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Motivation
In today’s society, audio and audio-visual telemeetings and audio- and video-conferences are gaining in importance. The term telemeeting is used here instead of teleconference to emphasize that a meeting is often more flexible and interactive than a business conference. Such meetings are more and more common also in private usage scenarios, e.g. when families communicate over large distances.
If the perceived quality is good enough, such telemeetings can be used as a complement to face-to-face meetings, and travel time and cost can be reduced. In spite of the increased use of telemeeting systems, there is currently no standardized method to evaluate telemeetinq quality, or to efficiently plan and lay out such telemeetings. Hence, there is a need to develop an agreed upon way of quantifying the perceptual quality of multi-party services that are conversational and interactive.
Telephony has traditionally been a point-to-point service, but a meeting is often a multipoint communication, where the participants can use different types of equipment to connect to the (virtual or real) meeting space, e.g. by fixed phone, mobile phone, PC, or videoconferencing equipment. To obtain a good evaluation of the telemeeting quality, the quality perceived by all participants in a conference needs to be assessed.
There are standardized subjective test methods for several components used in a telemeeting, such as speech, audio and video codecs, characterized by bit rate (fixed or variable), frame rate, resolution, noise cancellation, background noise, and synchronization and transmission impairments. Some recommendations on how to assess the interaction between these factors are available, too. In a telemeeting context, however, these factors need to be assessed in the light of multiple users connected via possibly asymmetric links.
Question
Study items to be considered include, but are not limited to:
- How can the subjective quality of multiparty audio and audiovisual telemeetings be evaluated?
- What performance criteria play a role when it comes to the assessment of audiovisual telemeetings?
- What is the quality impact of the different ways of connecting to a conference?
- What is the impact of multiple users connected to the telemeeting from one single-location?
- What is the impact of multiple users connected to the service from multiple locations?
- What is the impact when the users are connected via links of highly different quality?
- What aspects of communication performance need to be addressed when it comes to multimodal, multiparty interaction across links with limited resources for one or both modalities, or delay?
- How can different quality aspects related with conferencing and telemeeting quality be quantified, and how can their relative importance for the whole telemeeting quality be assessed with standardized evaluation methods?
- How do telemeeting assessment methods scale with the number of participants?
- Which additional performance criteria need to be assessed, especially when it comes to business meetings in a group-collaboration context?
- How can spatial sound and video be evaluated in a telemeeting (via headphone- or loudspeaker reproduction, with problems such as the microphone placement, echo-cancellation, camera adjustment, lighting conditions, etc.)?
- What are the relative roles of the transmission, the conference bridge or server, and the terminal equipment being employed, also with regard to the metaphor the user has of the service?
- What is the additional impact of data media such as presentation slides on user perception?
Tasks
Tasks include, but are not limited to:
- Recommendation on how to subjectively quantify the quality of audio and audiovisual multiparty telemeetings, where the participants can have different types of connections to the meeting.
- New recommendation on how the quality impact of separate components in a telemeeting that have been tested separately can be weighted together to give an overall telemeeting quality value (long term goal).
- Recommendation on how to evaluate spatial audio meetings. The methods should be applicable to listening through both headphones and loudspeakers.
- New recommendation on how different delays for different participants affect the meeting quality. Suitable test tasks for evaluation methods of interactive multiparty audio and audiovisual telemeetings are needed.
- Recommendation on the use of auditory and visual cues for high-quality telemeetings in different application contexts such as business and private meetings (including, for example, aspects such as eye-contact and other visual cues, e.g. in the light of technical characteristics such as screen sizes).
- Recommendation on the planning of telemeeting services of different overall quality requirements.
Relationships
Recommendations: P-series, G-Series
Questions: 6/12, 7/12, 8/12, 9/12, 14/12, 15/12
Study Groups: ITU-T SG 9, ITU-T SG 16 and ITU-R SG 6C
Standardization bodies: ISO-MPEG, 3GPP, 3GPP2, IETF, ETSI
Other groups: VQEG
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