Annex 1 to AVC-398R

Documents for the Torino/Roma meeting
(21-29 January 1993)

Normal Documents

	Note - [93/nnn] indicates MPEG93/nnn.

AVC-398R	REPORT OF THE NINTH MEETING IN IPSWICH and LONDON - PART I (CHAIRMAN)
AVC-399R	REPORT OF THE NINTH MEETING IN IPSWICH and LONDON - PART II (CHAIRMAN)

These two documents report the outcome of the sole and joint sessions held in October and November 1992.

AVC-400	TEST MODEL 3 (TEST MODEL EDITING COMMITTEE)
AVC-400b	TEST MODEL 3 (TEST MODEL EDITING COMMITTEE)
[N0328]

Achievements and clarification obtained at the London meeting were incorporated into Test Model 3, and several core experiments were defined for action.

AVC-401	FOURTH PROGRESS REPORT (CHAIRMAN)

This document reports major achievements of the Experts Group toward defining Recommendation H.26X for video coding in the ATM environments, covering three meetings in July, September and October.  Three particular items were raised for consideration of WPXV/1; work plan for broadband audiovisual Recommendations, common text approach for H.26X|MPEG-2, and very low bit rate videophone activities.

AVC-402	MEETING REPORT - EXCERPT (WPXV/1)

Items of the Experts Group concern are extracted from the outcome of the WPXV/1 meeting in November 1992; general SGXV and MPEG relationship, multimedia multiplexing, common text approach for H.26X|MPEG-2, timetable for broadband audiovisual system Recommendations, PSTN videophone, etc.   

AVC-403	EXPERIMENTS COMPARING LEAKY-PREDICTION AND ERROR CONCEALMENT 
[93/115]	(DSRC)

Experimental results are reported for three cell loss concealment techniques (temporal substitution, motion compensated substitution, motion compensated substitution plus I-frame concealment) and leaky prediction (Core Experiment F.3).  Slice size of 15 macroblocks is used.  It is concluded that leaky prediction degrades picture quality with or without cell losses while decoder only concealment techniques can significantly improve picture quality under cell losses.  Channel hopping performance of the leaky prediction is also tested to conclude that annoying artifacts are present even one second after hopping.

AVC-404	EXPERIMENTS ON COEFFICIENT SCANNING - F.5 (DSRC)
[93/108]

Experimental results are reported for two layer transmission of coded data by separating scanned coefficients at some point into High Priority and Low Priority channels.  It is concluded that the coefficient scanning approach provides an additional measure of robustness without losing coding efficiency in the no-error case.

AVC-405	EXPERIMENTS ON INCREASED ERROR RESILIENCE BY TRANSMITTING I-FRAME 
[93/116]	MOTION VECTORS (DSRC)

A syntax change and experimental results are reported for transmitting motion vectors for I-frames and subsequent use of these motion vectors for concealment at the decoder.  Experimental results for changing slice sizes at no loss and CLR=10-2 are also included.  It is concluded that this technique enables simple yet effective error concealment without impacting system features such as random access and bitstream editing via I frames and with only losing 0.7% of total bitrate.

AVC-406	EXPERIMENTS ON STRUCTURED PACKING WITH ERROR CONCEALMENT (DSRC)
[93/107]

Experimental results are reported for comparison of short slice and structured packing approaches (Core Experiment F.8).  It is concluded that using absolute macroblock intervals of 4 results in 0.3 dB loss in the no-error performance but 2.4 dB gain at CLR=10-2 relative to the 22 MB interval.

AVC-407	EXPERIMENTS ON SPATIAL SCALABILITY WITH ERROR CONCEALMENT (DSRC)
[93/114]

Experimental results are reported for cell loss resilience of two-layer spatial scalable coding compared that of non-compatible one.  Three different error concealment methods are tested; upsampled substitution, motion vector substitution, mixed (the first for I, the second for P, B)  It is concluded that the hierarchical transmission provides more possibilities for error concealment at cell loss rated higher than 10-3 and that the upsampled substitution performs best for error concealment at such high cell loss rates.

