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Annex 1 to Doc. AVC-256R
Annex 1 to Doc. AVC-256R

Documents for the sixth meeting of the Experts Group  
18-27 March 1992, Stockholm/Haifa


Normal Documents

	Note: Contributions with "*" have also been sent to MPEG for consideration at 
the joint sessions.  Some documents are also registered directly through the 
MPEG channel, which are not marked with * but have been considered at the 
joint sessions.  See AVC-257R. 

AVC-177R REPORT OF THE FOURTH MEETING OF THE EXPERTS GROUP FOR 
         ATM VIDEO CODING IN YOKOSUKA (CHAIRMAN)

Achievements and action points obtained at the Kurihama joint sessions and 
the Yokosuka sole sessions are recorded.

AVC-178  REPORT OF SGXVIII MELBOURNE MEETING 
         (SGXV REPRESENTATIVE TO SGXVIII MELBOURNE MEETING - 
          M. BIGGAR)

Outcome of the SGXVIII Melbourne meeting is presented focusing on the 
issues of this Experts Group concern.  SGXIIII response to our questions is 
outlined and further actions which we should take are suggested.  It is 
recommended that any further opportunities for the Experts Group members 
to attend SGXVIII meetings and vice-versa be exploited.

AVC-206R REPORT OF THE FIFTH MEETING OF THE EXPERTS GROUP FOR 
         ATM VIDEO CODING IN SINGAPORE (CHAIRMAN)

Achievements and action points obtained at the sole and joint sessions are 
recorded.  This meeting handled mainly those topics related to the source 
coding algorithm.

AVC-207  REPORT OF THE MEETING OF SWP XVIII/8-3 - SERVICES, IVS 
         AND AAL TYPES 1 AND 2 (SWP XVIII/8-3)

This report covers the following topics; AAL Type 1, AAL Type 2, liaison to 
this Experts Group and CMTT/3 regarding AAL Types 1 and 2, service aspects 
including updating the IVS Baseline Document  

AVC-208  LIAISON STATEMENTS TO ATM VIDEO CODING EXPERTS GROUP 
         (SGXVIII)

The following study results of SGXVIII are contained as responses to the 
questions sent from the Experts Group;

    -	IVS Baseline Document
    - 	AAL for supporting video signal transport
    - 	liaison statement to CMTT/3 on AAL for supporting high quality audio 
signals  
    - 	use of CLP bit and UPC for peak cell rate
    - 	standardization of Network Performance parameter values
    - 	G.82X provisional objectives and ATM cell loss


AVC-209  IVS BASELINE DOCUMENT (SWP XVIII/8-3 - EDITOR OF IVS 
         BASELINE)

This has been updated by incorporating new texts proposed by CCIR IWP 11/9, 
CMTT/3 and this Experts Group, results of the IVS coordination meeting, and 
recent achievements in SGXVIII.

AVC-210  OUTCOME OF AAL STUDY (SGXVIII)

Draft text of section 2/I.363 (AAL Type 1) and possible candidate functions 
for AAL Type 2. 

AVC-211  LIAISON STATEMENT TO EXPERTS GROUP FOR ATM VIDEO CODING 
         IN SGXV (WPXVIII/5 - MELBOURNE MEETING)

The following items are addressed concerning the multimedia service support 
on B-ISDN;

    - 	interworking user multiplexed signals from N-ISDN with those of VC 
      	multiplexed signals in B-ISDN
    - 	resource allocation rearrangements during a call
    - 	multimedia synchronization

Draft I.37y "Network capabilities to support multimedia services" is attached 
for information and comment.

AVC-212* PRELIMINARY WORKING DRAFT - PWD (PWD EDITING GROUP)

This document contains a basis of Test Model specifications which has been 
obtained by the adhoc group established at the Singapore meeting.  Some 
points are indicated as being not clear.

AVC-213  FILTERS FOR CONVERSION BETWEEN CCIR-601 AND SCIF 
         (NORWAY)

Filter coefficients for converting SCIF back to CCIR-601 signals are given.  
Tape demonstration for SCIF pictures converted from CCIR-601 sequences and 
CCIR-601 signals reconstructed are accompanied.  This document is 
supplementary to AVC-203.

AVC-214  INTRODUCTION TO AAL TYPE 1 
         (SPECIAL RAPPORTEUR SWP XVIII/8-3 - K. YAMAZAKI)

This document is a collection of tutorial diagrams and explanations to 
understand the specification of AAL Type 1 and their background.

