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Help contents > Managing recordings > H.239 (content channel video) support

H.239 (content channel video) support

The H.239 protocol allows the Codian IP VCR to support an additional video stream to or from each connected H.323 endpoint. Thus, there are potentially 3 media streams between each H.323 endpoint and the IP VCR: audio, main video and H.239 video. In general, the main video channel is used for motion video (i.e. high frame rate streams) and the content channel for less dynamic video such as an accompanying presentation - this is typically a high resolution, low frame rate video stream.

Support for H.239 video on the IP VCR encompasses:

Recording H.239

When a H.323 endpoint is being recorded, that endpoint may open a H.239 content channel video stream, in addition to its main video channel. The IP VCR records both video channels, and both are available when that recording is played back.

When using the Recording console, the presence of H.239 video is indicated by a "H.239" icon on the right of the screen.

In a point to point recording, the nature of H.239 means that only one of the recorded endpoints is able to supply the H.239 channel at any one time. Specifically, this means that if one endpoint is supplying the content channel stream then it must stop transmitting H.239 video before the other endpoint can start. This is in contrast to the main video channel, which both endpoints are able to transmit and receive simultaneously without restriction.

Playing back content channel video

If a recording includes a content channel video stream, that content channel stream (originally supplied by a H.323 endpoint via the H.239 protocol) can be played back to either other H.323 endpoints or to users viewing a recording via streaming.

Playing back to H.323 endpoints

Stored content channel video can only be played back to a H.323 endpoint if that H.323 endpoint is capable of receiving a H.239 video stream in addition to its main video channel. When playing back a recording which includes content channel video, a H.323 endpoint with no H.239 receive capability will see just the main video channel.

Streaming content channel video

Recorded content channel streams can be played back to users' desktops via web browser-based streaming in addition to the recorded main video and audio streams. When streaming, users have the choice of playing back just the audio and main video streams, just the recorded H.239, or both together.

The play back of content channel video is accomplished through use of a Java applet, and therefore Java must be installed on any machine wishing to view the recorded H.239 video.

Creating customized MPEG and Windows Media Video format files

The MPEG and WM Converter Tool is a tool that converts .codian files to MPEG-1 or Windows Media Video (.wmv) format. It is available from the Support area at The MPEG and WM Converter Tool enables you to create MPEG videos or Windows Media videos that include up to two video streams and/or the content channel. The resulting encoded MPEG/'.wmv' files can be stored on PCs or servers and can be viewed via streaming applications on users' desktops.

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