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Two audio tracks

 
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Joined: 02 May 2004
Posts: 45

PostPosted: Sun 13 Mar 2005, 19:47    Post subject: Two audio tracks Reply with quote

How can I create a DVD with two audio tracks, like the way you can pick from various audio selections on commercial DVDs? I am creating a music DVD, and I have one audio track that is untouched and the other has been refined in an audio editing program. They are both stereo tracks in LPCM 48kHz.

I use TMPGEnc software exclusively, so I have DVD Author. Any help appreciated.
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RMN
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Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Mon 14 Mar 2005, 1:13    Post subject: Reply with quote

I think TMPGEnc DVD Author doesn't have support for multiple audio tracks. I think it has an option for "multilingual" or "bilingual" audio (or something like that). Try enabling it and see if it lets you load two separate audio tracks, or if it simply assigns different languages to the left and right channels of a stereo track.

Most professional and semi-professional DVD authoring software (DVD Maestro, DVD Studio Pro, Encore, etc.), lets you include up to 8 audio tracks in each movie (typically the interface looks like a timeline, with multiple audio tracks, that you can switch between on the player).

RMN
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Joined: 02 May 2004
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PostPosted: Mon 14 Mar 2005, 1:39    Post subject: Reply with quote

I did some searching around the net and found a suggestion to use IfoEdit, though I didn't read it in-depth enough to talk about it here. Also DVD Lab.

The Bilingual setting in DVD Author seems to effect how the left and right channels are assigned. No help there.

While I'm at it, an encoding question. I noticed when I use your Calculator that when I change the setting from 1 audio channel to 2, the encode rate given for the video drops. What's the deal, are both audio channels tied into the encode rate total (never exceed 9.8Mb, etc) even though only one audio track is being used at a given time? If so, that sucks. Also I noticed that for two or more audio tracks it always gives a CBR setting. Does that mean you cannot use VBR when using more than one audio track?
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RMN
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Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Mon 14 Mar 2005, 7:29    Post subject: Reply with quote

You can use VBR, but if the maximum VBR bitrate would be equal to the average, the calculator suggests CBR (no point in wasting time during encoding if the end quality would be exactly the same). If you use compressed audio and there's enough room to make good use of VBR, the calculator will suggest VBR.

And yes, the total bitrate (including all audio tracks) must be under 9800. This is probably due to physical limitations of set-top players (since all the channels are multiplexed in the same file, the drive needs to be fast enough to read all of them, even if only one is actually being played). The original DVD standard was based on very basic drives and decoders.

I suspect any player that supports multi-angle would have no problems reading all audio tracks and skipping the ones not being used, which is basically what they do with the extra video angles (although video is neatly organised into GOPs; the audio isn't as easy to chew).

Anyway, as far as I can tell (from the documents included with professional authoring systems), that's the spec, and most software will reject your files if the total (video + all audio) goes above 9800 or if (in multi-angle segments), any individual video track + all audio goes above 8000. So, even if some players could theoretically handle it, the authoring programs won't let you do it.

The difference between single-angle and multi-angle limits is probably due to extra control information (the actual limit for a DVD stream is not 9800 Kb/s, it's 10080, but those extra 280 kb/s are reserved for control information; on multi-angle DVDs they probably need some extra padding to make it easier to skip unwanted angle packets, so the limit for actual video data is lower).

RMN
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Joined: 02 May 2004
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PostPosted: Tue 15 Mar 2005, 0:19    Post subject: Reply with quote

Well, that sucks considering I am using 48kHz PCM audio. Two audio tracks alone is 1536x2= 3072! Bleh.
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