Re: Dropped frames in video capture process
Vassili Leonov (vleo@pcisys.net)
Thu, 5 Nov 1998 12:56:43 -0700
>From: alan@lxorguk.ukuu.org.uk (Alan Cox)
>Subject: Re: Dropped frames in video capture process
>To: vleo@pcisys.net (Vassili Leonov)
>Date: Thu, 5 Nov 1998 19:56:31 +0000 (GMT)
>
>> And from reading the documentation I'm not even sure it indicates
>> these types of errors (i.e.. FIFO overflow).
>
>Argh so there isnt even a register you can poll ?
There is a register I can poll, it contains these statuses. Reading
the documentation I can't really figure out if any of them indicates
FIFO problems. Or you mean polling from the user space process?
There is a register though that driectly indicates the FIFO fullnes.
How you think I should poll it - maybe on the timer interrupt -
every 10ms (if i'm not wrong).
>
>> available (not used now). On the other hand, I want to timestamp
>> everything tightly. I was wondering, which system call gets data
>> directly from 8053 timer under Linux?
>
>8253 I think (well nowdays random bit of integrated chipset). The
Yes. I can't remember what was the difference between them... I think
somebody colned an IBM PC with 8053 instead on 8253. I think 8253 takes
higher clock. Anyway...
>gettimeofday() call reads it - but its actually quite slow to read. Pentium
How slow is it - in what range? If it's less them 100 usec I don't think
it matters.
>and higher processors use the RDTSC CPU internal time clock for the
>same purpose
Can you point my to more information on that - if I need it that is.
>
>
Thank you,
Vassili.
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