What bitrates ? + General settings for a DV source

[Lucius Snow]

Hello,

I export DV films to MPEG 2 with 3 VBR passes. They're usually between 30 and 60 min and with a PCM 48 kHz- 16 bit - stereo audio track (= 1536 kbit/s). For my first encoding, i put the max. value to 8400 kbit/s, the average to 8000 kbit/s and the min. at 0. Since the max. total bitrate can't be over 10 000 kbit/s for a DVD playback, i'll let the max at 8400 kbit/s. But i was wondering what would be the best values for the average and the min. to get the best quality possible. I heard the difference between the average and the max. must be more than this.

What do you think about it ? What bitrates do you advice me for 30-60 min of MPEG 2 encoding to put on a DVD ?

Thanks in advance.

[ronnylov]

When you use the maximum possible DVD bitrate you can still fit 60 minutes to one disc. So you might as well use CBR with 8000 kbit/s average because the video bitrate is close to max. Alternatively you can compress your audio to ac3 and increase your maximum video bitrate.

[Lucius Snow]

Would you advice me onepass CBR or multipass CBR ? My aim is to get the best quality possible, whatever the time it takes to encode.

Thanks.

[dvd_master]

If you want the best possible quality, I wouldn't reccomend using a CBR at all, a VBR is better and can be higher quality for a lower filesize.

To determine the max bitrate you should use for the exact size (does both CBR and VBR) use CCE Guesser.

[Kedirekin]

@Lucius Snow,

Don't get confused. I don't think dvd_master read ronnylov's post. A CBR encode at maximum bitrate will be (at least) as good as a VBR encode. Since you have ample space, there's no need to waste the time doing a multipass VBR encode.

I also can't see any advantage of doing a multipass CBR encode at that high a bitrate. The quality gains would be minimal. In the end though it is up to you to decide; as above, multipass will be (at least) as good as single pass.

[Lucius Snow]

Thank you all. So i'll do it in CBR, onepass, 8400 kbit/s. But do i still need to create the VAF file for that ?

Another question about the general parameters :

From a source in DV - Pal - Interlaced - 4/3, in order to make a DVD from the MPEG 2 video created by CCE, and still for a time situated between 0 and 60 min, i put these settings :

http://poubellelqt.free.fr/crap/CCE1.jpg
http://poubellelqt.free.fr/crap/CCE2.jpg
http://poubellelqt.free.fr/crap/CCE3.jpg

Is it correct ? That's what i selected from the informations i've collected in different forums. Then again, the ultimate goal is the best quality possible, not the speed.

Cheers ;)

[MLS]

I would turn off those 2 filters, and set your timecode to 00:00:00:00. Also would VBR instead of CBR.

/MLS

[Steve56]

I would set Offset Line = 0 and change the TFF flag in the encoded mpeg to BFF (if your source video material is dv) with a tool like ReStream.

[Lucius Snow]

@Steve56
Offset line = 0 means actually Lower Field First, right ? And so that's what i have to set for a DV interlaced source ?

I didn't understand the else though :/ Why would i need another tool ?

@MLS
OK for the timecode. What filters should i turn off ? The low pass one ? And ... ?

Thank you two.

P.S : I export from Vegas (project settings in DV Pal) to CCE SP 2.67 through the Pluginpac frameserving tool.

[Lucius Snow]

I'm confused. Here is what the FAQ says :

if the interlaced material is "bff" (bottom field first) like most DV camera footage is, check "Upper Field First" in Video settings (CCE-SP 2.50/CCE-SP 2.66), set "Offset Line" to 1 (CCE-SP 2.67/CCE-Basic).
That's actually for my video (botton field first / interlaced) so i have to set it on 1 and not 0.

And it's said again later :

So here is the rule of thumb: Always uncheck "Upper Field First" unless your video is interlaced AND bottom field first. Progressive material is always top field first.

Always set "Offset Line" to 0 unless your video is interlaced AND bottom field first in which case you set it to 1. Progressive material is always top field first.

I read about Restream in the FAQ but i don't know if i'm concerned for my DV source.

The last question is about the CBR / CBR deal for high bitrates. Nobody agrees :D . For 8400 kbit/s, it seems i can stick on CBR since there's no constraint of space (4,3 GB is largely enough for 30-60 min). But i still don't know if making a CBR multipass would make a better quality than CBR onepass ...

Thanks all for helping.

