Cisco Unified MeetingPlace Release 8.5 -- Choosing Between the Hardware Media Server and the Express Media Server

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Main page: Cisco Unified MeetingPlace Release 8.5

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Choosing Between the Hardware Media Server and the Express Media Server


About the Hardware Media Server and the Express Media Server

All Cisco Unified MeetingPlace Release 8.5 systems that will use audio or video need a media server and the media server can be either a Hardware Media Server (HMS) or an Express Media Server (EMS).

  • The Express Media Server is a set of software modules, including an audio mixer and a video switcher, that resides on the Application Server. The Express Media Server creates a single box software-only solution for Cisco Unified MeetingPlace. The Express Media Server is based on the Cisco Unified MeetingPlace Express Video Telephony (VT) product.
  • The Hardware Media Server is comprised of Audio and Video Blades.

All Cisco Unified MeetingPlace Release 8.5 systems automatically come with an Express Media Server. If you want to use a Hardware Media Server, you must purchase, install, and configure it first.


On a multinode system (with Cisco WebEx scheduling), you may use only the Express Media Server or the Hardware Media Server within a site. If you mix both EMS and HMS on the same site, then users may notice video quality differences for different meetings, depending on the media server that is being used. On a multinode system, one site can have the Express Media Server, while another site has the Hardware Media Server.


There can be more or less differences based on your configuration and the environment in which the media servers are deployed.

General Differences

Table: General Differences Between the Express Media Server and the Hardware Media Server
Feature Express Media Server Hardware Media Server

Type

Software residing on the Application Server

Hardware, comprised of Audio and Video Blades. For video to work, each Audio Blade must have a Video Blade associated with it.

Installation

Installed automatically when you install the Application Server

Separate chassis, audio/video blade installation required and configuration steps

Configuration

Configured through the Administration Center of the Application Server

Configured through the Media Server Administration

Recording


Can record the audio portion of scheduled meetings. Cannot record the video portion of scheduled meetings.


Can support 20 simultaneous recordings with each recording using one port.

Can record the audio and video portions of scheduled meetings.

Cascading

Does not support any internal cascading of audio and video data

Uses internal cascading for scalability

Resource management

Based on the number of System Resource Units (SRUs), which is based on the type of Cisco MCS on which the Application Server is installed.


High complexity codecs are used on a first come, first served basis.


The number of available audio ports does not decrease when the user configures a high complexity audio codec.

Based on the following:

  • The number of Audio and Video Blades that are physically installed on the chassis.
  • For audio: The global audio mode (higher capacity or higher quality) that is set for the system.
  • For video: The mode (standard or high rate) that is set at the user profile level.


The number of available audio ports decreases to two-thirds when the system is configured for high-quality mode.

High complexity codecs

G.729 is considered a high complexity codec

G.729 is not considered a high complexity codec unless line echo cancellation is turned on for it.

Video composition

Not supported.


All non-speaker participants see the video of the active speaker only and the active speaker sees the video of last speaker.

Supports video composition.


All non-speaker participants see the video of the last N speakers (where N is based on the layout selected by the system administrator).


N speakers see N-1 remaining speakers (minus themselves) and one additional participant.


N participants are composed into a single layout.

Muting

When audio is muted, video is not muted.

When audio is muted, video is muted.

Transrating

Not supported.


The system uses flow-control mechanisms to force all connections to the same bandwidth. It restricts a meeting to use only a range of the bandwidth to accommodate the lowest speed participant in the meeting.

Supports true transrating, so you can have an ISDN connection in the same meeting as a 2Mb connection, without affecting the interaction between high rate participants.

Transcoding between H.263 and H.264 AVC

Not supported between H.263 and H.264 AVC endpoints in the same meeting. A meeting can include either H.263 or H.264 video endpoints.

Supported.

H.261

Not supported.

Supports H.261 in high rate mode and provides transcoding between H.261 and H.263/H.264.

Video resolution

Supports the following:

  • 320x180
  • 640x360 (for Cisco soft clients)
  • 640x480 (for Roundtable phones)
  • 1280x720 (720p) for Cisco soft clients
  • CIF, QCIF

Allows 320x180, but it will probably be mangled. Does not allow the other resolutions.


Works with QCIF, QSIF, SIF, and CIF and provides transcoding between them.

Custom video types

Can make custom video types. Has more predefined video types.

Not supported.

Video type management

Supported.


Users can configure their own video types for a meeting (codec and bitrate)

Not supported.


Only two system defaults are available: standard rate and high rate.

H.263 at 4CIF

Not supported.

Supported.

In-band (voice band) DTMF detection, audio codec iLBC, jitter buffer configuration

Not supported.

Supported.

Automatic gain control (AGC)

Supported.

Supported.

Echo cancellation

Supported.

Supported.

The system calls a user for a web meeting, and the user turns on the desktop camera. When the user is speaking, the WebEx video shows the user to the other attendees in the meeting.

Supported.

Not supported.

Differences in Audio and Video Codecs

Audio Codecs Supported Video Codecs Supported

Hardware Media Server

  • G.711
  • G.7221
  • G.729a1
  • G.729b1
  • iLBC1
  • H.261
  • H.263
  • H.264/AVC2

Express Media Server

  • G.711
  • G.729a3
  • G.7223
  • H.263
  • H.264/AVC

1. When using these codecs, capacity changes from 250 ports per blade to 166 ports per blade.

2. Any combination in the same meeting.

3. For more information on using these codecs and capacity, see the Resource Management and System Capacity for Systems Using the Express Media Server.


Line Echo Cancellation

The Express Media Server and Hardware Media Server both include an echo canceller for controlling echo on incoming audio connections, so any echo originating from a phone or long distance connection can disrupt the conference. In general, echo cancellation is not required in a conference bridge, providing the following conditions are true:

  1. All the voice gateways connecting the public switched telephone network to the internal network are provisioned to provide echo cancellation. Usually 64ms of echo cancellation is sufficient, but intercontinental calls may benefit from 128ms.
  2. Substantially all calls are originating and terminating within the same continent. If you have 128ms of echo cancellation in the voice gateways, then intercontinental calls between developed countries will likely be covered, provided no connections through satellites are employed. Intercontinental calls involving 3rd world countries are likely to have echo exceeding 128ms., which cannot be controlled by most voice gateways.
  3. Internal phones and headsets are well maintained. Defective phones or headsets, including echo cancelling headsets with dead batteries, are a common source of echo.


Note that acoustic echo, typically from a speakerphone in a conference room, cannot be effectively cancelled by either type of media server. This type of echo should be controllable through proper configuration and use of a good quality speaker phone.

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