Mailing List Archive

I have been thinking the same thing about how hard it is to "fine-tune" the
settings, especially the watching live tv part. By the time I get back from
changing the settings, I can't really "remember" exactly how it looked and
if it's better (especially when it's close). Worse yet, whatever I was
looking at on the tv has changed and I'm comparing apples to oranges.
Here's an idea...

Could we add an option that turns on some "settings keys"? Maybe you press
S for settings and then you can change the resolution, quality lvl,
decimation, audio, etc. with some keystrokes and an onscreen indicator tells
you what you've picked. Then maybe you press a key to "save" them? That
would be awesome! Even better would be if the software could tell you your
current "framerate" and/or "frames dropped" statistic (like in PC games) so
that you could get an on-screen indicator of your progress.

We already have something like this with the bright/contrast/color settings
(jkl), I'm just wondering if we could expand this. Even if we just start
simple and do the quality (Q/q)? BTW, do the "jkl" settings get saved?
Where?

Thanks!
JC


----- Original Message -----
From: "Brian A. Vance" <bvance@egenera.com>
To: <mythtv-users@snowman.net>
Sent: Thursday, February 06, 2003 11:45 AM
Subject: [mythtv-users] best method to performance tune?


> It's probably safe to say that the primary goal of most MythTV'ers is to
> squeak the best possible performance out of the hardware they currently
> have. So the question is this...
>
> What is the best way to find optimal settings?
>
> (I realize 'optimal' is an ambiguous term and depends on personal
> preferences.. i.e. resolution, clarity, sound quality, file size, etc..)
>
> - Do you start at the lowest possible settings for each compression type
> and just slowly bring resolution/quality up until your hardware just
> can't keep up?
> (This can get very tedious as it's tough to make a determination on
> quality without taking a large sampling. i.e 30 mins on different
> channels)
>
> - Are there ways of gathering dropped frame rates other than counting
> messages from the console?
>
> Right now I just seem to be making stabs in the dark. Seems that
> without making a huge matrix and keeping track of quality levels for
> each setting, my attempts are futile!
>
> What are people's preferred methods? Are there general guidelines when
> picking settings?
>
>
> -Beev
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://www.snowman.net/mailman/listinfo/mythtv-users
>
>

I think that's a great idea! It would take alot of the pain out of
tuning!!

-Beev

On Thu, 2003-02-06 at 12:16, John wrote:
> I have been thinking the same thing about how hard it is to "fine-tune" the
> settings, especially the watching live tv part. By the time I get back from
> changing the settings, I can't really "remember" exactly how it looked and
> if it's better (especially when it's close). Worse yet, whatever I was
> looking at on the tv has changed and I'm comparing apples to oranges.
> Here's an idea...
>
> Could we add an option that turns on some "settings keys"? Maybe you press
> S for settings and then you can change the resolution, quality lvl,
> decimation, audio, etc. with some keystrokes and an onscreen indicator tells
> you what you've picked. Then maybe you press a key to "save" them? That
> would be awesome! Even better would be if the software could tell you your
> current "framerate" and/or "frames dropped" statistic (like in PC games) so
> that you could get an on-screen indicator of your progress.
>
> We already have something like this with the bright/contrast/color settings
> (jkl), I'm just wondering if we could expand this. Even if we just start
> simple and do the quality (Q/q)? BTW, do the "jkl" settings get saved?
> Where?
>
> Thanks!
> JC
>
>
> ----- Original Message -----
> From: "Brian A. Vance" <bvance@egenera.com>
> To: <mythtv-users@snowman.net>
> Sent: Thursday, February 06, 2003 11:45 AM
> Subject: [mythtv-users] best method to performance tune?
>
>
> > It's probably safe to say that the primary goal of most MythTV'ers is to
> > squeak the best possible performance out of the hardware they currently
> > have. So the question is this...
> >
> > What is the best way to find optimal settings?
> >
> > (I realize 'optimal' is an ambiguous term and depends on personal
> > preferences.. i.e. resolution, clarity, sound quality, file size, etc..)
> >
> > - Do you start at the lowest possible settings for each compression type
> > and just slowly bring resolution/quality up until your hardware just
> > can't keep up?
> > (This can get very tedious as it's tough to make a determination on
> > quality without taking a large sampling. i.e 30 mins on different
> > channels)
> >
> > - Are there ways of gathering dropped frame rates other than counting
> > messages from the console?
> >
> > Right now I just seem to be making stabs in the dark. Seems that
> > without making a huge matrix and keeping track of quality levels for
> > each setting, my attempts are futile!
> >
> > What are people's preferred methods? Are there general guidelines when
> > picking settings?
> >
> >
> > -Beev
> >
> > _______________________________________________
> > mythtv-users mailing list
> > mythtv-users@snowman.net
> > http://www.snowman.net/mailman/listinfo/mythtv-users
> >
> >
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://www.snowman.net/mailman/listinfo/mythtv-users

Brian-

Well, you can probably get in the ballpark by looking at what other people
are using for hardware and compression settings. I had some posts
yesterday talking about my setup (a search on the myth-dev archive for the
strings 'Mitchell' and 'PIII' should get you on the right thread. Even if
my hardware is vastly different than yours, you should be able to ballpark
what your box can handle.

For the tweaking after you're in the ballpark, I'd start by deciding which
compression method you want to use. I believe MPEG4 takes more grunt, but
gives you a larger file size, while rtjpeg is vice-versa (with
middle-of-the-road quality settings -- I'm sure you could switch this
around by screwing around with settings.) Then look at resolution, and
finally the compression settings.

Before starting this, you should brobably psyche yourself up for a
(possibly) lengthy, iterative process. Because "quality" is such a
subjective, nebulous term, you're not going to find a straight answer for
video settings. Just use Myth like you plan to use it, and play around
with settings until you find something that works for you. I played around
with the seetings for a few days, and haven't touched them since. Perhaps
I'll get the bug, but probably not any time soon. Obviously after a
hardware upgrade, I expect to go through the same rigamarole.

During your journey, if you have any questions about how you might be able
to tweak something specific (like problems during panning, etc.), you could
probably get some good insight from this list.

-Jeff

P.S. I should note that I had played around with settings for the same
card on a pretty much comparable machine under Windows XP before, and I did
that for probably 3-4 days, so I had a bit of a head start when configuring
the compression settings for Myth.

Brian,

I seem to recall you were on a PIII-450. I have a
dual PIII-550 server running a lot of other functions.
I finnally settled on mpeg at 320x240. It sucks up
about 65% of 1 processor while the other is busy. I
can't do 480x480 by any means. I was playing with
jtjpeg... but I found it to take up way too much disk
space 9gb/hour and really killed my system compared to
the mpeg4. Oh, I use default settings 2200 bitrate,
with the scale to size from 640x480 checked. I have
tried upping the bitrate to 3300, but I didn't notice
a huge difference. Now, please bear in mind that this
is my fileserver (.5 TB), and project box. I have an
average load of 3 computers swapping files/and running
light cpu tasks with occasional spikes of high cpu
activity. I nice my processes so myth is fine
recording (sometimes, I get stutter... but very very
very rarely). I also have 2 gigs of RAM so that might
make some difference too as almost everything is
cached. But this works for me.

Hope this helps.

-Chuck
--- Jeff_Mitchell@accessbusinessgroup.com wrote:
>
> Brian-
>
> Well, you can probably get in the ballpark by
> looking at what other people
> are using for hardware and compression settings. I
> had some posts
> yesterday talking about my setup (a search on the
> myth-dev archive for the
> strings 'Mitchell' and 'PIII' should get you on the
> right thread. Even if
> my hardware is vastly different than yours, you
> should be able to ballpark
> what your box can handle.
>
> For the tweaking after you're in the ballpark, I'd
> start by deciding which
> compression method you want to use. I believe MPEG4
> takes more grunt, but
> gives you a larger file size, while rtjpeg is
> vice-versa (with
> middle-of-the-road quality settings -- I'm sure you
> could switch this
> around by screwing around with settings.) Then look
> at resolution, and
> finally the compression settings.
>
> Before starting this, you should brobably psyche
> yourself up for a
> (possibly) lengthy, iterative process. Because
> "quality" is such a
> subjective, nebulous term, you're not going to find
> a straight answer for
> video settings. Just use Myth like you plan to use
> it, and play around
> with settings until you find something that works
> for you. I played around
> with the seetings for a few days, and haven't
> touched them since. Perhaps
> I'll get the bug, but probably not any time soon.
> Obviously after a
> hardware upgrade, I expect to go through the same
> rigamarole.
>
> During your journey, if you have any questions about
> how you might be able
> to tweak something specific (like problems during
> panning, etc.), you could
> probably get some good insight from this list.
>
> -Jeff
>
> P.S. I should note that I had played around with
> settings for the same
> card on a pretty much comparable machine under
> Windows XP before, and I did
> that for probably 3-4 days, so I had a bit of a head
> start when configuring
> the compression settings for Myth.
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://www.snowman.net/mailman/listinfo/mythtv-users


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this info could be used to auto-tune myth-tv settings

i mean mythtv could look at
cpu speed
amount of ram
hardware mjpeg acceleration
free disk space on the system
etc.
and auto tune itself
if it had access to this info

all the user would have to do is fine tune

On February 6, 2003 10:35 am, Jeff_Mitchell@accessbusinessgroup.com wrote:
> Brian-
>
> Well, you can probably get in the ballpark by looking at what other people
> are using for hardware and compression settings. I had some posts
> yesterday talking about my setup (a search on the myth-dev archive for the
> strings 'Mitchell' and 'PIII' should get you on the right thread. Even if
> my hardware is vastly different than yours, you should be able to ballpark
> what your box can handle.
>
> For the tweaking after you're in the ballpark, I'd start by deciding which
> compression method you want to use. I believe MPEG4 takes more grunt, but
> gives you a larger file size, while rtjpeg is vice-versa (with
> middle-of-the-road quality settings -- I'm sure you could switch this
> around by screwing around with settings.) Then look at resolution, and
> finally the compression settings.
>
> Before starting this, you should brobably psyche yourself up for a
> (possibly) lengthy, iterative process. Because "quality" is such a
> subjective, nebulous term, you're not going to find a straight answer for
> video settings. Just use Myth like you plan to use it, and play around
> with settings until you find something that works for you. I played around
> with the seetings for a few days, and haven't touched them since. Perhaps
> I'll get the bug, but probably not any time soon. Obviously after a
> hardware upgrade, I expect to go through the same rigamarole.
>
> During your journey, if you have any questions about how you might be able
> to tweak something specific (like problems during panning, etc.), you could
> probably get some good insight from this list.
>
> -Jeff
>
> P.S. I should note that I had played around with settings for the same
> card on a pretty much comparable machine under Windows XP before, and I did
> that for probably 3-4 days, so I had a bit of a head start when configuring
> the compression settings for Myth.
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://www.snowman.net/mailman/listinfo/mythtv-users

Brian A. Vance wrote:
> It's probably safe to say that the primary goal of most MythTV'ers is to
> squeak the best possible performance out of the hardware they currently
> have. So the question is this...

You may be right that this is a common goal but it baffles
me ;-). The goal should be to get good enough quality that
you will enjoy watching the recordings. This can be done with
a cheap CPU but that's another topic.

> What is the best way to find optimal settings?
>
> (I realize 'optimal' is an ambiguous term and depends on personal
> preferences.. i.e. resolution, clarity, sound quality, file size, etc..)

See http://www.mythtv.org/docs/mythtv-HOWTO-18.html#ss18.4
This was added to help with this process.

> - Do you start at the lowest possible settings for each compression type
> and just slowly bring resolution/quality up until your hardware just
> can't keep up?
> (This can get very tedious as it's tough to make a determination on
> quality without taking a large sampling. i.e 30 mins on different
> channels)

Start from an educated guess then move from there. If you
use LiveTV and watch the output of "top" you can test a
resolution in just a few minutes rather than recording a
half-hour show. Remember, LiveTV is really record and play-
back at the same time.

