It is currently Wed Oct 18, 2017 5:12 pm

All times are UTC - 7 hours





Post new topic Reply to topic  [ 3 posts ] 
Author Message
PostPosted: Wed Jan 25, 2017 6:41 pm 
Offline

Joined: Sat Oct 08, 2016 4:13 pm
Posts: 3
I am working on APU pulse channels. My music pitch sounds low. I didn't do down sampling or apply any enhancements. Is this normal or something is wrong with my period used in pulse waveform generator? If I use every other 40th samples, pitch sounds about right but it also sounds like there are gaps in between tones. Currently sweep and 11-bit timer can alter my period. Is there anything I am missing?


Top
 Profile  
 
PostPosted: Wed Jan 25, 2017 7:34 pm 
Offline
User avatar

Joined: Wed Nov 10, 2004 6:47 pm
Posts: 1845
You **MUST** do some form of down sampling. The NES outputs ~1790 KHz but you'll usually only want to output ~48 Khz (or 44KHz).

Outputting 1 sample every ~40 clocks is one form of downsampling (commonly referred to as "nearest neighbor"). It will work but will be very low quality. If the pitch sounds about right when doing that, then your pulse is probably fine -- you just need to properly downsample it.


Top
 Profile  
 
PostPosted: Thu Jan 26, 2017 5:45 am 
Offline
User avatar

Joined: Sun Sep 19, 2004 10:59 pm
Posts: 1389
If you're downsampling to 44100Hz, your divider needs to be exactly 3125/77 for NTSC (1789772.72727... / 44100, around 40.5844) rather than an even 40, otherwise your pitches will be off.

_________________
Quietust, QMT Productions
P.S. If you don't get this note, let me know and I'll write you another.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 6 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group