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Jeffrey BloomDialogic Research(Some work done while at Thomson)
Understudied Constraints Imposed by Watermarking Applications
1
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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