Encoding cast away quality is awful, how to improve

[waldok]

Hi,

I've been trying to backup the DVD cast away and I cannot get satisfactory results. Particularly in the end, when Tom Hanks goes back to his former wife, the walls in the house exhibit macroblocks and artefacts like it was a VCD. I wasted a DVD-R on this since I didn't check these scenes on the "test DVD+RW". After checking, same problems occur.
I used the 10% tweaked 1 pass VBR from Bach (selectrangeevery) to calculate the good Q factor, which always gives great results, but here it is awful. Parameters I finally used in CCE so the movie would fit on one reauthored CD were :
1pass VBR, QFactor=26, Image quality =10, min bitrate 300, max bitrate 9100.

I know increasing Image quality value would help improving results on flat surfaces (lie these damn walls), but I cannot believe there are so many artefacts and I don't want to ruin detailed scenes encoding with a too high value for image quality.

Is this movie known to be hard to encode ? Should I give a shot at 2 (or more) passes with fine tuning (you know, these grey and green areas, Markrb if you read this, you see I was probably wrong in one previous answer to one of your posts, saying you wouldn't notice the difference).

Can anybody who succeeded in getting great quality with this movie (check the scenes I mentioned before) help me on encoding parameters ? My resulting m2v file must not be bigger than 3.6 GB to fit.

Thanks in advance for you help

Waldok:cool:

[Taokane]

Sorry I cant be of more help but it always aids to experiment experiment. Try that second pass, try the standard Q's like 60 and 40 and just for the hell of it try an increased image quality.

[TRILIGHT]

Originally posted by waldok
1pass VBR, QFactor=26, Image quality =10, min bitrate 300, max bitrate 9100.

Woah! Q.Factor of 26 is seriously low! Couple that with only a 1 pass on the VBR and you're definitely in for some crappy quality!

[auenf]

Originally posted by waldok
Particularly in the end, when Tom Hanks goes back to his former wife, the walls in the house exhibit macroblocks and artefacts like it was a VCD.

well, i guess i cant watch it now that someone spoilt the ending :(

Enf...

[waldok]

@auenf,

Damn,

I was so busy about describing which scene caused problem that I didn't notice I was telling the end of the movie.:(

Well, auenf, you know, ehmm.., in fact, it's not true, in the end everybody dies and live happily ever after :D (that's the best I can do, sorry)


@Trilight

Qfactor 26 is the value I got from the Bach "10%-optimized" method, to make the movie fit on one DVD, keeping all extras and menus. As I know you are not a great fan of movie-only backups, you sure will understand I wanted to keep all the menus and stuff :p . Yesterday I reencoded the movie with VAF file creation so tonight I can tweak some local bitrate in the second pass on difficult scenes.
Would you suggest something else ?

Waldok.

[TRILIGHT]

You're having to go awfully low on the movie to fit everything. You've also not mentioned re-encoding your extras. They must be fairly large to force you to such a low bitrate on the movie. I suggest re-encoding the extras first and then moving on to the movie. The process I personally follow is all laid out in Das UberGuide at my site. I would do the same with this particular title.

[Calypso]

Originally posted by TRILIGHT
Woah! Q.Factor of 26 is seriously low! Couple that with only a 1 pass on the VBR and you're definitely in for some crappy quality! Quantization Factor as set for a single VBR is not the same thing as the resultant 'Q' factor. A Quantization factor of 26 is actually pretty good. I routinely encode extras with a Quantization factor of 60, and strive for a Quantization factor of 20 for the main feature. Setting the Quantization factor to 20 generally results in a final encoding with a Q factor of 8 - 8.5. 26 will likely result in an average Q factor of 9-12.

[TRILIGHT]

You're exactly right. In fact, now that I look at what I said again, I cannot for the life of me remember what the hell I was thinking at the time. LOL!! :D Far be it from me not to admit when I had my head straight up my arse on something. hehe ;) I really don't know why I said what I did. Sorry.

[waldok]

Thank you guys for helping out here.

Pleased to read this since that's what I get in the advanced tab in CCE (I mean acceptable resulting Q factor).

That's why I was surprised with the poor quality I got with tihs movie on particular sequence since this Bach method always produced great results. I still have to investigate what the original bitrate is on those sequences compared to the one I got after reencoding. I'll have to play around with local bitrates and also see if increasing "image quality factor" value may help in getting better results on those flat areas that drive me crazy.

Concerning extras, well in fact there are only menus on the disc, since the real extras are on a second disc. I just want to keep the original menus.
So there is no real way for gaining much room on this disc, since I already stripped useless subtitles and audio tracks. The problem is the movie is damn long and apaprently difficult to compress in the end sequences (mid-dark scenes, with lots of panning over big flat areas).

Any particular suggestion always welcome.