AVC-408	DEMONSTRATION OF TV AND INTERLACED SIF COMPATIBILITY (UK)
[93/002]

Compatible coding has been experimented for TV (at 2.5 Mbit/s) and Interlaced SIF (at 1.5 Mbit/s).  The results show that TM3 compatible coding is also effective to interlaced pictures in the base layer, that the simplified syntax in MPEG92/651 is valid, and that the two-layered coding is more efficient than the simulcast.

AVC-409	COMPATIBLE CODING (UK)
[93/004]

It is explained how compatible coding is advantageous for manufactures, service providers and consumers and a proposal is made that this approach be applied to the whole range of video coding developments.  Out of the three possible compatible arrangements (simulcast, tightly coupled layering, loosely coupled layering), loosely coupled layering is proposed for its more efficient bandwidth usage and more flexibility in coding format and algorithm selection.  As an evidence, four layered (QQSIF, QSIF, SIF, CCIR601) coding results are given with those of the simulcast approach, indicating significant difference in picture quality.

AVC-410	SNR SCALABLE EXPERIMENT WITH COMPATIBLE SYNTAX (UK)
[93/003]

Compatible syntax is used for the SNR scalability.  Experimental results are given to two schemes; one uses I pictures only for extension, the other uses I/P/B pictures.  For a particular case of coding Mob&Cal with 2.5 Mbit/s base layer and 1.5 Mbit/s enhancement, 1 dB and 0.66 dB gains were obtained for the I/P/B and I only enhancements, respectively, compared to simulcast.

AVC-411	SIMULATION RESULTS ON COMPATIBILITY (JAPAN)
[93/015]

Simulation results show that gain of embedded coding for the interlace-interlace case is smaller than that for the interlace-progressive case.  The sophisticated upsampling filter in MPEG92/758 does not improve coding efficiency, but intra quantization for compatible macroblocks provides more improvement.  Based on the coding efficiency comparison between spatio-temporal weighting and simple prediction from the base layer, it is proposed not to include the spatio-temporal weighting in the syntax taking its hardware complexity into account.

AVC-412	COMPARISON BETWEEN SHORT-SLICE METHOD AND STRUCTURED PACKING 
[93/079]	(JAPAN)

Experimental results and numerical evaluations are given for the comparison between the short slice method and the structured packing method, which are defined in Core Experiment F.8.  Considering the small difference in SNR and subjective quality, short slice is recommended since it does not need syntactic changes.  Experimental results for concealment and leaky prediction combined with short slice or structured packing are also given.  Evaluation of re-synchronization period by observation of processed pictures is described as 4 macroblocks being sometimes insufficient, requiring further study on applications, picture size, etc.

AVC-413	REPORT OF AC-LEAKY PREDICTION (JAPAN)
[93/158]

Experimental results are reported for Core Experiment F.7 "AC-leaky prediction", stating that DC refresh once every 6 frames gives the same coding efficiency as N=15 non-leaky prediction without limit cycle problem or noisy background.

AVC-414	FIX FOR THE NOISY BACKGROUND PROBLEM IN LEAKY PREDICTION (JAPAN)
[93/080]

Experimental results for adaptive DC quantization in leaky prediction (Core Experiment F.3) are reported, concluding that the noisy background is significantly improved thus the leaky prediction is a desirable method of temporal localization of errors.  Fixed step size of 8 is applied to DC components if a macroblock is identified as belonging to background according to the value of N_act defined in the TM3 rate control Step 3.  Use of adaptive quantizer weighting matrix is suggested for this purpose.

AVC-415	RESULTS ON NON-8X8  DCT CORE EXPERIMENTS (Q.5) IN LOW DELAY 
[93/083]	MODE(JAPAN)

Experimental results for the adaptive 8x1/8x8 DCT defined as Core Experiment Q.5 are reported, concluding that application of this technique is effective for the low delay operation in reducing mosquito noise, that adaptation based on absolute value summation of DCT coefficients is effective, and that the syntax can be simplified without significant loss of coding efficiency.

AVC-416	CASCADE CODING OF H.26X AND H.261 (JAPAN)
[93/081]

Cascade coding of TM2 (CCIR 601-525 format) at 4 Mbit/s and RM8 (CIF) at 1.5 Mbit/s, 384 kbit/s and 64 kbit/s has been experimented for Flower Garden to find that coding performance in terms of SNR and subjective quality does not differ from that of direct RM8 coding.  It is concluded that transcoding is a possible means of compatibility between H.26X and H.261.

