Exporting in FLAC

I frequently record 4-5 hour sessions. When I export a session in WAV there’s no problem – all of it gets saved and the file works fine. However when I export in FLAC the file contains the first 3 hours (2gb file size) only. The rest of the session doesn’t get saved at all. Am I missing a setting somewhere? Is there a time limit or file size limit?

As it says at the top of the page in pink:

If you require help, or think you have found a “bug”, please post on the forum board relevant to your operating system.

So please start by telling us your exact operating system and how you are encoding the FLAC (what menu items and buttons you press to make the export).

As far as I understand it there is a long-standing bug in the FLAC command-line encoder flac.exe for Windows that due to Microsoft limitations it does not support encoding files greater than 2 GB. This is despite that the FLAC format does not have an explicit file size limit.

I did not think Audacity suffered from that issue if you exported using “FLAC Files” rather than using (external program). Please confirm.

Note that not all players will play WAV files larger than 2 GB.


I’m still fairly new to Audacity so I didn’t know if I had it set-up right or not. At this point I didn’t consider it a bug as I didn’t find much else on the forum about this. I made the assumption then that the problem was unique to my machine/application – not that there was something universally wrong with Audacity. Hope that makes sense.

The operating system that I’m using is Windows 7 Ultimate 64-bit. To export, I choose File/Export/FLAC. FLAC is set for level 8, and 24-bit.

Being new to this type of thing I wasn’t aware of the Windows/FLAC limitation. That would certainly explain why anything larger than 2gb doesn’t get saved. Sounds like I won’t be using FLAC any more unless there’s a work around.

Thanks for the heads-up on the players/wav/2gb possible limitation.

Thanks, but if so it would be even more important for you to post in the Windows, Mac or Linux board so at a minimum we know automatically what operating platform you are on.

OK I can confirm on Windows 7 that even using “FLAC Files” rather than (external program), exports are truncated at 2 GB.

Audacity on Mac OS X can export FLAC above 2 GB using “FLAC Files” and I would assume it can do so on Linux. So I’ve moved this to the Windows board for 2.x now.

If you can get 3 hours from a specific 24-bit FLAC export then you should be able to get about 4 hours 30 minutes by choosing 16-bit FLAC export instead.


Thanks for the info.

From what I’ve read, the sound quality between 16 bit and 24 bit is barely discernible. But for archive purposes I would prefer to keep the master at the highest quality level possible, so I’ll just save everything in WAV – Storage space on this machine is not a problem.

Thanks again for the help.

What I still don’t quite understand is if you are exporting 24-bit WAV stereo at 44100 Hz, you won’t get a lot more than 4 hours within even the 4 GB WAV limit.

Compressing data that would produce a 4 GB 24-bit WAV to 24-bit FLAC should not produce a FLAC file much over 2 GB, assuming the same sample rate (because FLAC should achieve about 40% - 50% compression).


You are correct in that my WAV files are real close to 4gb. At 50% compression my file size would be 2gb. At 40% the file size would be 2.4gb. So I must be getting a little less than 40% compression in order to be coming up better than an hour short.