Video Codecs


elemedia® Video Codecs

Agora Labs offers software components in support of application developers in the multimedia over IP industry.  Agora Labs' customers typically build upon these components to develop new multimedia services or applications.

Agora offers many features, including a "software workbench" that ease the task of developing videophones, video servers, video conferencing equipment, MCUs, and other video systems.  Some of these features are:

  • Combined H.26x codec
  • Video Mixing support with alpha channel
  • Bit rate control
  • Selection of input region and rescaling
  • Traffic Shaping

The Combined Video Codec allows development engineers to get the greatest results from thier time.  Rather than learning three or four codec APIs, the developer only has to integrate one codec and write to one API from their code.  This means that the application does not care which codec is selected;  all the control messages and all the data go to the same video codec.

Video Mixing Support allows the encoder to read from several different video sources.  This means that a videoconferenceing system developer just has to tell the codec where each input video source is located, and its display size and coordinates.  The Agora codec takes care of all resizing and positioning. The Agora video codecs also support an Alpha Channel as a separate input for each video source.  An alpha channel can be thought of as a fourth color (in addition to red, green and blue) that controls how transparent each pixel is (and there are 255 levels of transparency).  This can be used to implement "picture in picture", but it can also be used to scroll text over a video input, add icons, add the participant's name as text overlaying that video in a videoconference, perform fades, cross-fades and other effects, implement sprites, add advertising messages, and adds a host of other features.

A region of the video input can be selected in the encoder and the encoder will scale it to the proper video size.  This allows a software feature similar to the Pan, zoom and tilt controls on a motorized webcam.  For example, you may have an HDTV camera that is viewed on a mobile phone.  The HDTV image won't fit into the small displays of most phones, but the user can command the codec encoder to select a smaller part of the camera's image and send only that selection.  This has as many uses as existing motorized videocameras do, and adds an entirely new range of applications.  For example, pan, zoom and tilt can be implemented on stored video, provided the video is captured at a significantly higher resolution than the display device.  Imagine discussing last night's football game, and reviewing a referee's call.  Your customers now have the ability to bring up the video on their mobile phones and zoom in to see if the receiver's foot really was out-of-bounds.  And there are many more uses for this feature!

The Agora video codecs support Traffic Shaping.  Developers can command the codec to prefer a higher framerate, better quality, or lower CPU utilization for a given bandwidth.  Agora has also implemented an automatic traffic shaping algorithm that uses perceptual encoding in order to give preference to the pixels that matter most to viewers.  This goes beyond a simple framerate/quality tradeoff because the codec can send the more important parts of the picture at a higher quality and still give more importance to the framerate than to the parts of the picture the viewer doesn't care about.

The Elemedia codecs have many more features that will help you in the development of your product, including privacy (the ability to either display a static image indicating that the camera is "muted" or pause the video at the last frame transmitted), sending still pictures at a higher resolution than the video stream,  the ability to add borders to any image and a great transmission rate control algorithm.

The Agora videocodecs have a great history--Several of them were originally developed at Lucent’s Bell Labs, and all have been developed by Bell Labs or former Bell Labs employees. 

Agora Labs is adding to their video codec product line, contact us if you don't see the codec you need!