[mythtv-users] channel changing speed, is 3 seconds normal?

[Boyd II, Willy]

(as to self-fulfilling prophecy of "until you spend some time with the
source"...)

Well I finally spent a few hours with the source last night.  So I will
continue the "babble".  

Timing things shows that the ChangeChannel call in tv_play.cpp (as far as I
can tell this is high enough abstraction to time from here) takes around 2.5
seconds.. in some cases more but I couldn't reproduce that very often.
However, I dug out my directv remote and tried manually changing channels,
while leaving myth on it's same "channel".  The stream is definitely right
around 4 seconds behind being live.  In fact by hitting FF (right arrow on
my remote) several times, to make sure I'm as far ahead as possible, and
changing just on the directv box, I can still only be 4 seconds behind, no
less.  Which falls right in line with what Bruce posted (thank you VERY much
Bruce for that post... I think it's enough explanation to get those of us
blindly guessing (like myself in the beginning) to shut up, but at the same
time give others who care about trying to make it faster some kind of
understanding as to what's going on).  The steps that are being taken to
ensure a safe stream are definitely creating quite a window of time.  And on
a stand-alone box with a pvr-250 (no time need be spent encoding here), the
player shouldn't *need* 4 seconds of data to play continuously (and yes I
realize that's only a narrow case, many people use software encoding and/or
take advantage of split frontend/backend's...) 

- Willy

-----Original Message-----
From: Isaac Richards [mailto:ijr at po.cwru.edu] 
Sent: Wednesday, October 01, 2003 2:34 AM
To: Discussion about mythtv
Subject: Re: [mythtv-users] channel changing speed, is 3 seconds normal?


On Wednesday 01 October 2003 01:26 am, Mark Edwards wrote:
> Hey Bruce....
>
> I appreciate your comments...
>
> From what I understand, the concept of a ringbuffer is fairly generic 
> across most technologies - you pretty much find them everywhere you 
> come across a digital stream... I first came across them in CD 
> players! I havn't delved into the code to any great extent here,

s/any great extent/at all/g

Please people, no more babble on this subject until you actually spend some 
time with the source.  Not that that will actually happen, but, I'm hoping 
for it at least.

Isaac
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