Bit Depth Conversion

[kozikowski]

Audacity 1.2, Any platform. I know how to change a clip sample rate with the little window at the bottom-left. How do I change the bit depth? I've actually done this once and I don't remember how. Google doesn't remember, either. I have a 32-bit clip that I need in 16.

Koz

[waxcylinder]

Can you do it by exporting and downsampling on export to 16-bit WAV - and then import the 16-bit bit to replace the original 32-bit clip?

WC

[kozikowski]

I remember this problem.

What do the three numbers on a work panel mean, the two numbers left of the timeline and the sampling number at the bottom left? the one lower left clearly isn't the Project sample rate because I can change it at will and the show try to follow me. That's not the sample rate listed in Preferences. So I can have four sample rates; the one in Preferences , the on on the lower left, the one the clip arrived in and the Audacity internal one. Did I get that?

I'm also remembering the bit depth conversion job I did wasn't in Audacity because I couldn't figure out how and/or I couldn't get the inspection tools to line up. QuickTime Pro Inspection tools keep disagreeing with Audacity.

"You may think you're in 24-bit, but QTP thinks you're in 16."
Or worse,
"You may actually have a 24-bit file, but the file header thinks it's 32."
Or far worse,
"You have a 16 bit file padded to 24 with a 32 header."

Koz

[steve]

Audacity 1.2, Any platform. .... How do I change the bit depth?

To change the bit depth of a track: Click on the track name and select the required bit depth on the "Set Sample Format" sub-menu.
To Change the bit depth when Exporting in an uncompressed format: Select the required bit depth in the Export dialogue (Audacity 1.3.x)

What do the three numbers on a work panel mean,

Screenshot please.

So I can have four sample rates; the one in Preferences

This is the default setting for your projects. Unless you override it, this is the sample rate that will be used.

the on on the lower left

This is the current project sample rate. This can be changed at any time and is taken as the default value when Exporting.

the one the clip arrived in

When you import audio into Audacity 1.3.x it retains its original sample rate. This is displayed below the track name and is the sample rate of that audio track.

and the Audacity internal one

I think this is the same as the "current project rate" (as indicated in the box in the lower left of the main Audacity window), so, unless you know otherwise, that's 3 not 4.


Note that if you import audio into an empty project, the project rate (as displayed in the lower left of the main Audacity window) will change to match the imported audio. This is based on the (reasonable?) assumption that you will be intending to use that sample rate for your project. While I think this is a reasonable assumption if only one audio track is being imported and worked on, it can get messy for anyone that is assembling a multi-track project from many different audio samples.

"You may think you're in 24-bit, but QTP thinks you're in 16."
Or worse,
"You may actually have a 24-bit file, but the file header thinks it's 32."
Or far worse,
"You have a 16 bit file padded to 24 with a 32 header."

That's not really an Audacity issue. When you export a 32bit (float) WAV file from Audacity, it is 32 bit (float). When you Export a 24bit WAV file, it is 24 bit. As far as I'm aware the header information supplied by Audacity is also correct. IIRC there were some issues with the Flac encoder, but I think these may have been fixed in recent releases of the Flac encoding library.

[kozikowski]

<<<To change the bit depth of a track: Click on the track name and select the required bit depth on the "Set Sample Format" sub-menu.
To Change the bit depth when Exporting in an uncompressed format: Select the required bit depth in the Export dialogue (Audacity 1.3.x)>>>


Nope. I opened up my 48000/16 sound file in Audacity 1.3.7 (hours old) and exported it after changing the timeline name panel dropdown to 32. The Actual Export step has no options.

Quicktime Pro INFO reports the new (and improved) sound file is 48000/16.

Koz

[steve]

Nope. I opened up my 48000/16 sound file in Audacity 1.3.7 (hours old) and exported it after changing the timeline name panel dropdown to 32. The Actual Export step has no options.

What format are you Exporting as?
I usually Export as "WAV (Microsoft) signed 16 bit PCM", which unsurprisingly produces 16 bit WAV files.
If you select "AIFF (Apple) signed 16 bit PCM", then you should get the same result - 16 bit files.
If you select "Other uncompressed files" there is a list of formats for various bit depths.

Exporting in compressed formats can be something of a different issue as, for example, using very high compression ratios for MP3 files, the Exported file will be resampled if necessary to achieve the set compression amount.

[kozikowski]

<<<What format are you Exporting as? >>>

WAV across the board.

<<<"Other uncompressed files" there is a list of formats for various bit depths.>>>

That's the spell! So bit depth and format are in that panel and sampling rate is the panel in the lower left of the edit window.

This is me writing that down.

I think we covered this next one before. Where is INFO? I imported a sound file and it plays. What was it?

Koz

[steve]

Where is INFO? I imported a sound file and it plays. What was it?

You mean information about the format of the file that you have just imported? lol - that's the tricky one. As far as I know Audacity does not give any information.
Could this be a "Feature Request" for incorporating MediaInfo into Audacity?
That could be a really good idea.