#1
hey guys,

I have a concern, which is probably not discussed that often in this forum. Well, let's see if someone's interested in it...

I am currently writing a thesis about automatic chord recognition by computers. While computers can be really good chess players, they have pretty problems in detecting the chords in musical recordings. Well, probably it's best to explain first, how current chord recognition systems work (don't worry, it's pretty easy!) before I point out my concern. They work like this:
For a time frame, where the chord is played, they extract the intensities of all the musical pitches that are played in this time frame. All pitches of the same tone but played in different octaves are added together. E.g. the intensities of the tones C3, C4 and C5 are added to form the intensity of the tone C (if a tone is not played at all, it has the intensity 0).

Now, we have the intensities of the 12 different tones. These intensities are analysed. Let's assume, we have high intensities of the tones C, E and G, while we have low intensities of all other tones, we would expect to have a C major chords. It's pretty straightforward, isn't it?

One problem of this approach is, that the extraction does not work so good. So even if the whole band plays a C major chord and no one plays a B, it is possible to have quite a high intensity of B. This might be caused by disturbing percussive sounds or harmonics of the instruments or other stuff. Still the intensity of C should be higher, but I only wanted to explain, why chord recognition is not trivial and has sometimes bad recognition rates.

Humans do perform much better. But probably the worse recognition rates of computers compared to those of humans, are due to the fact, that computers use the worse approach.
I think, probably the computer can learn from humans.

Well, I have learned to play the drums and a bit of piano, and appreciate playing the guitar sometimes when I am alone but I am not able to transcribe the chords from a song (Well, once I tried Them's: "I'm gonna dress in black" and after hard work, I figured out at least some chords, hmm, at least I guess they are correct)
My usual way to transcribe a song is to check the ultimate guitar community, where we have some damned experienced transcribers. That's why I wanted to ask, whether some of you guys can tell me, how you do, when you transcribe a song. Do you listen to the bass tone, do you only listen to the guitar (and try to mask all other sounds), do you first determine the key of the song, do you know the band and know the chords they favor, whatever??

I would be glad if I get some feedback from you. Thanks very much!!

Regards
hannes
#3
i determine the drums, then bass then guitar...
oh yea awesome
Quote by letsgocoyote
No I'm not Jesus. I would aspire to be though. I think under circumstances he would let you pay less if you needed to.
#4
Quote by blue_strat
You could do with posting this in Tab Talk.


Maybe... but we've had transcription technique stuff in here before. I'll keep it for now.


As for transcribing, I will generally try to concentrate on one instrument, let's say guitar. I try to just listen, first, and determine the quality of a chord: is it major, minor, dominant, etc. Prior ear training helps this stage. Then, the inversion; what note is in the bass? Then, I can usually find the top note.

The middle notes are sometimes a problem for me, but now I have (hopefully) the chord quality, and the top and bottom notes. Now I can just find the in-between notes and see what sounds accurate. I generally try to experiment with different voicings and positions until I've found the chord that sounds the closest to the recording, both in terms of actual notes, and tone from the position.

Some knowledge of the guitarist's techniques also helps; alternate tunings, capos, tapping, etc. If you go into a piece not expecting that these might be used, you can spend quite a while trying to work out very difficult (or impossible) fingerings in standard tuning.


It can be a very frustrating process at first, but it's also rewarding, if you put enough time in. I'd recommend (if possible) starting with songs that have few instruments, getting good at transcribing them, and then moving up.
(Slightly outdated) Electronic and classical compositions by m'self: Check 'em out
#6
For me the key is the most important step, once you have that you can work out 90% of the song by knowing a few basic progressions, I - IV - V etc. This works well for pop/rock songs where the chords are fairly striaght forward and simple. I've only ever tryed to transcribe basic guitar stuff though, this would work less well with jazz where you have alot of moulation and extended chords. I can't see how you'd apply this to your program unless you gave it what a preset I - IV - V progression sounded like for example.

Also knowing what key a band plays in helps alot, ie im playing along to GnR now, they, from what I can tell, play almost exclusively in Gb or Eb minor. So this can give me an educated guess as to what chords they use.
Quote by cakemonster91

*chuckle* A peanut. With a face.



Go to your staff paper and re-write this song a half step down so on the paper it'll be like you have a "C" just move it down to a "B#"




Know your theory, then play like you don't.

#7
When I'm transcribing I tend to follow something along the lines of psycodelia. Singling out tracks and focusing on them.

Specific to transcribing chords, when I hear a chord I immediately try to connect it to a chord in a song that I already know (consciously at first, for example when I started out and heard say a Dmaj chord I would think of Bon Jovi's Wanted Dead or Alive, or Lennon's Imagine when I heard Cmaj... then I can sort of tell from just listening after a while, and thus training my ear )

That gives me an idea of what chord I'm hitting at, then I'd figure out any little added notes or illustrious exotic inversions and so on.

I think training your ear is essential to get good at it. Keeping in mind that Perfect Pitch isn't a matter of being musically talented, you just have a good memory, I think anyone can get better with practice