> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > On Behalf Of Tim Davies > Sent: Tuesday, January 25, 2005 12:39 AM > To: Development of mythtv > Subject: Re: [mythtv] DVB Changes / Patch Applied > > As far as I can see, this patch (oz-ac3.diff) does at least four things: > > > 1) wantac3 setting in the setup > > 2) make the PS autopid use <1> > > 3) make AvFormatDecoder::autoSelectAudioTrack use <1> > > 4) deal with codec changes (?) > > > > <1> & <2> looks conceptually good to me although I'd implement it > > slightly differently, partly because I'm planning on removing the > > preferredFooStream hack completely and move that logic into > > dvbrecorder. I'd also call it "ac3wanted" or something to make it sort > > together with "ac3passthrough". I also have an idea for the > > dvbrecorder which, if it works, will make it possible to record > > multiple audio streams with PS recording too and then we won't need > > <2> any more. I think this would also eliminate parts of the tracksel > > patch. Once Taylor gets things going with the followup patch I'll try > > and sort this part out... > > > > I haven't looked that much at the rest of the patches (ffmpeg and the > > avformatdecoder is pretty much new territory to me) but you've seen > > what Isaac said. I think it would help if you could identify more > > clearly exactly what the problems are and how to fix them. And trim it > > down and split it up in distinct parts. Maybe some more comments? I'd > > like to help but I don't understand the patch yet and my time is a bit > > limited. :( > > I guess 1,2,3 are all to do with getting the preferred track into the > recording and then chosen for playback. It is quite common here to have > both an MPEG2 and AC3 audio track in a service. The ideal solution (for > me) is for both the PS and TS to record both audio tracks, and then one > is auto selected on playback but can be overridden by the user. I'm sure > some would disagree though :-p. > > Part 4 is the important bit. It reinits the audio if it detects a codec > change, as well as (what it did previously) detect the change in sample > rate and/or the number of channels. > > There were a couple of extra bits as well, like not aborting when a > decoder wasn't found. I'm not sure whether Mark did this just while > testing, but I know from experience that the frontend would crash if it > did abort. If you have multiple tracks, you'd really want to see if you > can decode the another one before giving up entirely. > > Does anyone else out there have multiple audio tracks? I would have > thought this kind of thing would be a necessity... > > I'm also a bit reluctant to do too much; this is Mark's baby - I'm just > pushing it along... > I'm glad to see the DVB patch into CVS, great work to all involved and thank you. I will take Tim's version of the patches to CVS and apply them tomorrow, get everything up and running and then start thinking about how to get the AC3 into CVS. Since it is a lot of different fixes, maybe lot of different patches is the way to go. A number of the changes are discrete fixes in their own right and so can be applied independently of the whole. From memory they include:
1. Fix for a crash in avformatdecoder when an unknown audio codec is encountered. 2. Auto selection of AC3 tracks when they are available, including the option to disable AC3 all together (in case you have no AC3 decoder). 3. Fix for transform.c to correctly transform the AC3 audio (include the full private stream header and fix problem with AC3 header detection). 4. Hack for mpeg.c to re-use the one audio track. This needs the PS multi track recording enhancement. 5. Change to mpeg.c to notify avaformatdecoder of a change to the audio tracks via a callback function (the call back was already there just wasn't getting called in the right spot) 6. Enhance avformatdecoder to re-initalise the audio when a change in codec is encountered. ??Did I miss anything?? With all of the above applied AC3 audio will work, at least here in OZ and probably in Europe. The biggest problem at the moment is sorting out the mpeg.c hack to only record a single audio track. Having the PS recording record all audio tracks is the right answer here, I am happy to code it if someone can point me in the right direction. BTW I noticed channel 7 are going to play the IMAX movies in HD and Surround Sound over the coming weeks, should be an interesting test for myth DVB and AC3 (if they use it?) Cheers, Mark Anderson > > Tim. > > > _______________________________________________ > mythtv-dev mailing list > [email protected] > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev
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