Been a while since i've checked into this. <br><br>Gonna start working on this again tomorrow evening so I decided to check up on the thread.<br><br>Steve:<br><br>I have a pcHDTV3000 Card, so i'm picking up a potload of OTA stations. In my local area (which is the same for everyone elses of course) i'm getting ahold of both the Analog and Digital Stations (for instance 2 vs
2.1). Now, in MythTV i've got the Analog Stations filtered out (i.e. They're not in my zap2it profile so they're not "valid" stations via Myth). So ALL of the stations i'm displaying are in fact Digital Stations (HD, Non HD, I don't know, but they're all at minimum Digital).
<br><br>Here's where my issue comes in, when I tune to a station, say 9.3 (pbs) I get digital television displaying what PBS is displaying, sound and video seem to be synced up just fine. When I then switch to 30.1 (ABC? I think - Grey's Anatomy, Alias, Commander in Chief, etc.) I get video with audio out of sync...we're talking 200 - 300 ms out of sync...mid distance past the "is it really out of sync or am I just seeing things?" but certainly not into "OMG that's WAY wrong". It's out of sync enough that it's noticeable and annoying without being unwatchable (other than the annoyance factor).
<br><br>Now, when I go to record shows: When I record something on 9.3 (pbs) which plays synced up, it records just fine and is perfectly in sync. When I play back something recorded on 30.1 the recording is about 2 seconds off the audio (people talk and then you hear the audio)...which is COMPLETELY unwatchable in any way at all.
<br><br>Now, here's where it gets wierd. That SAME video (recorded to disk as an MPEG file by Myth v0.19) played through Xine syncs up video/audio PERFECTLY with absolutly no hitch what so ever. This tells me a few things:
<br><br>1) The Live TV out of sync problem is due either to my machine not being able to keep up in playing real time HDTV Streams (it's a 2.8G Pentium 4 HT Processor with 1G of memory, nothing else besides myth frontend/backend/mysql/httpd running) or MythTV isn't able to sync it up right for some reason.
<br><br>2) The fact that the playback is farther off than the live show itself suggests that the ENTIRE problem is mythTV's issue, NOT the stations issue. That belief is exhaserbated by the fact that the videos play just fine on Xine outside of MythTV (if the show was recorded with sound/video off then it would be off played through xine as well), and my TV set with NO myth attached (just direct to TV) does just fine as well (there's no processing inside a TV that would sync up that audio/video stream, so it's GOT to be comming in synced up from the broadcast).
<br><br>The final "hum, that's interesting" note to this whole thing is that the recordings i'm doing on the various stations fit into two completely difering categories: 1) Kids shows recorded off of PBS running during the daytime and 2) "Parent" shows running in prime time recorded off of (generally) ABC(?).
<br><br>Now, I'm going to make the guess, and I think correctly, that the kids shows i'm recording are probably NOT being broadcast in HD with Dolby sound, but i'm pretty darn sure that Alias and Greys Anatomy sure as hell are. Tomorrow night i'm going to sit down and try to narrow the variables down alot more, see what I can find out. I also have a few possible things to try:
<br><br>1) could I be running into an issue where XvMC is actually hurting the performance or causing this issue?<br><br>2) Could Transcoding (which is supposed to fix audio sync issues) either be broken and making it worse or not working at all and not syncing up the audio? How can I tell whether a recording has been transcoded and to what? Where's good documentation on the whole transcoding thing and how it works/what it does/how it's setup?
<br><br>Again, general and somewhat random thoughts to re-start this discussion.<br><br>Now to your questions directly:<br>----------------------------------------------------------<br>ok, let me make sure I understand. You've got an ATSC/QAM tuner card.
<br>you pick up a bunch of HD and digital SD stations. digital SD stations<br>do not pose a problem with audio sync but *all* your HD stations do?<br>-----------------------------------------------------------<br>This is partly where my issue comes from, I can't tell which stations are HD and which are digital SD. If you assume that PBS is a Digital SD while something like an ABC, CBS and NBC are all HD stations then you get farther with the discussion by saying yes to this. I don't know which stations during prime time programming / HD broadcast all correctly record and which don't...that's a task I need to find out tomorrow.
<br><br>-------------------------------------------------------------<br>If so, then lets assume whatever the issue is has to do with HD<br>stations use of AC3 sound.<br><br>Are you using digital out of your soundcard to a receiver or are you
<br>running analog output from the soundcard to your receiver?<br>---------------------------------------------------------------<br>There is no digital sound in the setup other than what's comming in over the broadcast wire. Once it hits the pcHDTV3000 card it is going out the PCI slot (I have tried with both the patch wire between pcHDTV3000 out and soundcard in and without it, same effect) to the Sound Card's Bus, to the sound card, and out through the ANALOG out through a Mini->RCA plug (single mini plug in the green analog out hole of the SB Live! Value Digital card I have, to the Red/White RCA audio in on the TV I have. FYI the video is getting to the tv Via DVI->HDMI cable). There is no subsidiary receiver at all in this setup, just the TV itself.
<br><br>--Doug<br><br><div><span class="gmail_quote">On 5/19/06, <b class="gmail_sendername">Steven Adeff</b> <<a href="mailto:adeffs.mythtv@gmail.com">adeffs.mythtv@gmail.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
On 5/18/06, Douglas Wagner <<a href="mailto:douglasw0@gmail.com">douglasw0@gmail.com</a>> wrote:<br>> On 5/17/06, Douglas Wagner <<a href="mailto:douglasw0@gmail.com">douglasw0@gmail.com</a>> wrote:<br>> >
<br>> > Wierder yet: I'm not seeing this on PBS. BTW it IS happening on Live TV<br>> as well, not nearly as pronounced. When I run MPlayer through MythTV (I<br>> believe that's what's used to play back recorded shows by default correct?)
