Steven A. Morley, K.S. Thyagarajan, A. Chris Irvine QUALCOMM Incorporated San Diego, CA

Transcription

1 Steven A. Morley, K.S. Thyagarajan, A. Chris Irvine QUALCOMM Incorporated San Diego, CA 1

2 T he T echnology of Digital Cinema Can be Des cribed in Different Ways A Set of Functional Requirements A Set of Unique System Functions SMPTE DC28 Groups Have Been Focused on These Two Descriptions A System Level Design 2

3 General Functional Flow of Digital Cinema Picture/Sound Input Compression Central Functions Encryption Formatting Transport In-Theatre Storage Decryption Decompression Projection Theatre Management In-theatre Functions Sound System 3

4 A Systems-Level Digital Cinema Architecture Standard Geo-Synchronous Ku-Band Satellite Local Network Auditorium "N" Automation System Film Studio Magnetic Tape Telecine Compression / Encryption Modulation Duplication Physical Media Demodulator Central Disc Storage Projector Decryption Decoder Digital Post Central Hub Network Management/ Conditional Access System Phone Network or Internet Theatre System Theatre Management System Audio System 4

5 Advantages to the S ys tem L evel Approach Fewer System Components Due to Synergistic Design Combining Functions in Optimized Ways Extensive Use of Off-the-Shelf Technologies Ability to Design for System Level Security and Integrated Management Systems Provides Migration Path for Future Upgrades and Enhancements Modular Design to Meet Variable Theater Requirements Maximal Use of Off-the-Shelf Equipment Limits Requirement for Unique Technologies 5

6 Where Off-the-S helf Won t Work for Digital Cinema Electronic Projector Electronic Security Image Compression Plus, Lots of Software to Support the Digital Cinema System Operation 6

7 E lectronic P rojectors Even Though No Commercially Available Projectors Exist Today for Digital Cinema, Several Technologies are Being Developed and Advanced for this Specific Application, including: TI DLP Cinema Technology JVC D-ILA Silicon Light Machines Grating Light Valve Also offerings in Transmissive Light Valve and Laser Technologies 7

8 E lectronic S ecurity Existing DBS Conditional Access Systems do not Offer Adequately Strong Security However, Digital Cinema Offers Ability to Use More Powerful Security Methods Technologies Developed for Other Applications, such as Financial Transactions and Bulk File Encryption, Can be Adapted for Digital Cinema Recent Legislation Allows Export of Very Strong Encryption Technology But, the System is Most Vulnerable to Weakest Link Attacks and Thus Needs to Consider Security as a System Level Issue Because That s the Way the Hackers Will See It 8

9 Image Compression Existing Standards Based Compression Systems have Focused on Television Applications and Have Made Trade-offs Based on That Level of Quality and the Limited Bandwidths Available Cinema Quality Compression Requires a Different Approach Simply Turning Up the Knob on the Bitrate of Existing Systems Will Not Provide the Necessary Quality Fortunately, Technologies Exist that Meet the Requirements 9

10 Compression Considerations Special Compression Systems Designed Specifically for Digital Cinema Applications Provide Cinema-quality Images at Bit Rates Averaging Less Than 40 Mbps An Example Is QUALCOMM s Adaptive Block Size Discrete Cosine Transform (ABSDCT) System Which Is Implemented in a Single-chip Solution Closely Coupled With Encryption/Security Functions and Audio Processing A 2-hour Movie Requires Only About 40 GB of Storage and Can Be Sent in Real-time Over a Standard Satellite Transponder 10

11 Digital Cinema Image Compression Requirements 10-bits or Higher per Component Full Chrominance Resolution (i.e., 4:4:4) Support of Film-Like Colorimetry Gamut Ability to Support at least 1920x1080 pixels/frame (and preferably much higher) 11

12 Digital Cinema Image Compres s ion Requirements (cont.) Compression Ratios that Support Fast Transfers of Digital Cinema Programs Agile Support for Various Resolutions, Frame Rates, Quality Levels Support for Future Upgrading Ideally Would be a Low Cost, Small Size Implementation for Embedding in Projector System 12

13 Mos t Commonly Us ed Compres s ion Systems are Based on Discrete Cosine Transforms (DCT) Image Redundancy is More Readily Filtered Out by First Transforming from Pixel Domain to Frequency Domain DCT is a Nearly Ideal Transform for Conversion from Pixel Domain to Uncorrelated Frequency Representation Once in DCT Domain, Frequency-weighted Quantization Reduces Bit Rate with Graceful Layered Reduction in Image Quality 13

14 F low Diagram of a T ypical DCT - Based Compression System Uncompressed Digital Image Input Divide Frame into NxM Pixel Blocks Discrete Cosine Transformation Frequency Weighting Quantization Zigzag Scanning Run Length Coding Lossless Huffman Coding Compressed Digital Image Output 14

15 F low Diagram of a T ypical DCT - Based Decompression System Compressed Digital Image Input Huffman Decoding Inverse Zigzag Scanning Inverse Quantization Inverse Discrete Cosine Transform Re-mosaic Blocks into Frame Uncompressed Digital Image Output 15

