5.1 AC3 and DTS in Adobe Premier Pro

[zerohash]

Dear Friends,
We are doing DVD Authoring. We get DigiBeta tapes and 5.1 WAV sound or ProTools session on a DVD. We convert Video from Pal to NTSC but the Audio remains Pal on DVD(25 Frames).

Now we want to match that Audio with Video. I will have to convert Audio from 25 to 29 frames matching Video.After converting the Audio i will sinc the Audio with the Video. As all done i want the Audio in AC3 Format and DTS Format to incorporate with Video in my DVD Authoring Station. I am using Adobe Premier Pro for Audio.

Please help and advice as how do i do this in my premier.

Thanks.
Zerohash.

[tinker]

If you have AC3 or DTS audio on your PAL video just demax it from the file. Convert your PAL to NTSC and in DVD authoring tool import back your demuxed AC3 file. Everything should be OK unless you edited video file, like cutting parts out, after demuxing audio. Do not worry about 25-29 conversion, because length of the video file (in minutes) remains same after PAL to NTSC conversion.

[guns1inger]

because length of the video file (in minutes) remains same after PAL to NTSC conversion

If the framerate is changed, the running time will change, and you will get sync issues.

You have two choices

1. Resize the video to NTSC full D1 (720 x 480), encode @ 25 fps, then use DGPulldown to add pulldown flags to get 29.970 fps playback. While this will play in most players, it is not strictly by the book, and may give you issues in some circumstances. However it does have the advantage of not altering the running time because the base framerate remains 25 fps, and you will not get audio sync problems.

or

2. Demux your audio back 6 mono wav files, adjust the length to match the new running time, re-encode, then author. Audio does not have frames, it has length. You just need to alter the length using something like sound forge or audition so that the pitch doesn't alter.

I don't believe you can do any of this nicely in Premiere, except, perhaps, re-encoding the video.

[tinker]

Your choice #1, that what I do to convert.
I still do not get why running time should change from 25-29 since we are talking about frames per second, so 10 min movie will be 600 seconds no matter what.

[guns1inger]

No, it won't. A 10 minute movie at 25 fps is 15000 frames. If you play this back at 29.97 fps (which is what a standard conversion out of Premiere would do), you get a running time of 8.34 second, and audio sync problems.

However, if you encode at 25 fps, you maintain the original running time. You then use pulldown flags to tell the player to insert new frames on the fly to reach the playback rate required for the NTSC format.

You can achieve the same thing through software by inserting blended frames, however the quality is much lower than if you let the hardware do all the work. There is also an added bonus of having less frames, and therefore room for a higher bitrate and better quality.

[tinker]

Thanks guns1inger.
I was under impression that once the software does the conversion it does pulldown automatically.
I do this in TMPGEnc, but as you say, doing it by your first choice, results in better video.

[guns1inger]

Encoders will automatically apply 2:3/3:2 pulldown for NTSC 23.976 encoding, as this is required for DVD authoring. They don't do it for format conversion, as it is a bit of a kludge, rather than normal practice.