[mythtv-users] [OT] Trancoding 'live'

glen martin glenm at locutory.org
Sun Dec 4 14:45:23 EST 2005

Michael T. Dean wrote:

> Phill Edwards wrote:
>>> Due to hardware issues (haven't bought my big HD set yet), and wanting
>>> the additional channels (-2, -3 etc) and aspect ratio of HD, I'm
>>> looking
>>> to take the output from my HD tuners and stream-convert to NTSC (that
>>> is, *not* wait until the program ends).  The goal of stream-converting
>>> is of course to be able to use this for live tv when offline transcode
>>> would be a pain, eg. Superbowl. :)
>> MythTV already supports LiveTV if that's all you're trying to do. Or
>> perhaps I misunderstood your question.
> If you mean your frontend (or one of your frontends) can't handle
> high-def playback, 

My front-end can't support HD playback, and my TV can't display it. But
I like the aspect ratio and extra channels (eg. 5 subchannels on PBS) of

> your best option for "live" transcoding from ATSC -> NTSC is plugging
> the S-Video/Composite out of your cable box into a PVR-x50.  If you're
> using OTA instead of cable, you could get a STB ATSC receiver (like
> http://www.bestbuy.com/site/olspage.jsp?skuId=7292146&type=product&productCategoryId=cat03022&id=1118840815760
> -- note that I don't recommend this one as I've never used it, but
> it's the type of thing you would need).

That's an approach I hadn't considered. So for OTA use, I could get
something like this standalone ATSC receiver, set it for 480i output,
feed that into a PVR-250 through the s-video input, and use MythTV as
usual including pause etc. Interesting. I had a mental block on that,
but seems obvious once you suggest it.

> Put another way, if your machine can't do playback (=decoding) of
> high-def streams in real time, there's no possible way it could do
> transcoding (=decoding + encoding) of high-def streams anywhere near
> real time.

Well, yes. I guess I imagined doing the realtime transcode on a backend
machine, not the frontend which is highly incapable. :)



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