Mobile Blog: Video, Media, Augmented Reality, Rich Media, IVVR

photo credit: Iain Farrell

Even with a great deal of marketing, early attempts to convert users to the video telephony technology flopped (Jones and Marsden). In contrast, desktop video conferencing is incredibly popular for private person-to-person conversations and widely used for video conferencing in business environments such as telepresence for computer-supported cooperative work (CSCW).

In desktop video conferencing scenarios, typically a stationary computer is used. Camera and microphone are fixed and usually maintain the same distance from the person participating during the conversation. Moreover, lighting conditions are generally better than

photo credit: Steven Fernandez

Media compression, error concealment measures, and the characteristics of wireless networks have side effects on the quality of 3G video telephony and IVVR (Interactive Voice & Video Response) applications.

3G-324M requires only the use of speech codecs. In contrast to audio codecs, speech codecs are designed for speech transmission within a narrow frequency range, making them inappropriate for transmission of music or a range of artificial sounds. This fact needs to be considered when designing IVVR applications

photo credit: dno1967

3G video telephony generally operates over a single 64 kbit/s connection where both parties need to share the available bandwidth. Effectively, the application then is left with 60 kbit/s, or less that are dedicated for both media types, since H.245 call control messages reduce the gross bandwidth. In 3G-324M systems, the bandwidth is allocated dynamically; however, generally said, every party has 50% of the bandwidth available for sending audio and video signals. In a typical unidirectional scenario, 12.2 kbit/s are allocated for the speech codec, and a bitrate of 43-48 kbit/s is allowed for the video data (Sang-Bong, Tae-Jung and Jae-Won).

By employing rate control methods in the media encoders, the network can dynamically change these bitrates depending on network conditions and application demand. When two parties communicate simultaneously, the bitrates for the speech and video codec can be reduced in the encoders of both parties, keeping the overall bitrate below 64 kbit/s. For instance, when just one party shows speech activity, the speech bitrate for the other party can be reduced to a minimum where only comfort noise is generated on the receiver side (Holma and Toskala); AMR (Adaptive Multi-Rate) can perform these bitrate changes every 20ms. For video, the encoder can reduce the average bitrate by either reducing the frame rate or simply dropping frames during transmission. To increase the overall frame rate on the receiver side, the decoder can employ H.263 temporal scalability.

In 3G video telephony, the audio and video signals are bidirectionally streamed over dedicated circuit-switched W-CDMA (Wideband Code Division Multiple Access) paths. Streaming describes media is continuously being received or sent and played back on a terminal. Non-conversational one-way audio or video streaming requires a transport delay variation of below 2s (3GPP (3rd Generation Partnership Project)). In contrast, two-way video telephony introduces even higher real-time requirements with an end-to-end, one-way delay of below 150-400ms

IVVR (Interactive Voice & Video Response) Application: IVR (Interactive Voice Response) Supplement Example

IVVR applications use the IVVR mobile technology to create services based on 3G video calling. In my opinion, the easiest conceivable IVVR application is an IVR supplement that adds the video dimension to typical IVR services:

IVR Supplements are dialog-based IVVR applications founding on the notion of typical IVR applications for call dispatching or information services. They add the visual dimension to IVR applications by showing slides as a graphical representation of an IVR voice menu on the phone screen. This increases accessibility for the dumb, making it possible to interact with IVR where listening might not be desired

photo credit: jepoirrier

I just posted my article about the IVVR (Interactive Voice & Video Response) Game Santa Claus Sleigh Ride, and I totally forgot to post the number where you can play the game by yourself.

You can give it a try by placing a video call to +498938155555. You can probably only reach it within Germany. But I haven’t tested this, though.

By the way: Do you know more IVVR servics, either in Germany or worldwide? Use the comment function to post them and I will create a list of IVVR services!