[mythtv-users] Getting 1080p from comcast cable boxes (Was VUDU)

Robert McNamara robert.mcnamara at gmail.com
Wed Feb 25 02:52:41 UTC 2009

> I can, but you might be able to glean a bunch from this output from
> mplayer.   Some of it comes from later in the TS -- brief switches to
> short stretches of 24fps progressive.

I don't intend to analyze it with mplayer.  :)

> I understand the difference between fields and frames, but a 30 fps
> progressive stream does not have two fields per frame, while an
> interlaced one would.   As I am sure you know, some tools report
> 60 fields per second as 60 frames per second, but that is not the
> case here.

Again, I need to see a sample to make any determination.

> In the broadcast arena it's all 480i, 720p and 1080i, of course, as that is
> all some TVs are set to handle.  I wish that stations would do their SDTV
> in 480p but nobody seems to.

I am not talking about network TV only.  I am speaking about *all*
nationally televised networks, including premium networks.

> However, there is no such constraint on self-contained systems where
> the channel is never OTA, and is transmitted by private links to
> cable and satellite providers.   They _could_ transmit a 24fps progressive
> 1080 line signal to the cable company, and the cable company could then
> have its STB convert that to what the TV wants.  What I don't know is
> if they actually do this.  It makes a great deal of sense to do, but
> who said they have to do what makes sense.

They could, but they do not.

> Well, to some 1080p means 1080p 60 full-frames/second which is quite rare,
> very little is even shot at that rate.

1080p/60 is only one of several framerates available for 1080p, and by
far the least used.  Not sure why you mention it, though, as I hadn't
mentioned 1080p/60 at all.

> By firsthand experience, you mean you have accessed the private feed
> coming out of AMC HQ going to Comcast, DirectTV and Dish network?


> Well, if the feed out is interlaced, then what is happening is that
> Comcast is deinterlacing in their head end or in the cable box.

Yes, that's what I keep saying, and I'd like to see a sample stream by
which I could make that determination.

> The cable box had deinterlace hardware, as you are allowed to hook up
> a progressive TV to it over HDMI if I recall correctly from the
> setup process.

Of course it does.  That said, the cable box does not modify the
stream it outputs via firewire.

> I'll get some samples for you if this doesn't tell you enough.

Yes, please.


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