Auto-GK file output, low quality despite large size

[Fallout1]

I'm having some trouble encoding a larger .vob file and maintaining a decent amount of quality, despite success with several other backups.

The file is about 2.5 hours long (yes, I know this is a challenge). I'm choosing a file size of 2CDs (1399mb), Audio 128kbps VBR and auto-width dimensions. The default source size is 720x480 and yet I'm getting results of liess than 50% quality of original and widths of 300 or less. I've seen many shorter tracks encoded at higher quality at far less file sizes..Even a 1.5 hr movie with a size of 1GB ends up looking really poor with <50% quality. I've tried browsing all the how-to guides on AutoGK without much luck. I've seen some stuff regarding fixed width, min. width,etc but my experiments are consistently turning up rather poor..

Any advice? Auto-width usually a reliable setting? Is this simply too big to encode without an enormous size? What am I doing wrong here? I dont need a 1:1 rip, just something watchable would be nice.

Thanks

[zoobie]

this is just wrong on so many levels...

[manono]

Is this simply too big to encode without an enormous size? What am I doing wrong here?

The original size and even the length isn't really the issue. Apparently this movie is hard as heck to compress. The only solution is to increase the final file size, maybe to 3 CD, or to 2000 MB. You might post the log so we can have a look at what AutoGK is doing.

Auto-width usually a reliable setting?

Yes, it'll adjust the width down until it gets a result of 65-75%. Of course, although the final quality percentage might be good, with a resolution that low the movie itself won't look any good when full screened.

[jagabo]

Is the picture very noisey? Like a VHS tape? Does it flicker a lot (bad film transfer)? Does it bounce up and down a lot (also a bad file transfer)? All those things will increase the required bitrate.

[Fallout1]

this is just wrong on so many levels...

Wow, thanks for the empathetic reply to a question in a newbie forum.

I'll remember how helpful you were.

[Fallout1]

Is the picture very noisey? Like a VHS tape? Does it flicker a lot (bad film transfer)? Does it bounce up and down a lot (also a bad file transfer)? All those things will increase the required bitrate.

No, it seems to be a pretty quality original source, standard film backup.

[jagabo]

One thing to keep in mind is that AutoGK samples several small sections throughout the movie to determine what will work best. It's unlikely, but possible, that it happened to pick parts that weren't representative of the entire movie and made the wrong decisions.

[manono]

No, it seems to be a pretty quality original source, standard film backup.

Still, for whatever reason it seems to be very hard to compress. To know more, though, post the log, as already requested. And a small and typical sample of the source might be helpful as well. Open a VOB in DGIndex, use the [ and ] buttons to isolate a small 10 second section. Then File->Save Project and Demux Video. Upload the resulting M2V to a 3rd party file sharing site, one like MediaFire.

It's unlikely, but possible, that it happened to pick parts that weren't representative of the entire movie and made the wrong decisions.

Very unlikely, as it samples 5% of the source, 20 frames in every 200, using AviSynth's SelectRangeEvery command. While the percentages change a bit from the compression test to the final encode, because of small compress test errors and because of using a different final resolution than the one used for the test, the tests are surprisingly accurate in predicting the final quality and ordinarily don't vary by more than 5% or so.

[jagabo]

it samples 5% of the source, 20 frames in every 200

Isn't that 10 percent?

[Relayerman]

If your source is a backup of a DVD and it was compressed from a DVD9 to DVD5 then the quality will suffer in AutoGK. I have done several DVD VOBs (original discs) with movies of 2-3 hrs and have had great success every time. MY rule of thumb is to use the size of 2000 for 3hr movies and up, 1500 for 2.5 hr movies, and 1/4 DVD for all others. I also select Auto-size and every time it comes out 720x480 for my NTSC VOBs.

[manono]

it samples 5% of the source, 20 frames in every 200

Isn't that 10 percent?

You know, about 5 minutes ago it suddenly popped into my head for some reason that I had given the wrong figures and raced here hoping to edit it before you saw it, knowing that it was already much too late. Yes, I meant to say 20 in 400 frames. But I was even wrong about that, as it's really 15 in 300 frames (I just checked a log). Then the first one in each 15 is dropped, because all the I-Frames generated would skew the results. This was all worked out years ago.

I also select Auto-size and every time it comes out 720x480 for my NTSC VOBs.

Do you mean to say Auto-Width? In any event if, as you say, you're getting back 720x480 every time, then you're not using Auto-Width, and are, in fact, disabling any cropping and resizing at all in the Hidden Options, perhaps combined with setting a width of 720. And to make them play at the correct aspect ratio, if you do that you'll also have to set a PAR later on in an outside app. Either that or have your software player resize it at playback time. Are you sure that every AVI you make in AutoGK is 720x480?