I use an external mono microphone in a digital recorder. With the recording mode I’m using, the recorder outputs stereo tracks anyway, however, the right and left channels are exactly the same. I’d like to convert the recordings to mono, as they would take up half the space of the original stereo ones. I can take the steps - tracks - Mix - Mix Stereo Down to Mono, and to my ears, the new mono files sound exactly like the original stereo ones. My question is though, has the mono file lost any of the original characteristics, or is it otherwise different or worse?
I need to know, as I submit bird recordings for scientific research, and if the original files are better, I’ll have to deal with the extra space.
If the left & right are identical the mono mix should be identical to one channel.
…I’m pretty sure Audacity does it “correctly”. Mixing is done by summation, so the left & right samples (44,100 samples per second, etc.) are added together, and then to prevent the volume from doubling, the samples are halved. The end result is an average and when you take the average of two identical numbers you get the original number.
…Analog mixers are built-around summing amplifiers but every input has a level control and there is a master level control so you’re getting a weighted average. Same thing when you mix digitally in a DAW application.
That’s true for uncompressed audio but compression algorithms are smart-enough not to duplicate the data. A dual-mono FLAC is the same size as mono. With MP3 the file size is determined by the bitrate/quality setting but dual-mono doesn’t degrade quality.
However, it’s “nice” if a dual mono doesn’t show-up as stereo when you look at the file properties.
If it helps with the answer, I’m using a Tascam Portacapture C6.
Things just got a little weird. I just connected a mono XLR microphone into one of the inputs and set my source as 3-4. There are two XLR inputs (3 and 4) and I plugged it into #3. Now, however, is still outputs a stereo file, however, one channel’s track is populated normally, and the other has a little noise.
So, If I now Mix stereo to mono, and export the result, the file size is also exactly half the file size as the original. I will call the vendor tomorrow regarding the noise on the right channel, but for now, I’m just checking whether the exported mono file is still a perfectly accurate representation of the full sound. Also, I realize this forum isn’t for recorder support, but does anybody know whether this noise on the right channel that doesn’t otherwise match the left channel is normal for my recording setup?
Please see the spectrogram for what I’m taking about: