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

Luis Ochoa luis.m.ochoa at gmail.com
Fri Oct 21 17:29:13 CEST 2005

Ok, found a README in CVS that answers azap related questions, I'm
duplicating it here for future tinkerers benefit.


this are some trivial zapping applications explaining how to use the frontend
and demux API. They are also pretty useful to test your hardware.

For DVB-S, Astra Channel config file:

$ ./szap -c channels-conf/dvb-s/Astra-19.2E n24

will tune to N24. For DVB-C, Berlin Cable channel config:

$ ./czap -c channels-conf/dvb-c/de-Berlin Arte

For DVB-T, Berlin Config:

$ ./tzap -c channels-conf/dvb-t/de-Berlin phoenix

For ATSC, Raleigh Durham Config:

$ ./azap -c channels-conf/atsc/us-Raleigh-Durham WRAL

will tune to WRAL's Digital Channel 5-1.

By default the MPEG stream is routed to a hardware decoder. If you want to
record the stream to disk you will route it to the DVR device by using the
'-r' option:

$ ./tzap -c channels-conf/dvb-t/de-Berlin phoenix -r
[keep it running in one console]
$ cat /dev/dvb/adapter0/dvr0 > /tmp/recording.ts
[in a second console, will dump the MPEG transport stream to /tmp/recording.ts]

The status messages have the following meaning:

status 0x1f              --- The demodulator status bits.
			      0x1f means all bits set, everything ok.

signal [0x0000...0xffff] --- Signal Strength. Values above 0x8000 should be ok.

snr [0x0000...0xffff]    --- Signal/Noise Ratio. Values above 0x8000 are ok.

ber [0...0xffffffff]     --- Bit Error Rate. The less the better.

unc [0...0xffffffff]     --- Number of Uncorrectable Blocks.
			     Small numbers are Preferable.

If everything is alright and all frontend circuits are working stable
(are locked) you should see a FE_HAS_LOCK in the rightmost line.

Good luck,


On 10/21/05, Luis Ochoa <luis.m.ochoa at gmail.com> wrote:
> 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 |

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