Audacity Forum

Hi,

After record a sax solo with a external mic on a laptop, only one channel is filled (see screenshot below). Would it be possible to let the mono mic fill both channels? I assume it sounds better after both channels are filled (right?).
Thanks & regards,
Lee

Yes, but.

See all those red marks in your waves? That's where you were too loud and caused overload distortion and clipping damage in your song. You could do a world of good by backing away from the microphone a bit and not have those.

Store-bought music has been heavily processed to sound as loud as possible and you will never be able to play directly into a finished song.

external mic on a laptop

This is where you tell us all about that. Some microphones work directly into mono with no problem but some don't like to do that very much and will cause production problems.


In any event, See that drop-down menu on the left of the track? Split Stereo to Mono.

The music track should play to both sides now.

[X] delete the dead track.

Koz

LeeX wrote: ↑

Sun Sep 30, 2018 8:22 pm

Would it be possible to let the mono mic fill both channels?

Split the stereo track to mono, then delete [x] the unwanted silent (right) channel



In future you can set Audacity to record in 1 Channel (mono), not 2, in Audacity preferences.

BTW that's a lot of clipping you've got there, you should turn the mic gain down to leave some headroom so that doesn't happen.

LeeX wrote: ↑

Sun Sep 30, 2018 8:22 pm

I assume it sounds better after both channels are filled (right?).

It will probably sound better than silence in one ear, but it has no advantages over a proper single channel mono track.
To create a proper single channel mono track, set the "number of channels" in the device toolbar to "1 (mono)".

Also, your recording level is too high, which is why you see those red lines and hear crunchy distortion on the loud parts.

your recording level is too high

You're going to get a double psychoacoustic hit when you fix that. Distortion sounds loud, so you are going to get a volume drop from just recording lower volume, plus the distortion is going to vanish making it seem quieter yet.

There's tools to increase the density and force of the performance in post production. But your first job is to record the performance with no damage.

Start there.

Pay attention that your live performance doesn't start overloading at 50% waves. Some microphone systems do that.

Koz

Thanks so much for the information from you, all of you. It helps a lot.

After select "Split Stereo to Mono" and delete the dead track, both channels output sound now. This request has been resolved.

Two follow-up questions if you don't mind...

(1) Audacity Help shows:

"If your recording device is mono, such as most microphone ports for the inbuilt sound device,
selecting "2 (Stereo)" in Recording Channels duplicates the mono source to both channels,
merely producing a dual mono recording." Please see screenshot below.

Why cannot I see both channels are duplicated and filled when using this option with a mono mic?
Only one channel is filled even after I use this option.

(2) After opening the accompaniment file I received from another person, I can see those red vertical lines (clippings). How can we remove such clippings without affect the sound quality with Audacity 2.2.2? It's difficult to ask that person to re-record it with lower input level.

Thanks & regards,
Lee

It's difficult to ask that person to re-record it with lower input level.

Accept this one with the damage and send them a note to record lower volume next time.

I can see those red vertical lines (clippings). How can we remove such clippings without affect the sound quality with Audacity 2.2.2

You don't. Once you get multiple red lines in a file, it means the microphone stopped following the performance. Many nasty things happen when you overload the sound channel, the two worst ones are the sound channel starts making up its own sound, usually crashing, crunching, ticking and popping; and there is no clean voice or instrument there to rescue.

There is the Clip-Fix tool, but that is only to fix one of those red marks and then only if it's by itself. It won't do a thing for multiple overloads.

I did a cartoon about this.

viewtopic.php?p=352113#p352113

This is also why if you buy a USB microphone, it almost always records low volume. You can fix that later. You can't fix overload and clipping. It's called clipping because it looks like somebody came along and clipped off the tops and bottoms of the blue waves. Some microphones have a little red light that comes on when you are about to damage the sound. But you have to pay attention to the light.