AVC-417	CLARIFICATION OF LOW DELAY DESCRIPTIONS (JAPAN)
[93/084]

The following clarification is proposed for the syntax and semantics of the skipped picture (S-picture);
	- decoder operation,
	- value of the vbv_delay field to be set at the encoder and its use at the decoder,
	- data removing timing in VBV.

AVC-418	CORE PROFILE BASED ON COMMUNICATION APPLICATIONS CONSIDERATION 
[93/082]	(JAPAN)

Attributes and their values of the core profile is proposed in terms of TM3 syntax elements.  The approach taken here is first to select necessary elements for each of five typical audiovisual communication services on B-ISDN, and then to decide core profile elements considering those selection results and the fact that the core profile should cover other non-communicational services as well.  Some items are left for further study; compatibility/spatial scalability, chroma format, special prediction, non 8x8 DCT/NTC.  Influence of Cable TV on chroma format and special prediction is mentioned because of its demand size.

AVC-419	USE OF COMPATIBILITY/SPATIAL SCALABILITY IN MULTIPOINT AUDIOVISUAL 
	COMMUNICATION SYSTEMS (JAPAN)

Analysis is given to a multipoint communication system where H.32X terminals (containing H.26X) and H.320 terminals (containing H.261) are involved.  Three configurations (embedded, simulcast, switchable) are compared in terms of qualitative order for picture quality, delay, complexity of terminal and MCU.  It is concluded that video coding for H.32X should be switchable between H.26X and H.261, and if the transcoding approach for multipoint communications is not appropriate it should further support embedded or simulcast as a mandatory or optional specification.  Some items are listed for further study; bit rates, implementation complexity, multimedia multiplexing.

AVC-420	DEMONSTRATION OF HDTV CODING BY D1 VCR (JAPAN)
[93/014]

A part of TM2 coded HDTV pictures (presented in AVC-365) is demonstrated by using D1, where two sequences coded at 30/45/60 Mbit/s are contained.

AVC-421	MODIFICATION OF THE CCITT/MPEG ATM CELL LOSS MODEL 
[93/159]	(NL, UK, I, F, N, B, FRG)

In this document, it is pointed out that the characteristics of the random generator also influence the simulation of cell loss when cells of only one priority are used. A modification to the cell loss model is proposed to improve the simulation of cell loss.

AVC-422	ADDING COMPATIBLE PREDICTION TO EVEN FIELDS (PTT RESEARCH)
[93/048]

Experimental results are reported for adding compatible prediction to even fields from the odd field base layer in a field picture compatible scheme, concluding that this addition does not affect the performance in SNR and subjective quality.

AVC-423	INTERLACE TO INTERLACE CONVERSION (PTT RESEARCH)
[93/0049]

Experimental results are given for the maximum gain obtainable with interlace-interlace compatible coding and for impacts of horizontal upconversion filters.  It is concluded that the maximum gain by use of the non-coded base layer picture is 0.5 - 0.8 dB and that short and long horizontal filters presents no significant difference in SNR performance.  

AVC-424	RESULTS OF FREQUENCY SCALABLE CODEC ERROR RESILIENCE EXPERIMENTS 
[93/122]	(AUSTRALIAN UVC CONSORTIUM)

Cell loss experimental results are reported for the following four schemes;
	- single layered coding,
	- simple frequency scalable coding using scale_8 and scale_4 layered with no errors in scale_4,
	- the same with CLR=0.001 in scale_4,
	- the same with equal errors in scale_4 and scale_8.
It is concluded that the simple frequency scalable coding performed well with respect to cell loss resilience.

AVC-425	PROPOSED FRAMEWORK FOR ERROR RESILIENCE INFORMATIVE TEXT IN 
[93/016]	MPEG2/H.26X (AUSTRALIAN UVC CONSORTIUM)

A framework of informative text for the error/cell loss resilience is proposed for consideration and refinement.  It consists of general description of error/cell loss environments and possible techniques to cope with them; concealment, spatial localization, temporal localization, layered coding.

