From owner-freebsd-multimedia Mon Jun 9 09:51:54 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id JAA01063 for multimedia-outgoing; Mon, 9 Jun 1997 09:51:54 -0700 (PDT) Received: from bmccane.uit.net (bmccane.uit.net [208.129.189.48]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id JAA01037 for ; Mon, 9 Jun 1997 09:51:38 -0700 (PDT) Received: from bmccane.uit.net (localhost.mccane.com [127.0.0.1]) by bmccane.uit.net (8.8.5/8.8.5) with ESMTP id LAA12694 for ; Mon, 9 Jun 1997 11:51:15 -0500 (CDT) Message-Id: <199706091651.LAA12694@bmccane.uit.net> X-Mailer: exmh version 2.0gamma 1/27/96 To: multimedia@freebsd.org Subject: Old standards Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 09 Jun 1997 11:51:14 -0500 From: Wm Brian McCane Sender: owner-multimedia@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Howdy, I used to work for a company which built equipment for the railroads. We had a box called a Hot Box Detector (HBD) for detecting bad bearings on a train and telling it to stop. Anyway, it used a little dingus which did ADPCM, at 32K samples/second, and `spoke' the alarm to the train over the radio. If anyone knows about ADPCM, it only requires about 4K bytes to do a 32K/second audio stream. I was thinking about putting together a program for audio over the internet using a software version of ADPCM for real-time chatting. An 11K/second stream would need about 1375 bytes per second to tranfer, so it should work on a 14.4 modem with bytes to spare for the TCP/IP overhead, and ADPCM is fairly compressible by modems which might allow even better performance or quality. Anyway, I was curious if this is old hat (Real Audio maybe), or if noone has considered using this 10+ year old technology. brian