Transcoding vs Re-Encoding DVD Mpegs

[akrako1]

Here's the situation...

I'm recording concerts I've filmed on my DVR-320. I'm concerned about audio quality, so I need PCM sound. The recorder will only record in PCM at the highest quality level, 9000 kb/s. I'm putting the DVD-RW's into my PC and extracting the mpegs. Here's the problem, I'd like to get around an hour and a half to 2 hours on each disc - so I need to decrease the video bitrate somehow. Here are my 2 options as I see them. Use TMPGEnc and re-encode the MPG's at a lower bitrate, approx 4-5000 kb/s - this will take a bunch of time that I'm hoping to avoid. My other option is to author using either Ulead DVD Moviefactory 3.0 or TMPGEnc DVD author (I have both). I'd author at current quality, resulting in a too large DVD folder. Then I could transcode using DVD Shrink, and reduce the size to regular DVD5 size. Would this kill the quality too much? How about if I only reduced the video by 75% or so? I know generally re-encoding give better results, but I need to balance time and quality somewhat - but I don't want to compromise the picture much either.
Thanks.

[lordsmurf]

- this will take a bunch of time that I'm hoping to avoid.

If you want to retain high quality video, this is essential. I would not skip this step. Just deal with it taking a while

Then I could transcode using DVD Shrink, and reduce the size to regular DVD5 size. Would this kill the quality too much?

Very likely cause blocking or other issues. Homegrown material generally does not have enough overhead to do this.


Try it and see.

To be honest, what's wrong with 256-384k AC3 audio?
PCM won't make anything better.

[gshelley61]

I agree with LS. Based on the source material, I don't believe in a blind listening comparison that you would be able to tell the difference between 2-channel AC3 and PCM. Why waste disc space with PCM audio?

[akrako1]

alright, I'm going to give it a shot with reencoding with ac3 audio. I'm just always nervous to use compression of any kind with audio - especially when working with live recordings. How much of an improvement is ac3 at 384k over mp2 at the same bitrate?

[gshelley61]

AC3 is an official audio format of the DVD-Video standard, MP2 is not (although most DVD players will decode MP2 anyway). I don't know that there is any quality difference between AC3 and MP2.