24 bit input only 16 bit in Audacity

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rjm

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Joined 2004
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Windows 8 64 bit, Onkyo SE-200PCI and Onkyo SE-U33 soundcards, both purport to record at 24 bit 96 kHz.

For some reason the file recorded in Audacity shows up quantized at 16 bit (30 uV LSB) instead of 24 bit (0.1 uV LSB). Audacity project is set to 96 kHZ, and the hardware is set to 24 bit 96 kHz in the Windows control panel and/or the VIA envy device driver control panel (for the SE-200 PCI only, the SE-U33 works off the generic windows drivers).

You can see in the screenshot, showing noise after +70dB amplification, the points are about 0.1 V apart, which, after -70dB, works out to 30 uV approximately.

What am I missing here? Where is my data getting truncated to 16 bit?
 

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rjm

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Joined 2004
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For the record, I bought a copy of Digionsound6 Express from amazon. Long story, but its the updated (win8 compatible) version of the software than came with my Onkyo SE-U33. It records correctly in 24 bit. Its unfortunately only in Japanese. Fortunately, that's not a major problem for me anymore.

The .wav file from the same source as before, exported from digionsound and imported back into Audacity, amplified +70 dB, has no quantization artifacts as they are now below the (analog) noise threshold.

Take home message: do NOT use Audacity to record 24 bit audio in Windows! The files will only be 16 bit data padded out to look like 24 bit numbers.
 

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How about using the procedure outlined in the post - recording in ASIO application and importing the file into Audacity?

IME the "default sample format" in project tab of preferences must be switched to 24bit prior to importing for bit-perfect operation of audacity.
 

rjm

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Joined 2004
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Can confirm that Audacity does not support ASIO, only Directsound and MME.

"Wavosaur freeware audio editor works on Windows 98, Windows XP and Windows Vista"

Any idea if they just neglected to update the homepage, or has the software really not been updated for the last 6 years?

What about Win 8 64 bit support in ASIO4ALL?
 
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