[mythtv] Mythweb patch to add more fields for editing QAM channels

[Christiaan Lutzer]

About service ids...

A good way to think about it is that what you are capturing off your
HD card is a Multi-Program Transport Stream (MPTS).  You can see this
by looking at the PAT.  The service ID refers to a specific program in
the MPEG-2 MPTS.  In the U.S., cable providers like Comcast, Time
Warner, Cablevision, etc. implement VOD by supplying set tops with a
frequency and program number to tune to (let's forget about Motorola
plants and Virtual Channel Numbers for now).  Anyway, given a
frequency and program number, a client can tune to the MPEG-2 MPTS
multiplex, examine the PAT and locate the PMT PID associated with
their program number.  Once you have the PMT, you can figure out with
PIDs in the MPTS belong to you.  So, it's basically a big mess of
lookup tables, but ultimately, given a program number (service ID in
MythLand), you can figure out which PIDs are your video and audio (and
potentially data, encryption PIDs, etc.) and demux them into your
player.

To be as robust as possible, you would always want to NOT specify your
audio and video PIDs for a given program, because they can change,
unlikely they will, but they can.  In the U.S. under QAM 256, all you
need is frequency and program number given an MPEG-2 MPTS.

C.

On 7/27/05, Todd Ignasiak <ignasiak at gmail.com> wrote:
> I don't know what the scope of mythweb is, or if there are other plans
> for solving the issues involved with QAM channel configurations.
> This may or may not be usefule for general inclusion, but, several of
> us were having difficulties in configuring QAM channels that were not
> recognized in a channel scan.  So I wanted to post the patch in case
> others can use it.
> 
> Basically, I added a few fields to the mythweb channel configuration
> page, to make updating some channel settings easier.  The added
> variables are:
> 
> xmltvid:  Not directly related to QAM configs.  But, the xmltv
> listings had different channel numbers than what showed up in channel
> scans.  So, manually assiging the right xmltvid to the scanned channel
> was useful.
> 
> mplexid:  This refers to the entry in the "dtv_multiplex" table, where
> the frequencies for the scanned channels are defined.  So, if InHD is
> on channel 105, which is 681000000Hz, you find the dtv_multiplex entry
> for 681000000, and use that mplexid in the channel config.
> 
> serviceid: As far as I can tell, this equates to the subchannel in the
> transport stream.    e.g. InHD is on 105-1 and InHD2 is on 105-2, so
> the serviceid for InHD is 1.
> 
> atscsrcid: In the scanned channels, this value is more random.  It may
> relate to the PIDs for the audio or video in the transport stream
> (that's just a guess).  But, this value seems less important, as I can
> tune channels when I leave this value set to 0.
> 
> 
> -- The patch was made against the svn rev 6910, from 7/23/05.
> 
> 
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