This article introduces the ISO/IEC MPEG Immersive Video (MIV) standard, MPEG-I Part 12, which is undergoing standardization. The draft MIV standard provides support for viewing immersive volumetric content captured by multiple cameras with six degrees of freedom (6DoF) within a viewing space that is determined by the camera arrangement in the capture rig. The bitstream format and decoding processes of the draft specification along with aspects of the Test Model for Immersive Video (TMIV) reference software encoder, decoder, and renderer are described. The use cases, test conditions, quality assessment methods, and experimental results are provided. In the TMIV, multiple texture and geometry views are coded as atlases of patches using a legacy 2-D video codec, while optimizing for bitrate, pixel rate, and quality. The design of the bitstream format and decoder is based on the visual volumetric video-based coding (V3C) and video-based point cloud compression (V-PCC) standard, MPEG-I Part 5.

Subjective quality evaluation is widely used to optimize system performance as a part of end-products. It is often desirable to know whether a certain system performance is acceptable, that is, whether the system reaches the minimum level to satisfy user expectations and needs. The goal of this paper is to examine research methods for assessing overall acceptance of quality in subjective quality evaluation methods. We conducted three experiments to develop our methodology and test its validity under heterogeneous stimuli in the context of mobile television. The first experiment examined the possibilities of using a simplified continuous assessment method for assessing overall acceptability. The second experiment explored the boundary between acceptable and unacceptable quality when the stimuli had clearly detectable differences. The third experiment compared the perceived quality impacts of small differences between the stimuli close to the threshold of acceptability. On the basis of our results, we recommend using a bidimensional retrospective measure combining acceptance and satisfaction in consumer-/user-oriented quality evaluation experiments.

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Abstract-This paper provides an analysis on the optimal channel changing delay in DVB-H (Digital Video Broadcasting for Handhelds) channels for Mobile Television. DVB-H uses a time-sliced transmission scheme to reduce the power consumption used for radio reception in DVB-H receivers. Channel changing delay, i.e. changing from one audio-visual service to another, is increased due to the time slicing scheme in DVB-H. One of the significant factors in channel changing delay is the Decoder Refresh Delay. The Decoder Refresh Delay is the time from the start of video decoding to the start of correct output from decoder. This delay is minimized when a time-slice starts with a random access point picture such as an instantaneous decoding refresh (IDR) picture in H.264/AVC standard. In DVB-H, encapsulation into time-slices is performed independently from content encoding. At the time of encoding, the exact time-slice boundaries are typically unknown, and therefore it is impossible to align the location of IDR pictures to time-slice boundaries. The average decoder refresh delay can decrease by frequent IDR pictures in the bit stream. However, using very frequent IDR pictures drops the compression efficiency and the quality of compressed video dramatically. Another factor in channel changing delay is the delay required to compensate the variation in bit rate. In video streaming over DVB-H the improved quality and compression efficiency obtained by using variable bit rate should be exploited. Higher quality and compression performance can be provided by higher delay. Moreover, when changing channels, a delay is required until the start of the desired timeslice and a further delay is incurred to complete the reception of the entire time-slice. These delays depend on the time-slicing parameters that define the power saving percentage obtained as the result of the time-slice scheme. The lower the receiver power consumption, the higher delay is required. Therefore, there is a strong multilateral relationship between the quality of compressed video, the channel changing delay and the power consumption in the receiver. Simulations were conducted and based on the simulation results an optimal operating area is proposed.

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