At 6:32 PM -0800 11/8/06, John Willkie wrote:
IIRC, they're offering 16-20 linear video (each with two audio) program services, plus 'clip channels' and a handful of audio and data services in a multiplex that occupies a 6-mhz channel using 22 or so MBPS per mux.
John is confusing some elements of the system design here. If you want to fully understand how Flo works, and how it compares with DVB-H and ISDB, the following Qualcomm whitepaper may be informative:
http://www.qualcomm.com/mediaflo/news/pdf/flo_tech_overview.pdf The link to this whitepaper and other resources can be found here: http://www.qualcomm.com/mediaflo/news/resources.shtml When you work through all the details you will fine the following system specs. Overall efficiency ~1 bps/Hz OFDM using 4K symbol mode A total of 20 channels each with ~ 300 kbps (statistically multiplexed).Layered modulation combining a base layer that supports 320 x 240 @15 fps with an enhancement layer that brings the frame rate up to 24 or 30 fps. Uses MPEG-4 with streams optimized for an average of 360 kpbs.
The channels will be used as follows: 14 live streaming national interest 5 live streaming local interest50 national and 15 local services that will deliver ~20 minutes of content per day to receiver cache.
The system will also deliver IP data services.By comparison, the whitepaper claims that DVB-H can deliver 9 channels in 6 MHz.
In strong signal areas, the frame rate is 24 or 30 per second; otherwise, it's 12 to 15 per second. But, remember that those video channels at best are half the resolution of NTSC, but with image sharpening technology.
Really? The effective resolution of NTSC is 320 x 240 at 60 fields per second. With good de-interlacing, I would suggest that these streams will come close to equaling NTSC quality, however, that is irrelevant since we are talking about displays in handsets. Apple started the iTunes video service at this resolution, and the stuff looks fine when output to an interlaced TV. But the LPTV guys could deliver something like 640 x 480 @ 60P which would be significantly higher quality than NTSC, perhaps with a 320 x 240 base layer.
Remember: people don't watch technology, and they tend to seek quality when it is available and has a wide variety of content. (This includes the betamax argument, since it wasn't widely available and had limited variety of content.)
This argument must be tempered with reality. People are consuming vast amounts of video content via the Internet, most of which is less than NTSC quality. It is all driven by applications and competition. Mobile Tv does not need to equal the family room viewing experience.
Regards Craig ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways:- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.