Thanks for the quick reply!

My test last night used the standard NTSC DVD template in VV 3.0a. So the source material has the following specs:

Frame Size: 720x480 (NTSC)
Frame Rate: 29.97 frames/second
Video Data Rate: 4.2 Mbps VBR
Audio Settings: Stereo, 48 kHz and 224 kbps MPEG audio

This appears to work correctly in Ulear's DVD Workshop (which appears to use the same encoder as their DVD MovieFactory). My previous test started with the same template (but using VV 3.0), and then set the avg VBR to 2.5 Mbps. With this, I got strange results from DVD Workshop. If I played the DVD from the start, it played fine for the entire video. But if I selected any chapter other than the first, audio would be fine, but video would display only a single still frame continuously (always the same frame from about the 15 minute mark, no matter what chapter I selected). Not sure what caused this.

I then extracted the elementary streams off the DVD I just created, merged them back into a program stream, and brought them into VV to inspect. After the first 15 minutes on the timeline, the frozen frame appears to propagate all the way through the timeline - most of the time. If I zoomed all the way out, I would see correct thumbnails, but if I zoomed in any amount, I would see that one frame propagate through the timeline. In any case, it looks like Ulead's encoder ran into problems when it transcoded the source.



Regarding the MV "video type" setting, I see that setting it to SVCD drops the max and avg vbr bit rates to 2.8Mbps. I still can't see what difference selecting DVD or MPEG-2 makes though. They're both MPEG program streams with the same GOP and IBP structures, both are MP@ML, etc... Should I assume these two settings are identical?

Thanks,
Steve

Just to clear any confusion, the authoring side of Ulead DVD Movie Factory doesn't re-encode MPEG files - it just checks them for compliance.

Without going into too much detail, SVCD and DVD program streams have different pack sizes to suit the CD and DVD file systems they are used on. DVD compliant program streams have certain header information inserted which is optional in plain MPEG-2 program streams.

Tony

Thanks for the DVD PS notes. I've been looking for DVD format information without having to buy the $5000 specification. If anyone knows of an inexpensive reference, please let me know.

BTW, I beleive you are correct regarding Ulead's DVD MovieFactory not re-encoding MPEG files as I could master a DVD fairly quickly with that package. It seems Ulead's DVD Workshop is a bit different in that to build a disk image, you must choose a quality setting (or specify custom parameters) which dictates the stream bit rate of the final video. Then the process of building the disk image starts and takes a very long time.

For example, my video sequence is about 2.5 hours. VV 3.0a render to MPEG-2 (using the NTSC DVD template) takes about 12 hours on a 1.7 GHz P4 w/392 MB RAM. If I bring the resultant MPEG file into DVD MovieFactory, I can build a DVD (with no menus due to a bug handling large files) in about an hour if I remember properly.

On the other hand, if I bring the same MPEG file into DVD Workshop and build a DVD, it takes almost 8 hours where most of the time is "processing" the input file (I suspect the input file is being re-encoded at the bit-rate specified for the build.

The options it actually gives to build a DVD are:

High Quality (8000 Kbps, 60 min per DVD)
Fair Quality (6000 Kbps, 90 min per DVD)
Low Quality (4000 Kbps, 120 min per DVD)
Half-D1 (352 x 480, 2400 Kbps, 4 hr per DVD)
CIF (352 x 240, 1500 Kbps, 6 hr per DVD)
Customize...

Selecting "Customize" allows you to select predefined frame sizes, select variable or constant data rate and its value, and select from predefined audio bit rates.

BTW, I compared VBR to CBR in DVD Worksop and found VBR files to be quite a bit larger than the CBR for the same bps setting. That doesn't sound right.

Anyway, DVD Workshop seems like it is actually re-encoding and not allowing me to bypass that process. If that's the case, I'll have to keep looking for a better mastering package.

Hey SF - wink wink, nudge nudge

Steve

The best DVD reference I've found is the 'DVD Demystified' book (about $50) - http://www.amazon.com/exec/obidos/ASIN/0071350268/qid=1015506735/sr=1-1/ref=sr_1_1/002-9771276-6673643 . It has a huge amount of info and is very readable.

My feelings about DVD Workshop are much the same as yours - nice menu creation tools, but re-encoding the files is a no-no, especially at that price level. I'll stick with DVD Movie Factory for now which I really like.

Tony

Re: re-encoding MPEG source files in Ulead DVD Workshop

I discovered that if you use a 'make disk' template with video/audio bitrates set higher than the source MPEG files it doesn't appear to re-encode them (also assuming frame size, frame rate, audio sampling rates etc are the same in source and disk template).

Note the VBR bitrate value in the DVD WS template is equivalent to the 'max' setting in the VV3 encoder - if you do a 'file properties' in DVD Workshop this is the value it reads from the MPEG file (and presumably the value it compares against the template settings to decide if it needs to re-encode it).

Tony

Thanks for the tip oon using a higher bit rate than the source. I'll try that out tonight.

Recently, I re-rendered my source at a higher bit rate and then use it in DVD WS. The behavior I am now getting is that audio and video are out of sync on the final DVD by about 2-3 seconds. If I look in the temp directories, I can see a re-encoded MPEG-2 program stream file. When I play this, there are no sync problems, but if I play from the DVD image (VIDEO_TS directory), audio is out of sync there just as on the DVD.

From this, I assume the VOB video/audio multiplexing is running into problems. It seems odd that as I vary the source material bit rate, I get substantially different issues with the final DVD output. More testing this weekend...

Steve