On Tue, 21 Dec 2004 05:12 pm, you wrote: > Mark Anderson wrote: > > Big DVB 3.2 > > It rocks.. doesn't it... :)
It's getting pretty good, once I get ac3 working then it might time start thinking about getting the program guide integrated. > >On my system it was not going into the do_ac3_passthru block becuase > >autoSelectTrack was selecting non ac3 tracks for audio. I would also get > >errors in the UI referring to incorrect number of audio channels when it > >tries to configure the alsa device. This I believe was caused by the code > >trying to configure the ALSA:spdif device with 5,7 or even 8 audio > > channels, i.e it was not selecting the ac3 track. This is what my patch > > for autoSelectAudioTrack solved for me. I am not sure if the patch was > > the right thing to do but it certainly allowed do_ac3_passthru to become > > enabled correclty, and for it to be disabled when no ac3 stream existed. > > Not sure if the mpeg.c patch would have fixed this? > > Not sure, mpeg.c is just a hack that "preserves" the startcode at 0x1bd > for a private stream, and set codec_id to CODEC_ID_AC3 when it sees a > startcode of 0x1bd. (would be nicer if I can actually get the 0x80 part > to work). Juha is also looking into this issue.. It could be a DVB only > problem as Taylor says he got AC3 sounds from his HDTV (and so do many > other pple).... I applied the mpeg.c patch and it definitely imporved things, it now reliably finds the AC3 stream when it is available, I get logs like this with AC3 2004-12-21 17:55:36.586 SIParser: AC3 Descriptor 2004-12-21 17:55:36.586 DVB#1 AutoPID selecting PID 514, Video 2004-12-21 17:55:36.587 DVB#1 AutoPID selecting PID 672, AC3 2004-12-21 17:55:36.587 DVB#1 AutoPID Complete - PAT/PMT Loaded for service 2004-12-21 17:55:36.587 DVB#1 Service is FTA 2004-12-21 17:55:36.588 DVB#1 Successfully tuned to channel 1592. 2004-12-21 17:55:36.590 DVB#1 Data read from DMX - This is for debugging with transform.c AC3 Audio: BRate: 256 kb/s Freq: 44100 Hz Framesize 1024 Videostream: ASPECT: 16:9 Size = 1440x1088 FRate: 25 fps BRate: 12.80 Mbit/s 2004-12-21 17:55:38.665 SIParser: SI Standard Detected: DVB and like this with no AC3, note that there is no AC3 pid so it falls back to pcm audio. 2004-12-21 17:56:05.436 DVB#1 AutoPID selecting PID 770, PCM 2004-12-21 17:56:05.436 DVB#1 AutoPID selecting PID 772, Teletext 2004-12-21 17:56:05.436 DVB#1 AutoPID selecting PID 769, Video 2004-12-21 17:56:05.436 DVB#1 AutoPID Complete - PAT/PMT Loaded for service 2004-12-21 17:56:05.436 DVB#1 Service is FTA 2004-12-21 17:56:05.437 DVB#1 Successfully tuned to channel 1330. 2004-12-21 17:56:05.439 DVB#1 Data read from DMX - This is for debugging with transform.c Audiostream: Layer: 2Videostream: ASPECT: 16:9 Size = 720x576 FRate: 25 fps BRate: 15.00 Mbit/s 2004-12-21 17:56:07.133 SIParser: SI Standard Detected: DVB 2004-12-21 17:56:07.133 SIParser: SDT: sid=1328 type=1 name=7 Digital 2004-12-21 17:56:07.133 SIParser: SDT: sid=1332 type=1 name=7 HD Digital 2004-12-21 17:56:07.141 SIParser: SDT: sid=1329 type=1 name=7 Digital 1 2004-12-21 17:56:07.141 SIParser: SDT: sid=1330 type=1 name=7 Digital 2 2004-12-21 17:56:07.141 SIParser: SDT: sid=1331 type=1 name=7 Digital 3 2004-12-21 17:56:07.141 SIParser: SDT: sid=1334 type=1 name=7 Guide However, there is still no audio when I select a channel sending AC3, I only get audio when no AC3 is being sent. The front end is complaining about "2004-12-21 18:00:20.230 No codec for stream index 2" so I will now have to start tracning that code. I think it is getting much closer though. > If you still have problems with ac3 passthru, check out what > EncodeAC3Frame is actually doing.. Does it encode the data in another > AC3 frame? What are the parameters that's passed in.. Is this the > function that actually sends something to the external decoder? I'm > just speculating here. > > I assume you had already confirmed AC3 passthru to be working by using > other softwares like mplayer, etc? Works fine with dobly-city through mplayer > >If I trace through the code in transform.c it doesn't seems to be reliably > >finding the AC3 frame. I only occasionaly see the "AC3 Audio..." line in > > the backend trace, and often it only apears when I stop watching TV, > > which is a bit late! Occasionally a frame passes through all the tests > > and gets written to the sound card which is when I hear brief noises come > > from the decoder. > > Hmmm. different behaviour here.. When I switch to a HDTV channel, > mythbackends always says it's AC3. if I switch to SDTV channel, backend > says it's either Layer 1 or Layer 2, yadda yadda. > > What card, kernel and version of ALSA r u using? Me using Twinhan DVB-T > and 2.6.9, with ALSA 1.0.7. Dual Avermedia 771, alsa 1.0.7, FC3 with 2.6.5-1 kernel > I can't watch HDTV properly, there are artefacts and jitters in it.. > Processor too slow (I am using Intel 2.6Ghz)? Or is it a bug (introduced > by my mpeg.c hack perhaps?). my CPU usage is 30% when watching HDTV with > bob, and 20% with xmvc and bob. I'm not gonna bother until I get a display that can do HD, although I do get similar symptons, maybe we need an option to disable the HD stations for poor people like me without plasmas :-) > Would have used xvmc and bob, but OSD flickers horribly... So I'm now > back to SDTV. Do you know how do I switch the audio from mpeg to ac3 in > SDTV? The changes I made to autoSelectTrack will make it choose ac3 if it is available, and PCM when it it not. > Hope you can get ac3 working soon.. Share in this list what you did... So do I, except once I get this going I have to get my dads box running with software ac3 decode, but that's another story... Mark > Regards. ------------------------------------------------------- _______________________________________________ mythtv-dev mailing list [EMAIL PROTECTED] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev
