[mythtv-users] Plextor Mpeg4 Hardware Encoding & N00b Requesting Advice

Brad Templeton brad+myth at templetons.com
Tue Dec 21 04:00:50 UTC 2004

On Mon, Dec 20, 2004 at 07:22:53PM -0800, Bryan Miller wrote:
> Hello to all,
> Does the hardware from plextor run under Myth?
> http://plextor.com/english/products/TV402U.htm

Not that I have heard so far.  Google searches of the form: Tv402U mythtv
will find the answers to such questions far quicker than asking here.

> It says it has hardware encoding for mpeg4, and it has a firewire port. 
> If it has firewire, is it merely telling the device to record, and it 
> spits it out as a stream through the FW port? Kinda like an on/off 
> switch... Prolly more coding involved, but I would figure something 
> like that would be a little easier to code than the 150. Am I wrong? I 
> haven't looked. Again, I'm TEH N003. :P

The web page doesn't say.  The firewire support could mean supporting
streaming mpeg over firewire, such as dtvlink, but I doubt it.  It is probably
just an interface, like usb 2.

> I haven't subscribed long enough to return any results for a search 
> through my local e-mail. The list archive doesn't have a search 
> function, so sorry if this is a repeated question.

Google indexes all the list archives at mythtv.org and gossamer-threads.

> I am planning to build a system, and I was originally looking at one 
> 350 and a 250 with a 6800 Ultra. Heard that the VPU was broken on the 

I would not advise the 350 if you plan to someday use this box (if it
gets linux support) or if you have a fancy dancy video card.

The 350 outputs mpeg-2 in hardware to a tv-out.  Handy to have, but
it won't do divx/mpeg-4.   It's also apparently fun to get X working
on it, though people do.

If you have the fancy GPU, it will probably come with tv-out.  Consider
using that.

> a deciding factor. Will the 350/250 be able to decode this kind of HD 
> content? Aside from 1080i content, I would -like- to use this machine 

Boy, we need to have a faq about this one, it gets asked every day.  In
fact there are a couple of threads today on this question.  Short answer,

> would also be interested in archiving seasons onto DVD, but 4 shows per 
> DVD versus 12 sucks. True, DVDs are relatively inexpensive nowadays.

HDTV is about 8 gigs/hour, though it can be transcoded down to less.
So about 30 minutes on a DVD, not that you could play it in a DVD player.

However, you can transcode HDTV down to 1280x720, 30fps, mpeg-4 and it
is quite watchable in the 2 gigs/hour range, or even less.

> consumption am I looking at?) What would the requirements be for 
> recording 1080i content? Am I only limited to commercial hardware that 
> cost a lot?

Search the web for hundreds of threads on this one.
> Also, I was planning to have a SCSI drive with the system installed on 
> that with a SCSI DVD ROM, so as to free up as much CPU cycles as 
> possible. (I never really liked the fact that IDE/ATAPI/SATA takes up 
> your main CPU just to read and write data.) ...Anyway, is there a way 

You're overparanoid.  CPU load for any of these protocols is minimal.
SCSI is a decent protocol, but the equipment is overpriced.  For video,
USB 2 disks can even work.

> Hrm. I was just thinking... What if Myth could store data (when a 
> setting is checked) on a network drive in chunks of 1gig. Then, a 
> script running on a Dual G5 2G would encode the files into a mpeg4 
> video file and delete the read 1gig chunks as it goes? I dunno. Just 
> thinking aloud.

There is a thread from 2 days ago about removable media.  Right now
Myth stores in one dirctory only.   Some day that will probably change.

The files can be transcoded by mencoder.   It is easy to write the code
to do that.  Scripts, really.

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