Managing video transcoder resources

Video transcoding is the process of converting video media from one video codec type to another (for example, from H.264 to H.263) between two endpoints to suit the requirements of the device at each endpoint. Transcoding involves decoding and encoding of each frame of a video stream.

Video transrating adjusts the number of video frames per second (and bitrate of the video) between two endpoints to suit the requirements of the device at each endpoint.

Image resizing converts video from one image size to another (for example, from CIF to QCIF) between two endpoints to suit the requirements of the device at each endpoint.

In this document, the term video transcoding or video transcoder encompasses video transcoding, video transrating, and image resizing.

For a list of video codecs supported by the video transcoder, see Media capabilities. For an overview of the ways in which a video transcoder can be deployed, see Models with Video Transcoders.

The procedures for managing video transcoder resources include:

Configuring a video transcoder system

Follow these steps to configure each video transcoder system in your environment:

Step

Action

1

Access the Vision Console for your video transcoder system.

2

Click Video Transcoder on the Configuration menu, and the Video Transcoder page is displayed with default values based on your license.

  • Modify the number of full-duplex video transcoder channels that are available for this system as needed. The default value is the maximum number of licensed channels. The number of channels configured for use may be less than or equal to the maximum allowed by the license. To restrict usage, you can specify a number that is less than the maximum number of licensed video transcoder resources.

  • Modify the high water mark for CPU usage in percentage as needed. If this threshold is reached, the system issues an SNMP notification.

  • Modify the low water mark for CPU usage in percentage as needed. If this threshold is reached, the system issues an SNMP notification.

  • Modify the upper limit of high water mark for CPU usage in percentage. If this threshold is reached, the system issues an SNMP notification and begins to reject calls.

  • Modify the lower limit of low water mark for CPU usage in percentage. If this threshold is reached, the system issues an SNMP notification and begins to accept calls.

  • Click Submit to apply the changes.

3

Click Services on the Operations menu. On the Services page, start or restart the Video Transcoder service to apply the new configuration.

Defining video transcoder resources for the Video Gateway

This procedure applies to a Video Gateway that is mated with one or more video transcoder systems, which may be external or co-located.

To define video transcoder resources for a Video Gateway, follow these steps:

Step

Action

1

Access the Vision Console for your Video Gateway, as described in Accessing the Vision Console.

2

Click Resources on the Configuration menu, and the Resource Configuration page is displayed.

  • In the Global resources group, enable video transcoding. This global flag indicates whether video transcoder resources are available for the Video Gateway.

  • Click Submit to apply the change.

3

Click Services on the Operations menu. On the Services page, start or restart the Call Server service to apply the new configuration.

4

Click Video transcoder resources on the Provisioning menu, and the Video transcoder resource configuration page is displayed.

  • Specify the IP address of a video transcoder system to be attached to the Video Gateway and click Add video transcoder. The IP address is listed in the table as well as the system name and number of channels. The Video Gateway determines if video transcoder services are running on that system and displays a message accordingly.

  • Specify the IP address of each additional video transcoder system to be deployed, if any, and click Add video transcoder.

  • To remove a video transcoder system, click Remove.

  • Click Submit to apply the changes.

After you have updated values on the Provisioning menu, you do not have to restart the Call Server service to apply the new configuration.  

Specifying video transcoding in a call leg

If you have enabled video transcoding for the Video Gateway on the Resources page in the Configuration menu, transcoding will be used only when incompatible video codec characteristics are detected by the Video Gateway. If needed, you can force every call to use video transcoding through the routing profile.

To force video transcoding for every call, create or edit the profile as follows:

Step

Action

1

Access the Vision Console for your Video Gateway, as described in Accessing the Vision Console.

2

Click Gateway profiles on the Provisioning menu, and the Routing profiles configuration page is displayed with a default profile.

3

In the General section, edit the default profile (or select the desired profile to be edited from the Current profile drop-down list) and select Force in the Video transcoding field.

4

Click Submit to apply the changes.

5

Click Gateway routes in the Provisioning menu. The Call routing table page is displayed. Verify that the updated profile is associated the appropriate routing entry.

When Force is specified in the profile and associated with a route, video transcoding is inserted in the video path regardless of the negotiated video codec on either side. When Dynamic is specified, video transcoding only applies to calls with different video codec characteristics such as a different codec or a different picture frame. For more information on routing tables, see Understanding the gateway routing table and Routing table expressions.

Benefits of always enabling video transcoding in the path can include the following:

Video transcoder logging

Video transcoder log files are created in the /opt/nms/video/logs directory on the video transcoder system.

Note: Video transcoder log files are intended for use by Dialogic Technical Services and Support.

The default logging level is ERROR. The logging level is configurable on the Maintenance page, Operations menu of the Vision™ Console. The logging levels are identical to the Call Server system log levels described in Logging levels.

The following information is provided to help you manage your system requirements according to the number of video transcoder resources in use in your environment:

For example, in a system that uses 60 video transcoder channels, the maximum number of log files that reside in the logs directory may be up to 1632 files (272 active log files along with 5 rollover log files for each). The maximum combined size of these log files may be up to about 16 GB (1632 files at 10 MB each).