Home Computer Audio Asylum

Music servers and other computer based digital audio technologies.

RE: Converting DSD to PCM

You can do the filtering at the original sample rate to provide the needed suppression of aliases. This is just a matter of making sure that the low pass cut off is below FS/2 of the output sample rate. If the output sampling rate is an integer divisor then no interpolation is needed to get the final points, just discarding and reindexing. However, if it is not an integer multiple then you have to do interpolation between the points you do have (at the original sampling rate, but now filtered). You will find two articles in the linked web page that may be useful.

Converting from 44100 to 48000 can be done by converting to the least common multiple which is 7056000 and then downsampling by an integer multiple. This approach will work so long as the two sampling rates are related by a rational number.

44100 * 160 = 7056000
48000 * 147 = 7056000

Another fact is that the samples will line up for all of the common sampling rates every 1/75 of a second, which corresponds to the frame rate on the CD audio format (CDA). Because CD tracks have to be an exact multiple of frames many tracks are integer multiples of 1/75 of a second, with the number of samples depending on the frame rate. This means it is possible to place a set of markers in a continuous sound file at frame boundaries and then resample it to a variety of sampling rates that will be compatible. (Necessary when mastering CD audio of live concerts where playback is to be gapless.)

1 frame: 588 samples at 44100, 640 samples at 48000, 37632 samples at 282400.






Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar



This post is made possible by the generous support of people like you and our sponsors:
  Amplified Parts  


Follow Ups Full Thread
Follow Ups
  • RE: Converting DSD to PCM - Tony Lauck 08/5/1519:45:20 08/5/15 (0)

FAQ

Post a Message!

Forgot Password?
Moniker (Username):
Password (Optional):
  Remember my Moniker & Password  (What's this?)    Eat Me
E-Mail (Optional):
Subject:
Message:   (Posts are subject to Content Rules)
Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:  Automagically notify you when someone responds.