AVC-215  CONSIDERATIONS ON SUPER CIF (BELGIUM, FRG, ITALY 
         FRANCE, THE NETHERLANDS, NORWAY, SWEDEN, UK)

Three options (single format, dual format, generic) and their combinations
are discussed for the H.26X format specification.  Since the development of 
MPEG-2/H.26X video coding is directed toward a generic standard, it is 
argued that the selection of a SCIF format will not aid the algorithm 
development in the way that CIF did for H.261.  As a conclusion, the 
following is proposed;

Though a solution which permits world-wide conversational services is 
needed, the CCITT Experts Group should defer making a firm decision about 
the incorporation of Super-CIF in H.26X.  Study on the topic should 
continue.

AVC-216  THE NETWORK ACCESS FOR MULTI-LAYER AND MULTI-RESOLUTION 
         VIDEO SERVICES OVER THE B-ISDN (UK)

Multi-layer coded signals require sufficiently small transmission delay for 
low bit rate components, differing QOS for different layers, and minimal 
relative skew timing (or stipulation of maximum value of skew between 
layers).  After discussing three possible scenarios (1 VP with 2VCs having 
different QOS, 1 VP with 1 VC having CLP bit for multiplexing, 2VPs each with 
1 VC), some questions for clarification are placed to the network 
specialists. 

AVC-217* PROPOSAL FOR THE JOINT WORK BETWEEN ISO/MPEG AND 
         CCITT/AVC EG (BELGIUM, FRANCE, FRG, ITALY, NORWAY, 
         THE NETHERLANDS, SWEDEN, UK)

It is proposed that the meetings of the Video and Requirements groups on 
matters related to H.26X/MPEG-2 should be held in sequence.

AVC-218  A SURVEY ON CBR VERSUS VBR (DBP-TELEKOM)

Choice of CBR or VBR is discussed by comparing the five potential codings; 
CBR, VBR with peak rate regulation where charge may be based on the 
declared rate or number of transported cells, VBR with peak and average 
regulation, and 2-layer VBR.  Checkpoints are listed for each VBR 
alternative, stressing the impact of preventive UPC and possible coding 
efficiency loss of 2-layer schemes.  

AVC-219  FLEXIBLE SPATIAL RESOLUTIONS (AUSTRALIA)

Flexible spatial resolutions, which lie within some maximum resolution limits, 
is proposed so that a wide range of applications be covered.  It is claimed 
that this approach does not significantly impact on the complexity of 
codecs and MCUs.

AVC-220  FLEXIBLE FRAME RATES (AUSTRALIA)

It is proposed to introduce a limited flexibility through frame dropping (as 
used in H.261) in H.26X.  Since the quality requirements of some applications 
make frame rate conversion unacceptable, it is proposed to consider 
introducing mechanism to allow a range of frame rates.  One simple mechanism 
to insert explicit source frame timing information in the bitstream is 
proposed as a starting point of discussion. 

AVC-221  TRANSPORT OF LAYERED VIDEO ON B-ISDN (AUSTRALIA)

The following is pointed out concerning layering of video signals;

    -	to use network capacity efficiently in a layered multipoint video call, 
multiple virtual channels are required,
    -	layering within an interworking layer, to control the effect of cell 
loss and match ATM loss priority, should be studied, and 
    -	the components within each layer need to be multiplexed in a way that 
minimizes the impact of cell loss.


AVC-222  ATM ADAPTATION LAYER TYPE 2 FUNCTIONALITY (AUSTRALIA)

Necessary functions for AAL Type 2 are discussed, raising the following for 
discussion and communication to SGXVIII;

    -	commonality between AAL Type 2 and AAL type 1 is not required,
    -	aligning video data with cell payload may assist in minimizing error 
propagation,
    -	cell payload length indicator may be needed to deal with partially 
filled cells,
    -	sequence number is required to detect cell loss, whose length is to be 
determined by the B-ISDN cell loss characteristics,
    -	multiplexing capabilities within the AAL may be required to indicate 
different layers of coded video signal.

AVC-223  END TO END SIGNIFICANCE OF THE ATM HEADER CLP BIT 
         (AUSTRALIA)

It is proposed that the CLP bit of the ATM header be used only for its 
intended purpose of cell loss priority indication.  Video layer indication is 
a function which is independent of the CLP bit.

AVC-224  NETWORK REQUIREMENTS FOR MULTIMEDIA INTERWORKING 
         (AUSTRALIA)

In order to allow smooth migration to the long term goal of VC-base 
multimedia multiplexing, and to avoid that B-ISDN terminals must emulate 64 
kbit/s ISDN user based multiplexing, the following is proposed for liaison to 
SGXVIII and SGXI;

    -	B-ISDN ISCP signalling and VC-base multiplexing must be able to 
provide user-user signalling and multimedia multiplexing facilities 
currently provided by H.221 etc. at a reasonable cost,
    -	network based interworking between B-ISDN and N-ISDN terminals must 
be provided.

