LinuxQuestions.org
Did you know LQ has a Linux Hardware Compatibility List?
Go Back   LinuxQuestions.org > Forums > Non-*NIX Forums > Programming
User Name
Password
Programming This forum is for all programming questions.
The question does not have to be directly related to Linux and any language is fair game.

Notices


Reply
  Search this Thread
Old 06-19-2003, 11:41 PM   #1
microtim
LQ Newbie
 
Registered: Mar 2003
Location: Cambridge, M
Posts: 16

Rep: Reputation: 0
audio sampling Skews!


hi, i am working on the Zaurus handheld and am trying to have a bunch of these devices simultaneously record audio with a microphone. ideally, given that all Zauri "hear" the same sound, the resulting audio files would be almost exactly the same. for example, a clicking sound at regular 1 second intervals results in audio files that produce clicking sounds at regular 1 second intervals.

however, the problem is that the resulting audio files are NOT the exactly the same. after an hour or so, the audio files are off by up to 2 seconds which is unacceptable. doh!

i am looking for suggestions. is it hardware, software, or other related? how can i test and experiment to hopefully identify the problem? thanks.

-Tim
 
Old 06-23-2003, 04:50 AM   #2
nowonmai
Member
 
Registered: Jun 2003
Posts: 481

Rep: Reputation: 48
Re: audio sampling Skews!

Quote:
Originally posted by microtim
hi, i am working on the Zaurus handheld and am trying to have a bunch of these devices simultaneously record audio with a microphone. ideally, given that all Zauri "hear" the same sound, the resulting audio files would be almost exactly the same. for example, a clicking sound at regular 1 second intervals results in audio files that produce clicking sounds at regular 1 second intervals.

however, the problem is that the resulting audio files are NOT the exactly the same. after an hour or so, the audio files are off by up to 2 seconds which is unacceptable. doh!

i am looking for suggestions. is it hardware, software, or other related? how can i test and experiment to hopefully identify the problem? thanks.

-Tim
slight variations in sample rate, perhaps... as to why this is happening.. issues with multitasking, maybe? or varying processor/RTC speeds... 2 seconds in an hour is less than 0.03% variance
 
Old 06-23-2003, 06:45 PM   #3
microtim
LQ Newbie
 
Registered: Mar 2003
Location: Cambridge, M
Posts: 16

Original Poster
Rep: Reputation: 0
i've determined the problem/solution

google lead me to the answer: UCLA published a paper about their solution to synchronizing audio-recording on several devices (iPAQs). apparently, the problem is, essentially, that different devices have different clock sampling rates. Also, audio hardware has its own clock which causes further variation in audio sampling.

http://lecs.cs.ucla.edu/Publications...ots-sensor.pdf
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
AC'97 Conexant audio (aka, AC-Link Audio) (Gateway 7510GX) Vexamus Linux - Hardware 25 10-07-2009 09:15 PM
now sampling 'Santa Fe'. STILL no internet useing wireless adapter! randell6564 Linux - Wireless Networking 1 11-28-2005 07:08 AM
Reading audio data files as an actual audio file? Erik_the_Red Linux - Software 1 06-01-2005 07:22 AM
Sampling bits of information in bigger and bigger pieces lugoteehalt General 0 10-29-2003 05:38 AM
setting gprof sampling time? togunter Programming 0 04-26-2002 03:55 PM


All times are GMT -5. The time now is 11:04 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration