iTV, cablecard, .n

[rogerhoward at rogerroger.org]

On Dec 27, 2006, at 9:11 PM, LuKreme wrote:

> On 27-Dec-2006, at 12:02, Roger Howard wrote:
>> On Tue, December 19, 2006 1:38 pm, LuKreme wrote:
>>> On 12-Dec-2006, at 13:22, Roger Howard wrote:
>>>> Same here; it would be a major flop if it required realtime
>>>> transcoding of video.
>>>
>>> Isn't that exactly what the Xbox 360 does with a MediaCenter PC?
>>
>> In most cases, no, I don't believe it does. Maybe it can, for  
>> formats not
>> supported natively on the Xbox 360 though? But the Xbox itself has  
>> native
>> support for common MS formats, and I'm fairly sure any
>> decoding/conformance happens on the XBox during playback.
>
> Hmm... it was my impression that the only thing the 360 could play  
> natively was DVD (MPEG-2) and possibly WMV10 and that everything  
> else, including divx, mpeg-4, MP3, h.264, and even WMV9 was  
> transcoded on the fly by Windows MC to some 360 only format.

Well, XBox 360 definitely has native support for MPEG-1 and -2, as an  
HD-DVD player it must also do H.264, it has WMV covered (if you  
support WMV10 then you support WMV9 and 7 at a minimum as they are  
completely backwards compatible), and I'm quite sure it does MP3  
natively too.

Anyway, back to the point - it's a really dumb idea to waste the not- 
insignificant CPU time on transcoding video streams, especially  
Standard Def or higher resolution. And especially when there are  
embedded chipsets on the market capable of decoding just about  
anything you throw at it. Again, it's not at all like Airport Express  
where they transcode on the fly to a *lossless* format that takes  
almost no CPU to encode; if you did that with video on iTV you'd be  
trying to send more bits across the wire(less) than you can afford.  
And that's saying nothing about the inherent latency when doing that  
- it's not easy to get great compression efficiency (quality vs  
bandwidth) with extremely low latency in realtime... how many frames  
can a product like iTV afford to be late with? Forget anything close  
to "channel surfing", responsive controls, etc.

-R