[mythtv] Help diagnosing HD channel recording problem

[Bob Rakosky]

On 11/25/06, Bob Rakosky <brakosky at gmail.com> wrote:
>
> I've been trying to diagnose a problem that I've (always) been
> experiencing with one of the high-def QAM channels I'm getting from my cable
> provider.  I'm not convinced that the problem isn't with the CableCo feed,
> but I'm starting to suspect that there is something in Myth's recording
> logic that isn't quite right.
>
> First, some basic info.  I'm using a HDHomeRun tuner connected to the
> cable system.  Running SVN version 11820 (current as of this AM).  My cable
> feed has one channel (the local CBS digital channel) that is the only
> channel on one of the QAM transports, which is the one that is causing me
> problems.  The following lines show the channel info for this transport,
> using hdhomerun_config (aliased as the "hr" command below):
>
> bobr at morris:~/tmp$ hr get /tuner0/status
> ch=qam256:699000000 ss=87 snq=90 seq=100 bps=38809216 pps=0
> bobr at morris:~/tmp$ hr streaminfo 0
> program 13: 0.0  filter="0x0000 0x0030 0x0800 0x0801"
>
> This looks good, so far.  If I tune to this channel and set the filters,
> fire up VLC and set the hdhomerun target for the tuner to the VLC's network
> port, I get the video feed correctly.  Doing the same thing, but using
> netcat and saving the stream to a file, the file will play back correctly
> using Myth's internal player routines (via MythVideo).
>
> However, setting up a recording for this channel in Myth, I get an MPEG
> file that Myth won't play.  Neither will VLC (nor various other MPEG
> players) that I've tried on both Linux and Windows boxes).  However (and
> this is a little weird), I can load the same MPEG file into avidemux, set
> avidemux to save an MPEG TS file, and save the video (without doing anything
> else), and I get a resulting MPEG file that will play fine in both VLC and
> MythVideo.
>
> Attached is a snippet from my myth backend log with -v record,channel for
> a 1-minute manual recording, as well as the output I got when I ran the
> command "vlc -v 2 4080_20061125131500.mpg >vlcout1.txt 2>&1".
>
> Note that the other high-def channels that I can get from the cable feed
> work fine.  However, those channels are packaged differently in that they
> are multiplexed on a couple of other QAM channels, as evidenced by the
> following commands/output:
>
> bobr at morris:~/tmp$ hr get /tuner1/status
> ch=qam256:729000000 ss=98 snq=70 seq=100 bps=38807712 pps=0
> bobr at morris:~/tmp$ hr streaminfo 1
> program 4: 25.2 WEEK-SD filter="0x0000 0x0032 0x0880 0x0881"
> program 3: 19.1 WHOI-DT filter="0x0000 0x0030 0x0800 0x0801"
> program 1: 25.1 WEEK-HD filter="0x0000 0x0031 0x0840 0x0841"
>
> The CBS channel is the only "singleton" channel that I get.
>
> I'm kind of at a loss as to how to further debug this problem (and not
> particularly familiar with the MPEG data structures or spec).
>
> Suggestions (or other assistance) would be nice.  If you want, I will/can
> move this to the -Users list, but felt that it was more appropriate for the
> -dev list.
>
>  -- Bob
>
>
>
> No ideas?  I'd open a Trac ticket, but I don't think I have enough data
for someone to remotely diagnose the problem (yet), which is why I'm looking
for suggestions here.

 -- Bob
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