Query about 16-bit and 32-floating bit (solved)

I have Audacity set at 32-floating bit. But when I make recordings, the final file, when loaded again into Audacity, indicates a 16-bit file. What am I doing wrong?



What format are you exporting as?
What format do you want the final exported file?
(Note that when you use “Save” in the Audacity File menu, it saves an “Audacity Project” which is not an “audio file”. To create an audio file you must “Export” from Audacity.)

I export it as an ogg file.

Lossy formats such as Ogg, MP3 and so on, are a bit different from lossless formats such as WAV, AIFF, FLAC in that they do not aim to preserve the data integrity, but rather preserve the subjective sound quality. As such, they don’t have “bit depth” in the same way that lossless formats do, but rather just have “bit rate”, which is the number of bits per second - usually written as kbps (kilobits per second). The effective bit depth in an Ogg file changes dynamically according to the perceptual model algorithm. Converting from Ogg to 24 bit or higher PCM format would sound no better than converting from Ogg to 16 bit PCM, even at the highest quality Ogg settings.

By default, Audacity tries to import all audio as 32-bit float, which is best for processing the audio, but due to a limitation in the Ogg importer, Ogg files are imported as 16 bit. The same applies to importing compressed formats with FFMpeg. (see this section in the manual: http://manual.audacityteam.org/o/man/quality_preferences.html#sampling).

Ideally you should use a lossless format throughout the production process and if a compressed file is required for the final project, export in that format at the end. It is also highly recommended for important work to also export a high quality backup in a lossless format.

If you have to use Ogg files in a project, I’d recommend converting the track to 32 bit float format as soon as it has been imported. This will not change the sound quality at all, but it will allow higher quality processing in Audacity. See “Set Sample Format” in the Track Drop-down Menu: http://manual.audacityteam.org/o/man/track_drop_down_menu.html

Thank you for the info Steve. I guess this leads me to a final question: what is the best format (and settings) to use to get the best quality audio file, yet not too big for my website demos?

Thanks again,

For very short audio extracts you could use WAV format, but note that they weigh in at around 10 MB per minute for CD quality.

For longer tracks, Ogg can produce excellent quality at around 3 MB per minute, or good quality at around 1 MB per minute (exact size depends on the audio).
Unfortunately, a lot of people do not have the necessary codecs installed to play Ogg files, so if you feel evangelical about open source it would be worth also adding information and a link about how to play Ogg files (http://www.vorbis.com/)

MP3 is the de-facto format for Internet audio, in spite of its limitations and license restrictions.

Ok, very last question: since I prefer the .ogg format, how can I set Audacity so that I have the highest quality ogg file?



When you export from Audacity, in the export dialogue screen; select “Ogg” as the file type and then click on the “Options” button. 10 is highest quality (biggest file size) and 0 is lowest quality (smallest file size). Not that the default setting of 5 gives pretty good quality and much smaller files than 10. I’d highly recommend that you try different settings to find the best compromise between file size and sound quality - the difference in sound gets smaller as the setting goes up because the sound quality is already good.

Perfect! Thanks a million Steve! :slight_smile: I’ll do some tests saving the same recording at different qualities and see what I like best.

If there’s any way I can help future development (such as testing) just let me know. Audacity’s a wonderful app! :wink: