Where to insert the end credits?

[rlin]

Hi


I am unable to find out where to "insert" the end credits key-frame in Xvid 1.0 RC4. Is it somewhere in the zone options? Tried to search this forum for an answer but couldn´t find a useful thread.

[Teegedeck]

Hi rlin,

it's in the 'zone options'. Check 'begin zone with a keyframe' for the credits' zone.

[rlin]

Originally posted by Teegedeck
Hi rlin,

it's in the 'zone options'. Check 'begin zone with a keyframe' for the credits' zone.

Ok, tnx. Is there a "recomended" setting for "weight"? Is it a good idea to check "greyscale encoding" if the end credits, for example are white text on black background?

[Teegedeck]

Using 'weight' is a bit unpredictable (quality/filesize ratio) because it is relative to the bitrate used in 2nd pass. Better use a fixed quant for credits in both passes. Quant=20 seems alright as for the quality, I believe; it leaves enough headroom for b-frames at 1.5 ratio + offset. Credits should come out something around 10 MBs. With quant=32 you could perhaps get them down to 6 MBs but I don't know if its worth it.

Don't forget to choose a higher B-frame sensibility for credits.

As for greyscale, theoretically; yes. But make sure that there really isn't a coloured logo or something at the end that you might want to keep that way.

[rlin]

Originally posted by Teegedeck
Using 'weight' is a bit unpredictable (quality/filesize ratio) because it is relative to the bitrate used in 2nd pass. Better use a fixed quant for credits in both passes. Quant=20 seems alright as for the quality, I believe; it leaves enough headroom for b-frames at 1.5 ratio + offset. Credits should come out something around 10 MBs. With quant=32 you could perhaps get them down to 6 MBs but I don't know if its worth it.

Don't forget to choose a higher B-frame sensibility for credits.

As for greyscale, theoretically; yes. But make sure that there really isn't a coloured logo or something at the end that you might want to keep that way.

Thanks for your help. I think i get it, but i got one more question. Is it enough to "insert" the keyfram for the end credits in the "second pass" options? Or should i set the zone options exactly the same for both passes?

I mean... how will the encoder be able to calculate the target size if i dont enter the "end credits" in the first pass also? Stupid question maybe? :/

[Pen-Pen]

I never insert KF at the beginning of credits... I once did, but then I gave myself a little thinking and came up with THIS conclusion :

since I ususally encode my movies with Q2 and my credits with Q20, the last frame before the credits begin is Q2 (or Q4 if it's a b-f)

that means, if the credits' first frame isn't made a KF by XViD IPB engine, it would anyway refer to a Q2 or Q4 frame... and which is better ? referring to a Q2 P-F/I-F (or a Q4 B-F), or a Q20 I-F... not sure, but I think that's pretty much the same

am I wrong ? :confused:

[_rEuTeL_]

I don't use a forced keyframe either
just set the quality to ~0.2 and you're fine

usually I use black and white for the credits too

[rlin]

Oh no! Now my end credits are encoded in a lower bitrate, but the file is undersized? I use quant 20 as recomended by Teegedeck, and i also check greyscale and keyframe.

Yes, qpel is turned on...

What are we gonna do now! Game over man! Game over man!

:scared:

[Teegedeck]

Rejoice; at least this is not caused by the credits... ;) The size of the credits is absolutely calculable (same size in both passes). Do a search on 'undersized'.

[Arska]

Teegedeck,

the xvid 1.0 guide on doom9 says this:"However, you might want to use a fixed quantizer in the range of 20 for now as the weight option seems to be bugged."

Does this mean something worse than that the calculations for credits with weight 0.25 (for example) might be quite complicated and the results unpredictable unless you know exactly what you're doing?

I've been using koepi's 24062003 build so far and been very happy with setting a 25-30% bitrate for credits, so is this still functionally the same as before? It's very useful if you just change resolution slightly after 1st pass, since filesize predictability stayed right on the money.

