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GOP Structure recommendations.

 
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neil wilkes



Joined: 26 Dec 2003
Posts: 51
Location: London, England

PostPosted: Thu 11 Sep 2008, 11:58    Post subject: GOP Structure recommendations. Reply with quote

Can I please pick brains for recommendations for the following situations, using TMPG of course.
NTSC Motion Menu.
GOP must be either GOP 10 or GOP 15. (Preferably the latter).
Do I use a structure of 14p frames & 1 I frame, with scene detection enabled?

Although it is an NTSC disc, because of a known issue in the Menu Import tool (Sonic DVD-Audio Creator) the movie file must be divisible by the GOP structure.

EDIT.

Can I set a GOP limit of 15 frames max/GOP for an NTSC project?
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RMN
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Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Mon 22 Sep 2008, 4:57    Post subject: Re: GOP Structure recommendations. Reply with quote

For some reason I didn't see this message until today. Sorry for the delay, but here goes:

neil wilkes wrote:
Can I please pick brains for recommendations for the following situations, using TMPG of course.
NTSC Motion Menu.
GOP must be either GOP 10 or GOP 15. (Preferably the latter).
Do I use a structure of 14p frames & 1 I frame, with scene detection enabled?


Assuming average or high motion, yes. If it's very low motion and you can't use a very high bitrate, you might get slightly better quality adding 1 B-picture. In that situation you might need to enable closed GOPs to get the number of frames per GOP that you want.

Quote:

Although it is an NTSC disc, because of a known issue in the Menu Import tool (Sonic DVD-Audio Creator) the movie file must be divisible by the GOP structure.


What do you mean by "the movie file must be divisible by the GOP structure"? That's kind of the whole structure of MPEGs (movie stream divided in GOPs). Do you mean the frame rate must be a multiple of the GOP length? Or the movie length (in frames) must be a multiple of the GOP length?

Quote:

Can I set a GOP limit of 15 frames max/GOP for an NTSC project?


For NTSC you can set any value up to (including) 18.

RMN
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neil wilkes



Joined: 26 Dec 2003
Posts: 51
Location: London, England

PostPosted: Mon 22 Sep 2008, 8:18    Post subject: Reply with quote

I meant that the movie length must be a multiple of the GOP length.
This is the quote from an ex-Sonic engineer:

Quote:
Trim the video file (before compressing to M2v) so that its duration is exactly divisible by the GOP structure. e.g. if it’s a 30 second loop, make sure there are exactly 900 frames for a GOP 10 or GOP 15 M2V.


This only applies to motion menus though.
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RMN
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Location: Lisboa, Portugal

PostPosted: Thu 25 Sep 2008, 3:15    Post subject: Reply with quote

Ah, yes, Sonic and its high-quality software... Razz

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neil wilkes



Joined: 26 Dec 2003
Posts: 51
Location: London, England

PostPosted: Thu 25 Sep 2008, 21:24    Post subject: Reply with quote

Tell me about it!
£13,000 for that, and they will not even support me.
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PostPosted: Fri 26 Sep 2008, 5:33    Post subject: Reply with quote

Of course. You are supporting them. Wink

In case you don't know, it was precisely due to Sonic's superior software that I started using TMPGEnc and it was precisely because of Sonic's superior support that I created this website.

Someone in the "Sonic Support Forums" complained that no one from Sonic actually gave any support. Apparently someone from Sonic read that and fixed it in two days: the forums were renamed "Sonic User to User Forums". Rolling Eyes

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neil wilkes



Joined: 26 Dec 2003
Posts: 51
Location: London, England

PostPosted: Fri 26 Sep 2008, 9:59    Post subject: Reply with quote

RMN wrote:
Of course. You are supporting them. Wink

In case you don't know, it was precisely due to Sonic's superior software that I started using TMPGEnc and it was precisely because of Sonic's superior support that I created this website.

Someone in the "Sonic Support Forums" complained that no one from Sonic actually gave any support. Apparently someone from Sonic read that and fixed it in two days: the forums were renamed "Sonic User to User Forums". Rolling Eyes

RMN
~~~


And now there are no forums at all.....
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