[mythtv-users] ATSC Encoder change breaks Mythtv

[Taylor Ralph]

Greg,

On Sat, Oct 9, 2010 at 4:02 PM, Greg Maus <g.maus at fnmmail.com> wrote:
> Taylor,
> On Fri, 2010-10-08 at 23:12 -0400, Taylor Ralph wrote:
>> Greg,
>>
>> On Fri, Oct 8, 2010 at 7:30 PM, Greg Maus <g.maus at fnmmail.com> wrote:
>> > Taylor,
>> >
>> > On Fri, 2010-10-08 at 14:30 -0400, Taylor Ralph wrote:
>> >> Greg,
>> >>
>> >> On Fri, Oct 8, 2010 at 6:28 AM, Greg Maus <g.maus at fnmmail.com> wrote:
>> >> > On Thu, 2010-10-07 at 21:06 -0400, Taylor Ralph wrote:
>> >> >> On Thu, Oct 7, 2010 at 7:41 PM, Greg Maus <g.maus at fnmmail.com> wrote:
>> >> >> >
>> >> >> >> Have you tried playing back the video files in another player
>> >> >> >> (MPlayer,
>> >> >> >> VLC, etc). What format is the audio stream in (MPlayer will tell
>> >> >> >> you)?
>> >> >> >> What is your audio output configuration? That information will
>> >> >> >> certainly
>> >> >> >> help.
>> >> >> >
>> >> >> > The recorded files that will not play in Myth frontend play fine in all
>> >> >> > of the common media players.  I am not exactly sure what you mean what
>> >> >> > format is the audio stream.  I know that it is AC3, and that is the same
>> >> >> > audio format as files that were recorded prior to the encoder change.
>> >> >> > Is there a command line option in mplayer to get more specific audio
>> >> >> > stream info?
>> >> >> >
>> >> >> > My Mythtv audio config is pretty basic.  ASLA:default.  I have also
>> >> >> > tried ALSA:spdif, but there is no difference in playback regardless of
>> >> >> > the settings.
>> >> >> >
>> >> >>
>> >> >> You need to provide a small sample so a dev can take a look at what's going on.
>> >> >>
>> >> >> Regards.
>> >> >> --
>> >> >> Taylor
>> >> >> _______________________________________________
>> >> >> mythtv-users mailing list
>> >> >> mythtv-users at mythtv.org
>> >> >> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>> >> >
>> >> > A sample file has been uploaded here:
>> >> > http://filebin.ca/mhvyt/KSTP_5.1sample.mpg
>> >> > Thank you!
>> >> >
>> >>
>> >> I've analyzed this video and unfortunately the FFmpeg mpegts demuxer
>> >> doesn't provide any valid video timestamps (DTS or PTS). Obviously,
>> >> this makes A-V sync impossible to accomplish. In mplayer the video
>> >> plays fine with perfect A-V sync but by default it doesn't use the
>> >> FFmpeg mpegts demuxer. So it is most likely a valid video format.
>> >> FFmpeg prints the following error when processing the video:
>> >>
>> >> [mpegts @ 0x93da2c0]invalid dts/pts combination
>> >>
>> >> The only way to get this resolved is to file a bug report at
>> >> http://ffmpeg.org/bugreports.html and provide the sample which you've
>> >> already created. Then open a ticket at
>> >> http://svn.mythtv.org/trac/newticket and reference the FFmpeg ticket.
>> >> Sorry I don't have better news but the sooner we get this fixed the
>> >> better since I can only imagine other broadcasters will start using
>> >> this new encoder at some point.
>> >>
>> >> Regards.
>> >>
>> >> --
>> >> Taylor
>> >> _______________________________________________
>> >> mythtv-users mailing list
>> >> mythtv-users at mythtv.org
>> >> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>> >
>> > I have opened tickets:
>> > FFmpeg Issue2286
>> > Mythtv #9076
>> >
>> > I mentioned your name as helping me to find the problems in the file.  I
>> > hope this is okay.
>> >
>> > Thank you,
>> > Greg
>> >
>>
>> Thanks for providing the sample and bug reports.
>>
>> This should now be fixed in trunk and 0.23-fixes.
>>
>> Baptiste is correct that the file is technically broken but their
>> solution is a bit extreme for a player since it has to have a valid
>> video timestamp for A-V sync purposes. You might want to forward the
>> information in the roundup ticket to your broadcaster so they can
>> report the issue to the maker of the encoder.
>>
>> Regards.
>>
>> --
>> Taylor
>> _______________________________________________
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>> mythtv-users at mythtv.org
>> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>
> Thank you for your help with this.  The fix provided does indeed resolve
> this issue.  I will let the engineer at KSTP know what you found, and
> that he should let Harmonic know that encoding video without a timestamp
> is not probably not a good idea.
>
>

They aren't encoding without a timestamp at all. The problem is
related to how they are setting some fields which cause FFmpeg to
invalidate the timestamps. I would suggest just sending them a link to
the ticket at FFmpeg and let the experts do the explaining.

Regards.

--
Taylor