[bond]

Originally posted by Teegedeck
Don't forget to choose a higher B-frame sensibility for credits.does anyone already made some tests, which sensitivity setting would be suitable for normal scrolling credits?

Originally posted by rlin
Oh no! Now my end credits are encoded in a lower bitrate, but the file is undersized? I use quant 20 as recomended by Teegedeck, and i also check greyscale and keyframe.any news already what was causing this?
anyone else (not) having problems with the filesize when using fixed quant 20 with xvid 1.0?

[tedgo]

If I use quant = 20 or weight < 0.20 for the credits my files always got undersized, but if I use weight >= 0.20 my files are always well sized. Maybe caused by too high compressed B-Frames, when set the weight too low (or the quant too high)?
But these results were made with the RC4-Build, i hadn't the time to test the 1.0-Final since its release...

[bond]

hm this doesnt sound good :eek:

[sysKin]

Yes, I would never recommend using weight below 0.2 - in general XviD does not work at such bitrates, filesize prediction stops working.

And I do recommend weight over fixed quant - 2nd pass assumes that the size of fixed quant zone will match exactly, what does not have to happen all the time - certain settings (qpel, gmc) will activate with a delay on 1st pass (will activate on nearest keyframe. They have to activate as they are disabled in fast 1st pass) and that will change 1st pass' size of the whole zone (a bit).

Plus, weight zones give much faster 1st pass ;)

Good luck,
Radek

[bond]

And I do recommend weight over fixed quant - 2nd pass assumes that the size of fixed quant zone will match exactly, what does not have to happen all the time - certain settings (qpel, gmc) will activate with a delay on 1st pass (will activate on nearest keyframe. They have to activate as they are disabled in fast 1st pass) and that will change 1st pass' size of the whole zone (a bit). so thats the reason for the undersizing some people got i assume?

Yes, I would never recommend using weight below 0.2 - in general XviD does not work at such bitrates, filesize prediction stops working. i did some testing with weight = 0.2 and quant = 20 and noticed that weight 0.2 gave much better quality than q20, therefore i think it doesnt compress the credits that strongly :confused:
(i tested it on normal movies scenes not credits)

[crusty]

does anyone already made some tests, which sensitivity setting would be suitable for normal scrolling credits?
From RC3 and RC4 I found that setting these very high works great.
The biggest effect on size/quality is Qpel. It can cut your size down by as much as one 1/3 for vertically scrolling credits.

My process of encoing the credits is really simple:
1 - Use heavy avisynth filtering, especially filtering that stabilizes the picture
2 - encode either in greyscale (either in XviD or in avisynth) or in lowered color intensity (avisynth option). Unless of course there's a colored background.
3 - Encode with lots of B-frames (2-4) and high sensitivity settings to a fixed filesize.
4 - Look at the file
5 - If it's not good enough return to step 3 and increase filesize. If it's good return to step 3 and decrease filesize. If size/quality is good enough for end credits to my taste goto step 6
6 - Done. Credits are ready.

It's far from scientific, but it works.

[Didée]

Dear Mr. Crust,

I tried to follow your procedure for encoding credits - but I got stuck on step 5:
5 - [...] If size/quality is good enough for end credits to my taste goto step 6
I am at a loss here. How do I know if my encoded credits are good enough for your taste? May I send you some of my credits?

:D


Good advice, crusty.

Only one note: On typical end credits, I often use two different zones. End credits often fall apart in the "first part" where stationary text is put with fade-in and fade-out, and the "second part" the scrolling text.
Now - while much B-frames with high threshold are good for the scrolling text, it's not so good for the fadings of the stationary text.

So, usually, I set MaxBframes = 4|5, and use thresh=0 for the first part, thresh = 40~80 for the second. Exact values change, of course.


- Didée


P.S. _Alas, I still couldn't do those tests, crusty ... they stay scheduled.

[Alxemi]

Just a note for credits-encoders:
be aware with movies that has a short "bonus" scene after the credits.. it´s always a very bad surprise to notice it after the encode (happens to me sometimes so now i always look at the final frames of the movie before encode)