Jeffrey BloomDialogic Research(Some work done while at Thomson)

Understudied Constraints Imposed by Watermarking Applications

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With post-presentation

comments added in green.

Workshop on Multimedia, Mathematics, and Machine Learning IIBanff International Research Station for Mathematical Innovation and DiscoveryBanff, Alberta July 5-10, 2009

Understudied Problems

Watermark embedding in the compressed domain

Watermark detection in the compressed domain

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“Compressed Domain Watermarking”

DecodeWatermark Embedding

Original Compressed Stream

Marked Compressed Stream

Encode

Entropy Decode

Watermark Embedding

Original Compressed Stream

Marked Compressed Stream

Entropy Encode

Watermark Embedding

Original Compressed Stream

Marked Compressed Stream

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This slide discusses the evolution of watermarking compressed streams: from full decompression to partial decompression to true compressed

domain watermarking; the last of which is the subject of the first part of this presentation. For situations where partial decode is too expesive.

Partial Decode

Stream Replacement Watermark Embedding

… …

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Shows the concept of stream replacement watermarking. A chunk of the stream is replaced with different data (in brown). But where

does the brown data come from? Need to step back and review some basic frameworks on the next few slides.

Watermarking Frameworks

Blind Embedding

EmbedEmbed

Informed Embedding

EmbedEmbed

AnalyzeAnalyze

Blind Detection

DetectDetect

Informed Detection

DetectDetectAnalyzeAnalyze

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It is this last case (informed embedding /

informed detection) that represents the application that motivates this work.

An informed embedder can analyze the content

off-line and generate side information for the

embedder and for the detector.

Where does the D come from?

2-stage Embedding

Analysis

Stream Stream EmbeddingEmbedding

Entropy Entropy DecodeDecode

Full Full DecodeDecode

AnalysisAnalysis

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The Analyze part of the embedder can be separated from the Embed part. The analysis can take place in a powerful server where it can examine the pixel data, the compressed domain syntax elements, and the entropy encoded

bitstream.

Example: Blu-ray

BD Player

Virtual Machine

Media Transform

Self-ProtectingDigital Content

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SPDC is described by CRI in their white paper http://www.cryptography.com/resources/whitepapers/SelfProtectingContent.pdf

Use of this technology in Blu-ray is discussed at http://www.cryptography.com/technology/spdc/index.html

among other places.

SPDC

Multiple values for each repair

Enables forensic watermarking during repair

Original Compressed Stream

Damaged Compressed Stream

Preprocess

Repair Info

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Damaged compressed stream is not valuable to a pirate. Damage is done off-

line, repair is done at play time. Repair info must be carefully protected.

Identifying the hard problem Blu-ray

MPEG2, VC1, H.264/AVC H.264/AVC

CAVLC - Context-adaptive variable-length coding CABAC - Context-based adaptive binary

arithmetic coding VLC case has been addressed CABAC is hard

Arithmetic Code Context Adaptive

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Blu-ray supports three compression standards

VC1 is not widely used

H.264 supports two entropy encoding schemes

Both MPEG2 and CAVLC

Will be more widely needed

This scenario is not limited to Blu-ray CABAC-encoded H.264 is becoming widely

deployed High volume watermarking systems will not

have the luxury of doing an entropy-decode/watermark/entropy-encode cycle

Stream Replacement

CABAC Encoded Bitstream

CABAC Encoded Bitstream

For adoption of watermarking in high volume network applications,

this is an important and understudied problem

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Mobile Video Handoff Points

Content Owner

• eg., MTV

Content Provider

• eg., Hulu

Content Delivery Network

• eg., Akamai, Internap

Backbone

Network

• eg., Global Crossing

Content Delivery Network

• eg., back to Internap

Mobile Network Operator

• eg., AT&T

Local Access

Network

• eg., Rogers Wireless

Each participant will optimize the content for its own network. This often

involves transcoding.Watermarks can be used to help track

content. Detectors distributed throughout multiple networks.

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What happens when I want to watch The Daily Show on my mobile phone from here in Banff? Many different people “touch” the content. This slide shows an example of

the how the video gets to my phone.

Watermarking Challenge

Tracking watermark embedded by content owner Embedding can be done in any convenient domain

Watermark detection at various points in the network for tracking Watermark must be recoverable from any

compressed domain without decoding MPEG2 H.263 MPEG4 H.264/AVC

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Watermarking Challenge

Assume that we can do entropy decode

Encode Decode Encode

Decode Detectpixels

Intermediate transcodes look like noise model as a single transcode plus noise

Information is in there

Decode Encode

pixelspixels

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At any point, the stream can be decoded and the

watermark recovered from the pixels

Conceptually, we can consider a transcoder as a decode/encode pair with

pixels in the middle.

Note the colors indicate matching encode/decode pairs (same coding standard). Consider pixels before the red encode and the pixels after the red decode. The pixels after are the same as the

pixels before plus coding noise from the red encode.

Transcoder Transcoder

Watermarking Challenge

Assume that we can do entropy decode

Encode Decode Encode

Decode Detectpixels

Intermediate transcodes look like noise model as a single transcode plus noise

Information is in there

Decode Encode

pixelspixels

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Transcoder Transcoder

Watermarking Challenge

Assume that we can do entropy decode

Encode Encode

Decode Detectpixels

Intermediate transcodes look like noise model as a single transcode plus noise

Information is in there

Decode

pixels

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Watermarking Challenge

Assume that we can do entropy decode

Encode Decode Encode

Decode Detectpixels

Intermediate transcodes look like noise model as a single transcode plus noise

Information is in there

pixelspixels + noise

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Transcoder

Summary

Watermark embedding in the entropy-coded compressed domain

Watermark detection in the compressed domain after uncontrolled transcoding

For adoption of watermarking in high volume network applications,

this is an important and understudied problem

For adoption of watermarking for tracking in network applications,

this is an important and understudied problem

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