Field order and number of gob fields

[Crazyjoe]

Hi there!

I have a question to the expert settings of TMPEG Encoder. I'm now encoding videos for use with miniDVD for a long time, alway using TMPEG, but there are two things, I never really understood.

What exactly is the difference between using "Top field first" or "Bottom field first" when encoding videos for miniDVD or DVD use? Whats the best selection?

The second things is, when I'm multiplexing the videos with scenarist, I always get the warning, that the number of gob fields is larger than 30 (I'm producing PAL miniDVDs). It's always between 32 and 34. I read, that the number of this fields should be at a maximum of 30 for PAL videos, but the videos playback fine also with a number over 30. So what are these gob fields and how can I reduce that number by using TMPEG Enc?

Thanks for the help!

Greets

Joe

[Arky]

Settings > GOP structure (Group Of Pictures) Now set your GOP parameters as follows:

IBBPBBPBBPBBPBB


Which is:

Number of I picture in GOP = 1

Number of P picture in GOP = 4

Number of B picture in GOP = 2

Output Interval of Sequence Header = 1

Max number of Frames in GOP = 15

Detect Scene Change = enabled

Output Bitstream for edit = OPTIONAL (only necessary if you intend to edit your finished MPEG file (NOT a good idea), or if you are creating a multiple-angle DVD title).

Force Picture Type Setting = Not necessary except in very extreme circumstances where you need to adjust bitrate at difficult areas of the file.

Regarding Top and Bottom field first encoding, this refers to the SOURCE file, not the output file. This can vary with Ripped material, so you need to find this out or you will possibly end up with jumpy encodes (field order inappropriately reversed). DV footage, captured over firewire, is generally bottom field first, and it is with DV footage that TMPGEnc excels over Cinemacraft.


Arky ;o)

[Crazyjoe]

Thanks a lot! It worked! My settings for I, P and B Pictures were correct, but I forgot to set the maximum number of frames. :rolleyes:

[Crazyjoe]

Now another problem arises. Now, that I've set the maximum number of frames in the gob to 15 (before your hint it was unlimited), the video doesn't play as fluently as before. :(

[Arky]

Originally posted by Crazyjoe
Now another problem arises. Now, that I've set the maximum number of frames in the gob to 15 (before your hint it was unlimited), the video doesn't play as fluently as before. :(

Erm...I never said anything whatsoever about GOP frames being "unlimited" without setting the "Max GOP Length" box in TMPGEnc!

In fact, if you follow the settings I listed above, it is actually, strictly-speaking, unnecessary to specify anything in the "Max GOP Length" box, because you will ALREADY have specified this with your I,P, and B frame settings. It is not good enough to stick with illegal GOP settings, and simply set the Max GOP length to 15 to compensate - you need to specify ALL parameters correctly.

For a broader explanation:

http://forum.doom9.org/showthread.php?postid=132567#post132567


Arky ;o)

[Crazyjoe]

Originally posted by Arky


Erm...I never said anything whatsoever about GOP frames being "unlimited" without setting the "Max GOP Length" box in TMPGEnc!

In fact, if you follow the settings I listed above, it is actually, strictly-speaking, unnecessary to specify anything in the "Max GOP Length" box, because you will ALREADY have specified this with your I,P, and B frame settings. It is not good enough to stick with illegal GOP settings, and simply set the Max GOP length to 15 to compensate - you need to specify ALL parameters correctly.

For a broader explanation:

http://forum.doom9.org/showthread.php?postid=132567#post132567


Arky ;o)

Thanks again for your help! :)

Yes, I know you didn't say anything about an unlimited number of frames within a gop, but that was the setting I originally had. TMPG gives me only 5 options to manipulate the gop size: "Number of I pictures", "Number of P pictures", "Number of B pictures", "Output interval of sequence header" and "max. number of frames in a gop". My original settings for the last option were "0 (unlimited)". My settings for I, P and B pictures were the same as you said. But Scenarist produced the warnings about a gop size over 30. But the videos played back perfectly either on my pc and on my cyberhome stand alone player. Then I changed the maximum number to 15 (as you told me). It worked fine, 'cause Scenarist didn't warn me anymore and the videos played back on my pc as fine as the did with the unlimited frame number. But now the videos were a little "stuck" when playing them on my stand alone. :rolleyes:

[mb1]

That has nothing to do with you GOPs.

Maybe your dvd standalone does not like yor dvd-r brands or dvd-rw brands.
Maybe you need to burn it with another prog.
Maybe you muxed it not correct (will scenarist complain on that ?).
And some more ...

[Crazyjoe]

Originally posted by mb1
That has nothing to do with you GOPs.

Maybe your dvd standalone does not like yor dvd-r brands or dvd-rw brands.
Maybe you need to burn it with another prog.
Maybe you muxed it not correct (will scenarist complain on that ?).
And some more ...

Mit dir könnte ich eigentlich deutsch reden... :rolleyes: :D

Schön, wenn man hier auch mal gleichsprachige Kollegen findet. :)

Mangels des nötigen Kleingelds muss ich mich im Moment noch mit miniDVD begnügen. Scenarist muxt die Streams selbst. Das merkwürdige ist, dass bei gleichgebliebener Bitrate (5 MBit konstant; ich weiß, ist für CD etwas viel) das Bild am PC immer noch absolut flüssig läuft, aber auf meinem Stand Alone nicht mehr. Obwohl die maximale Frame Zahl für die GOP das einzige ist, was ich verändert habe.

So, if anyone wants the above text in english, please let me know. ;)

[mb1]

5 Mbps is too much for miniDVD on standalone.
Lower the bitrate to 4 - 4.5 Mbps and it should play fluently.
On PC almost everything plays fluently (no bitrate borders like 4xcdrom for dvd standalones).

What standalone do you have (maybe you have to reduce bitrate more).


Ich spreche hier deswegen nicht deutsch, weil es ein englisches Forum ist und anderen Besuchern gegenüber unhöflich.
(I don't speak german here because it is an english forum and it would be not polite to other visitors)

[Arky]

http://forum.doom9.org/showthread.php?threadid=12199&highlight=arky+velocity

[[ 1) Bitrate too HIGH (data cannot be read fast enough from the disk - this is a rotational velocity / data density issue - because the data is not as densely packed on a CDR as it is on a DVD, the CDR cannot spin fast enough for enough bits to be read when a high data-rate MPEG file demands it, during playback). ]]


Arky ;o)

[Arky]

Useful translation tool:

http://world.altavista.com/sites/gben/pos/babelfish/trns

(but only 150wds at a time, unfortunately)


Arky ;o)

[Crazyjoe]

Originally posted by Arky
Useful translation tool:

http://world.altavista.com/sites/gben/pos/babelfish/trns

(but only 150wds at a time, unfortunately)


Arky ;o)

Thanks Arky, but I think my english is good enough... ;) Sorry for switching to german in my last posting, but it was nice to see a "comrade". :p :D