Added silence when saving

Discussion forum for Amadeus users

Moderator: Martin Hairer

Post Reply
coverland
Posts: 2
Joined: Fri Nov 16, 2007 10:29 pm

Added silence when saving

Post by coverland »

(I am neither an audiophile nor technophile, so please bear with me! :) )

I'm trying to create basic waveforms (sine, 440Hz) of very precise durations (to the nearest millisecond, actually) as mp3 files for an experiment I'm running.

After making files with the Waveform Generator, all looks well - graphs in the main window appear as intended. However, after saving and reopening waveforms I've made, I find that the durations have been changed slightly.

Specifically, about 20ms of near-zeroed data is added to the beginning of each file, creating a (granted, inaudible) gap before playback begins. The overall duration of the sample is thereby subsequently shortened. I've tried cropping this out and resaving, but the near-zeroed data returns.

Is there some kind of meta-tag info that's stitched on the beginning of mp3 files that I can turn off? Could this be some kind of artifact that Amadeus adds during saving? I'm stymied...

Any help would be greatly appreciated!

User avatar
Martin Hairer
Site Admin
Posts: 1975
Joined: Wed Nov 08, 2006 11:49 am
Contact:

Added silence when saving

Post by Martin Hairer »

Is there some kind of meta-tag info that's stitched on the beginning
of mp3 files that I can turn off? Could this be some kind of
artifact that Amadeus adds during saving? I'm stymied...
Mp3 files are chopped up into "frames", their smallest constituents
(think of it as an atom). Each frame contains about 1500 samples,
which is about 30ms, so millisecond precision is just not achievable
with Mp3 files. Furthermore, most Mp3 encoders (like LAME which is
what Amadeus Pro uses) will add "dummy" frames at the beginning / end
of a file in order to reduce some artifacts. Some other compressed
formats will have similar problems. I therefore suggest to use
uncompressed AIFF or WAVE files instead. Regards,

Martin

HairerSoft
http://www.hairersoft.com/


_______________________________________________
Amadeus forum mailing list
Unsubscribe / change settings at http://two.pairlist.net/mailman/listinfo/forum_list

coverland
Posts: 2
Joined: Fri Nov 16, 2007 10:29 pm

Post by coverland »

Many thanks! This was very helpful!

lyden
Posts: 1
Joined: Fri Jan 25, 2008 4:24 pm
Location: Denmark
Contact:

Post by lyden »

Hi!!

I have the same issue here, I am trying to make a smooth loop without any clicks or similar with "succes". But every time I save, and on reopen there has been added silence in the beginning and end and my loop is no longer smooth

I do understand your reply, but is there really no way to make a smooth loop using mp3 then? (I have to use mp3).

Best Jonas

NB. thank you for a great product!

Post Reply