RB supposed to replicate DVD structure?

[Jeffster]

Hi,

I thought one of the goals of RB is to replicate the original DVD structure when rebuilding, at least that is what I've read many times, so I was surprised to see this.

I have a PAL disc that I ran thru DVD-RB 0.95 free last night -

the main movie on the original DVD is interlaced, BFF
but the rebuilt vobs are interlaced, TFF...

This can't be a good thing can it, encoding bff video as tff?
I was expecting RB to change the tff flag during the rebuild phase but it didn't :confused:


An additional unrelated note, I was looking at the log after the prepare phase and there is a discrepancy in the bitrates reported. It's using the vbr_brate_max as the HIGH bitrate... now I'm pretty sure previous versions gave the highest average vbr bitrate for a segment?
It doesn't matter at all, but thought I'd point it out.


- Reduction Level for DVD-5: 73.7%
- Overall Bitrate : 4,894Kbs
- Space for Video : 3,763,172KB
- HIGH/LOW/AVERAGE Cell Bitrates: 8,808/819/4,894 Kbs

[jdobbs]

When you are reencoding, the field order of the input stream really isn't relevant. All that matters is that it plays the fields in proper sequence. In fact, if I recall correctly CCE will only output TFF. If DVD-RB changed the TFF flag from what the encoder used the output would be jittering mess when played back on an interlaced device (like a TV).

As for the second question, I'm guessing you probably have a very short segment that is very high action -- so it maxed out the bitrate...

[Jeffster]

So RB doesn't try to reproduce the exact structure of the original DVD in all cases?

Okay, but I thought if you encoded bff video as tff you'd mess up the field order and have jerky playback. What you say appears to be at odds with the CCE FAQ (sticky) in the CCE forum about handling bff video. :confused:

BTW - in CCE 2.70 you do have the option of whether or not the TFF flag is set, unlike earlier versions.


As for the second question, I'm guessing you probably have a very short segment that is very high action -- so it maxed out the bitrate...
No, the highest target bitrate is 6000 (CBR) for a segment with 1 frame.
v 0.93 correctly reports the HIGH bitrate as 6000, but v 0.95 reports it as 8808 which, as I said above, is from the vbr_brate_max setting, not the target bitrate.

[Jeffster]

When you are reencoding, the field order of the input stream really isn't relevant. All that matters is that it plays the fields in proper sequence.
Exactly, but it won't play the fields in the proper sequence if BFF video has the TTF flag set to yes.

In fact, if I recall correctly CCE will only output TFF.
Not exactly, CCE would always set the TFF flag (now optional in 2.70), but that is different from actually outputting TFF video.
In CCE that depends on the "Line offset". If the line offset is set to 0, which is what DVD-RB tells CCE to do, then the field order isn't changed, and BFF is still BFF but now it has a TFF flag. Do you see what I mean?

CCE will output TFF from BFF source if the line offset is the default of 1, but it does that by shifting each frame up one line... and I'm sure you don't want that.