Audio/Video compression Recent progress Alain Bouffioux December, 20, 2006.

Audio/Video compressionRecent progress

Alain Bouffioux

December, 20, 2006

December, 20, 2006AV Compression / Alain Bouffioux

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Agenda

Digital cinema

3D-television

High-definition television and DVD


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Agenda

Digital cinema

3D-television



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Introduction

2002 – Digital cinema initiative created by 7 studios

2006 – First standardized (non-proprietary) trial

Advantages of digital cinema– Higher quality image– No deterioration with time (scratches, dirt…)– Possibility of 3-D offering (need to carry glasses with polarized lenses)

• Passive: one lens polarized in one direction, the other one in the other one(cheap lenses but special screen for keeping polarization of reflected light)

• Active: lenses are switched on/off by an infrared signal(normal screen but need to collect and wash the lenses at the end of the projection)

– Ease of copy and distribution (satellite or hard-disk drive via truck) – Possibility of new applications: football match or concert in real-time 3D

rendering


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About the digital cinema standard

Some numbers;– Film still shot on 35-mm film– After capture and digitization: about 5000 Terabytes– Final uncompressed movie: some terabytes– After compression: about 300 Gigabytes

The standard– Resolution: equivalent to 35 mm film

Minimum resolution: 2048 * 1080 (called 2K)Other resolution: 4096 * 2160 (called 4K)

– 16 bits per color/48 bits per pixels– Video compression: Not MPEG-2 to avoid motion artifact

JPEG2000 – each frame encoded individually (no removal of intra-frame redundancy, wavelet transform)

– Audio compression: “uncompressed” CD-quality


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System workflow (From Digital Cinema System specification v1.0, www.dcimovies.com)


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Agenda

Digital cinema

3D-television



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3D-television (1/2)

3D-television without wearing glasses is possible.

The television screen is covered with small lenses. Each eye sees other parts of the television screen and perceives other images. When the two images are stereoscopic views of the same scene, a 3D-experience is provided.

3D content is needed

3D content may be provided from traditional film after processing.Depth information may be computed when the camera is moving. Depth information encoding within MPEG stream currently under definition.


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3D-television (2/2)

2D-to-3D conversion may occur in real-time. 3-D television possible with 2D-content and processing within television set.But, problem when hidden surface becoming visible (no depth information)

2D-to-3D conversion off-lineFilm may be processed in both directions (begin-to-end and end-to-begin) to solve the problem of hidden surface becoming visible. Depth information is then stored in MPEG stream.


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Agenda

Digital cinema

3D-television



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Two competing format:Blue-ray and HD-DVD format

Some readers equipped with both formats

Blue-laser for both but different wavelength

Blue-Ray (25Mbps) versus HD-DVD (15 Mbps)

Blue-ray versus HD-DVD


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Audio/Video compression Recent progress Alain Bouffioux December, 20, 2006.

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