AVI to DVD. Bitrates?

[martinlest]

I know this is a bit of a stupid question, but just to make sure..

I have three avi files (three acts of an opera) whose bitrates show as being about 2100kbps. When I run these through AVStoDVD, to make a single 4.7GB DVD, the VOBs created are about 2150kbps.

Presumably, if I use a 9GB DVD, when the bitrates then show as around 4200kbps, there will be no advantage. Nothing will improve the quality of the original avi files, at their given bitrate, no?

Thanks,

Martin

[Cornucopia]

99% efficiency of quality kept from fair/mediocre sources isn't going to be any better than the source (fair/mediocre) no matter what bitrate you throw at it. Remember, those "originals" probably aren't really the ORIGINALS. And you can't really gain back what you've lost once you've lost it.

Scott

[martinlest]

Exactly. Just wondered if there might be any 'hidden advantages'. Might as well keep to a 4.7GB DVD - the results are actually pretty good visually.

[jagabo]

No doubt your sources are encoded with Xvid or Divx. Those only require about half the bitrate of MPEG 2 used on DVD. You will get better quality using twice as much bitrate on your DVD.

[martinlest]

I can always try both.. will post back when I have done this,

M

[martinlest]

The bitrates of the VOB files created for a DVD-9 are of course about twice that of the DVD-5, but comparing one with another (played side by side in GOM player on my PC, fame by frame), shows no difference in quality at all as far as I can make out. I guess burning to disc would produce the same results...

M.

[jagabo]

Open your VOB files in an editor and look at enlarged still frames. The differences should be more apparent. Look for blocky artifacts when things are in motion. Also look for loss of small, low contrast, details.

[martinlest]

I'll do that, out of interest, but comparing the results side by side on the TV (I burned equivalent DVD5 & DVD9 VOBS to disc) I could see no difference at all at any of the sample points I tried.

Martin

[jagabo]

I'll do that, out of interest, but comparing the results side by side on the TV (I burned equivalent DVD5 & DVD9 VOBS to disc) I could see no difference at all at any of the sample points I tried.

Martin

One way to compare:
https://forum.videohelp.com/threads/354753-Video-encoding-and-Bitrate-Quality-Newbie-ne...64#post2231764

[martinlest]

Thanks. As soon as I have the time I'll give it a go ...

But I am new to this - the script will work on a vob file, will it? How do I adjust it (I have a common source remember - a single avi file from which I can make either a DVD5 or DVD9 DVD)? Like this, for example (looks odd - it's not an avi source file)?

v1 = AviSource("C:\VTS_01_1.VOB")
v2 = AviSource("D:\VTS_01_1.VOB")
Interleave(v1, v2)

Is it possible to run the avs script via AVStoDVD somehow (Edit Video/AviSynth tab)?

[_MrC_]

@martinlest

you cannot use AVISource for mpeg2 (VOB) streams. You should use DirectShowSource:

v1 = DirectShowSource("C:\VTS_01_1.VOB") 
v2 = DirectShowSource("D:\VTS_01_1.VOB") 
Interleave(v1, v2)

or, even better to be frames accurate, you should index the VOBs: load the VOB with DGIndex and save the d2v file (assuming you have installed AVStoDVD):

LoadPlugin("C:\Program Files\AVStoDVD\DGIndex\DGDecode.dll")
v1 = MPEG2Source("C:\VTS_01_1.d2v")
v2 = MPEG2Source("C:\VTS_01_1.d2v")
Interleave(v1, v2)

Then open the avs script file with VirtualDub.



Bye

[jagabo]

AviSource() is only for AVI files. You'll need a different source filter for VOB. I recommend using DgIndex to build an index file then use Mpeg2Source() to open that index file:

v1 = Mpeg2Source("C:\VTS_01_1.d2v") 
v2 = Mpeg2Source("D:\VTS_01_1.d2v") 
Interleave(v1, v2)

You'll need to copy DgDecode.dll from the DgMpegDec package into AviSynth's plugins folder. Or you can manually import the filter within the script:

LoadPlugin("X:\path\to\DgDecode.dll")
v1 = Mpeg2Source("C:\VTS_01_1.d2v") 
v2 = Mpeg2Source("D:\VTS_01_1.d2v") 
Interleave(v1, v2)

There are other things you may have to worry about, trimming the video if they don't sync exactly, viewing fields of interlaced video separately, etc.

