[linux-dvb] Re: Strange buffer overruns...

[Ralph Metzler <rjkm@metzlerbros.de>]

Josef Wolf writes:
 > On Wed, Dec 01, 2004 at 12:13:52PM +0100, Robert Schlabbach wrote:
 > > From: "Josef Wolf" <jw@raven.inka.de>
 > > > I experience strange buffer overruns.  I have:
 > > > - Called DMX_SET_BUFFER_SIZE to set 256*1024 byte buffer.
 > > 
 > > What DVB CARD do you use? If you're using one of the TechnoTrend "budget"
 > > cards, try 188*1024, since that is the "chunk size" in which the hardware
 > > delivers the DMA buffers. With 256*1024, you're requesing one DMA buffer
 > > and a fraction of the next, and since the DMA is somewhat time-critical on
 > > the budget designs, especially on your relatively slow 450MHz CPU, that
 > > might cause overruns.
 > 
 > Your guess is perfectly correct: I have TechnoTrend budget.  I tried with
 > 188*1024, but the problem remains.  From the symptomps it looks more related
 > to IDE than to the DVB driver.


I don't know about your IDE blocking problem but you should try if
actually changing the DVR device buffer size helps getting over
those delays.
As has been discussed here many times before, DMX_SET_BUFER_SIZE calls 
will not help you if you are using DMX_OUT_TS_TAP. AFAIK, this is not
implemented for dvr in the linuxtv tree.


Ralph