Picture Format Group

Working Group Report Problem Statement

• Current permutations of Picture formats may be too broad to economically support by device manufacturers • Content producers have a compelling business interest in supporting as many permutations as possible as conversion can be costly, infeasible, or impact quality • How to support formatting for legacy rendering devices, and are there enough still in use to justify? Charter

Produce a Conceptual Block Diagram that communicates the steps and the cost of supporting any picture format Produce a summary analysis of Device Capabilities, Current Top Retailer Format Analysis, Content Provider Requirements Identify Current Tradeoff points Reconcile any BWG requirements Define a Decision Framework that attempts to quantify the proposed solution effect on Retailers, Equipment Manufacturers, and Content Providers Define the Picture Formats supported by each profile, and recommend some possible reconciliation strategies for edge cases

Some Image format Variables

• Sample Aspect Ratio (NTSC, PAL, anamorphic, sq) • Picture Aspect Ratio • Overscan • Subsampling (4:2:0, 4:1:1, 1440h, etc.) • Interlaced temporal subsampling, filtering • Quantization range (e.g. 16-235, 0-255, +/- 128) • Color space (Rec 601, 709; negative coeficients) • Gamma curve, render intent, display adaptation • Frame rates 15.00p, 23.97p, 25.00i, 29.97i/p, 50.00p, 59.97i/p (1000/1001 video rates) Problem Areas

• Playback of 25i content on 60Hz interfaces/displays i.e. support of interlaced content produced at 50 fields per second • Setup, color space, 3:2 pulldown, deinterlace, crop, p/s, letterbox, pillarbox, tiltscan, cylindrical stretch • Common aspect ratios: – 1.33 (4:3 TV), 1.78 (16:9 TV), 1.85 2.0, 2.33, 2.4(film), 16:9 anamorphic – 708x483 SMPTE D1 display aperture – 704x480 ATSC 4:3? – 720x480 DVD 4:3? • Overscan – CRT legacy. New model 1:1 sample to pixel (but reality usually involves scaling). Need to explicitly state SAR in video. “Hypothetical reference display”. • Output signal limitations: e.g. 1280x720 may require 1366x720, etc. connection to allow “overscan” cropping and 1:1 sample to pixel mapping (without scaling and filtering) PD

• Optimized for simple device (cell phone) and fast download with front end (post production) format conversion • Video format limited to 320x240, square pixel, 4:3 “exact scan” aspect, deinterlaced (if necessary), (601 color space and setup?), 15, 24, 30, 50, 60 frames/s. • Content often requires special editing, framing, processing, etc. for small screen anyway; studio can do better deinterlacing, pan/scan, etc. than device. SD • Optimized for wide range of devices, with post processing in device (high end cell phone, PMP, game device or console, computer, TV STB, internet TV, etc.) • Default is native format encoding (SAR, PAR, i/P, fps, color space 601 with setup). • Device will handle SAR, PAR, interlace, and frame rate conversion according to user preferences and display capabilities. • 2.35 PAR 24fps scope movie might be displayed on PC window or projection at 2.35 PAR 72Hz or 120Hz, flat panel 1.78 PAR LB or “full screen”, 4:3 CRT at 30i with 3:2 pulldown, etc. • Best system is to maintain original content format and encoding information, and let user preferences and device capabilities decide best presentation format. Will vary by device, user, content, and viewing circumstances. Most new devices already convert SAR, interlace, PAR, etc. for flat screens, so devices are capable of conversion. • Attempting to precorrect for limited devices at encoding (e.g. vertical resolution filtering to prevent “CRT flicker”, encoding letterbox bars, encoded pulldown, etc.) usually compromises high end devices (progressive displays, 120Hz, motion interpolation, automatic PAR adaptation, etc.) HD

• Optimized for wide range of content, moderate range of devices (more HD TV content shot for 1.78 PAR, but plenty of 1.33, 1.85, 2.X PAR content. More HD displays 1.78 DAR) • Native format encoding (same as SD, but 709 color space) e.g. 2.33 PAR > 1920x840 • Devices must convert SAR, PAR, interlace, frame rate • Should allow for negative YCrCb coefficients for wide color (e.g. xvYCC) Edge Cases

• Frame rates: – Any frame rate is OK on a self contained device with decoupled refresh or multisync; but NTSC, PAL, HDMI, etc. video connections have limited frame rate options. – STB can output 24Hz to new displays, or 30i to old (3:2 pulldown) – STB can output 24Hz with 3:2 or +4% to 50/60 Hz displays; problem is 25i content to 60Hz only displays. Devices can insert pulldown • Might recommend safe areas based on device cropping to 4:3 • Clarification of “exact scan” pixel dimensions to avoid unnecessary scaling (e.g. 704 or 720 = 4:3? = 16:9 anamorphic?) Display intent must be specified explicitly using correct SAR in h.264 In Summary

• Team to deliver specification proposal to TWG for ratification. • Summary and data points will be delivered to support proposal. • Dates for deliverables need to be defined. • Weekly calls will be held to synchronize.