Includes brief descriptions and explanations of three of the most important standards relevant to multimedia today-JPEG for still images, H.261 for conversational services and MPEG for storage and broadcast applications. They are presented in order of increasing complexity though this is not in accordance with the chronological order of completion. It should be noted that these standards effectively specify only the syntax and semantics of a coded representation such that a decoder can interpret it and reconstruct what the encoder intended. Many coder aspects are deliberately left open and different designs will produce different representations and different decoded results when fed with the same input pictures.<
>
This paper presents the ITU-T Study Group 15 development of H-series Recommendations that allow interworking between different audiovisual communication terminals manufactured by different equipment providers. The paper focuses on H.310 and H.321 systems for broad-band ATM environments and H.322 and H.323 systems for LAN environments where the quality of service may or may not be guaranteed. The paper first lists the Recommendations developed by the ITU-T for audiovisual communication systems and the network environments in which they may be used. It then describes the design philosophy, the network specific characteristics, and hardware trials for each system. Then it describes the communication control protocol defined in H.245 which is used commonly by different audiovisual communication systems. Finally, the paper discusses interworking scenarios for communication between the different types of terminal on different networks.
Describes the test procedures and the hardware field trials carried out in Europe and in Japan in order to participate in the definition of the n*384 kb/s standard. The authors also describe how five countries, starting with a simple document (flexible hardware specifications), undertook to build up flexible hardware prototypes. Detailed test procedures are presented which allowed the different laboratories to make sure that their codec worked properly: loopback test at the encoder side, use of test signal generators for debugging the decoders, and back-to-back or satellite connections for full compatibility checks. The hardware field trials have demonstrated the consistency of the hardware specifications, shown that the algorithm could be implemented with a reasonable hardware complexity, revealed that the picture quality is better than expected, and confirmed the interworking capability of the codecs (use of a common intermediate format) between 625- and 525-line-television countries.< >
A novel approach to image mosaicking from MPEG video is presented in this paper. The motion vectors in both P- and B-frames are used for global motion estimation. The bi-directional information in B-frames provides multiple routes to warp a frame to its previous anchor frame. A least median of squares based algorithm is adopted for robust motion estimation. In the case of a large proportion of outliers, we detect possible algorithm failure and perform re-estimation along a different route. Based on the motion parameters between consecutive frames, the static background panorama and dynamic foreground panorama are constructed from warped images over a whole video sequence.
We propose a new architecture which enables a motion estimation (ME) processor to be constructed using analogue components. At present, due to the arduous scale and nature of the computations required in digital hardware realisations, the ME processor is invariably the most complex and expensive component of a modern video codec. Our preliminary results indicate that very considerable reductions in size, power consumption and hence cost are available using our proposed method.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