[martinlest]

AviSource() is only for AVI files ... yes, which is why I got stuck. I think that, as it's just an experiment, I'll skip this for now. It'll be time consuming..

You are probably right that there may be a difference, but since I have burned both lower and higher bitrate vobs to DVD and can see absolutely no difference on my TV screen, I might as well stick with what I have.

Thanks a lot for the input. May well have an idle moment over the weekend and try out what you suggest, just out of interest. Will post back if so of course,

Martin

[jagabo]

AviSource() is only for AVI files ... yes, which is why I got stuck. I think that, as it's just an experiment, I'll skip this for now. It'll be time consuming..

Post a few short samples of your two conversion and we'll show you some of the differences. You can use a program like Mpg2Cut2 (free) to mark short sections of your VOB files and turn them into small MPG clips you can post here.

You are probably right that there may be a difference, but since I have burned both lower and higher bitrate vobs to DVD and can see absolutely no difference on my TV screen, I might as well stick with what I have.

Except once you learn what to look for you'll start to notice it. If this video is important to you you'll eventually come to regret not using the higher bitrate.

[martinlest]

I already have one or two VOB cutters installed, so here are two short VOB files of roughly the same scene - I have simply added false file extensions to differentiate them.

Thanks for this...

Martin

[theewizard]

I know this is a bit of a stupid question, but just to make sure..

I have three avi files (three acts of an opera) whose bitrates show as being about 2100kbps. When I run these through AVStoDVD, to make a single 4.7GB DVD, the VOBs created are about 2150kbps.

Presumably, if I use a 9GB DVD, when the bitrates then show as around 4200kbps, there will be no advantage. Nothing will improve the quality of the original avi files, at their given bitrate, no?

Thanks,

Martin

as was stated in previous posts above, for the same quality avi and vob use different bit rates
2100kb bit rate is HIGH for avi, so the quality should be good
to maintain that quality, you need to encode at 5-6000kb for DVD vobs at mpeg2
encoding for size or at 2150 etc what ever, is reducing quality of the vobs

try 6000kb HENC, 2 pass , DVD setting as DVD9, let the output size be what ever it is

i think you will see a difference over your previous attempts

[Cornucopia]

Strange comparison:

Audio bitrate is higher in the Lower example (this confounds the filesize issue)
High clip is ~8 sec long and Low clip is ~23 sec long, and they don't match in time (not able to do simple A/B comparison)
Both say VBR, but only one show max BR (probably due to how the encoder set flags in the header), you'd have to run BRViewer to get an accurate understanding of TRUE average & peak bitrates.

Even with that in mind, I can see a difference. The "low" is more "smeared". Could be darker too, but can't tell if that's because it's at a different time segment.

Neither encode is great (both are blocky), but I'm guessing that's more to do with the fact that the original was probably already very compressed and this is Low-Key (darker ranged) material.

Scott

[jagabo]

Yes, there's something odd going on with those two files. The low bitrate file has an average bitrate of 1475 kbps with a variation of about +/- 150 kbps. The high bitrate file has an average bitrate 8500 kbps with no variation (constant bitrate), not 2x the bitrate of the first as the OP claimed. The high bitrate file has a maximum GOP size of 24, too large for DVD. There is a 220 frame overlap between the two videos. During that overlap the image quality difference between the two is less than I would have expected for MPEG 2 at 1475 and 8500 kbps. If anything the low bitrate file might look a little better! That could be a case of dark, low contrast artifacts in the source being smoothed out by bitrate starvation. I'd like to see some more excerpts. Some bright shots with moderate motion?

I wonder if the high bitrate file was made from the low bitrate file, not the original source?

[martinlest]

Hi...

Both sets of VOBs were made from the original avi files, whose bitrates are only just over 2000kbps, so I don't expect perfection! In any case, I am quite tolerant of a less than blu-ray quality image, so the DVD5 disc I have made is perfectly adequate. Maybe side-by-side, I might notice a small difference, but when I listen to something like this (Wagner opera) my thoughts are not really focussed on the picture quality!

I will archive the avi files on an external drive so can always try again at some stage of course,

Thanks to all for the input,

Martin