TUT: (Sort of) separating guitar from music for customs

[HansenIsGod]

Okay, so you want to make a cool custom song, but the artist was not kind enough to provide you with separate master tracks for the guitar and the rest of the band? Unfortunately, it's impossible in practice to perfectly split the guitar from the rest of the mix. So what you could do is call your friends and record a cover of the song, or you could use the final mix in all three streams in GH - or you use the final mix on just the guitar track. That's not that cool - if you miss a note, the song will just play on as if nothing happened, or will go completely mute.

Since GH works by mixing a 'band' track and a 'guitar' track and will mute the guitar if you miss, one has to figure out a way of making two tracks that will sound like the original if mixed together, and sound like the original without the guitar if just one of them is played.

The approach I tried here is based on using band pass and band reject filters to split out the frequency range where the guitar is mostly predominant, i.e. the mids (400-3500 Hz).

Compared to the usual "all 3 streams the same/only guitar" method, this has the following advantages and disadvantages:

- it's a chore
- of course, it will not perfectly separate stuff (because that's impossible)
- the resulting "mixed" audio might sound a bit different than the original, depending on how good your filters are
- vocals will be in the new guitar track and therefore will be also muted if you miss a note (this is unavoidable since the periodic parts of speech are in the same frequency range)
- if you miss the last note before a vocal solo, you're out of luck

+ the player will get a better reaction upon missing a note, i.e. cutting out the guitar instead of nothing happening or the song going completely mute
+ whammying will now effect only guitar (well, and vocals) instead of everything

Now that we know the nuts and bolts of this method, let's begin a step-by-step walkthrough of how to do this using the free audio editor audacity.

Open audacity and import the audio file you would like to work with. (FYI, I use Gamma Ray's 'Heaven Or Hell' here).
Since we will do some filtering and get 2 tracks that will be later played back simultaneosly, we first must reduce the volume of everything to avoid clipping (digital distortion).

To do this, go to Effect --> Amplify:


Reducing volume using -3 dB is fine.


Now, we want to create a second stereo track. Go to Tracks --> Add New --> Stereo Track


Double click the first audio track to select everything, then copy it to clipboard:


Go to the beginning of the second audio track and paste it there:


Good, now we have two copies of the mixed audio. Let's split it!

The first track is gonna be the band track, so we want to apply a band reject filter that cuts out the midrange (i.e. guitar) and keeps everything else. Select the first track and go to Effect --> Equalization.


Now you will have to draw your filter curve. Remember that we want to cut out the midrange, I used the range 440-3300 Hz, but you can tweak this a little. Filtering by 30dB is ok, going deeper will give you ripple problems with the filter. You want your transitions to be as steep as possible - smooth filter curves gave me strange flanging sounds when mixing the tracks back together. Between the transitions, take care that the curve is flat. Drag the "filter length" all the way to the right (largest size, best precision). Here's how my curve looks (you can save the curve as a preset to use again later):

Press OK and it will do the filtering.

For the guitar track we will have to apply the exact(!) opposite filter. Now this is important, since if your filter curves don't match really good, you will produce holes or spikes in the spectrum which will sound nasty.

Unfortunately, you cannot just tell audacity to invert a curve, so you will have to swap your points by dragging them while remaining at the same frequency.

Select the second track, and again open the equalization menu.
Your band reject filter should still be there. To turn it into a band pass, pull the bottom points up and the top points down - do not change their horizontal position. It should look like this:

Press OK.

That's it! Filtering done.
Now, you can test your separated tracks right away: Just press play (SPACE) and you will hear how they sound mixed together. If you MUTE the guitar track, you will hear what will happen if you miss a note ingame.


If you like what you hear, save it! If not, go back using undo and fiddle around a bit. Select 'Export Multiple' from the File menu.


Set your format to whatever you want (e.g. 128k MP3), select the place where the files will go, "Numbering consecutively", split based on tracks.

Whee! We're done.

Now you can use the guitar track as guitar and the band track on the song section (use only 2 files and put silence on the rythm/bass track, or the filtering will not be very effective).

Go and try it now!
I've made a little demo for interested, yet lazy people using "Tell the Devil" by Predator, available on Jamendo (Licensed CC-BY-NC-SA)

Here's the demo: http://www.savefile.com/files/1298823

Feel free to tell me what you think! Maybe this could be automated by i.e. using SoX (haven't toyed around with that much) if it has an appropriate filter. Of course you can also use other editing software like Audition.

On a sidenote: Avoid transcoding! It's sad that GH will just take 128k non-joint stereo MP3 (that's soo 90s), but don't make things worse by going from mp3 to mp3, as this will cost even more quality. The best thing to do here is rerip from CD. Best to use the latest LAME beta (3.98b6). If you're interested in encoding, audio quality and such, you will learn a great deal at www.hydrogenaudio.com

[HansenIsGod]

Okay, so you want to make a cool custom song, but the artist was not kind enough to provide you with separate master tracks for the guitar and the rest of the band? Unfortunately, it's impossible in practice to perfectly split the guitar from the rest of the mix. So what you could do is call your friends and record a cover of the song, or you could use the final mix in all three streams in GH - or you use the final mix on just the guitar track. That's not that cool - if you miss a note, the song will just play on as if nothing happened, or will go completely mute.

Since GH works by mixing a 'band' track and a 'guitar' track and will mute the guitar if you miss, one has to figure out a way of making two tracks that will sound like the original if mixed together, and sound like the original without the guitar if just one of them is played.

The approach I tried here is based on using band pass and band reject filters to split out the frequency range where the guitar is mostly predominant, i.e. the mids (400-3500 Hz).