> - Are there ways of gathering dropped frame rates other than counting
> messages from the console?

The delaying to next trigger message are for the audio being
so far out of synch that it needs to reset. There are no
messages for individual dropped frames.

> Right now I just seem to be making stabs in the dark. Seems that
> without making a huge matrix and keeping track of quality levels for
> each setting, my attempts are futile!
>
> What are people's preferred methods? Are there general guidelines when
> picking settings?

Yes ;-). My rule of thumb is to choose the highest resolution
from 18.4 where the CPU "idle" time in "top" averages at least
10% during record and playback (or live tv). Average of 90%
means that at some moments 75%, other times 105%. It is when
the CPU is pegged that frames are dropped. Some frame dropping
is tolerable as long as there are at least 24fps. So generally,
if there is an average of 10% idle time you won't notice
stuttering.

-- bjm

Isn't most of that information in /proc? I know CPU Speed, Ram and free
space are all in proc.. along with pci specs, possibly mpeg decoder
stuff.. but not sure...

--Micah Morton
--Linux Network Test Engineer
--Intel Corp

> this info could be used to auto-tune myth-tv settings
>
> i mean mythtv could look at
> cpu speed
> amount of ram
> hardware mjpeg acceleration
> free disk space on the system
> etc.
> and auto tune itself
> if it had access to this info
>
> all the user would have to do is fine tune
>
> On February 6, 2003 10:35 am, Jeff_Mitchell@accessbusinessgroup.com
> wrote:
>> Brian-
>>
>> Well, you can probably get in the ballpark by looking at what other
>> people are using for hardware and compression settings. I had some
>> posts yesterday talking about my setup (a search on the myth-dev
>> archive for the strings 'Mitchell' and 'PIII' should get you on the
>> right thread. Even if my hardware is vastly different than yours, you
>> should be able to ballpark what your box can handle.
>>
>> For the tweaking after you're in the ballpark, I'd start by deciding
>> which compression method you want to use. I believe MPEG4 takes more
>> grunt, but gives you a larger file size, while rtjpeg is vice-versa
>> (with
>> middle-of-the-road quality settings -- I'm sure you could switch this
>> around by screwing around with settings.) Then look at resolution,
>> and finally the compression settings.
>>
>> Before starting this, you should brobably psyche yourself up for a
>> (possibly) lengthy, iterative process. Because "quality" is such a
>> subjective, nebulous term, you're not going to find a straight answer
>> for video settings. Just use Myth like you plan to use it, and play
>> around with settings until you find something that works for you. I
>> played around with the seetings for a few days, and haven't touched
>> them since. Perhaps I'll get the bug, but probably not any time soon.
>> Obviously after a hardware upgrade, I expect to go through the same
>> rigamarole.
>>
>> During your journey, if you have any questions about how you might be
>> able to tweak something specific (like problems during panning, etc.),
>> you could probably get some good insight from this list.
>>
>> -Jeff
>>
>> P.S. I should note that I had played around with settings for the
>> same card on a pretty much comparable machine under Windows XP before,
>> and I did that for probably 3-4 days, so I had a bit of a head start
>> when configuring the compression settings for Myth.
>>
>> _______________________________________________
>> mythtv-users mailing list
>> mythtv-users@snowman.net
>> http://www.snowman.net/mailman/listinfo/mythtv-users
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://www.snowman.net/mailman/listinfo/mythtv-users

John wrote:
> I have been thinking the same thing about how hard it is to "fine-tune" the
> settings, especially the watching live tv part. By the time I get back from
> changing the settings, I can't really "remember" exactly how it looked and
> if it's better (especially when it's close). Worse yet, whatever I was
> looking at on the tv has changed and I'm comparing apples to oranges.

I like to use The Weather Channel or CNN Headline News since
these are the exact same stuff all day and night. CNNHN has
the crawler that you can watch for jitter, and repeats the same
film reports each half-hour. If you record two half-hours, at
different resolutions, you can compare the same film segment.

As far as remembering, I've literally used pencil and paper ;-)
to jot down parameters, top stats, and jitter and quality
observations.

