RFC: dvbzap application based on DVBv5 API

In order to test the large chunk of patches I've made those days, I wrote a dvbzap application using DVBv5 API, based on tzap.

It is at my experimental v4l-utils tree, at branch dvb-utils:
http://git.linuxtv.org/mchehab/experimental-v4l-utils.git/shortlog/refs/heads/dvb-utils

in order to test, please use:
git clone git://linuxtv.org/mchehab/experimental-v4l-utils.git

While I tested it only with ISDB-T, it will likely work with DVB-T, ATSC and DVB-C, if CA is not needed.

TODO:
- Add proper support for Satellite delivery systems. It will likely recognize a DVB-S zap file, but it won't work, as polarization setting were not implemented, nor any DISEqC commands;
- Add support for CA;
- Be more flexible with regards to the channels.conf files.

One of the changes I'm experimenting with this tool is to define a new format to show DVBv5 channels/transponders.

As you likely know, the current formats on the existing DVBv3 tools are standard-dependent. Even the existing DVBv5 applications I'm aware of currently write the channels file on a DVBv3, due to compatibility issues.

So, a new format for channels is needed.

The current code has one function to write on a new format. I lacks a parser for it (it shouldn't be hard to write one - a few hours should be enough for doing that).

The format I'm thinking is to use:

[channel name]
property = value
...
property = value

This allows the same format to be used by any DVBv5 supported delivery system. It will even allow to mix channels from different delivery systems on the same file. This could be useful for devices like DRX-K, that supports multiple delivery systems with different parameters.

As an example, this is what it produces from a DVB-T zap file:

[TV Brasil SD]
VIDEO_PID = 769
AUDIO_PID = 513
SERVICE_ID = 16161
DELIVERY_SYSTEM = DVBT
FREQUENCY = 479142857
INVERSION = AUTO
BANDWIDTH_HZ = 6000000
CODE_RATE_HP = AUTO
CODE_RATE_LP = AUTO
MODULATION = QAM/AUTO
TRANSMISSION_MODE = AUTO
GUARD_INTERVAL = AUTO
HIERARCHY = NONE

The same entry without audio/video/service ID's (like the ones used by scan) would look like:

[CHANNEL]
DELIVERY_SYSTEM = DVBT
FREQUENCY = 479142857
INVERSION = AUTO
BANDWIDTH_HZ = 6000000
CODE_RATE_HP = AUTO
CODE_RATE_LP = AUTO
MODULATION = QAM/AUTO
TRANSMISSION_MODE = AUTO
GUARD_INTERVAL = AUTO
HIERARCHY = NONE

My next steps with regards to this tool are to:

1) convert a scan tool to use the same libraries as dvbzap is using, in order to generate an output file for scan with the same format;

2) to implement a parser for the new format (this should be easy, so maybe I'll start with this).

Comments, ideas, patches, etc are welcome.

Regards,
Mauro

Currently, at least gstreamer's dvbbasebin and mplayer assumue that
the channel configuration file has the format of one line per channel.
So when I personally patched them to use v5 parameters,
I chose the one-line-per-channel format of
<channel name>:propname=val|...|propname=val:<service id>, for example,
NHKBS1:DTV_DELIVERY_SYSTEM=SYS_ISDBS|DTV_VOLTAGE=1|DTV_FREQUENCY=1318000|DTV_ISDBS_TS_ID=0x40f2:103
, to minimize modification (hopefully).
I understand that it is not that difficult nor complicated
to adapt applications to use the ini file style format,
but the old one line style format seems slightly easier.

and I wish that the channel configuration can allow nicknames/aliases,
as the canonical channel name can be long to type in or difficult to remember correctly. If I remember right, MythTV has its own database,
and it would be convenient if we could share the database,
because applications currently have their own channel configuration separately, and the configuration change like new service or parameter changes must be propagated manually.

regards,
Akihiro

Hi Akihiro,

It is not that harder to parse a multiple lines file, but using something like above makes harder for humans to read. Also, the format I've proposed is already handled by several existing tools. So, there are several parsers for it already written.

Yes, this is an interesting feature. Some carriers broadcast nicks/aliases via the emphasis encoding. It shouldn't be hard to add support for it.

Btw, I finished writing a dvbv5-scan application. It reads (currently) the legacy channels/transponders format found on dvb-apps, and outputs channel scans on the new format.

I decided to write the scan tool from scratch, instead of importing the code from w_scan or dvb-apps/scan, as it allowed me to avoid importing DVBv3 legacy stuff on it, and to separate the scan code into a few function calls.

Due to that, only a subset of the features found on the other scan tools are there (the ones that are needed for ISDB-T - and - likely DVB-T). I'm currently without DVB-C signal, but, as soon as I return back to my hometown, I'll add the missing bits for it.

I also wrote a small utility to convert from the legacy zap and channels.conf formats into the new one. It is at:

http://git.linuxtv.org/mchehab/experimental-v4l-utils.git/shortlog/refs/heads/dvb-utils

Of course, patches, help, etc are welcome!

Regards,
Mauro