[linux-dvb] Finding in-the-clear digital cable channels: a few questions.

Luis Ochoa luis.m.ochoa at gmail.com
Fri Oct 21 17:08:55 CEST 2005


Hi all,
I finally got my FusionHDTV5 Lite working (thanks Mike Krufky, et.al.)
and the first thing I wanted to do was trying to find out what digital
cable channels I can receive in my house.

After doing a lot of reading and a few tests, I have a few questions.

I found somewhere here, a list (actually 5 lists) of cable
frequencies. I concat'ed them all together and fed them to "atscscan
-A2 cable-freq-file" and this found about about 48 services, like:

[0003]:639000000:QAM_256:0:145:3
[0002]:639000000:QAM_256:0:81:2
[0002]:651000000:QAM_256:0:2061:2
[0001]:651000000:QAM_256:0:17:1
[0003]:651000000:QAM_256:0:145:3
[0001]:657000000:QAM_256:0:17:1
[0002]:657000000:QAM_256:0:2061:2
[0003]:657000000:QAM_256:0:145:3

My first question is, what does each portion of a line mean?
I think the first item is the channel "name" (which atscscan sets to
the same as the last item), but what is this number?
I know the second entity is the freq, and QAM_256 is of course the
modulation, but what are the rest of the numbers?

I saved all these to ~/.azap/channels.conf , changed the first item
from say [0003] to say "c1" and proceded to try to azap.
I wanted to use mplayer, and I read I had to do "azap -r", but don't know why.
What does the -r option do?

this is what I get:

azap -r c1
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
tuning to 621012500 Hz
video pid 0x0000, audio pid 0x0211
status 00 | signal 0000 | snr 0000 | ber 00000000 | unc 0000ffff |
status 1f | signal 0000 | snr feb6 | ber 00000000 | unc 0000ffff | FE_HAS_LOCK
status 1f | signal 0000 | snr feb4 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status 1f | signal 0000 | snr febb | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status 1f | signal 0000 | snr feba | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status 1f | signal 0000 | snr febd | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status 1f | signal 0000 | snr febb | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status 1f | signal 0000 | snr fec1 | ber 00000000 | unc 00000000 | FE_HAS_LOCK

Looks good by what I've read, if you care to comment on the portions
of each individual line, please do so. I know the signal is always
zero because the author of the driver is making it so, as he's not
happy with the number he's getting from the card/driver (or something
like that).

I fire up another terminal, and do "dvbtraffic" and this is what I
get, although I don't know what to make of these numbers, so please
enlighten me. I do know the final 0x2000 PID is the whole TS, but, is
the PID here audio PID, video PID? could be both?

-PID--FREQ-----BANDWIDTH-BANDWIDTH-
0000     7 p/s     1 kb/s    11 kbit
0010  2413 p/s   443 kb/s  3629 kbit
0011    89 p/s    16 kb/s   133 kbit
0029    23 p/s     4 kb/s    35 kbit
0210  3893 p/s   714 kb/s  5855 kbit
0211    89 p/s    16 kb/s   133 kbit
0229    24 p/s     4 kb/s    37 kbit
0310  3087 p/s   566 kb/s  4642 kbit
0311    89 p/s    16 kb/s   133 kbit
0312    46 p/s     8 kb/s    69 kbit
0329    24 p/s     4 kb/s    37 kbit
1fff 16039 p/s  2944 kb/s 24123 kbit
2000 25827 p/s  4741 kb/s 38845 kbit

Finally, I found another thread suggesting how to use mplayer, so I do:

mplayer /dev/dvb/adapter0/dvr0 -tskeepbroken -cache 8192

and I get:

MPlayer 1.0pre7try2-3.2.3 (C) 2000-2005 MPlayer Team
CPU: Intel Pentium 4/Xeon/Celeron Foster (Family: 8, Stepping: 4)
Detected cache-line size is 64 bytes
CPUflags:  MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1


Opening joystick device /dev/input/js0
Can't open joystick device /dev/input/js0 : No such file or directory
Can't init input joystick
Setting up LIRC support...
mplayer: could not connect to socket
mplayer: No such file or directory
Failed to open LIRC support.
You will not be able to use your remote control.
Playing /dev/dvb/adapter0/dvr0.
Cache fill: 19.92% (1671168 bytes)    Win32 LoadLibrary failed to
load: avisynth.dll, /usr/lib/win32/avisynth.dll,
/usr/local/lib/win32/avisynth.dll
TS file format detected.
DEMUX OPEN, AUDIO_ID: -1, VIDEO_ID: -1, SUBTITLE_ID: -1,
PROBING UP TO 2000000, PROG: 0
NO VIDEO! AUDIO A52(pid=17) NO SUBS (yet)!  PROGRAM N. 0
Opened TS demuxer, audio: 2000(pid 17), video: ffffffff(pid -1)...POS=3008
==========================================================================
Opening audio decoder: [liba52] AC3 decoding with liba52
Using SSE optimized IMDCT transform
a52: CRC check failed!
AC3: 3.1 (3f+lfe)  32000 Hz  64.0 kbit/s
Using MMX optimized resampler
AUDIO: 32000 Hz, 2 ch, s16le, 64.0 kbit/6.25% (ratio: 8000->128000)
Selected audio codec: [a52] afm:liba52 (AC3-liba52)
==========================================================================
Checking audio filter chain for 32000Hz/2ch/s16le -> 32000Hz/2ch/s16le...
AF_pre: 32000Hz/2ch/s16le
alsa-init: 1 soundcard found, using: default
alsa: 32000 Hz/2 channels/4 bpf/43688 bytes buffer/Signed 16 bit Little Endian
AO: [alsa] 32000Hz 2ch s16le (2 bps)
Building audio filter chain for 32000Hz/2ch/s16le -> 32000Hz/2ch/s16le...
Video: no video
Starting playback...
a52: error at resampling
a52: CRC check failed!  %
a52: error at resampling
a52: CRC check failed!  %
a52: CRC check failed!
a52: error at resampling
a52: CRC check failed!
a52: error at resampling
alsa-space: xrun of at least 0.032 msecs. resetting stream
a52: CRC check failed!
a52: error at resampling
a52: CRC check failed!
a52: error at resampling
a52: CRC check failed!
a52: error at resampling
a52: CRC check failed!
a52: error at resampling
A:   0.0 (00.0) ??,?% 0%

I know most likely the stream is encrypted, but I want to know if I'm
going about this the right way, or if I should be more selective as
far as picking individual PIDs from the stream, and which programs
should I specify these to, etc.

Thanks for your help,

Luis.



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