[mythtv-users] Best way to integrate a Netflix feed into Myth ?

Raymond Wagner raymond at wagnerrp.com
Mon Aug 22 22:55:19 UTC 2011

On Mon, 22 Aug 2011 15:07:35 -0400, Eric Sharkey <eric at lisaneric.org>
> A couple of seconds is huge.  I would hope this could be kept to
> somewhere in the vicinity of 200-500ms.

On Mon, 22 Aug 2011 17:39:36 -0400, Eric Sharkey <eric at lisaneric.org>
> I don't follow.  We live in a day and age when I can order 8GB of RAM
> for under $50.  Why do I need to go to disk to hold a few seconds or
> at worst 10s of seconds worth of video?

Huh? I'm confused. First you want to cut buffering to only a couple
hundred milliseconds, and then you want to buffer the world?

Linux has a great disk cache.  Anything you store to disk gets stored in
cache, until such time as something else flushes it out.  The more memory
you have, the longer it takes to get flushed out.  We only need to be
storing a short amount of video on the server end, because the filesystem
will do it for us.  The filetransfer read thread will read from disk, but
it will only incur a modest amount of overhead because it is reading from
the disk cache.  If the content is not in the disk cache, and we need to go
the physical disk, then Linux has made the much more informed decision that
the memory should be used elsewhere, and flushed the data we were looking

The only limitation going to the disk cache is doing is that we must wait
for the sync loop to hit the recording, so we can ensure we are getting the
latest data.  Since it is a short loop for performance reasons, we don't
have to wait long, maybe a second at the most.  Streaming and buffering on
the remote end may add for another half second or so.  Even if we can
remove that latency, that's only half the problem.  Framegrabbers only have
about a frame of latency, but are going to have to be compressed in real
time, adding some lag.  Besides which, they are standard definition and no
one is using those anyway, right?  IVTV cards run an internal buffer that
is around a second long.  HDPVRs run a larger internal buffer.  Even if we
get rid of the lag in MythTV, don't think that means we are getting rid of
the lag.

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