[Kedirekin]

Welcome to the wonderful world of MPG encoding. Everyone has their own opinions, and you're lucky enough to get conflicting advice. On top of that, I think few people fully understands exactly what all the settings in CCE do (I know I don't understand them all). Just try to treat it as a learning experience, and start forming your own opinions.

In my opinion, CCE treats the field precedence thing very confusingly. The problem is there is more than one way to screw up video. And unfortunately it's very hard to explain these things with just words - you really need moving pictures.

From your posts, I think you already understand interlacing and top field first.

What complicates matters is sometimes the fields can be interposed. I've heard this is often a problem with capture drivers.

It's easiest to see this on a diagonal line in the video. When the fields are not interposed, you get a clean diagonal as you would expect.

0 xxxxxxx
1 xxxxxxx
2 xxxxxxx
3 xxxxxxx
4 xxxxxxx

When the fields are interposed, the diagonal becomes jaggy.

1 xxxxxxx
0 xxxxxxx
3 xxxxxxx
2 xxxxxxx
4 xxxxxxx

I don't know for sure (because the explanations are so confusing) but I think the field offset setting is to correct problems with interposed fields.

So the question becomes, is the video really bottom field first (bottom fields were recorded 1/50 second earlier than top fields), is the video really top field first, but with the top field incorrectly offset downward, or both, or neither?

Then of course you have to try to figure out the slightly wacky settings in CCE to match (or correct) the video.

Is this getting complicated enough yet?

I don't know of any easy way to figure what applies to any particular piece of footage. I believe you just have to experiment with some test clips till you figure out which settings are correct. Following the suggested rules of thumb might (hopefully) help you find the right setting on your first go.

Sorry I can't be more help on this.

As for the one pass versus multipass CBR thing, again you have to be the final judge. In my opinion you don't get much quality difference between one pass and multipass, even at lower bitrates. I would think the quality difference at 8,000 kbps would be truly negligible; the video should look stunningly good in either case. However, I think you've mentioned that encoding time is not an issue for you, and doing multipass certainly wouldn't be any worse than single pass.

[Lucius Snow]

When the fields are interposed, the diagonal becomes jaggy.

1 xxxxxxx
0 xxxxxxx
3 xxxxxxx
2 xxxxxxx
4 xxxxxxx

I've got this effect when i play my MPEG2 file (whatever the offline set is, 0 or 1). But i've been told it's normal to get it on a PC monitor because my video is interlaced. Also, i've got it in Vegas when i preview my AVI - DV original file. But when it's seen on a TV, then this bad effect disappear since it "understands" the interlace thing. So i don't worry about that because the final DVD will be played on TV. Not sure we're talking about the same thing but what you described me reminded me that interlace problem. Anyway the final result on TV is always good.


I don't know for sure (because the explanations are so confusing) but I think the field offset setting is to correct problems with interposed fields.

So the question becomes, is the video really bottom field first (bottom fields were recorded 1/50 second earlier than top fields), is the video really top field first, but with the top field incorrectly offset downward, or both, or neither?
I don't know. Here is what Vegas says about my original AVI DV file : 00:25:38,920, 25.000 fps interlaced, 720x576x24, MainConcept DV Codec 2.4.4. And in the DV Pal project, the field order is always set on "Lower field first".


Then of course you have to try to figure out the slightly wacky settings in CCE to match (or correct) the video.

Is this getting complicated enough yet?
Yes, it's complicated :).


I don't know of any easy way to figure what applies to any particular piece of footage. I believe you just have to experiment with some test clips till you figure out which settings are correct. Following the suggested rules of thumb might (hopefully) help you find the right setting on your first go.

Sorry I can't be more help on this.

As for the one pass versus multipass CBR thing, again you have to be the final judge. In my opinion you don't get much quality difference between one pass and multipass, even at lower bitrates. I would think the quality difference at 8,000 kbps would be truly negligible; the video should look stunningly good in either case. However, I think you've mentioned that encoding time is not an issue for you, and doing multipass certainly wouldn't be any worse than single pass. [/B]
I have done some tests but i haven't seen any difference between CBR 8400 kbit/s one pass and 3 passes.

Well, i've already made a DVD recently, also from a DV source. The video quality was very good and i had no problem with it. I used the CCE settings i've posted in screenshots earlier, except it was in VBR with 3 passes. Like i said in my first post, it was 8400 kbit/s for the max, 8000 kbit/s for the average and 0 kbit/s for the min. My interrogation was actually to know if i could improve that. For now, i have changed to 8400 kbit/s CBR with 3 passes and disabled the filters. I'll let the offline set on 1 though.

Cheers.