One other note, you don't need sound on both the Left and Right tracks to be heard in both speakers or headphones. As above, tag the single blue wave as "Mono" and speaker systems will automatically send the show to both speakers. This is how audiobook companies strongly suggest you submit voice recordings.



Koz

Why cannot I see both channels are duplicated and filled when using this option with a mono mic?
Only one channel is filled even after I use this option.

Of course your microphone is mono (stereo mics are rare) but you might have a stereo mic jack on your particular computer (somewhat rare too) or it could a be a driver quirk.

(2) After opening the accompaniment file I received from another person, I can see those red vertical lines (clippings). How can we remove such clippings without affect the sound quality with Audacity 2.2.2? It's difficult to ask that person to re-record it with lower input level.

If the file is truly clipped (and it probably is*) the original height & shape of the waveform is permanently lost.

There is a Clip Fix Effect that will lower the overall level and "rebuild" and round-over the peaks.

Or, if it sounds OK you can leave it as-is or you can run the Amplify or Normalize Effect to bring-down the levels slightly and "hide" the clipping. (Of course it you lower the volume you still have squared-off waves so that doesn't fix the distortion.)


* Audacity shows potential clipping when the waveform goes over 0dB (over 1.0 or 100%) or if there are multiple 0dB samples in a row. And, Audacity itself can go over 0dB without clipping. So for example, if you boost the bass and that pushes your peaks over 0dB, you'll "see red" but the wave isn't actually clipped yet. If you play the file at "full digital volume" you'll clip the digital-to-analog converter, or if you export as a "regular" WAV file or if you make a CD, the waveform will be clipped.

So, if boost the bass (or otherwise boost the volume) and Audacity shows clipping, you can simply run the Amplify or Normalize effect to bring-down the level and you'll be OK.

Your analog-to-digital converter (and digital-to-analog converter) are both hard-limited to 0dB. If Audacity shows clipping immediately after recording, your ADC was clipped. Regular WAV files and CDs are also hard-limited to 0dB.

MP3s and floating-point WAV files can go over 0dB without clipping. If open such a file in Audacity it will show (potential) clipping. In fact, "something funny" happens with MP3... As you probably know MP3 is lossy compression. The wave shape changes and some peaks get higher and some peaks get lower. So it not unusual to start-out with 0dB normalized WAV file and end-up with an MP3 that goes over 0dB and "shows red". ...Probably about half of my MP3s go over 0dB (but I haven't opened them all in Audacity so I haven't "seen" them all).

LeeX wrote: ↑

Mon Oct 01, 2018 3:54 pm

Why cannot I see both channels are duplicated and filled when using this option with a mono mic?
Only one channel is filled even after I use this option.

I think that part of the manual is a bit out of date.
How many channels are recorded from a mono mic when the device toolbar is set for 2 channels, depends on the device drivers.
When that bullet point was written back in 2011, the behaviour as described was pretty common. These days it seems more common for mono devices to give you one audio channel and one silent channel (though either behaviour may happen, depending on the specific hardware and drivers.

I'll tag that section of the manual for updating.

steve wrote: ↑

Thu Oct 04, 2018 10:50 am

I'll tag that section of the manual for updating.

It has now been updated. The updated version will appear in the next Audacity release.
That section now says:

• If your recording device is mono, such as most microphone ports for the inbuilt sound device, it is recommended to set the number of recording channels to "1 (mono)". Selecting "2 (Stereo)" in Recording Channels may duplicate the mono source to both channels (merely producing a dual mono recording), or may give audio in one channel and silence in the other.
• Mono recording devices should also be set to 1 channel mono in the system or sound device control panel.
• If your recording device is stereo, then as well as setting Recording Channels to "2 (Stereo)", ensure any settings in the system or sound device control panels are stereo. Many input devices on Windows default to mono recording even if they are stereo devices. To correct this, follow these instructions.
• Typically, USB audio devices with two inputs will send their first input to left/mono, and their second channel to the right channel of a stereo track.