[mythtv] Simple player

Henk Poley mythtv-dev@snowman.net
Wed, 11 Dec 2002 16:26:40 +0100

> Van: Ray <maillists@sonictech.net>
>> On Wed, Dec 11, 2002 at 01:00:50AM -0600, misleb@onshore.com wrote:
>>> On 10 Dec, Matt Zimmerman wrote:
>>>> On Tue, Dec 10, 2002 at 07:32:37PM -0800, Harondel J. Sibble wrote:
>>>> Hmm, I have an XP1800+ and mpeg4 is just not usable on my system.
>>> Then there is a missing variable in this equation.  You have more than
>>> enough CPU for this task.
>> Tiny L3 cache and lots of RAM? That'll slow things down.
> Er.. almost no recent systems have ANY L3 cache and if you are talking
> the cachable memory limit issues that went away along with socket 7
> motherboards.

You're right, but still his RAM might be the point, here's a little
SDRAM/DDR-RAM table I had laying around.

The first column is the "CLx" speed, how many clocks it takes to put up an
adress and to read the bus. The second is the bus clock (in Mhz) and the
last one is the resulting microseconds "per transfer" (kinda).

The entries with a * are usable on most modern motherboards.

  3  /100 0,03
  2.5/100 0,025
* 3  /133 0,0225563909774436090225563909774436
  2  /100 0,02
* 2.5/133 0,018796992481203007518796992481203
* 2  /133 0,0150375939849624060150375939849624
* 3  /266 0,0112781954887218045112781954887218
* 2.5/266 0,0093984962406015037593984962406015
* 3  /333 0,00900900900900900900900900900900901
* 2  /266 0,0075187969924812030075187969924812
* 2.5/333 0,00750750750750750750750750750750751
  3  /400 0,0075
  3  /440 0,00681818181818181818181818181818182
  2.5/400 0,00625
* 2  /333 0,00600600600600600600600600600600601
  2.5/440 0,00568181818181818181818181818181818
  2  /400 0,005
  2  /440 0,00454545454545454545454545454545455

[Yes, I know, too much precision]

Hope that helps. Please note that the actual gain in speed is much lower,
since the rest of the hardware (CPU or DMA) must be able to put up another
request in the mean-time (AFAIK that's the *problem*).

It also depends on the (combined) memory usage of the running programs. For
example kernel compiling won't gain that much when switching from CL3 to
CL2 (just 3%). Modern memory is quite optimized in accessing sequential
data, programs that do that kind of things will gain about 20% of time when
switching from CL3 to CL2.

AFAIK MythTV is such a program, it uses relatively big blocks of memory
when encoding and decoding.


Other speedfactors are things like how the hardware talks with the CPU.
Might be his 2 tv-cards need polling or are interrupting eachother (or his
SCSI card). Another thing might be a network-device that's broken and
sending malformed packages or malformed ethernet-signals (or

And something in the "Did you connect the device?"-magnitude: I hope you
set the correct FSB in your BIOS? The Athlon XP1800+ uses 133MHz FSB,
though most motherboards set the FSB standard to 100MHz out of safety
precautions (mine does, anyways, and I heard about others too).

	Henk Poley <><