AVC-225  DISPLAY FACILITIES (SWEDEN)

Information is given about the display facilities during the Stockholm 
meeting, which can display progressive as well as interlaced pictures.  A 
synthetic test picture is also provided to compare progressive and 
interlaced displaying.

AVC-226  CONSIDERATIONS ON MULTIMEDIA MULTIPLEX METHODS (JAPAN)

Multimedia multiplex methods (user/SAR/VCI) are reviewed in the light of AAL 
Type 1 specification and AAL Type 2 functionality candidates.  Then it is 
pointed out that the multimedia multiplex on one VC should be studied in 
addition to the reference VCI multiplex method.  Finally, MPEG1 system is 
indicated to have potentially delay and error recovery problems for real 
time audiovisual communications.

AVC-227  REQUIREMENTS FOR TD - TRAFFIC DESCRIPTOR, ESPECIALLY 
         CDV - CELL DELAY VARIATION (JAPAN)

After analyzing the terminal configuration with focus on cell delay 
variation (CDV), the following is proposed as liaison to SGXVIII;

    -	guidance is required for translation between service rated at AAL-SAP 
and cell rate at ATM-SAP,
    -	CDV of NT2 is the most influential in the terminals system,
    -	definition of CDV should be such that the maximum value is easily 
calculated at a certain probability, thus the receiving buffer can be 
designed,
    -	CDV specification should limit the total delay between the two S 
points so as to meet the requirements of conversational services.

AVC-228  CONSIDERATION OF LAN AND MAN (JAPAN)

LAN/MAN is characterized by the fact that there is no guarantee when a next 
video frame signal can be transmitted after the current video frame has 
been transmitted.  Hence commonality between AAL Type 2 and AAL Type 3/4 
may become more important in the LAN/MAN environments.

AVC-229* STUDY ITEMS FOR EMBEDDED CODING (JAPAN)

In addition to coding performance, hardware complexity, end to end delay 
and service aspects are listed as study items which should be clarified 
before adopting embedded coding with existing standard core in H.26X.  
Multipoint communication is discussed as a case involving H.26X and H.261.

AVC-230  JITTER PERFORMANCE OF AN ADAPTIVE CLOCK METHOD (JAPAN)

Clock recovery experiments are carried out using an adaptive clock method, 
where PCM video signals with 14.3 MHz (4fsc) sampling frequency are subject 
to the ATM cell arrival jitter and reproduced pictures are observed by 
varying the low pass filter characteristics of the VCO loop.  It is concluded 
that the jitter of clock should be reduced to such level as EIA RS-170A 
standard requires.

AVC-231* CODING EFFICIENCY COMPARISON BETWEEN MULTI-FIELD 
         PREDICTION AND ADAPTIVE FRAME/FIELD PREDICTION (JAPAN)

Multi-Field prediction and four frame based predictions (combination of 
adaptive/frame and MC/DCT) are compared in the TM0 framework.  It is 
concluded that adaptive field/frame coding performs better in coding 
efficiency at the cost of delay and hardware complexity.

AVC-232  FIELD ADJUSTED MC FOR FRAME-BASE CODING - 2 - (JAPAN)

Prediction efficiency and coded results are reported for the field-time 
adjusted MC which uses different parity field to get high resolution 
reference pictures.  From these results and analysis on complexity and 
syntax similarity with MPEG1, it is concluded that this be adopted instead of 
adaptive field/frame MC.  Comparison of multi-field prediction and this 
technique is also given, supporting the frame base prediction. 

AVC-233* A STUDY OF LOW DELAY MODE (JAPAN)

TM0 simulation is carried out for IBBP, IP'P'P, IPPP and IppP structures (P': 
non-recursive forward prediction, p: recursive forward prediction with 
larger stepsizes than those of P).  It is concluded that backward prediction 
improves coding efficiency at the sacrifice of coding delay.



AVC-234* SIMULATION RESULTS ON COMPATIBLE CODING (JAPAN)

Results of two experiments are reported for the coding efficiency 
improvements obtained by using base layer pictures as a prediction mode; 
uncoded CIF pictures in an RM8 based algorithm, and coded SIF pictures in 
TM0.  Consideration of down- and up-sampling filters, field skipping vs field 
merging is also included to have better prediction from the base layer.  It 
is concluded that the coding efficiency does not deteriorate due to the 
base layer prediction mode but improvements are necessary for prediction of 
P and B pictures.