-- bjm

right
that info is easy to get

what is needed is a database of sorts that would let myth tv say
most ppl with 512MB of ram with 1500 bogomips of processing power ;)
a g200 card and 1 bt based tuner
went with ??? settings.

so myth tv could automatically give itself some "optimal" settings

this way you can make an rpm


On February 6, 2003 02:03 pm, Micah Morton wrote:
> Isn't most of that information in /proc? I know CPU Speed, Ram and free
> space are all in proc.. along with pci specs, possibly mpeg decoder
> stuff.. but not sure...
>
> --Micah Morton
> --Linux Network Test Engineer
> --Intel Corp
>
> > this info could be used to auto-tune myth-tv settings
> >
> > i mean mythtv could look at
> > cpu speed
> > amount of ram
> > hardware mjpeg acceleration
> > free disk space on the system
> > etc.
> > and auto tune itself
> > if it had access to this info
> >
> > all the user would have to do is fine tune
> >
> > On February 6, 2003 10:35 am, Jeff_Mitchell@accessbusinessgroup.com
> >
> > wrote:
> >> Brian-
> >>
> >> Well, you can probably get in the ballpark by looking at what other
> >> people are using for hardware and compression settings. I had some
> >> posts yesterday talking about my setup (a search on the myth-dev
> >> archive for the strings 'Mitchell' and 'PIII' should get you on the
> >> right thread. Even if my hardware is vastly different than yours, you
> >> should be able to ballpark what your box can handle.
> >>
> >> For the tweaking after you're in the ballpark, I'd start by deciding
> >> which compression method you want to use. I believe MPEG4 takes more
> >> grunt, but gives you a larger file size, while rtjpeg is vice-versa
> >> (with
> >> middle-of-the-road quality settings -- I'm sure you could switch this
> >> around by screwing around with settings.) Then look at resolution,
> >> and finally the compression settings.
> >>
> >> Before starting this, you should brobably psyche yourself up for a
> >> (possibly) lengthy, iterative process. Because "quality" is such a
> >> subjective, nebulous term, you're not going to find a straight answer
> >> for video settings. Just use Myth like you plan to use it, and play
> >> around with settings until you find something that works for you. I
> >> played around with the seetings for a few days, and haven't touched
> >> them since. Perhaps I'll get the bug, but probably not any time soon.
> >> Obviously after a hardware upgrade, I expect to go through the same
> >> rigamarole.
> >>
> >> During your journey, if you have any questions about how you might be
> >> able to tweak something specific (like problems during panning, etc.),
> >> you could probably get some good insight from this list.
> >>
> >> -Jeff
> >>
> >> P.S. I should note that I had played around with settings for the
> >> same card on a pretty much comparable machine under Windows XP before,
> >> and I did that for probably 3-4 days, so I had a bit of a head start
> >> when configuring the compression settings for Myth.
> >>
> >> _______________________________________________
> >> mythtv-users mailing list
> >> mythtv-users@snowman.net
> >> http://www.snowman.net/mailman/listinfo/mythtv-users
> >
> > _______________________________________________
> > mythtv-users mailing list
> > mythtv-users@snowman.net
> > http://www.snowman.net/mailman/listinfo/mythtv-users
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://www.snowman.net/mailman/listinfo/mythtv-users

> Van: Risto Treksler <risto@elkhornbanff.ca>
>
> right
> that info is easy to get
>
> what is needed is a database of sorts that would let myth tv say
> most ppl with 512MB of ram with 1500 bogomips of processing power ;)
> a g200 card and 1 bt based tuner
> went with ??? settings.
>
> so myth tv could automatically give itself some "optimal" settings
>
> this way you can make an rpm

Okay, that's for the quick and dirty auto settings. Why not just make a
recorder program that will record a channel (that you pointed it to), look
if there are any missing frames, adjust and tries again?

Just do it with some common resolutions, in increasing (data rate wise)
order. Use the different codecs. Check CPU-usage, build a table. Use a
binary search algorithm for obtaining the best res/codec/bitrate value.

You are going to leave the MythTV-box on over night for the rest of the
time anyways, so you have plenty of time for automagical tweaking.

Henk Poley <><