[MPlayer-users] Handling "bursty" data sources

[Haas Wernfried]

hello,
are you sure, you set cache to a value, that's big enough (e.g. 32536,
which is the value i normally use, i guess the bigger - the better)
and not just 1 to activate it? ;)
other idea: play around with hdparm -E <value>, which sets the cdrom
speed to <value>. maybe if you slow down the cdrom, it never gets
the chance to spin down, because it never gets to deliver enough
data to be allowed to spin down. of course, if you set it too slow,
not enough data will be delivered to watch the movie. 
if you combine different values
for -cache and hdparm -E <value> /dev/cdrom you'll get dozens of
combinations to try out and so can waste a lot of time ;)
maybe it helps, good luck.

regards,
	wernfried



On Fri, Aug 09, 2002 at 04:35:21PM -0700, alex at foogod.com wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Greetings,
> 
> I am having a problem which I'm hoping somebody here can suggest an adequate
> solution for..
> 
> I'm trying to play a video (XviD-encoded AVI) off of a CDROM on a laptop
> machine, and am getting very jerky output.  Before anybody suggests it, this is
> not a problem with an underpowered machine, as the same movie plays just fine
> if I copy it to the hard drive first.  The overall data transfer rate of the
> CDROM drive seems copiously adequate for this task, as well, so I'm fairly
> certain that isn't the problem.
> 
> What does appear to be the problem is the following:
> 
> Mplayer starts up and reads the beginning of the movie off the disc and
> proceeds to play it.  While mplayer is happily playing this first portion of
> the movie, the CDROM drive (being a laptop-variety drive and thus very eager to
> conserve power) decides it's going to spin down.  This means that shortly
> afterward, when mplayer decides it needs the next bit of movie to play, the
> CDROM drive has to spin up again.  While mplayer is waiting for this, it runs
> out of data to play, and has to pause briefly until the CDROM comes fully up to
> speed and can give it more data.
> 
> The result, of course, is a lot of play-pause-play-pause, which ultimately
> isn't the most satisfying viewing experience..
> 
> It seems to me that this problem could be avoided with the adequate use of
> pre-buffering the movie as it's read off the disc, but I can't figure out any
> way to do this.  I have tried increasing the cache size given with mplayer's
> -cache option (to quite a wide range of values, with no discernable change in
> behavior), but this seems to do little good because as far as I can tell
> mplayer doesn't actually _use_ the cache.  (From what I can see from the
> outside, it looks like it decides during the initial read that it's getting
> data "nice and fast, thank you" so it doesn't bother to buffer any of it
> because it figures it won't need to, and then later finds out it really should
> have (but apparently still doesn't learn its lesson, because it does the same
> thing all over again a few seconds later).)
> 
> So, my question is this:  Is there any way to make mplayer better cope with
> "bursty" data sources?  Can I somehow tell it that yes, trust me on this, it
> would actually be a good idea to use the cache to prebuffer stuff instead of
> just letting it sit there (mostly) empty?
> 
> Alternately, if somebody has some other explanation for what's going on, and
> preferably a way to fix it, I'm all ears..
> 
> Thank you for your consideration..
> 
> -alex
> 
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-- 
-> Wernfried Haas - w.haas at xover.mud.at / amnenion at xover.mud.at 
-> Homepage: http://xover.mud.at/~amnenion
-> Beutelland: http://bl.mud.at