Uber-Trilight, hope you managed to get your head out of your arse without too much damage (mind the ears particularly in such cases) :D

Waldok:cool:

[TRILIGHT]

Well, I never really go on one pass VBR only so I don't know precisely what to tell you. I have a hard time accepting it as a method because there just isn't enough information to go on IMO. Now if you were doing multipass VBR, I would suggest the following (some of which you might try anyway)...

1) Make sure your Intra DC precision is set to "auto"
2) Change your Image Quality slider so that it's set to about 20.
3) In the "Advanced" section (multipass only), set the "bias" to around 20-25. You might even try as high as 40 if the ABR was as high as around 3500-4000 or so.

Those are the best suggestions I can give you for affecting the contouring you're seeing in the flat areas.

[waldok]

I just checked bitrates. The original "problematic" scenes are 5.8 MBits/s, and it turns out the reencoded ones are 2.5 Mb/s :eek:

I don't really understand this, since I asked for a min 0 to max 9100 bitrate, Q = 26. So the only thing I can think of is increasing Image quality value since it seems the encoder does not allocate enough bits to these "flat" scenes. I'll have to rip the difficult chapter separately and see what combination of bitrate and Image quality level I must use to get acceptable picture.

I think continuing this thread would be more appropriate to the CCE forum now.

Well, I'm in for some more in depth parameters....

Waldok:cool:

[auenf]

Originally posted by waldok
@auenf,

Damn,

I was so busy about describing which scene caused problem that I didn't notice I was telling the end of the movie.:(

Well, auenf, you know, ehmm.., in fact, it's not true, in the end everybody dies and live happily ever after :D (that's the best I can do, sorry)

i love movies where everyone dies, you better not dissapoint ;)

Enf...

[waldok]

Thanks to all.

Now you can rest a bit and drink a few beers, until I have tried some of the settings you suggested and then I'll come back to you with another bunch of questions.

@auenf : Give me some time to call Hanks and Zemeckis on the phone so they manage to prepare an alternate version of the movie for you : At the very beginning, Tom hanksfalls from the Fedex car because of a bad tied shoe and breaks his neck :D THE END.

Waldok :cool:

[markrb]

Have you tried increasing the local bitrate on these scenes you do not like? I know this goes against the Bach method, but sometimes not all methods work for all videos.
The Getting the best out of CCE guide explains better then I can how to do it.

I am a big fan of Trilight's tricks to reduce the size of the DVD. I have now started to use his blank mpv files for trailers and such to reduce the overall size of the DVD by a bunch. In my last encode I was able to drop the extra's by greater then 70% and still keep the stuff I wanted and the disk structure like the original.

If I may be so bold as to tack on a small request of Trilight. Would it be possible for you to make available the "This selection has been removed from the DVD" bmp as a 16:9 and 4:3 mpv file or make a quick note how to change it to one on your site?
I am using the blank ones now and they are a godsend. Thanks for the tips.

Mark

[waldok]

Yes Mark, I tried increasing the local bitrates in these problematic sections.Oddly enough, CCE showed perfect green areas there, but the bitrate was only about 2Mb/s (original in these scenes was 5.8 Mb/s).
Problem is if I raise the local bitrate there, I'll have to wait for the 8 hours it takes to encode before I can check it had some effects
:(

I don't really understand why CCE shows these areas as green when bitrate is obvisouly not sufficient there to ensure good quality. I thought it was more related to the Image quality settings, but I tried to raise it without better results.

Can any expert out there explain why these difficult scenes come in green for a 2mb/s bitrate when they should be at least 5mb/s to get decent quality ?

Waldok:cool:

[TRILIGHT]

@markrb

Thanks! :) If you go and download the "Selection Removed" zip again, you'll find both 4:3 and 16:9 versions.

@Waldok

The areas being colored green do not necessarily indicate they "look good" but that there is relatively small quantization differences between the I, P, and B frames. Your bitrate and bit allocation at this area is obviously not good enough to produce what you would consider "acceptable" on-screen. You either have to increase the bitrate of this area, or try changing the bias to a higher setting to allocate more bits for "flat" areas. I really don't know what other suggestions to give other than those I've already stated.

[waldok]

TRilight, you already gave a lot of help here. thanks.
(thanks to the others too).

I'll go for the tedious reencoding with local bitrate raised to 5 mb/s.

Waldok:cool:

[auenf]

Originally posted by waldok
Thanks to all.

Now you can rest a bit and drink a few beers, until I have tried some of the settings you suggested and then I'll come back to you with another bunch of questions.

@auenf : Give me some time to call Hanks and Zemeckis on the phone so they manage to prepare an alternate version of the movie for you : At the very beginning, Tom hanksfalls from the Fedex car because of a bad tied shoe and breaks his neck :D THE END.

Waldok :cool:

Bob Zemeckis did that movie?

was the other bob with him (ie BTTF)

Enf...

[waldok]

What's BTTF ?
the only thing I can think of for BTTF is BoB The Turtle Fu**er, but I doubt it is correct.

Waldok:cool:

[auenf]

Back To The Future

and i dont want to know what that turtle guy movie is about ;)

Enf...