Multichannel wav file export is cut

Good day

I can not make the export of multi-channel wav file.
I use Windows 7 64bit sp1 and Audacity 2.0.5

I uploaded the file successfully with duration of about 2 hours and 43 minutes, but the file is cut with a duration of about 39 minutes, I can not figure out where I’m wrong.

Source Files (2h 43’)

Exported file (39’)

Can you kindly give me some advice?

Yours sincerely thank

What format are trying to export as?
The maximum file size for a WAV file is 4 GB (WAV - Wikipedia). 6 tracks at 48 kHz sampling rate, 16 bits per sample for 2 hours and 43 minutes will be a little over 5 GB, so too big for a WAV file.

The sound source is the trace of a movie.
In fact, by exporting in AC3 format I have not found any problem for the duration, the problem is only in the limit of file size.
So I ask how can I solve this limit in Audacity.

Yours sincerely thank

You could select the first half of the project and export that as one file then select the other half and export it as a second file (File > Export Selection).
Alternatively use some other format such as Flac, AC3, Ogg, MP3 …

Unfortunately, I must have a unique file format multichannel PCM, in order to preserve the high quality.

If the author of the program could turn the limit of 4 GB would be a great thing.

The 4 GB limit is not imposed by Audacity. It is a limit of WAV format (see the wikipedia link that I posted).
Flac format is lossless.

Then FLAC exceed 4 gb?
and is equivalete to PCM (wav)?

There is an article here about Flac:

In their wisdom Microsoft decided to not support Flac, but support for Flac in Windows Media Player (and other Windows audio programs) can easily be added by installing the Directshow Filters:

The home page for Flac is here:

FLAC is lossless but has a size limit of 2 GB on Windows: Audacity Manual .

16-bit FLAC will be about half the size of 16-bit WAV, so in terms of total audio length you can fit into the file, FLAC will have about the same length limitation as WAV.

So unless you set FLAC compression to maximum 8 (click “Options…” in the file export dialogue) and are really lucky, your file will be too large. Maximum compression will take a great deal longer to complete and will probably only save a few MB’s.

If the FLAC file exceeds 2 GB, try exporting as RF64 which is essentially PCM audio without the length limitation. Choose “Other uncompressed files” when you export, click the “Options…” button, choose “RF64 (RIFF64)” Header and choose the bit depth in “Encoding”.

Foobar2000 and VLC should play RF64. I don’t know of any solution to make Windows Media Player do so.


Excuse my insistence

But how do I add a track to pcm multichannel larger than 4 GB?

Many HD movies include this type of track.


What do you mean by “add a track”? If you want to make a 7.1 file instead of 5.1, add the tracks in Audacity.

Have you tried to see if the file is under 2 GB if exported as FLAC?

If you must make a PCM file larger than 4 GB you must use RF64, because the WAV specification does not allow more than 4 GB. RF64 is lossless PCM, but it should not use WAV extension, so it has RF64 extension instead. See my post for how to export as RF64.


None. HD movies do not use WAV files.

As Gale suggested you can try RF64.

PCM is a form of encoding, not a file format. The 4GB limit applies to the WAV file format, not to PCM encoding.
RF64 is a file format that can contain PCM encoded audio data and the file size may exceed 4GB.

Thanks Gale. I’d forgotten about that size limitation, though I believe the limitation only applies to encoding on Windows. We had a user a few years ago that produced a 4 GB Flac file on a Linux machine and confirmed that it played correctly in WinAmp on Windows.

Excuse me.
I expressed myself badly, I mean how do you export a multichannel pcm track from Audacity, to muxing (add) this track to a hd video?

I meant to say, linear PCM.

This is the medianfo a Blu-ray

ID                                       : 0 (0x0)
Complete name                            : F:BDMVSTREAM\00004.m2ts
Format                                   : BDAV
Format/Info                              : Blu-ray Video
File size                                : 21.4 GiB
Duration                                 : 1h 45mn
Overall bit rate mode                    : Variable
Overall bit rate                         : 29.1 Mbps
Maximum Overall bit rate                 : 48.0 Mbps

ID                                       : 4113 (0x1011)
Menu ID                                  : 1 (0x1)
Format                                   : MPEG Video
Format version                           : Version 2
Format profile                           : Main@High
Format settings, BVOP                    : Yes
Format settings, Matrix                  : Custom
Format settings, GOP                     : M=3, N=12
Codec ID                                 : 2
Duration                                 : 1h 45mn
Bit rate mode                            : Variable
Bit rate                                 : 21.8 Mbps
Maximum bit rate                         : 35.0 Mbps
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 23.976 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.439
Time code of first frame                 : 00:59:59:00
Time code source                         : Group of pictures header
Stream size                              : 16.1 GiB (75%)

Audio #1
ID                                       : 4352 (0x1100)
Menu ID                                  : 1 (0x1)
Format                                   : PCM
Format settings, Endianness              : Big
Format settings, Sign                    : Signed
Muxing mode                              : Blu-ray
Codec ID                                 : 128
Duration                                 : 1h 45mn
Bit rate mode                            : Constant
Bit rate                                 : 4 608 Kbps
Channel(s)                               : 6 channels
Channel positions                        : Front: L C R, Side: L R, LFE
Sampling rate                            : 48.0 KHz
Bit depth                                : 16 bits
Stream size                              : 3.40 GiB (16%)

Audacity just exports the file as you have done it already. You have to use a Blu-Ray authoring program to make the Blu-Ray disc. We can’t help you with that here.

As I understand it, but don’t take it as definitive, 5:1 LPCM channel mapping on Blu-Ray is L R C LS RS LFE - but most authoring programs will remap from the 5:1 WAV mapping of L R C LFE LS RS. Therefore the MediaInfo readout is not the channel mapping order - it always groups the positions Front then Side.


Thank you for this information.
Now I have the ideee clearer on this concept.

Yes I “think” it is only a problem with the FLAC encoder - and they seem to think it only “priority 7” to fix it: FLAC-Free Lossless Audio Codec / Bugs / #306 Windows >2GB file sizes :frowning: .

But I’ve seen some reports that > 2 GB FLAC files encoded on Linux won’t play in Windows Media Player where smaller ones will (with the appropriate DirectShow filter installed).

So until I try it myself I won’t document exactly what works and what doesn’t.