AVC-426	ERROR RESILIENCE AND FREQUENCY SCALABLE CODING 
[93/017]	(AUSTRALIAN UVC CONSORTIUM)

Advantages of the frequency scalable coding are discussed with respect to increased cell loss resilience, obtained by allocating most important DCT coefficients to a guaranteed channel, and by-product of some scalability features.  It is proposed that an error resilience method with scalable extensions be considered for the MPEG-2 core and that converging this technique with "Coefficients Scanning" in Core Experiment F.5 be merged to add additional functionality.

AVC-427	SPATIAL LOCALISATION FOR CELL LOSS RESILIENCE 
[93/018]	(AUSTRALIAN UVC CONSORTIUM)

Experimental results are reported regarding the number of lost macroblocks per lost cell for four different AAL packetization schemes; combination of whether AAL is streaming mode or message mode and whether macroblock resynchronization is used or not.  It is summarized that the number of macroblocks per lost cell is roughly half of the slice size for the case without macroblock resynchronization, and that it reduces to 1/3 to 1/10 for the case with macroblock resynchronization regardless of the AAL packetization scheme if the slice size is not smaller than 22, and that if the slice size is shortened message mode with macroblock resynchronization becomes overly inefficient due to overhead of unused cell capacity.  

AVC-428	A HYBRID AAL PACKING SCHEME (AUSTRALIAN UVC CONSORTIUM)
[93/019]

A new AAL packing scheme is presented which combines features from the structured packing and the short slice size method; the first macroblock in every cell is made the first macroblock of a slice.  AAL has 1 bit of "Slice Start Present" and 9 bits of "Slice Start POSition" to indicate the start of the slice, the encoder taking into account where the cell boundary is.  It is shown that coding efficiency and performance under cell loss condition is very comparable to that of the structured packing approach.

AVC-429	DEMONSTRATION OF COMPATIBILITY WITH H.261 (UK)
[93/005]

Experimental results are reported for a loosely coupled 'spatial split' scheme using H.261 coded 30 Hz CIF at the base layer and TM3 coded 25 Hz CCIR601 at the upper layer.  Bit rates are 0.5 Mbit/s for the base layer and 2 Mbit/s in total.  It is concluded that the 'spatial split' from TM3 provides the possibility of compatible layered coding with such combination, but that requirements of the general upsampling process needs further study.  It is pointed out that temporal imperfections of up- and down-sampling process have an effect on the performance of the compatible prediction, suggesting motion compensated interpolation.

AVC-430	ON THE CHARACTERIZATION OF THE CELL LOSS PROCESS OF VBR MPEG ON 
[93/???]	ATM (DSRC)

Simulation results for average burst length and average inter burst length are presented for a wide range of network utilization by modeled VBR MPEG-1 video traffic (average bit rate = 5.4 Mbit/s, average peak/average ration = 4, average SNR = 31dB).  

AVC-431	LEAKY PREDICTION (TELIA RESEARCH)
[93/076]

Experimental results are reported for leaky prediction with limit cycle solutions 1 and 2 in TM3 with adaptive macroblock quantization, concluding that the two solutions present no difference in SNR performance.  It is also reported that leaky prediction for Mob&Cal produces quite noisy background.

AVC-432	CELL LOSS ON ONE LAYER CODING (TELIA RESEARCH)
[93/0077]

Decoding strategies for transmission errors (cell losses in particular) are first discussed for cases with and without error detection, two possible ways when an unused VLC codeword is encountered, and two possible ways to process undecoded area lying between a discovered error and a next start code.  Simulations results are also presented to compare these to conclude that cell loss detection is preferable, that undecoded areas should be carefully reconstructed, and that for panning scenes use of the last correctly received motion vector is effective but further study is necessary for intelligent prediction frame store for other type of scenes.

AVC-433	SPATIAL SCALABILITY, INTERLACED TO INTERLACED (TELIA RESEARCH)
[93/078]

Experimental results are reported for compatible coding of Mob&Cal using interlace-interlace scalability, concluding that the best spatio-temporal weight is (w1,w2)=(0.25,0.25) and that simple spatial filters are not useful.