AVC-235* CELL LOSS COMPENSATION METHOD (JAPAN)

Information is provided on the two experiments addressing cell loss 
countermeasures; one is on estimation method for a lost motion vector using 
those of surrounding macroblocks, and the other is on cell loss concealment 
a) using two vertically adjacent macroblocks, B) cyclic intra pictures (N=12) 
and C) leaky prediction plus video structured cell in addition to A).  The 
second experiment follows the agreed cell loss experiment specification and 
method C) is demonstrated to show acceptable picture quality even at 
CLR=10E-03.

AVC-236* COUNTERMEASURES AGAINST CELL LOSS FROM VIEWPOINT OF 
         IMAGE DETERIORATION AND TRANSMISSION EFFICIENCY (JAPAN)

Several questions are raised to lead to the choice of cell loss protective 
measures in H.26X.  Discussion is given on the picture quality degradation 
(spatial and temporal) and synchronization recovery from cell loss focusing 
on the transmission efficiency.  There are also raised questions on cell loss 
characteristics of the network and necessary compromise between 
requirements from communication, broadcast and DSM.

AVC-237  SIMULATION RESULTS ON HALF PIXEL ACCURACY MOTION 
         ESTIMATION (JAPAN)

Half-pel motion compensation is compared between searching in the decoded 
picture and searching in the original picture using TM0 field based coding.  
It is concluded that there is little difference in coding efficiency.

AVC-238  EVALUATION OF TM0 ALGORITHM AT LOW BIT RATE (JAPAN)

TM0 experiments are carried out to test lower bit rate operation.  Lower 
bounds of 1.5 - 2 Mbit/s are found as the limit of normal rate control.

AVC-239  PERFORMANCE OF PROGRESSIVE SCIF (JAPAN)

Three format conversion methods for 525/60 CCIR-601 and progressive SCIF 
are compared with respect to picture quality of reconstructed local format 
as well as SCIF and coding efficiency; intra-field line insertion, adaptive 
intra-field/inter-field line insertion, intra-field line shift.  It is also 
pointed out that interlace SCIF format may not necessarily be advantageous 
in coding efficiency.

AVC-240  PICTURE FORMAT CONVERSION ACCORDING TO AVC-203 (JAPAN)

Frame rate and line number conversion are carried out to obtain progressive 
scan SCIF pictures according to the filter suggested in AVC-203/213 and 
another higher order filter.  Based on the observation results, it is 
concluded that distortion due to the current format conversion is larger 
than the coding noise envisaged for directly coding 525/60 or 625/50 CCIR-
601 pictures at 5-10 Mbit/s.  Particularly, frame rate conversion is found to 
suffer from large area flickers.

AVC-241  IMPACT OF SCIF CONVERSION ON PREDICTION STRUCTURE 
         (JAPAN)

SCIF pictures converted form 525 line CCIR-601 test sequences using NTA 
filters (AVC-203) are coded with an RM8 based algorithm.  It is shown that 
single frame prediction suffers significant reduction in coding efficiency 
compared to multiple frame prediction, pointing out that the definition of 
coding structure may have to take into account the practical conversion 
methods.

AVC-242  HARDWARE CONSIDERATION ON LINE SCANNING CONVERSION 
         (JAPAN)

Comparison of several methods for converting interlace to progressive scan 
signals are tabulated with respect to camera cost, hardware of scanning 
converter, hardware size of video codec, coding efficiency and picture 
quality.  It is concluded that the progressive scanning format improves 
picture quality for only those who have expensive cameras (or complicated 
scanning converters) and progressive monitors.

AVC-243  COMMENTS ON THE PICTURE FORMAT FOR ATM VIDEO CODING 
         (JAPAN)

Based on the experimental and other surveys on the impacts of SCIF to 
picture quality degradation, loss of coding efficiency, increase of delay and 
hardware/software burden, it is concluded that progressive scan format as 
proposed in AVC-29 is not promising.  It is pointed out that interlace 
formats my need further study, and that if the SCIF approach cannot give 
satisfactory solutions, dual format and other approaches should be checked 
against the above mentioned items.

AVC-244  OBJECTIVE EVALUATION SCHEME FOR PICTURE FORMAT 
         CONVERSION (JAPAN)

To evaluate the possibility of SCIF, an objective method for comparing 
format conversion is proposed, which used synthetic test pictures so that 
exact representation in any format is carried out.

