Annex 2 to AVC-554R

Questions to the Video and Implementation sub-groups

1. Questions to the Video

1) AC-leaky prediction
2) Other coding tools being experimented

3) Impact of B-pictures and Dual-prime at High Level on the coding efficiency

To choose among the following;

•	not to define it as a profile at all
•	not to define it now but to include it at a later stage if found necessary
•	to define it as Main minus B pictures
•	to define it as Main minus B-pictures and Dual-prime

4) Comparison of coding efficiency between 

•	3 resolution scale scheme,
•	2 resolution scale + 1 SNR scale scheme

SNR scalability is newly identified functionality for Next Profile in addition to the three resolution scales which were listed in Sydney.  See MPEG93/600, 687.

4) Possibility of integrating spatial scalability and frequency scalability

As per Mr. Holtzman's presentation.

5) To be confirmed

•	Aspect ratio of existing or planned formats to be included in the table

		0.7500	1440x1080, 16:9
		0.7826	1440x1035, 16:9
		1.0435	1920x1035, 16:9

•	Flexible format relationship between layers (not only 2:1 but other ratios)

		See MPEG93/598.

6) Tools for scalability other than sscalabe

•	10/8 bit scalability
•	Progressive/interlace hierarchy
•	...

7) Copyright, copy management indications

Is there a mechanism for allowing 2 bits of copy guard information to be defined in the picture header in a way which does not impact on the frozen status of MP@ML ?  One suggestion is to define 2 of the 8 bits of extra_information_picture for this purpose.  Alternatively, this information could be carried at the Systems level.

2. Questions to the Implementation

1) Impact of B-pictures and Dual-prime at High Level on the implementation cost

To choose among the following;

	• not to define it as a profile at all
	• not to define it now but to include it at a later stage if found necessary
	• to define it as Main minus B pictures
	• to define it as Main minus B-pictures and Dual-prime

Which elements of the Main Profile need to be excluded to define Simple Profile which is suitable for low cost applications; e.g. 8 Mbit/s DRAM at Main Level (see MPEG93/690)?

Assuming that Simple Profile is Main Profile minus some elements as stated above, is there significant implementation cost penalty incurred if we specify that Simple Profile at High Level should be able to decode Main Profile at Main Level bitstreams, and similarly Simple Profile at Main Level should be able to decode Main Profile at Low Level?

2) Quantization in High Level Parameter values: any particular thresholds?

To determine the necessity of additional Level parameters other than 

horizontal_size_value	up to 2048 in multiples of 16	
vertical_size_value	up to 1152 in multiples of 16	
picture_rate	up to 60	
Horizontal x Vertical. x Frame rate	up to 62.7 million pels/s	

See the table in §3 1) in the main body of this report for existing or planned HDTV formats which should be considered.

3) The same question at Main Level

The discussion in the Requirements sub-group indicated impact of Dual-prime may be more significant at Main Level than High Level.

4) Level definition for EDTV and 483 lines

A possible Level structure to cover both EDTV and 483 lines for 525/60 is as follows

HL			1920x1088x30	
EL	na		960x496x30	
ML		na	720x480x30	
LL				
	MP
4:2:0	NP
4:2:2	Parameters for 525/60	
		na: not applicable

Is there a threshold between 960x496x30 and 720x480x30 for Next Profile (4:2:2) so that we need separate Levels, or can they be covered by a single Level of 960x496x30?

5) Definition of Low Level for Next Profile

As a lowest layer of the hierarchical coding, the following is listed;

	• 352x288x25 (MPEG-1, MPEG-2)
	• 352x240x30 (MPEG-1, MPEG-2)
	• 480x256x30 (quarter of EDTV, 4:2:2, MPEG-2)
	• 352x288x30 (CIF, H.261)

Any suggestions to handle "quarter of EDTV" from implementation consideration?

6) Bit rates at High Level

Is there any threshold in implementation cost in coded data rate at High Level?  If so, what is the value(s)?  Time scale may be relevant?

7) Comparison of implementation cost between 

•	3 resolution scale scheme,
•	2 resolution scale + 1 SNR scale scheme

SNR scalability is newly identified functionality for Next Profile in addition to the three resolution scales which were listed in Sydney.  See MPEG93/600, 687.

What is the cost of introducing each additional layer of spatial scalability and is there any particular threshold?  We are considering introducing a limit such as 1 or 2 on the maximum number of spatially scalable layers (in addition to the base layer) for the Next Profile.

What is the cost of introducing each additional layer of SNR scalability and is there any particular threshold?  We are considering introducing a limit of about 2 or 3 on the total number of SNR and/or spatially scalable layers (in addition to the base layer) for the Next Profile.

8) Possibility of integrating spatial scalability and frequency scalability

As per Mr. Holtzman's presentation.

3. Questions to the Systems

Is there a mechanism for allowing 2 bits of copy guard information to be associated with each elementary stream within a Systems stream ?  The information should be capable of being independently set for each elementary stream and should survive conversion between Program Stream and Transport Stream.  Alternatively, this information could be carried at the Video level.

END