Compared to the usual "all 3 streams the same/only guitar" method, this has the following advantages and disadvantages:

- it's a chore
- of course, it will not perfectly separate stuff (because that's impossible)
- the resulting "mixed" audio might sound a bit different than the original, depending on how good your filters are
- vocals will be in the new guitar track and therefore will be also muted if you miss a note (this is unavoidable since the periodic parts of speech are in the same frequency range)
- if you miss the last note before a vocal solo, you're out of luck

+ the player will get a better reaction upon missing a note, i.e. cutting out the guitar instead of nothing happening or the song going completely mute
+ whammying will now effect only guitar (well, and vocals) instead of everything

Now that we know the nuts and bolts of this method, let's begin a step-by-step walkthrough of how to do this using the free audio editor audacity.

Open audacity and import the audio file you would like to work with. (FYI, I use Gamma Ray's 'Heaven Or Hell' here).
Since we will do some filtering and get 2 tracks that will be later played back simultaneosly, we first must reduce the volume of everything to avoid clipping (digital distortion).

To do this, go to Effect --> Amplify:


Reducing volume using -3 dB is fine.


Now, we want to create a second stereo track. Go to Tracks --> Add New --> Stereo Track


Double click the first audio track to select everything, then copy it to clipboard:


Go to the beginning of the second audio track and paste it there:


Good, now we have two copies of the mixed audio. Let's split it!

The first track is gonna be the band track, so we want to apply a band reject filter that cuts out the midrange (i.e. guitar) and keeps everything else. Select the first track and go to Effect --> Equalization.


Now you will have to draw your filter curve. Remember that we want to cut out the midrange, I used the range 440-3300 Hz, but you can tweak this a little. Filtering by 30dB is ok, going deeper will give you ripple problems with the filter. You want your transitions to be as steep as possible - smooth filter curves gave me strange flanging sounds when mixing the tracks back together. Between the transitions, take care that the curve is flat. Drag the "filter length" all the way to the right (largest size, best precision). Here's how my curve looks (you can save the curve as a preset to use again later):

Press OK and it will do the filtering.

For the guitar track we will have to apply the exact(!) opposite filter. Now this is important, since if your filter curves don't match really good, you will produce holes or spikes in the spectrum which will sound nasty.

Unfortunately, you cannot just tell audacity to invert a curve, so you will have to swap your points by dragging them while remaining at the same frequency.

Select the second track, and again open the equalization menu.
Your band reject filter should still be there. To turn it into a band pass, pull the bottom points up and the top points down - do not change their horizontal position. It should look like this:

Press OK.

That's it! Filtering done.
Now, you can test your separated tracks right away: Just press play (SPACE) and you will hear how they sound mixed together. If you MUTE the guitar track, you will hear what will happen if you miss a note ingame.


If you like what you hear, save it! If not, go back using undo and fiddle around a bit. Select 'Export Multiple' from the File menu.


Set your format to whatever you want (e.g. 128k MP3), select the place where the files will go, "Numbering consecutively", split based on tracks.

Whee! We're done.

Now you can use the guitar track as guitar and the band track on the song section (use only 2 files and put silence on the rythm/bass track, or the filtering will not be very effective).

Go and try it now!
I've made a little demo for interested, yet lazy people using "Tell the Devil" by Predator, available on Jamendo (Licensed CC-BY-NC-SA)

Here's the demo: http://www.savefile.com/files/1298823

Feel free to tell me what you think! Maybe this could be automated by i.e. using SoX (haven't toyed around with that much) if it has an appropriate filter. Of course you can also use other editing software like Audition.

On a sidenote: Avoid transcoding! It's sad that GH will just take 128k non-joint stereo MP3 (that's soo 90s), but don't make things worse by going from mp3 to mp3, as this will cost even more quality. The best thing to do here is rerip from CD. Best to use the latest LAME beta (3.98b6). If you're interested in encoding, audio quality and such, you will learn a great deal at www.hydrogenaudio.com

[st4t1cv01d]

That's very cool. Thanks for the guide!

[st4t1cv01d]

That's very cool. Thanks for the guide!

[RGBrewer]

What about then attempting to remove the vocals, thereby leaving only the band track? Ala... http://audacityteam.org/wiki/index.php?title=Vocal_Removal

[RGBrewer]

What about then attempting to remove the vocals, thereby leaving only the band track? Ala... http://audacityteam.org/wiki/index.php?title=Vocal_Removal

[stereth]

[stereth]

[HansenIsGod]

[HansenIsGod]

[Headbang]

Thanks for the great guide!

I'm going to be trying this.
_________________

Justin Hawkins signed my butt.

[Headbang]

Thanks for the great guide!

I'm going to be trying this.
_________________

Justin Hawkins signed my butt.

[stereth]

[stereth]

[GuitarsNGirlz]

Hey.. Thanks for the neat Tut.
few questions though..
What version of Audacity are you using? I have it too, but i am seeing the things like the equaliser different on mine..
Also, should i be able to hear the drums in my guitar track? or is it just the frequency that the drums are at? Because i am just trying to separate the Guitar from the main audio to help while trying to make a chart.
Thanks again.

[GuitarsNGirlz]

Hey.. Thanks for the neat Tut.
few questions though..
What version of Audacity are you using? I have it too, but i am seeing the things like the equaliser different on mine..
Also, should i be able to hear the drums in my guitar track? or is it just the frequency that the drums are at? Because i am just trying to separate the Guitar from the main audio to help while trying to make a chart.
Thanks again.

[EpicKris]

Hey, if I would like to do the same as this but with rhythm / bass instead, would I use the same method but with different frequencies and what would those frequencies be?

[EpicKris]

Hey, if I would like to do the same as this but with rhythm / bass instead, would I use the same method but with different frequencies and what would those frequencies be?