Lesson plan
Host media processing
A telephony system based on host media processing (HMP) is one that uses a general-purpose computer to process a telephony call's media stream rather than using digital signal processors (DSPs) to perform the task. When telephony call streams started to be digitized for time-division-multiplexed (TDM) transport, processing of the media stream, to enhance it in some way, became common. For example, digital echo cancellers were added to long-haul circuits, and transport channels were shaped to improve modem performance. Then, in the mid-'80s, computer-based systems that implemented messaging, for example, used DSPs to compress the audio for storage, and fax servers used DSPs to implement fax modems. However, since the late '90s, the millions of instructions per second (MIPS) of processing power available on low-cost PCs have been adequate to process several media streams, while still leaving enough processing power to handle the application. And, following Moore's Law, PC capacity continues to double every 18 months, while the MIPS required to process a call's media stream have remained relatively constant. Now, in the latter half of the century's first decade, a single PC can handle well over 100 simultaneous calls. Prior to IP telephony, when you wanted to connect a telecommunications system to a telecom network it was necessary to have a telecom-specific physical interface.…
Article summary
A telephony system based on host media processing (HMP) is one that uses a general-purpose computer to process a telephony call's media stream rather than using digital signal processors (DSPs) to perform the task. When telephony call streams started to be digitized for time-division-multiplexed (TDM) transport, processing of the media stream, to enhance it in some way, became common. For example, digital echo cancellers were added to long-haul circuits, and transport channels were shaped to improve modem performance. Then, in the mid-'80s, computer-based systems that implemented messaging, for example, used DSPs to compress the audio for storage, and fax servers used DSPs to implement fax modems. However, since the late '90s, the millions of instructions per second (MIPS) of processing power available on low-cost PCs have been adequate to process several media streams, while still leaving enough processing power to handle the application. And, following Moore's Law, PC capacity continues to double every 18 months, while the MIPS required to process a call's media stream have remained relatively constant. Now, in the latter half of the century's first decade, a single PC can handle well over 100 simultaneous calls. Prior to IP telephony, when you wanted to connect a telecommunications system to a telecom network it was necessary to have a telecom-specific physical interface.…
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.