Trouble downsampling audio in VirtualDub prior to compression

[rmiller3]

I started recording with OBS and it seems to have recoded my audio in the following format. I'm ultimately just trying to compress it into a pretty small file (24Kbit/s, 24000Hz, Mono).

If I try to just keep it raw PCM and use the conversion option in virtualdub to downsample, switch it to mono, or convert it to 8bit or 16bit, it gives me an error:

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VirtualDub Error
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Cannot convert audio: the source audio format is not supported (must be 8-bit or 16-bit PCM).

I did see this thread from several years ago which was a bit hard for me to follow. I assume much of the discussion is irrelevant since it seems my audio is just PCM. Plus, virtualdub can play the audio fine, and I can edit my video fine as long as I don't compress. https://forum.videohelp.com/threads/...ith-VirtualDub

I did get it to compress using some online converter just for sanity. Any idea how to get VirtualDub to get it to work?

I'm using an older version presumably (build 44282 from 2020), but I don't expect this would've changed much.


File info:

From VirtualDub file information:

Audio:
Sampling rate: 48000Hz
Channels: 2 (Stereo)
Sample precision: 32-bit float
Compression: PCM (chmask 3)
Layout: 5774 chunks (1.37s preload)
Length: 378379200 samples (2:11:22.90)
Min/avg/max/total frame size: 318976/524252/524288 (2956088K)
Data rate: 3072 kbps (0.00% overhead)

From a free online tool (Maztr):

File Summary:

sox WARN wav: wave header missing extended part of fmt chunk
Channels : 2
Sample Rate : 48000
Precision : 24-bit
Duration : 00:02:01.50 = 5832000 samples ~ 9112.5 CDDA sectors
File Size : 46.7M
Bit Rate : 3.07M
Sample Encoding: 32-bit Floating Point PCM

Full Details:

File Detail
sox WARN wav: wave header missing extended part of fmt chunk
Samples read: 11664000
Length (seconds): 121.500000
Scaled by: 2147483647.0
Maximum amplitude: 0.614301
Minimum amplitude: -0.511002
Midline amplitude: 0.051650
Mean norm: 0.036291
Mean amplitude: -0.000067
RMS amplitude: 0.056860
Maximum delta: 0.548948
Minimum delta: 0.000000
Mean delta: 0.010106
RMS delta: 0.017150
Rough frequency: 2304
Volume adjustment: 1.628

Channel Detail
sox WARN wav: wave header missing extended part of fmt chunk
Overall Left Right
DC offset -0.000076 -0.000076 -0.000059
Min level -0.511002 -0.511002 -0.508057
Max level 0.614301 0.614301 0.583200
Pk lev dB -4.23 -4.23 -4.68
RMS lev dB -24.90 -24.91 -24.89
RMS Pk dB -15.71 -15.71 -15.71
RMS Tr dB -54.62 -54.62 -54.62
Crest factor - 10.82 10.25
Flat factor 0.00 0.00 0.00
Pk count 2 2 2
Bit-depth 32/32 32/32 32/32
Num samples 5.83M
Length s 121.500
Scale max 1.000000
Window s 0.050

[ProWo]

Use virtualdub2.
Menu Audio, full processing mode, conversion 16 or 8 bit.
Tested with a 32 bit PCM.

[rmiller3]

That's what I'm trying. VirtualDub2 build 44282. I might try a different build later, but I doubt a different build would change it.

Is it because it's float?

I get the error if I try to do any conversion (or compression) on this audio file (or any audio file captured by OBS). Video compression works.