What's MyDVD doing to TMPGEnc'd MPEGs?

[Karl Engel]

I'm trying to determine if MyDVD is re-encoding during authoring MPEGs imported into it encoded with TMPGEnc DVD Source Creator(VBR MPEG-1 Layer II Audio). I was happy to see no "transcoding video" messages for these clips, though there were "transcoding audio" messages for each clip. However the resulting .VOB file for each clip is about 18% larger than the TMPGEnc'd MPEGs. Should a passive (non-encoding) authoring program leave these about the same? Was it perhaps converting the audio back to PCM? A second test with the files converted VBR but with PCM audio, resulted in .VOB files 21% larger than the M2V files TMPGEnc created.

The bitrate of the MPEGs jumps around a lot & v quickly as you'd expect from VBR encoding. I was surprised to see the bitrate of the .VOB files also jumping around, albeit more slowly. But the rate was low in the same places. This surprised me since I thought if MyDVD was re-encoding the clips it would be doing so at it's default "high quality" rate for imported video, which I think is 8000 mbs CBR.

So what do you think is going on here? Basically I'm trying to determine if I can get away with coding with the flexibility of TMPGEnc while authoring with the MyDVD software that came with my burner.

[Craig Tucker]

MYDVD does reencode the audio to PCM, this is obviously not good news as PCM audio takes up a huge amount of space compared to mpeg audio or AC3. I believe the deluxe version of MYDVD will convert to AC3.

My advise would be to dump MYDVD and get a decent authoring software that will accept mpeg and ac3 audio. DVDlab is very good.

[chakrax]

Ditto to what Craig said. The basic MyDVD that comes with burners re-encodes audio to PCM, and video using its own MPEG2 encoder.

I purchased the TMPG DVD Author + TMPGEnc Plus bundle for $99. I'm a happy camper now.

-Chakra.