AC3 playback problem

[sawm24]

i have just finished my first two DVD projects using AC3 audio which has been converted from WAV using AC3 machine, the main reson for this was to change the FPS for a pal DVD.

The DVD plays fine on my PC but when i put it into my pacific / asda dvd payer the picture is fine but instead of the audio i get i high pitched buzz?

[julitomg]

Does your AC3 audio play OK in your computer?, does your DVD player play correctly other AC3 materials (like commercial DVDs with AC3 audio)?, in its display, does it show it´s reading an AC3(or dolby) track?

[sawm24]

the ac3 file plays back fine in media player and after the DVD has been burned it plays back fine on the pc , it is just in the dvd player that the audio is screwed.

unfortunately i have not payed much attention to the audio content of other dvd's i have played i know this isnt very helpful, the dvd player only has a couple of audio settings on it, one that seems to be sterio / mono and a dolby menu that has a sliding scale of off to full with numerical increments in between.

I have tried messing with all of these options but it hasnt helped.

I have just used "px3 ac3 to wav" to convert my ac3 to wav and i am running the audio and video through TMPG enc again to see how it turns out.

[guns1inger]

It sounds like, for some reason, your player is pushing the AC3 out the anolgue outputs without converting it first.

[redwudz]

AC3 audio can be a problem. Most software encoders don't put out a 100% compliant AC3 stream. I use ffmpeggui most of the time and it works for me.

But a lot depends on your standalone player. Most software players in a computer can accept out of spec audio and not report an error. A standalone might work differently. julitomg has it right, 'does your DVD player play correctly other AC3 materials'? A better software player like PowerDVD that emulates a hardware player would be a better choice for testing. Still not the same as a standalone, but much closer than 'media player'.

You just need to find a combination that works for you and stick with it.

You also mentioned a PAL>NTSC framerate conversion, if I understand correctly. That complicates things, but a compliant AC3 audio file should still work alright. Usually the PAL>NTSC conversion results in sync problems if not done properly.

Try some different programs for the AC3 conversion. If you have too many problems, use MPEG-1 Layer2 audio. It is acceptable in PAL or NTSC with most players and avoids some conversion problems. It will give you a larger audio file, though.

[canadateck]

I've had this problem before with TMPGEnc, did you multiplex with your encoder Tmpgenc? I must say it has nothing to do with being 100% compliant, I bet it has to do with the multiplex and De multiplex of the video files and audio files.

[sawm24]

i just finished the project again using wav instead of AC3 and it played back fine in my hardware DVD player.

The only reason i used AC3 in the first place was that my avi source was xvid 23.976 fps and i wanted to change it to 25fps for a pal dvd.

The simpleist guide i could find for this was http://www.users.bigpond.net.au/sauron/CONVERTING%20PAGE%201.htm which uses AC3 machine to convert the frame rate of the audio so that you keep audio sync. obviously you are left with AC3 audio at the end which the guide says you dont run through TMPG enc, but instead add to the DVD usuing your authoring software (TMPG Autor 1.6 for me)

At least now i know that if i need to do a frame rate conversion again i can convert the AC3 back to wav using px3 ac3 to wav and end up with a disk i can play in my dvd player.