"Mix+Render To New Track" Lossy?

[nileswinscombe]

Hello all, thanks for Audacity.

My ears tell me it is lossy, whilst exporting to wav and re-importing is OK.

When I alter the the gain slider of a stereo track and then use Mix and Render on it, the resultant waveform on the "mixed" track has altered accordingly.

[kozikowski]

Isn't there a setting to mix and render to a new, separate track?

Which version of Audacity are you using?

Koz

[Gale Andrews]

Please, have a look at the pink panel at the top of the page and fill in the information requested.

My ears tell me it is lossy

Can you say in what way exactly it sounds lossy?

When I alter the the gain slider of a stereo track and then use Mix and Render on it, the resultant waveform on the "mixed" track has altered accordingly.

Would it not be a bug if the waveform had not altered?

Try this. Edit > Duplicate your stereo track.

Effect > Invert the duplicate track. The samples in the two tracks will now cancel each other out exactly and when you play the project you will hear silence.

Edit > Select > All, then Tracks > Mix and Render to New Track.

Select the new mix track, Effect > Amplify... . You should see a New Peak Amplitude of "Infinity" which means the mix track is absolute silence. If the output of mix and render was lossy, there would not be absolute silence.


Gale

[steve]

(Assuming that you have the current version of Audacity)
If your "Quality" preferences are at their default settings (32-bit float), and the project rate is at least 441000 Hz, then Mix and Render is not lossy.
If you have changed the Quality settings to 16-bit, then Mix and Render is very slightly "lossy".
If your project rate setting (bottom left corner of the main Audacity window) is very low (below 44100 Hz), and your tracks have a higher sample rate, then there will be losses due to the reduced sample rate.
In other words, no, Mix and Render is generally lossless (unless you have made some bad settings to cause it to be lossy).

[nileswinscombe]

I am using Installer version of Audacity 2.1.0 in Windows7. Exporting a mix of several tracks sounds better to me. I don't know how to verbally quantify this, in the same way that I can tell flac from wav but the number crunchers say I shouldn't be able to.

Here is an after the event query. Change the gain slider on a track and then duplicate the track. The waveform does not change on the original's display nor the duplicate's. I've read this is because the Gain adjustment does not change the data. This leaves me wondering why the waveform changes when mixing and rendering the same track with altered gain to a new track within Audacity? When all that has changed is the Gain slider setting.

[steve]

I can tell flac from wav but the number crunchers say I shouldn't be able to.

Have you tried ABX testing? (see: http://wiki.hydrogenaud.io/index.php?title=ABX)

Change the gain slider on a track and then duplicate the track. The waveform does not change on the original's display nor the duplicate's. I've read this is because the Gain adjustment does not change the data.

That's correct.

This leaves me wondering why the waveform changes when mixing and rendering the same track with altered gain to a new track within Audacity?

Because when you Mix and Render, the gain change is applied to the audio data, so the data does change, and that change is visible in the waveform display.