AVC-434	SIMULATION RESULTS ON DTV AND HDTV COMPATIBILITY (ETRI)
[93/160]

Experimental results are reported for embedded coding of HDTV (1920x1024 Y-pels per picture) and DTV (960x512 Y-pels per picture).  The coding scheme is a spatial pyramidal one which uses TM2 for both layers, assigning 15 Mbit/s to DTV and additional 20 Mbit/s to HDTV.

AVC-435	LIAISON STATEMENTS SENT TO SGXVIII (CHAIRMAN)

This document contains the following three liaison statements sent to SGXVIII from the Experts Group;
	- support of H.320 terminals in B-ISDN,
	- VBR video coding advantage vs UPC time constant,
	- update of the multimedia multiplex summary table in IVS Baseline Document.

AVC-436	LIST OF OPEN ISSUES (CHAIRMAN)

Open issues are listed with description of options, status, input required. aimed Recommendation, applications and target date according to the following categories;
	- framework for video coding standardization,
	- picture format,
	- video coding,
	- VBR vs CBR,
	- interface with networks,
	- end-to-end signalling,
	- multipoint communication system,
	- B-N interworking,
	- audio coding.
Background information such as system configuration, applications, milestones and target date (priority) is also contained.  

AVC-437	NEW WORK ITEM ON H.320 ADAPTATION TO ATM (F,UK,B,I,N,G,NL)

It is stated that ETSI/NA5/VCM members agree to include a new work item on adaptation (or extension) of existing H.320 terminals to ATM environments in the studies of the Experts Group.  The target date to complete this Recommendation should be 1994.

AVC-438	CLARIFICATION ON PROFILES (F,UK,B,I,N,G,NL)
[93/154]

This paper is a discussion paper that first lists some questions for clarification on profiles. It then describes two profiles as a basis for discussion:  Telecom profiles for conversational applications and Telecom profile for retrieval services.

AVC-439	EXPERIMENT ON SPATIO-TEMPORAL WEIGHTED H.261/MPEG2 COMPATIBILITY 
[93/106]	WITH BASE LAYER AT 128/384 KBIT/S (FRANCE)

This paper present the results of a (core) experiment about H.261/H.26X compatibility by using a two layered prediction scheme with base layer at 128/384 kbit/s with subsampling. It also includes a combination of MC based temporal prediction from top layer with a spatial prediction from base layer.

AVC-440	SPECIFICATION OF UPSAMPLING FILTERS FOR HIERARCHICAL CODING IN 
	H.26X/MPEG-2 (UK)

A question is raised whether the upsampling filters in the encoder and decoder must be identical in arithmetic processing.  A possible alternative approach of defining an ideal target filter and tolerable deviation from it is discussed to encourage consideration and study of this approach.

AVC-441	PROPOSALS FOR AND DISCUSSION ON THE SYNTAX TO EXPLOIT THE 
[93/179]	CORRELATION BETWEEN SIMILAR VIDEO SIGNALS OVER A PAIR OF VIDEO 
	CODECS (PTT RESEARCH)

Based on considerations of several embedded coding applications, this document proposes to include a 2 bit interlaced indication code in the sequence header and a stream_id codeword in the if(embedded) {...} section.  Renaming of sscalable to embedded, replacing sscalable_code by a 3 bit ssr code and adding a note to clarifying ssr referring to frame pictures are also proposed.

AVC-442	RESULTS OF EXPERIMENTS ON LEAKY PREDICTION (AT&T)
[93/178]

This document present views on the leaky prediction, summarizing that it ought to be included in the MPEG-2 core bitstream.  It is also mentioned that impairments are much less visible with 60Hz, progressively scanned pictures.

Temporary Documents

TD-1	Agenda for the sole sessions in Torino (Chairman)
TD-2	Available documents (Chairman)
TD-3	List of tape demonstrations (Chairman)
TD-4	Noise in leaky prediction (Chairman)
TD-5	Excerpt from "Guide for CCITT and ISO/IEC JTC1 Cooperation"
TD-6	Proposed CCITT EG positions for items requiring decision (Japan)
TD-7	Error resilience framework for informative text and experimentation (CCITT EG)
TD-8	Draft meeting report (Chairman)

END