File Size vs Disk Space Confusion

[Andrew2006]

This scenario is representative of a number of similar cases I've encountered where mpg file size on HDD bears no relation to space required on DVD.

I have two files from my (PAL) set top box. These are both episodes of the same series. Each has been topped & tailed in VideoRedo and converted from .ts fomat to .mpg format, being output using identical options, resulting in files of approx 1.9GB each.

When I "add" these files to NeroVison 4 one of them says it needs 1.9GB (as I was expecting) and the other says it needs 3.4GB (which is what baffles me). The former gets 100% Smart Encoding and readies in a couple of minutes, the latter gets 0% Smart Encoding and estimates nearly an hour for transcoding.

So far as I am able to tell, both files are identically PAL "compliant" (720x576, 4:3, 8Mbit/s) so, with Smart Encoding enabled, I would expect both to receive minimal treatment.

Thus, my question becomes: How do I track down the cause of the different handling in Nero? Is there more to "compliance" that I have yet identified (yes, I have read What is DVD). Are there tools that specialise in mpg content analysis (I've got DVDPatcher which provided the data above).

I have also looked at DVDStyler, but that doesn't appear to provide any feedback on disc utilisation so I don't know if it is doing anything differently from Nero.

I know that NeroVision is not well thought of on this forum but, apart from this sizing issue, it does what little I require in terms of menus, etc. and does it quickly and simply. I am thus reluctant to shell out another seventy quid on a competitors alternative unless absolutely necessary.

Regards,

[Cornucopia]

What does the newest Gspot say?

Or try MediaInfo, MPEGValidator, Restream, VideoInspector. There are others.

Are the codecs the same? What about the audio? It could be that one is AC3 (compliant) at 192kbps, while one is MP2, DTS, AAC, etc at 192kbps. Nerovision may just throw it's hands up and try to transcode that into AC3, or failing that, PCM. That might explain the "ballooning" of the resultant filesize.

Scott

[Andrew2006]

I'm not sure I understand the significance of this, but...

Video Inspector returns identical results for the two files in every field:
Movie
Valid: Yes (MPEG)
Movie Complete: No
Video
Resolution 720x576(1.25:1)
FPS: 25.00
Bitrate: 7812kbps
Quality Factor: 0.77 b/px
Codec: MPEG 2
Audio
Number of Channels: 2
Sample Rate: 48000Hz
Bitrate 112 kbps
Codec MPEG 1 Layer 2


With GSpot, I haven't had time to work out what all the abbreviations mean (it's past bed-time here in the UK) but both files report:

Container
MPEG-2 Program Stream <<(1 vid, 1 aud) Sys Bitrate 15000kb/s VBR

Audio
MPEG-1 Layer 2
0xC0: 48000Hz 192kb/s total, Stereo

Video (c,S)
Codec: MPEG2_Video
Name: MPEG2
IPBS: 11% 22% 65%
B-B: 4 max
I-I: 9.2 avg / 19 max

Video (d)
Resizing: 1 None, already DVD format
Resizing: 2 None, already DVD format

The only respect in which GSpot reports a variation for the two files is in the Video (f) fields where one reports 2622 kpbs and the other 2820kbps. Curiously, it was the 2622kbps file that ballooned when fed to Nero, whereas the 2820kbps was untouched.

Why these values should be so different from VideoInspector is a question I leave to the experts.

Does any of the above provide any clues? Or simply more evidence in the case against Nero?

Regards,

[redwudz]

I don't really see anything unusual there. If those files are already DVD compliant, you really don't need Nero to do any more than author and burn them, which should only take a short time. Instead, you can just author them with a freeware program like Gui for dvdvauthor or DVDAuthorgui. They can also generate simple menus.

Then you could burn it to DVD with ImgBurn. It can accept VIDEO_TS folders directly without making a ISO. Or if you want to use Nero just to burn use the DVD-Video format and drop the contents of the VIDEO_TS folder in there.

It sounds like Nero is trying to recode the video, which if it is DVD compliant, is just a waste of time and will give you reduced quality. I would try one of those other authoring programs. At least that may show if Nero is the problem or if it's something in the files themselves.

[guns1inger]

As soon as I saw NeroVision the mystery was gone. NeroVision is known to want to re-encode perfectly good video on a whim. As authoring tools go, it is fine, if you also like russian roulette as a sport.

[Andrew2006]

Thanks Gents (though who knows what really lurks behind those avatars),

As soon as I saw NeroVision the mystery was gone.

Not at all, the mystery remains, and possibly deepens. What triggers the "whim"? The first person to identify the cause could win the eternal gratitude of an awful lot of people, and save quite a lot of traffic on this forum. Especially when some coding-guru writes the pre-processor to eliminate it.

As for my own problems, if the files I'm working with are as compliant as they seem, I fear I'll have to bite the bullet and learn another tool. (Just when I was developing a "style" with NeroVision).

PS: Can anyone suggest why I get two, such wildly different, values of bitrate from GSpot and VideoInspector? 7812kbps from one and 2622kbps from the other. Are they in fact reporting different things? if so, what?

[Cornucopia]

If they're VBR streams, maybe one is showing PEAK/MAX bitrate, and the other is showing AVG bitrate?

Scott