I-frame, P-frame, B-frame?

[stenews]

Hi to everyone!
Does anyone to know what I-frams, P-frame, B-frame mean?
When I use Cuttermaran to cut my video, http://www.cuttermaran.de/site/294/default.aspx
I don't know how and when to properly use those buttons for cutting.

Thanks for any help,
Stefano.

[LoRd_MuldeR]

http://tinyurl.com/bcewx7

[stenews]

right...I see what you mean :rolleyes:
Anyway I already searched the net for a description of them but what I was looking for is a practical explanation on how to "work" with them inside cuttermaran.

Thanks the same...
Stefano.

[LoRd_MuldeR]

Well, if you read the Wiki article, that a Google search for "Group of Pictures" will return, it's not hard to conclude ;)

* I-Frames don't reference to anything -> No special attention needed
* P-Frames refer to the preceding I-Frame or P-Frame -> Never keep a P-Frame in but cut away its required reference frame, as you'd get an orphan (undecodeable) P-Frame
* B-Frames refer to the preceding and to the subsequent I-Frame or P-Frame -> The same as for P-Frames, only that you need to take care in both directions


I marked the places were you could do a "valid" cut:

http://img16.imageshack.us/img16/9906/gopcutbb7.th.png (http://img16.imageshack.us/img16/9906/gopcutbb7.png)

[stenews]

okay LoRd_MuldeR thanks for your reply, I'm appreciating that! :)
I had a look the article...and so should I always stop at next I-frame when I'm cutting?
Am I right? or I'm still miss understanding something?

Bye,
Stefano. :p

[stenews]

I see now!... :eek:
that's was exactly what I was asking for! thanks mate :thanks:

just one more question...
when I finished to cut my video what application can I use to check my job?
May be GSpot?

Stefano.

[Rumbah]

You can enable an encoding mode in Cuttermaran, then you can cut everywhere you want and only the GOP you cut in gets reencoded. The rest is simply copied like in the normal mode. That way you can cut with frame accuracy without reencoding the whole file.

[stenews]

Hi Rumbah and many thanks to have joined this thread! :)
you said that:
You can enable an encoding mode in Cuttermaran...
...but what is this "encoding mode" you're talking about?

Thanks for your help,
Stefano.

[Rumbah]

As you now know you can only cut in at an I frame and cut out at an I or P frame without reencoding. Cuttermaran has an option that lets you cut everywhere and just reencodes the GOP that would get damaged if you simply cut it.
Example:

IBBPBBPBB IBBPBBPBB

now you cut after the first P frame, you would get:

BBPBB IBBPBBPBB

Cuttermaran does not allow that as the first 5 frames could not be properly decoded. With the encoding option on, it reencodes the 5 frames to let you cut even there. You would get:

IBBPB IBBPBBPBB


I made a small video so you know how to configure the encode mode in Cuttermaran:

http://de.sevenload.com/videos/UwqODu6-Cuttermaran-muxed

Just remember to click on the HD button or else it's hard to read anything :)

[stenews]

hi Rumbah,
first off I have to say thanks to you for the great help!
I really appreciate what you did... :)
I think that I learned a lot about cuttermaran while I was watching the video and I see now what you was trying to explain me about the "encoding mode".
Basically, I see your procedure:
1) find a I-frame or P-frame
2) hit once the B frame button to include the I-frame (or P-frame) in the cut in
3) do the same for the cut out point
Am I right? I hope I'm not miss understanding something else this time :p

Thanks again,
Stefano.

P.S.
how do you make a such nice video tutorial?
I mean, which application have you used? Maybe VirtualDub?

[Rumbah]

Hi,

for the video I used Camtasia Studio 3 (was for free on a DVD of a German computer magazine).

In the video I just wanted to show you that with the encode option you can cut anywhere you want, even at 2 B frames. The cut was totally random, I just wanted to show you that you can cut there.

When I usually cut with Cuttermaran (cutting out the commercials) I first use the quick search function to find the beginning of the section I'd like to cut, then I use the I frame button to get closer and then use the P and B buttons to get to the frame where I want to make the cut. That can be a B frame, but a P or I frame, too, I just don't watch for the frame type to cut.

If you want to I can record something on TV this night and cut it like I normally would do it.

[stenews]

If you want to I can record something on TV this night and cut it like I normally would do it
yes do it if you can, it'll be great to see the right way to use cuttermaran. :)

many thanks again for your help, I'm really appreciating all that!

Bye,
Stefano.

[Rumbah]

Well, here you go:

http://de.sevenload.com/videos/nzSuF3S-Cuttermaran

By the way, that's my way of cutting with Cuttermaran, it does not have to be the right way ;) if there is a right way.

[stenews]

hi Rumbah and thanks for your reply!
I just had a look your tutorial video clip and to me, it has been pretty useful to watch it. :goodpost:

Thanks,
Stefano.

P.S.
I'd like to use your DVDRBEndEstGraph application but what I don't know is if I can use it even when DVD-RB is not minimized.
Because I read in the txt that to make it works one have to minimize DVD-RB. Am I miss understanding something? :o

[Rumbah]

When you minimize DVD-RB, then the progress percentage is shown in the title and that's the way the tool gets its information.
You can maximize DVD-RB without a problem, but for DVDRBEndEst to catch up you need to minimize it again and get a new estimation the next time a percentage is shown in the title.

[stenews]

okay...I see now what you mean.
In other words, after the tool is first launched, every time I minimize DVD-RB I'll get the estimation end time. Am I right?

Thanks again, :)
Stefano.

P.S.
the difference between the graphical version and the other one is just in the way the end estimation process is showed, isn't it?

[Rumbah]

Well, DVD-RB only shows the percentage after minimizing and a new part encode is finished. Then you'll get the new estimation. It would be good to minimize DVD-RB right after the encoding starts so it can get the correct start time.

And yes, the only difference between the two versions is the visualisation.

PS: Why don't you want to let DVD-RB run minimized ;) .

[stenews]

first off, I'm scaring about the fact that some moderator could strike we off...because we are talking about something different from the beginning subject of this thread.
Anyway about your question: Why don't you want to let DVD-RB run minimized
There is nothing in particular, just because I think useful to have a look the window log, but I know that is not important for every encoding process.

Thanks for all!
Bye,
Stefano.

[PhillipWyllie]

ProjectX, allthough it only does I-frame cutting.

[stenews]

Hi PhillipWyllie and thanks for your reply.
You said exactly what I wanted to know too. :goodpost:
Let me ask you one more question:
and when I use DGIndex to cut in a VOB file?

Thanks again,
Stefano.

[PhillipWyllie]

I-frames too. I'd go for ProjectX though as DGIndex can only do 1 cut(in and out).

[stenews]

but if you need to cut a VOB file how do you think to manage within ProjectX?

[PhillipWyllie]

Just fine, although it'll demux(as will DGIndex).

[stenews]

Hi PhillipWyllie and sorry for my late in reply you.
Can ProjectX open VOB(s) file? or I'm just miss understanding your answer?

Thanks,
Stefano.

[LoRd_MuldeR]

Can ProjectX open VOB(s) file?

Yes, it can.

[stenews]

Hi LoRd_MuldeR and thanks for the reply :)
I see now... but let me ask you another question please:
How to check at the end that all the cut(s) are made properly?
I mean, is there any way to be sure that one made all the job right?
I saw that GSpot can show a visual rapresentation of the each individual GOP(s).

Bye and thanks,
Stefano.