[mythtv] HDTV doc diff for channel settings

Brandon Beattie brandon+myth at linuxis.us
Tue Jul 20 18:06:02 EDT 2004

2 additions.

I added one paragraph regarding what CPU is recommended for systems with
multiple HDTV tuners.  I've had so many problems with watching HDTV when
myth is trying to commercial detect more than one or two shows at a
time (Commercial detect set to low CPU).  A 2.4Ghz box may work just
fine for viewing live HDTV or previously recorded, but if you drop even
2 HDTV tuners and have more than 1 or 2 shows to commercial flag a 2.4Ghz
system is not going to cut it.

The other addition is regarding how to setup myth for subchannels with
HDTV.  Examples, links to dtvstream, and explanation on how things work.

I did change the sgml file, but I didn't add anything more than <sectx>
tags, someone who knows sgml may want to beautify my technical jabber.

-------------- next part --------------
? diff.diff
Index: mythtv-HOWTO.sgml
RCS file: /var/lib/mythcvs/mythtv/docs/mythtv-HOWTO.sgml,v
retrieving revision 1.240
diff -u -d -r1.240 mythtv-HOWTO.sgml
--- mythtv-HOWTO.sgml	9 Jul 2004 20:22:14 -0000	1.240
+++ mythtv-HOWTO.sgml	20 Jul 2004 21:48:18 -0000
@@ -432,6 +432,15 @@
 accelleration.  If you enable the hardware accelleration, you may be able to
 use a 1.8GHz processor.
+If you plan on having multiple HDTV tuners, transcode, commercial
+detect and then want to watch 1080i using software decoding having
+stuttering audio/video you will want to get the most CPU power you
+can or use a client/server setup.  Even a 3.2Ghz system can dstay at
+full load almost 24x7 in this type of setup.  Most systems have a hard
+time keeping video smooth with a system load past 4.x which is common
+in multi-tuner configurations.
 <sect2>Hardware known NOT to work and other issues
 <item>Hauppauge WinTV-D or -HD (no driver)
@@ -2604,6 +2613,120 @@
 setup and running <bf>mythfilldatabase</bf> at least once to populate the
+<sect3>HDTV Channel Configuration
+  Setting up HDTV channels requires a few extra steps right now.  Although
+  HDTV goes by channels 2, 3, 4, 5 and so on, they are not broadcasted at these
+  frequencies.  You can find out what frequencies are really being used by
+  going to www.antennaweb.org and entering your address or zipcode.  This
+  website gives you a list of all channels, HDTV and NTSC, in your area.
+  The channels with a * next to them are noted as Digital channels.  The
+  table you are given has the stations 4+ letter callsign, the station name
+  (The NTSC channel such as 2, 3, 4, 5) and then the frequency broadcasted
+  on (Between 14 and 83).  For each channel in your channel editor, modify
+  the freqid column and change it to the broadcast frequency (the 14-83
+  number).  You will probably have duplicate entries in the channel editor
+  for each channel, with a slightly different callsign, but everything else
+  should be identical and don't worry -- why that is is explained below.
+  An example is:
+  channum  callsign  name                freqid  finetune  videofilters  ....
+  7        KUEDDT    KUEDDT (KUED-DT)    42      0
+  7        KUEDDT2   KUEDDT2 (KUED-DT2)  42      0
+  7        KUEDDT3   KUEDDT3 (KUED-DT3)  42      0
+  If your channel editor has no channels in it, make sure you've followed
+  the section on populating the guide database via mythfilldatabase.
+  Next you will want to get the dtvstream program found at:
+  http://www.buzzlabs.com/~peter/
+  Use this program on each of the freqid values for each channel.  This program
+  will return all the availible programs that you can watch.  An example is:
+  myth at mediabox:~myth/dtvstream-linux-1.0b2/dtvstream -i /dev/video32 -c 42
+  Stream contains 3 valid program(s).
+    Program 2: 7-1 KUED:
+        Video (MPEG-2)
+        Audio (Dolby AC-3), language = eng
+    Program 3: 7-2 KUED-DT:
+        Video (MPEG-2)
+        Audio (Dolby AC-3), language = eng
+    Program 4: 7-3 7 Kids:
+        Video (MPEG-2)
+        Audio (Dolby AC-3), language = eng
+  The above station has a total of 3 different programs inside the main
+  broadcast channel.  You would also have 3 almost identical entries in your
+  channel editor with only the callsigns and names being slightly different.
+  You will now need to modify the freqid again and add a "-x" on the end, that
+  matches up to the Program number. If you find more programs availible with
+  dtvstream than what your program guide has configured the channel editor for,
+  you can manually add in new channels but you will not have guide data for them.
+  An example for the above dtvstream is:
+  channum  callsign  name                freqid  finetune  videofilters  ....
+  7        KUEDDT    KUEDDT (KUED-DT)    42-2    0
+  7        KUEDDT2   KUEDDT2 (KUED-DT2)  42-3    0
+  7        KUEDDT3   KUEDDT3 (KUED-DT3)  42-4    0
+  The last thing to do is change the channum so that you don't have any duplicate
+  values.  The following scheme is used commonly.  (Channum plus the program ID)
+  channum  callsign  name                freqid  finetune  videofilters  ....
+  72       KUEDDT    KUEDDT (KUED-DT)    42-2    0
+  73       KUEDDT2   KUEDDT2 (KUED-DT2)  42-3    0
+  74       KUEDDT3   KUEDDT3 (KUED-DT3)  42-4    0
+  Repeat this for each channel.
+  Notes: Stations can change the number of program ID's or subchannels availible at
+  any time.  In the example above there is no program ID 1.  Program ID 1 is
+  normally reserved for a stations main 720P or 1080i (Known as HD, not just Digital
+  TV) stream. There however can be up to 3 HD sub channels per channel or 10 Digital
+  subchannels per channel.  (Each station has 45Mb/s of data that they can send.
+  This can be anything from encrypted movies to radio stations, program guide data,
+  and so on.)
+  Myth goes by the Program ID to determine which subchannel is needs to record data
+  from, not by the subchannel location in the stream.
+  If you see odd subchannels like 99-x:
+  Stream contains 6 valid program(s).
+    Program 2: 14-1 KJZZ-DT:
+        Video (MPEG-2)
+        Audio (Dolby AC-3), language = eng
+    Program 10: 99-1 USDTV:
+        Video (MPEG-2)
+        Audio (Dolby AC-3), language = eng
+        Unknown (0x0b)
+        Unknown (0x0b)
+        Unknown (0x0b)
+    Program 11: 99-2 ESPN:
+        Video (MPEG-2)
+        Audio (Dolby AC-3), language = eng
+    Program 12: 99-3 ESPN2:
+        Video (MPEG-2)
+        Audio (Dolby AC-3), language = eng
+    Program 15: 99-6 FOOD:
+        Video (MPEG-2)
+        Audio (Dolby AC-3)
+    Program 18: 99-9 HGTV:
+        Video (MPEG-2)
+        Audio (Dolby AC-3)
+  This means there is USDTV (Or a similar technology) in your area.  USDTV is a pay
+  service like satalite and cable that piggy backs on HDTV's broadcast bandwidth.
+  Some TV stations make extra money by re-selling their TV bandwidth to companies
+  like USDTV.  If you were to try to get data from any program ID starting with 99
+  you will only get an encrypted data stream as they require proprietary HDTV setop
+  boxes that can only decode the signals.  You would also see these channels on most
+  regular HDTV tuner boxes.
 <p>Run the <tt>mythfilldatabase</tt> program as directed.  The master
 backend will obtain guide data for all the video sources you defined during

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