On 05-12-2011 22:07, HoP wrote:
I doubt that scan or w_scan would support it. Even if it supports, that
would mean that,
for each ioctl that would be sent to the remote server, the error
code would
take 480 ms
to return. Try to calculate how many time w_scan would work with
that. The
calculus is easy:
see how many ioctl's are called by each frequency and multiply by the
number
of frequencies
that it would be seek. You should then add the delay introduced over
streaming the data
from the demux, using the same calculus. This is the additional time
over a
local w_scan.
A grouch calculus with scandvb: to tune into a single DVB-C
frequency, it
used 45 ioctls.
Each taking 480 ms round trip would mean an extra delay of 21.6 seconds.
There are 155
possible frequencies here. So, imagining that scan could deal with 21.6
seconds of delay
for each channel (with it doesn't), the extra delay added by it is 1
hour
(45 * 0.48 * 155).
On the other hand, a solution like the one described by Florian would
introduce a delay of
480 ms for the entire scan to happen, as only one data packet would be
needed to send a
scan request, and one one stream of packets traveling at 10GB/s would
bring
the answer
back.
Andreas was excited by your imaginations and calculations, but not me.
Now you again manifested you are not treating me as partner for
discussion.
Otherwise you should try to understand how-that-ugly-hack works.
But you surelly didn't try to do it at all.
How do you find those 45 ioctls for DVB-C tune?
With strace. See how many ioctl's are called for each tune. Ok, perhaps
scandvb
is badly written, but if your idea is to support 100% of the
applications, you
should be prepared for badly written applications.
$strace -e ioctl scandvb dvbc-teste
scanning dvbc-teste
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
ioctl(3, FE_GET_INFO, 0x60a640) = 0
initial transponder 573000000 5217000 0 5
tune to: 573000000:INVERSION_AUTO:5217000:FEC_NONE:QAM_256
ioctl(3, FE_SET_FRONTEND, 0x7fff5f7f2cd0) = 0
ioctl(3, FE_READ_STATUS, 0x7fff5f7f2cfc) = 0
ioctl(3, FE_READ_STATUS, 0x7fff5f7f2cfc) = 0
ioctl(3, FE_READ_STATUS, 0x7fff5f7f2cfc) = 0
ioctl(4, DMX_SET_FILTER, 0x7fff5f7f1ad0) = 0
ioctl(5, DMX_SET_FILTER, 0x7fff5f7f1ad0) = 0
ioctl(6, DMX_SET_FILTER, 0x7fff5f7f1ad0) = 0
ioctl(7, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(8, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(9, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(10, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(11, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(12, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(13, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(14, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(15, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(16, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(17, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(18, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(19, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(20, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(21, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(22, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(23, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(24, DMX_SET_FILTER, 0x7fff5f7f1910) = 0
ioctl(4, DMX_STOP, 0x1) = 0
ioctl(15, DMX_STOP, 0x1) = 0
ioctl(11, DMX_STOP, 0x1) = 0
ioctl(22, DMX_STOP, 0x1) = 0
ioctl(17, DMX_STOP, 0x1) = 0
ioctl(16, DMX_STOP, 0x1) = 0
