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August 20, 2008
Bring back sprocket holes
By Cliff Roth

Film and analog video have one admirable feature that digital video lacks: sprocket holes. For over 80 years sprocket holes have done a superb job of keeping picture and sound in sync, providing a mechanical point of reference for each. Of course
analog videotape never really had sprocket holes, but it had the electronic equivalent, in the form of sync pulses marking each video frame.

As our featured article in Video/Imaging DesignLine this week explains in more detail, compressed and digitally transmitted digital video has unlocked picture and sound, wreaking havoc on synchronization (see HDMI's Lip Sync and audio-video synchronization for broadcast and home video.)

The problem ultimately requires feedback from the TV or display -- because how else can you know the delays that video signal processing is introducing, including delays caused by scaling and other processes within the television itself?

It's a big problem, and the HDMI Lip Sync spec doesn't provide the complete solution, but it's an important first step that CE manufacturers should broadly adopt (like most new aspects of HDMI 1.3, Lip Sync is voluntary.) It also makes one yearn for the good old days of sprocket holes.
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August 13, 2008
Video over Internet stealing headlines (and Olympics audience!)
By Cliff Roth

Internet
video -- along with the Olympics -- seems to be grabbing the spotlight this week. Front page newspaper articles, such as last Saturday's New York Times. describe how NBC's tape-delayed Olympics broadcast of the opening ceremonies was usurped by online postings, and NBC's efforts to stop these postings. (See Tape Delay by NBC Faces End Run by Online Fans.)

In Sunday's New York Times, an article about Time-Warner explains that part of their movie studio's success comes from thwarting online movie rip-offs, using tactics that included flooding movie-sharing web sites with fake versions of "The Dark Knight" to frustrate would-be illegal downloaders. (And the studio takes pride in the fact that a real illegal copy didn't appear online until a full 38-hours after its debut.)

On the political front last week we saw the debut of "Paris Hilton for President" -- a mock ad, responding to a McCain attack ad against Obama -- noteworthy here because it was released only on the Internet, not a dime spent on TV time, yet if you watch news in the U.S. you've probably seen it.

Four years ago, in the previous U.S. elections / Summer Olympics cycle, Internet video was still an oddity. Two years ago, this curious new development lost one U.S. Senator his job (after his ethnic slur was posted on YouTube), but Internet video was still a new thing the kids were doing. Now, as reflected by recent headlines, Internet video is mainstream, and as a threat it's taken quite seriously.
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August 06, 2008
Codecs: 24 design ideas for video and imaging
By Cliff Roth

Codecs are essential to
video and image processing. Here are twenty-four codec-related design articles.

Massively parallel processing arrays (MPPAs) for embedded HD video and imaging (Part 2)

On2's TrueMotion VP7 video codec and "golden frames"

Video codecs, part 1: Intraframe coding and bitrates

Video codecs, part 2: Interframe coding, MPEG-2 & MPEG-4

Video codecs, part 3: H.264 & video over networks

Video codecs, part 4: Wavelet codecs

Introduction to video transcoding for CE

System and Memory Architectures for High-Definition Consumer Electronics

MPEG-4 system layer and A/V containers for wireless video

Multi-core MPEG-4 video encode partitioning

Video compression artifacts and MPEG noise reduction

Introduction to video compression

Video codecs tutorial: Trade-offs with H.264, VC-1 and other advanced codecs

Encoding JPEG2000 video by combining DSP and FPGA

H.264 encoder design using Application Engine Synthesis

Image compression software with region-of-interest (ROI) codec reduces bandwidth

Video quality assessment with motion and temporal artifacts considered

Video quality analysis with automated, scripted testing

Data compression for high-speed DSP, part 2

How to use field-programmable object arrays (FPOAs) in image processing

Bandlet de-interlace and up-conversion for HDTV via "super-resolution" framework

Surveillance IP camera design with intelligent encoding for reduced bandwidth, higher quality

Streaming video with "TimeSlice" multicore-friendly processing eliminates dropped frames

Encoding JPEG2000 video by combining DSP and FPGA
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July 30, 2008
3-chip vs. 1 image sensor
By Cliff Roth

During a briefing on Kodak's new high-end 50-megapixel image sensor -- costing a few thousand dollars each -- I finally got the answer to a question that has puzzled me ever since multi-megapixel
imaging became commonplace over a decade ago. The question: Why do high-end pro video cameras continue to use three separate image sensors -- for red, green and blue -- while pro-quality digital still cameras (DSCs) use a single high-megapixel image sensor, such as the new "world's most megapixels" Kodak sensor (see Kodak delivers next-generation 50-MP CCD image sensor.)

Kodak's new CCD image sensor boasts 50-megapixels

In the video world, the 3-chip imaging system is widely considered better for color accuracy, improved contrast, and more "film-like" images. It requires more optics however -- a prism to split the image three-ways.

The answer, explained Kodak, has to do with artifacts that are created by having red, green and blue-sensing pixels located right next to each other, rather than on top of each other, in the single-chip color image sensor. The processing circuitry must, in essence, create a pseudo red, green, and blue image by calculating in-between pixels. As the image sensor's resolution goes higher and higher, into the multi-megapixel and tens of megapixels zone, these artifact errors become slighter and slighter.

But for the comparatively coarse resolution of standard def video (720 x 480 = 350k pixels, or just 0.35 megapixels) -- and even HD video (which at 1920 x 1080 works out to 2-megapixels) -- the artifact errors are more significant. Hence, 3-chip imaging continues to rule for pro video, but not for pro still cameras.
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