AAC files change sample format displayed at left of track?

[allencmcbride]

I asked a question last year that Gale Andrews answered for me: http://audacityteam.org/forum/viewtopic.php?f=17&t=6418

Based on that, I thought the sample format displayed at the left of each track was just a reflection of one's default settings, telling you that any newly created audio would be in that format, even though the current audio might be in a different format.

But I just noticed that, even though I have my default set to 32-bit, when I import an AAC file, the track's sample format display changes to 16-bit PCM. Importing WAVs, FLACs, or MP3s doesn't do this; the display keeps saying 32-bit no matter what the format of the audio I imported.

Can anyone explain the subtleties of Audacity's sample format display?

--Allen

[kozikowski]

This is me with fresh coffee, waiting on the edge of my seat.

Koz

[Gale Andrews]

I asked a question last year that Gale Andrews answered for me: http://audacityteam.org/forum/viewtopic.php?f=17&t=6418

Based on that, I thought the sample format displayed at the left of each track was just a reflection of one's default settings, telling you that any newly created audio would be in that format, even though the current audio might be in a different format.

But I just noticed that, even though I have my default set to 32-bit, when I import an AAC file, the track's sample format display changes to 16-bit PCM. Importing WAVs, FLACs, or MP3s doesn't do this; the display keeps saying 32-bit no matter what the format of the audio I imported.

Can anyone explain the subtleties of Audacity's sample format display?

The subtleties are (I believe) as I describe. I'm on Windows, where FFmpeg is the only way you can import AAC, and whenever FFmpeg is used to import a file, 16-bit resolution is used for 16-bit files, even if Default Sample Format is 32-bit float. I didn't notice that before, and I don't know yet if this is intended, or is some kind of limitation with FFmpeg, or our implementation of it in Audacity.

Have you installed FFmpeg:
http://www.audacityteam.org/manual/inde ... -Ins#macff

and when you go File > Import Audio what filter do you use to import the AAC file - is it "FFmpeg-compatible files" (which forces FFmpeg to import the file)? If you don't use the FFmpeg filter I believe QuickTime would import AAC, though not being on Mac I don't know if there is an explicit "AAC Files" filter.


Gale

[allencmcbride]

Thanks! This does help me to understand. I hadn't thought about different import filters; I had assumed the only purpose to that drop-down menu in the import dialog was to gray out different files in the display. The AAC files come in at 16 bit whether I use the ffmpeg filter or Quicktime filter (there's no explicit AAC filter). But now I see that if I import a 16-bit WAV with the ffmpeg filter, it comes in at 16 bits too, even with default at 32. --Allen