<br>> I do get the issue, but when I run it OUT of MythTV, I do not. So it's not<br>> a function of the player software either (unless MythTV uses it's own media<br>> player to playback the MPEG stream, in which case it would be Myth's player
<br>> that would be the cause of the problem).<br>> ><br>> > Did some TOP testing, looks like i'm only running 29% CPU when live TV is<br>> playing or when i'm playing back a video through Myth. What I DO notice is
<br>> that whether i'm running as root, have the bits set in /etc/security/ or<br>> whatnot for Real Time scheduling, I STILL don't get a realtime thread. I do<br>> have the option checked in Myth TV (use realtime scheduling)...the settting
<br>> in MythFrontend's setup, main page I think. Could that be an issue (it's<br>> the thread's value seems to be 15, which is somewhat higher than most of the<br>> rest of the processes, tho I do have several marked as RT, which I assume is
<br>> Real Time).<br>> ><br>> > So, it doesn't look like a function of the hardware, it doesn't look like<br>> the function of the software player (mplayer or xine). It's either some<br>> kind of delay that myth isn't picking up on that the externals are, or it's
<br>> something to do inside myth with the way it's syncing up audio.<br>> ><br>> > I'm guessing i've come to the end of my rope on this board, but before I<br>> go subscribe to the dev list and bother them, i'm looking for any last
<br>> advice here...<br>> ><br>> ><br>> > --Douglas Wagner<br>> ><br>> ><br>> ><br>> > On 5/17/06, Steven Adeff <<a href="mailto:adeffs.mythtv@gmail.com">adeffs.mythtv@gmail.com
</a>> wrote:<br>> > > On 5/16/06, Douglas Wagner <<a href="mailto:douglasw0@gmail.com">douglasw0@gmail.com</a>> wrote:<br>> > > > On 5/16/06, Christopher Rodd < <a href="mailto:cmrodd@yahoo.com">
cmrodd@yahoo.com</a>> wrote:<br>> > > > > I have this problem all the time when watching network primetime<br>> shows in<br>> > > > the US. Fox never has a problem but ABC and NBC seem to give me sound
<br>> sync<br>> > > > problems from time to time. It doesn't happen every week. Syndicated<br>> shows<br>> > > > on HD network stations never seem to have a problem either. I run SVN<br>> > > > versions (update every couple weeks) it has shown up in every version
<br>> since<br>> > > > at least 0.18. I don't use LiveTV all that often so I can't comment<br>> on sync<br>> > > > issue or lack thereof there.<br>> > > > ><br>> > > > > Don't just pause and restart. Fast forwarding a few seconds resyncs
<br>> > > > everything for me. You may have to play with the number of seconds<br>> though.<br>> > > > ><br>> > > > > Chris<br>> > > > ><br>> > > > Just tried it, fast forward, rewind, pause, play etc. All useless.
<br>> > > ><br>> > > > Commersials are synced up perfectly, the tv show is not. This used to<br>> work.<br>> > > > Settings are the same. I've not upgraded or changed anything since I
<br>> > > > started this project.<br>> > ><br>> > > commercials are fine but the show is off? Sounds like there is a set<br>> > > delay in the mpeg stream that MythTV isn't picking up on but xine and
<br>> > > mplayer are. this may be something to ask on the Dev list.<br>> > ><br>> > ><br>> > > --<br>> > > Steve<br>> > > Before you ask, read the FAQ!<br>> > >
<br>> <a href="http://www.mythtv.org/wiki/index.php/Frequently_Asked_Questions">http://www.mythtv.org/wiki/index.php/Frequently_Asked_Questions</a><br>> > > then search the Wiki, and this list,<br>> > >
<a href="http://www.gossamer-threads.com/lists/mythtv/">http://www.gossamer-threads.com/lists/mythtv/</a><br>> > > Mailinglist etiquette -<br>> > ><br>> Just did a little mental backflip and came up with something...
<br>><br>> Reading another thread got me thinking...it hadn't occured to me that<br>> Digital != HD, I'd always coupled the two. Not all programming comming<br>> through is HD...typically just prime time on major networks (for over the
<br>> air). Given that all of my KIDS shows come in without a hitch and all of MY<br>> shows (which are all prime time major network shows...like Alias, Gray's<br>> Anatomy, etc...) are off when played through Myth TV's internal player...
<br>><br>> Could it be something having to do with HD content? Is there maybe an issue<br>> with AC3 sound in my setup? (HD programming comes across with<br>> digital/encoded sound where as non HD programs I assume do not?)
<br>><br>> Grasping at straws here...<br><br>ok, let me make sure I understand. You've got an ATSC/QAM tuner card.<br>you pick up a bunch of HD and digital SD stations. digital SD stations<br>do not pose a problem with audio sync but *all* your HD stations do?
<br><br>If so, then lets assume whatever the issue is has to do with HD<br>stations use of AC3 sound.<br><br>Are you using digital out of your soundcard to a receiver or are you<br>running analog output from the soundcard to your receiver?
<br><br>--<br>Steve<br>Before you ask, read the FAQ!<br><a href="http://www.mythtv.org/wiki/index.php/Frequently_Asked_Questions">http://www.mythtv.org/wiki/index.php/Frequently_Asked_Questions</a><br>then search the Wiki, and this list,
<br><a href="http://www.gossamer-threads.com/lists/mythtv/">http://www.gossamer-threads.com/lists/mythtv/</a><br>Mailinglist etiquette -<br><a href="http://www.mythtv.org/wiki/index.php/Mailing_List_etiquette">http://www.mythtv.org/wiki/index.php/Mailing_List_etiquette
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http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users</a><br></blockquote></div><br>