[mythtv] Need help regarding AvFormatDecoder
mark.buechler at gmail.com
Mon Oct 30 19:00:42 UTC 2006
Daniel, I think I understand what you mean by making the PID description
more specific and from what I can see that's done by mpegts_parse_desc in
libavcodec. However, this particular PID does not have a descriptor tag and
I know of no way (yet) of automatically determing what type of data lies
within this PID.
I do know, however, that my provider uses MHP and I suspect that somehow
that ties into it but I could be wrong.
On 10/30/06, Mark Buechler <mark.buechler at gmail.com> wrote:
> Please see below..
> On 10/26/06, Daniel Kristjansson <danielk at cuymedia.net> wrote:
> > On Thu, 2006-10-26 at 15:07 -0400, Mark Buechler wrote:
> > > Thanks for replying Daniel. My DVB provider has audio-only channels
> > > which have Artist/Album/Title information in plain text on a PID which
> > > I am now recording. I've modified dvbrecorder.cpp to record the PID
> > > and have verified it exists from the frontend. I need an entry point
> > > in avformatdecoder where I can parse the PID and send it off to the
> > > display in a simular manner as mythnotify. If you notice in the patch
> > > below the commented out lines in GetFrame I'm looking at the PID type
> > > for every call. So far I've only been able to see auto & video PIDs.
> > Does your provider identify this PID somehow in the PMT or other table?
> > We don't want to hard code this type of functionality.
> They put it in the PMT and Myth passes the PMT off to the frontend with
> all three PIDs (audio/video/privsec) even though the pirvsec PID isn't being
> recorded. I thought I'd make it generic and activated by a setting on the
> backend for "Dishnet Radio/Text Information" or something simular.
> > Here's the patch I'm using:
> > > + CODEC_ID_PRIVSEC= 0x18000,
> > <snip>
> > Ok, so this will let you pass the data along as a stream, like we
> > do the DVB subtitles. This is a viable option, but you might just
> > want to decode these strings in avformat and stick them in the context.
> > If you do want to pass the stream to avformatdecoder, you should
> > name it something other than PRIVSEC. Perhaps DVB_AUDIO_INFO?
> I started going the avformat route but my fear is that recording privsec
> is too much a generic thing for avformat. It really should be contained
> within Myth. What do you think?
> > + case CODEC_ID_PRIVSEC: return "PRIVSEC";
> > > + case CODEC_TYPE_PRIVSEC: return "PrivSec";
> > Same as above. If you are going to pass this stream to avformatdecoder,
> > name it something better.
> > > @@ -857,6 +857,7 @@ static int is_desired_stream(int stream_
> > > case STREAM_TYPE_AUDIO_AAC:
> > > case STREAM_TYPE_AUDIO_AC3:
> > > case STREAM_TYPE_AUDIO_DTS:
> > > + case STREAM_TYPE_PRIVATE_SECTION:
> > This is no good, you need something more to identify the stream.
> > All kinds of data gets passed in private sections. We ran into
> > a problem with this when we first added DVB Subtitles and again
> > when we first added MHEG decoding.
> My thought was to name it generic until avformatdecoder and somehow either
> determine from settings or from the stream what type it is and run the
> appropriate decoder on it. As far as avformat, shouldn't this be as generic
> as possible? We're just labling the PID at this point since I'm not planning
> on decoding the stream until it hits avformatdecoder.
> > I don't see why this is failing. It looks like you basically looked
> > at the DVB_SUBTITLE code for inspiration here, that should work.
> > You might want to look at the DVB_VBI code as well, it's a little
> > different in how the streams are added and might help. But I do
> > think you should think about just placing this info in the context,
> > look at how the program name is extracted from the SDT for an example.
> > (We don't use the SDT code in MythTV, but it should still be there
> > and is still used in the pure ffmpeg mpegts.c code.)
> I'll take another look. It's odd how I can see the stream within
> ScanStreams() but not within GetFrame(). I assumed there was some structure
> I was missing.
> -- Daniel
> Thanks for your help, Mark.
> > mythtv-dev mailing list
> > mythtv-dev at mythtv.org
> > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev
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