[mythtv-users] RAID versus Drobo

Brian Wood beww at beww.org
Mon Sep 10 19:15:02 UTC 2007


Eric Robinson wrote:

>> Have a look at this:
>>
>> http://library.creativecow.net/articles/gerard_rick/premiere-pro-HD.php
>>
>> Of course if you plan to record one stream while watching another,
>> record multiple streams, or do anything else requiring disk I/O at the
>> same time you'll want more than that chart implies.
>>   
> Umm... If you're pointing to the graph on that page then it's a little
> different.  That's completely Raw HD.  Nothing in MythTV is done in
> Raw.  My understanding is that it's Mpeg2 generally and can be converted
> using Mythtranscode to some version of mpeg4.  In any event, I figure
> MythTV buffers a certain portion of the video on the frontend before
> beginning to play in case of heavy network jitter.  One hour of 1080p
> content is 7GB or so, right?  I feel like I read that somewhere in the
> docs...  Anyone have any success stories with playing back HD content
> and with what drive interface speed?

Ooops, right you are. I confused your thread with another from another
group and sent you the wrong link.

You might look at:

http://broadcastengineering.com/news/broadcasting_psip_data_broadcasting/

(though it's a bit dry and obscure), or:

http://en.wikipedia.org/wiki/ATSC_Standards

Basically the full G3 data rate for an ATSC transport stream is 19.4
Mbps, so if your storage system can handle that you should have no
problems with a single stream, even if it's using the full available
bandwidth (which most don't).

I've had no problems playing back HD (as the original MPEG2 or MPEG4
(H264-2)) from a single PATA or SATA drive. I haven' tried multiple
streams but from the specs it should work for 2 or even 3 streams
without trouble.

beww


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