AVC-245  TM0 AND IMPROVEMENTS (NORWAY)

The following improvements to TM0 are tested and actions in Test Model are 
suggested;

    - 	offset of quantizing decision levels (to be included in TM)
    - 	use of decoded pictures for half pixel motion search (to be included 
in TM)
    - 	averaging two fields/frames for prediction (testing to be continued)
    - 	adaptive VLC
    - 	3-D VLC (room for further testing to be made)




AVC-246  SCIF FORMAT + REQUIRED TESTS (SWEDEN)

Based on the reality that progressive cameras and monitors are not widely 
available now, the purpose of a new coding format is questioned by listing 
the following three scenarios;

    - 	interlaced input/output with intermediate format being always used,
    - 	interlaced input/output with intermediate format being used only for 
interregional communications,
    - 	progressive input/output with interlaced input as a temporary 
solution.

Necessary tests including conversion and coding are listed.

AVC-247  MONITORING VBR VIDEO TRAFFIC (BELLCORE)

After reviewing the current activities of SGXVIII on Usage Parameter Control 
and Traffic Descriptor, it is pointed out that the codec rate controller and 
the UPC may monitor the traffic differently, thus some congruency may be 
needed between the UPC parameters and the codec rate controller 
parameters.

AVC-248  COMMENTS ON THE TABLE FOR MULTIMEDIA MULTIPLEXING 
         METHODS (BELLCORE)

It is raised that the following three service attributes be added to the list 
of requirements; Quality of Service (QOS), Operation and Management (OAM), 
Cost per VC.

AVC-249  CLOCK RECOVERY FOR VIDEO (BELLCORE)

SRTS defined by SGXVIII is examined against CBR and VBR video applications 
which requires recovery of video sampling clock.  CBR can use the current 
specification as it is, but VBR needs some modification in the RTS channel; 
restricting the minimum information generation, increasing the counting 
period, or buffering to store RTS temporarily.  Collaboration with SGXVIII 
on this matter is suggested.   

AVC-250  MERITS OF SQUARE-PEL ASPECT RATIO 
         (AT&T, BELLCORE, DIS, NCS)

Currently used pel aspect ratios are listed for such applications as 
personal computer and workstation, videoconferencing, digital TV 
broadcasting, HDTV, digital film production and super HDTV.  Based on the 
the fact that computer and film industries require the square pel, and that 
HDTV follows similar trend, some of its merits are further elaborated.  It is 
concluded that specific parameters close to CCIR-601, such as 704x528 or 
768x576, require further study. 

AVC-251* IMPROVED PREDICTION FOR LOW DELAY VIDEO CODING MODE 
         (FRG - DAIMLER-BENZ)

IBBP, IPPP and IP'P'P' structures are compared on SM3 where P' is forward 
predicted pictures and a prediction mode using weighted interpolation from 
two preceding coded pictures is added to the preceding frame prediction.  
IP'P'P' is reported to perform significantly better than IPPP but not better 
than IBBP.

AVC-252* CODING RESULTS FOR SCIF PROGRESSIVE IMAGES (AT&T) 

Progressive scan signals having 720 pels x 576 lines x 60Hz and obtained 
from two films were coded according to MPEG1 encoder.  Simulation results 
are presented for coding efficiency comparing the IBP and IP'P structures, 
VBR traffic descriptor parameters for leaky bucket and sliding window, and 
impact of cell loss on the one-layer and two-layer transmission.

AVC-253  LIST OF REQUIREMENTS FOR VIDEO REQUIREMENTS LISTING 
         (ADHOC GROUP FOR VIDEO REQUIREMENTS LISTING)

This is a report of the adhoc group correspondence work, providing a 
general requirements list for the MPEG Phase 2 video coding standard and a 
guide for the Video group work. 

AVC-254* COMPATIBLE CODING STRUCTURE (PTT RESEARCH)

A proposal is made for inclusion of a compatible coding structure in the 
Test Model.  The encoder system consists of two loops, an upper loop 
processing the high resolution image, and a lower loop processing the 
compatible image.  The prediction error in the upper loop is predicted by 
the coded error signal in the compatible loop.  

AVC-255* ABOUT THE CONSTRAINTS ON VARIABLE BIT RATE CODING 
         (DBP-TELEKOM)

This is an update of AVC-218, including discussion on VBR coding for 
distribution purposes.


Temporary Documents

TD-1	Agenda (Chairman)
TD-2	Available documents (Chairman)
TD-3	Chronicle on the disclosure of patents relevant to px64 (Chairman)
TD-4	List of tape demonstrations (Chairman)
TD-5	Report of small group meeting on video format (Mr. Morrison)
TD-6	Report of small group meeting on network issues (Mr. Biggar)
TD-7	Proposal on low delay mode experiments (Mr. Bjoentegaard)
TD-8	Draft meeting report for the sole sessions (Chairman)


END