Hi,
I am experiencing problems with exporting multiple tracks. After recording a whole Mini Disc in one stereo track I labeled every song with Ctrl + B and named them, then I chose export multiple… and selected split files based on labels. What I get is the right number of tracks. Only that at the end of each track there are 1-4 seconds of the beginning of the next track included (labels are at other positions!). These parts are not missing in the next track, so that when listening to all songs in the recorded succession I hear the first seconds of each song twice (except the first song). Do not know if this is part of the problem but to achieve the right pitch I first had to record in 48kHz and then switch to 44.1kHz (see Topic: “records from optical-in too fast”). It is reproducable, I recorded two discs and exported them, both show this error.
Any ideas how to prevent this, without having to export every song separately?
Thanks in advance!
Resample the track to 44100Hz before doing the export. To do this, select the track, set the Project Rate to 44100Hz, and do Project > Quick Mix to re-sample the track. It will take some time, but will save that time back on the export.
Well, I was wondering if there is a quality loss by downsampling in this way!? I know normally there is, but in this case it is a bit weird because of the way I am recording (see Topic: “records from optical-in too fast”). What I mean is, I am recording from a 44,1 kHz-source. But my soundcard delivers it in 48kHz, so that I am recording in 48kHz and playing back at 44,1kHz to get the right pitch. Before I discovered that the recordings have loops, I exported them to wav-files just by switching the sample rate of the track, without changing the project rate and without doing the quick mix. In that way the wav-files were in 48kHz with right pitch. I do understand that this is not 48kHz quality, because the source is in 44,1kHz. But I didn’t alter the track and therefore keeping quality at whatever quality.
Downsampling the recorded files normally means loosing data and the recorded file won’t contain more information than the source, right? So, am I reducing quality by downsampling this (recorded) “virtual” 48kHz track to 44,1kHz.
What I try to say is: The recorded 48kHz track just contains the information of a 44,1kHz-track. By downsampling it to 44,1kHz, I will get a track with the information of a 40,2kHz-track (= 44,1kHz - (48 - 44,1kHz)), right???
Does this make sense or am I completely wrong in my understanding?
Yes, re-sampling from 48000Hz sample rate to 44100Hz sample rate will loose some high-frequency information (in theory between 22 and 24 kHz). However if you are producing content for CD, you don’t have a choice about the sample rate, because the sample rate is set by the CD standard to 44100Hz. Thus if you are recording at 48000Hz (because that’s all your hardware is capable of), you have to re-sample.
In the strange special case you are talking about, you aren’t re-sampling. When you change the track sample rate using the “Set Rate” command, all you do is change the information in the project on what sample rate to play the data at. This will always cause the audio data to become 1.09 (48000/44100) times longer. This has no effect on the sound quality because the data hasn’t been modified. Because your original data was sampled at 44100 Hz, it only contained frequencies up to 22kHz. So after the trip through to your computer in principal it still retains the same range of frequencies up to 44100Hz. Note that either way you have to put the labels in after you have changed the track’s sample rate, because of the change in the length of audio that occurs.
If you then want to export from the project you have two choices:
You want files sampled at 44100Hz. You change the project rate to 44100Hz, and export, with the selections in the right place.
You want files sampled at 48000Hz. You change the project rate, quick mix to re-sample the data, and then export in order to avoid overlapped selections.
When you change the track sample rate using the “Set Rate” command, all you do is change the information in the project on what sample rate to play the data at. (…) This has no effect on the sound quality because the data hasn’t been modified.
Ok, when I use the “Set Rate” command, I do not alter the quality. But to avoid the overlaps I changed proceedings according to your first reply. Maybe your last reply already answers my next question but I am unsure about it and do not want to spend time for nothing, so I ask again.
The following is what I do now:
record the 44,1kHz source at 48kHz
change the project rate to 44,1kHz
do the quick mix
Do points 2 to 3 alter the quality? I am wondering because audacity spends about 10min on it for a track of 73min.
Oh, and thanks so far!
The quick mix does reduce the quality, but you can skip it by just setting the project rate to be 44100Hz instead (the track rate and the project rate then match, no need to do quick mix).
do you mean that Quick Mix will always reduce quality - or only just in the special case above whre rate changes are applied?
If for instance I record one side of an LP in one track and then side two in a second track - if I then use Quick Mix (Or Mix & Render in 1.3) will I get reduced quality? Should I just leave the audio in the two tracks and work with it that way?
Just the case where the sample rates don’t match, and so resampling is going on. Running a quick mix to merge tracks at the same rate has no effect on the quality, because all it is doing is adding and multiplying floating point numbers for each sample.
The quick mix does reduce the quality, but you can skip it by just setting the project rate to be 44100Hz instead (the track rate and the project rate then match, no need to do quick mix).
Thanks a lot, that works, much easier than I thought!