16 E nhancing the B asic DCT Approach While Basic DCT Approaches (such as JPEG) are OK, Enhancements Have Been Developed to Increase Efficiency Efficiency Means the Bit Rate Necessary for a Given Quality Level Most Popular Enhancement is to Use Interframe Compression (e.g., MPEG) Encodes the Differences from Frame to Frame Adds Additional Concern for Motion Artifacts and Synchronization Adds Circuit Sophistication Due to Additional Memory and Processing Difficult to Edit 16

17 The Adaptive Block Size DCT Solution Adaptive Block Size Discrete Cosine Transform (ABSDCT) Takes Advantage of the Wealth of Developed Technology Using DCT s, but Adds Unique Characteristics 17

18 QUAL COMM s AB S DCT Compression System Uses Adaptive Block Sizing Uncompressed Digital Image Input Block Size Assignment Discrete Cosine Transformation Discrete Quadtree Transform (DQT) of DC Co-eff Frequency Weighting Quantization Zigzag Scanning Run Length Coding Lossless Huffman Coding Compressed Digital Image Output 18

19 Adaptive Block Size Example 19

20 QUAL COMM s History with Image Compres s ion Invented and Developed Adaptive Block Methods Initially for Specialized Higher than Hi-Def Applications Demonstrated Realtime Compression/Decompression Hardware Implementation Enhanced ABS Algorithm Specifically for Digital Cinema Applications Introduction of Single-chip Implementation of Multi-rate Decoder 20

21 Advantages to AB S DCT Compres s ion Based on Well Developed DCT Technology with Added Special Aspect of Adaptive Pixel Block Sizing Applies Extra Attention to Local Areas with Greatest Detail Rather than Fixed 8x8 Pixel Blocks (i.e, 64 square pixels), the Average Block Area is Approx. 120 Square Pixels Excellent Compression Quality at Reasonable Bit Rates without Requiring Inter-Frame Compression Is a Much Simpler Algorithm than Inter-frame Methods Decoder or Encoder Circuits Are Implemented in a Single ASIC chip Searching and Editing are Straightforward 21

22 Advantages to AB S DCT Compres s ion Implements Compression Without Compromise Works with 10-bit Non-linear, up to 4:4:4 Sampled Images Scalable Operation from Ultra-High Quality Originals to Multiple Distribution Formats Is Scalable for Various Resolutions, Aspect Ratios, Frame Rates, Compression Ratios Format Independent Operation Transcodable to Simplify Compression Rate Conversions and Ease of Implementation Quality-based Compression (Not Fixed Rate) 22

23 Quality B as ed Encoding Approach Rather Than Set a Fixed Bit Rate for Compression, Set a Required Quality Level and Let Bit Rate Automatically Adjust to Meet that Quality Yields Better Quality at Lower Average Bit Rate 23

24 Quality-bas ed vs. F ixed R ate Compres s ion Average Bit Rate for Quality-Based Compression Approach Bit Rate for Rate-Based Compression Approach % of Frames Bits/pixel for a Given Quality Level 24

25 Scaling the ABSDCT Algorithm Once a High Quality Digital Capture Master is Generated, Various Manipulations Can Be Performed, Often in the DCT Domain Frame Resolution (Downconversion) Component Resolution (Bits per Pixel Component) Chrominance Decimation (4:2:2, etc.) Aspect Ratio (Letterbox and Pan/Scan) Frame Rate 25

26 F uture-proofnes s of AB S DCT Expanded Resolution Is Supported by Multiple Devices e.g., a 4Kx2K Image Requires Four Chips (Using Today s Technology) Still Provides Low Cost, Small Implementation The Decoder Device is Very Flexible to Work with Enhanced Encoding The ABSDCT Algorithm can Support Layered Compression, Flexible Transcoding and Resolution Remapping 26

27 T he AB S DCT Decoder Device Based on Standard CMOS Technology Implements Complete ABSDCT Decompression on a Single Chip Includes 3-DES Decryption of Image and Sound Channels Synchronizes Image and Sound Files 27

28 T he AB S DCT Decoder Device (cont.) Compressed Information is Input on Standard PCI Bus Format Output Images Provided in Standard SMPTE- 274 Interface Output Audio Supports AES-3 Formats (up to 8 Channels) Interfaces with Standard Smart Card Module which Stores Long-term Secret Key Information 28

29 QUAL COMM s Digital Cinema Decoder Module QUALCOMM ABSDCT Decoder 29

30 S ummary Implementing Digital Cinema as a System Results in the Most Cost-Effective, Secure, Future-Proof Design to Serve the Industry s Needs Off-the-Shelf Technology Can Be Used in Many of the System Functions Special Development is Needed for Projectors, Security, Management Software, and Image Compression 30

31 S ummary (cont.) Existing Television-based Image Compression Systems Do Not Meet Cinema Quality, but Specially Designed Algorithms Such as QUALCOMM s ABSDCT Approach Will The ABSDCT Algorithm Implemented in a Single Device with Built-In Encryption, Synchronization, and Audio Processing Provides a Very Effective Solution to this Key Digital Cinema Technology 31