incomplete, that’s NOT the problem.

If you export at 192kHz, 32-bit mono, I calculate almost 7GB.

…Computers are the least reliable things we own. :frowning: With audio recording, there are lots of settings that can get messed-up and the multitasking operating system often gets in the way. With 4 computers that’s 4 times the chance of something going wrong.

It helps to have a dedicated computer that doesn’t get used for anything else.

For important recordings where there’s no chance of “take-2”, I always recommend a back-up system recording in parallel. That can be another computer, a cell phone, or a solid state recorder, etc.

Solid state recorders (or a “portastudio”) are probably the most reliable. Cell phones are probably more reliable than computers and the microphone is usually very good, but the mic is non-directional so it picks-up room noise from all directions, and you need some kind of stand-holder to position the phone.

Even with a solid state recorder, you’d want a back-up for anything critical.

…Back in the analog days, with a 3-head reel-to-reel machine you could monitor the tape a fraction of a second after it was recorded. With digital, you often don’t know there was a problem 'till the next day. Of course, that required an engineer/sound guy running & monitoring the tape machine. And digital is technically superior in so many ways that I wouldn’t want to go back!

This was a broadcast radio interview I shot.

I’m the gold microphone and Audacity on the left. The backup recorder is on the right. Both survived. They broadcast my recording with no changes.

You don’t have to go nuts, either. This is my iPhone SE doing a voice recording on my desk.

It can produce an audiobook submittable track with very little processing. Of course, it can’t ring in the middle of the performance…

In separate locations? Zoom will be happy to record your work on their servers.


Did they do that a goal in mind? Even recording studios rarely go above 24KHz.

Are you trying to live record on an operating and connected Zoom machine? Competition for system resources with Zoom rarely comes out well. Zoom made its reputation in part by being bulletproof. It takes over your machine and you have nothing to say about it.

I see you answered that already…


While the show is still on the timeline, you can listen to the whole thing?

I think I would be setting up to record street traffic or something and see if the recording goes over 39 minutes. If that succeeds, set up again and leave it going for 2.5 hours.

If that fails, find out what the magic time is.

And speaking of magic, Audacity doesn’t much like being connected to non-internal drives. You can do some serious damage by trying to do production on a cloud drive.

If you’re doing the show in Zoom, disconnecting a cloud drive might be pretty interesting. You should make it so Audacity can’t see it.


Is it possible that there’s a sample rate mismatch between Audacity and the mic (or the mic drivers or whatever)? Perhaps Audacity thinks it’s recording at 192 kHz but the mic is recording at only 88.2 kHz. So an 85-minute show would end up being recorded as 39 minutes long in Audacity (every recorded second ends up being only about 0.46 seconds in Audacity—88.2/192 ≈ 0.46).

When the show is played back in Audacity, does it sound like chipmunks talking? If it does then try changing the track’s sample rate down to 88.2 kHz (or try other sample rates if that doesn’t sound right either).

The wav was not that large. It is only 39 minutes though (just like the project file and the mp3).

I don’t know what rate the wav exported at. When I mentioned 192kHz I was referring to the project rate in Audacity.

It may be possible, though this is not the first time we’ve recorded with this set up. It’s roughly the 70th episode we’ve done.

  1. Unfortunately, no, we can only see, listen to, interact with, and export 39 minutes. The whole project only contains 39 minutes, and this entire length exports when we sent it to MP3 or WAV.
  2. This isn’t the first time we’ve recorded on this set up, though he recently upgraded his computer to Windows 11 (from 10). I’ll see if he can set up something like this to make sure it’s even possible to record that length before we record next.
  3. He recorded and saved to an internal drive. It’s a desktop computer, and we were not trying to write to any cloud services.
  4. We were not doing the show in Zoom.

We were not using Zoom.
I don’t know why he records at 192, he said he prefers it. The rest of us use 44.1, which is the default setting on our Audacity installations.

We are discussing a way to implement this.


I removed part of your post up the thread. The forum doesn’t like naughty language.


I’m picturing four tea carts around a dinner table with desktop computers connected to monitors and microphones in front of each performer.

We have to build your system in our heads to figure out what’s going on. The more info the better.

Pretend you need to tell someone how to set up exactly the same system you have.

Are you all on Windows? Did you all do an Evil Windows Update the night before?

It’s not rocket surgery. Put your phone on Airplane Mode, set the local voice recorder running, place the phone on the desk with its butt ( or wherever the microphone is) pointed to you. At worst, you might get paper shuffling in the background. That will be far better than what you have now: Flatline Nothing.


I’m not joshing. This is a two-versions old iPhone SE plugged into a wall wart for power.

The microphone is on the bottom—aimed toward me. I recorded (in my quiet, echo-free room) a voice test that easily passes audiobook sound standards.


That makes sense, sorry - didn’t think about that until after I’d posted it. I was in between things at work and checking this out to see if I could provide any more info.

Here’s a better version (with a different name and more info)

The reason I didn’t include any additional information is because there’s nothing else that was pertinent to the way that we record. We’re in separate locations, on a call together over the internet (though not on Zoom), but as far as our recordings go, all of them are entirely isolated and disconnected from the internet. Each of us uses Audacity with default settings and with our respective microphones connected.

At the end of the day, as far I understand, the only thing that matters for the setup is that he was recording in Audacity. Nothing else about what we were doing was affecting the recording.

I know that he recently did an update from Windows 10 to Windows 11, but I don’t know when exactly. I can’t say specifically about whether he did a recent update.

I appreciate the suggestion, but respectfully, I’m not asking for suggestions on how to do backup recordings. I’m only looking for some help figuring out whether the audio from his Audacity project is recoverable.

Based on the research we’ve done, it sounds like it isn’t. We’ve decided to re-record the session.

Before you check the machines?

There are enough holes in this posting to make me wonder about a bogus post. You’re not really recording a four-way podcast are you? You’re just enjoying watching us struggle to solve an impossible problem.

Did I hit it?