There are many schemes you could adopt. But they depend on if you are storing speech or music. Another factor is if you are transmitting this data over a noisy serial or rf link. regards, SW. -----Original Message----- From: Roman Black [mailto:fastvid@EZY.NET.AU] Sent: 13 August 2001 17:10 To: PICLIST@MITVMA.MIT.EDU Subject: Re: [OT] Audio Compression Tim Crist wrote: > > Help. > > I'm trying to reproduce low fi of 300 to 8Khz while using a minimal amount > of flash memory to do so. I also want to keep the code simple, and within > the confines of an 8 bit processor if possible. > > I've looked at MP3 and other compression techniques, but most of them > require a large amount of processing. > > First a sanity check: If I want 3 minutes of 8 bit sound reproduced with > the max freq. of 8Khz I'll get: > > (180 seconds) * (8 bits) * (16000 pulses/ second) = 23.04 megbits of memory > required > > right? > > Is there an easy method to half, quarter, or more this audio info to save on > memory space? Yes. Use a skilled sound engineer and good recording equipment. If you have a decent analog "compressor" to compress the dynamic range of the sound, especially speech, and a REAL good microphone, you can get excellent quality at 8bit 5000Hz or even 2000Hz. I have personally recorded CD music to 8bit 10kHz and almost sounded CD quality, but you need to know all the tricks. You didn't mention if this was speech?? If so, a trained speech person (Radio DJ etc) will help a huge amount and usually have their own mic and know all the tricks for pop suppresion and leveling. Contact local small recording studios, they have local speech people on file for pay per hour stuff. If you state your exact needs i'm sure there are lots of people here with experience who can offer suggestions. :o) -Roman -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads