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Dsp quattro lame encoder5/6/2023 ![]() The sound driver must also support duplex operation, something that gave me a great deal of trouble on my Linux laptop until I discovered that the ALSA driver for my sound card lacked duplex support. Only duplex-capable sound cards are suitable for telephony, because a telephone isn't much good if it can't send and receive at the same time. Although I haven't tested it, the program should work fine on any system equipped with the 4Front drivers. ![]() A commercial vendor called 4Front Technologies sells an inexpensive package of sound drivers that work with a large number of sound cards on a variety of Unix operating systems, including FreeBSD, Solaris, HPUX, and AIX ( ). Linux sound drivers are available from a number of sources, including the kernel itself and an open source project called ALSA (for Advanced Linux Sound Architecture, available at ). The programs in this article runs on Linux systems, and assumes the sound device is named /dev/dsp. Just open the device like an ordinary file, read from it to capture sound data from the microphone, and write to it to send sound data to the speaker. Common names include /dev/dsp, /dev/audio, and /dev/sound. Audio-capable Unix systems have a special device file for communicating with the digital signal processor (DSP) driver. We know how to do item three with Berkeley sockets, but what about items one and two? In this article, I'll show you the two versions of the application: a simple one which requires ISDN-speed connections to work well, and a somewhat more sophisticated version that uses the MP3 format to reduce the bitrate for slower connections. It isn't elegant, and it lacks most of the functions of real IP telephony applications, but it works. I hate being left behind on the technology curve, so I decided to write my own IP telephone application in Perl. In the words of the industry pundits, convergence will change everything, and the technology hailed as the forerunner of convergence is IP telephony, which allows you to make long distance calls with nothing more than an Internet connection and a high quality sound card. ![]() Convergence is the magical integration of the desktop computer, the Internet, television, radio, and the telephone. ![]() Ĭonvergence! The latest buzzword of the dot com era. ![]()
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