[mythtv-users] HD PVR: What does "13.5 Mbps" mean?

Brian Phillips brian.phillips at gmx.net
Sat Apr 5 05:45:40 UTC 2008

Yeechang Lee wrote:
> We'd heard back in January that the Hauppauge HD PVR device allegedly
> could handle up to 25Mbps and so could encode 1080p (Blu-ray) video. 
> However, the description now claims "up to 1080i," and in the
> official specifications
> (<URL:http://www.hauppauge.com/site/products/hd_pvr.html>), we see  
> # Hardware encoder
>     * H.264 AVCHD video encoder
>     * Datarates from 1Mbit/sec to 13.5 Mbits/sec
> What could these datarates mean in this case? The maximum bitrate of
> the component-input video it accepts, or the maximum bitrate of the 
> h.264 files it spits out? If the former, what does this imply about
> the device's ability to properly capture the full breadth of 1080i
> 19.39Mbps input?[1] If the latter, is a 13.5Mbps h.264 recording
> really sufficient to capture the full quality of 19.39Mbps MPEG-2?[2]
> [1] I don't have a Blu-ray player so all I need is 1080i.
> [2] I am told that h.264's vaunted efficiency versus MPEG-2 is mainly
> at lower bitrates, and that the relative efficiency decreases
> significantly at higher bitrates, to something like only 25% better.  

Since component is analog, there is no "bitrate" associated with it.  It
would have to be the h.264 being pumped out of the box.  As for the quality
of that signal... I dunno.


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