[linux-dvb] Re: Help on use of DMX_OUT_TAP (II)

[Johannes Stezenbach <js@convergence.de>]

Hi,

(Sorry, this mail was hanging in my postponed queue for some days.)

Andreas Oberritter wrote:
> On Thu, 2003-06-05 at 12:55, Johannes Stezenbach wrote:
> > 
> > What if you want to record what you are currently watching? The current API
> > does not have a nice way to specify that. That's why the Metzler Bros.
> > chose to implement DMX_PES_AUDIO/VIDEO + DMX_OUT_TAP to mean
> > "DMX_OUT_DECODER and DMX_OUT_TAP". Which makes sense, IMHO.
> 
> Just set two separate PES filters. That's how it works on the dbox2 and
> the dreambox for example. Usually one does not tune to a channel and
> start a recording simultaneously unless the recording is timered by the
> same dvb application. Starting to record while watching would require to
> stop the old pes filters and restart them if you don't want to set a
> second set of filters. Setting separate filters also allows to switch
> channels on the same transponder while recording one channel
> continously.

You can set only one PES filter per PID (at least for av7110 based
cards -- try e.g. szap and test_pes on the video PID).

It would be cleaner to change all implementations to allow two seperate
filters for decoding and recording, but that's not in the current av7110
driver.
See also the dvb-kernel-v4 CVS and the related discussion on linux-dvb.

> Buffers do fill up very quickly and it is almost impossible to read all
> data, neither on the dbox2, where host cpu speed could be the cause, nor
> on a pc (I am using a 1.3 Ghz Athlon and a premium card. A Friend
> reported to have the same problem with a budget card. The "old" driver
> core (before newstruct) seems to be more reliable regarding this.
...
> Buffers fill up too quickly, no matter whether you read pes or sections.

Is that the read() after select() blocks without O_NONBLOCK issue,
or is there more to it?


Johannes


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