[mythtv-users] Semi-OT: HD Questions

Allan Wilson allanwilson at gmail.com
Tue May 16 11:08:42 EDT 2006

On 5/16/06, Ivan Kowalenko <ivan.kowalenko at gmail.com> wrote:
> Hash: SHA1
> Hi. I'm kind of an HD n00b, but from what I've read about HDTV, I'm
> kind of confused.
> I'm wondering how HDTVs are coping with the differences between
> MPEG-2 and H.264. That is, I mean, with the BBC doing its HD trials
> with H.264, how is it that existing HDTVs will know what to do with
> it? Has H.264 compatibility been around for a while? Shouldn't H.264
> in HD (even interlaced) require a marked increase in processing power
> to decode and scale (assuming your TV runs at a resolution lower than
> the signal)?

Good question, never thought about it.

Second, I'm wondering if anyone would care to try to explain why this
> item requires on a 500 MHz PPC G4? Since doing 1080i on a PC seems to
> require greater than an AMD 1800, something doesn't seem to quite add
> up here. I'm guessing that 500 MHz is the minimal requirement for
> capturing, not playback.

I would think just about any computer will be able to record hidef I'm not
sure where the G4 comes from.

Third, what is the minimum requirement for an HD back-end? I'm
> guessing not much, since the stuff is already encoded, but then
> again. There really hasn't been a lot of documentation that I can
> find about this (then again, I could just be looking in all the wrong
> places).

I actually just started being able to record hidef and I was looking at the
numbers last night. From what I saw it takes next to nothing to record hidef
over firewire since it is already encoded and I think it is the same with
hidef with an antenna and a pci card. On playback mythfrontend takes up
about 10% of my processor and watching 1080i content mythfrontend jumped up
to using about 50% of my processor. Memory usage stayed the same the entire
time and the box was as responsive as it normally is. I have an PIV 3.2 GHz.
Hope this helps you can search this mailing list and find where a lot of
people have talked about this.
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