20% Bitrate recovery possible on 29fps movies?!

[Trenton_Net]

Hi,

I was wondering if it is possible to recover your 20% of bitrate with a 29fps movie (SVCD Format). I did an interlace to progressive to it, but it didn't change it back to 23fps. I think thats because it was truely shot in 29fps and not IVTC. If I force change the Fps to 23, the screen jumps as some frames are dropped to maintain the fps you selected.

[adam]

You cannot just change your interlaced video to progressive or just convert it to 23.976fps and expect to get any quality improvements. The only way to properly convert 29.97fps to 23.976fps is to do an IVTC (inverse telecine.) There are avisynth and vdub filters which can do this quite well but it might take some setting up. The easiest way to use these would probably be to download and install the latest dvd2svcd and use something like gordian knot to create an avs script for you, if your not familiar with avs scripting.

The easiest way to do an IVTC is probably just with TMPGenc. Double-click on the IVTC tab and tell it to do it during encoding. Under your settings make sure and tell it to encode at 23.976fps with 3:2 pulldown while playback. Also make sure to tell it that the source is interlaced in the advanced tab.

Not all material originates as film and not all 29.97fps material underwent the same telecining process. It may not be possible to perform an IVTC. If this is the case then you should keep your video at 29.97fps interlaced.

[Trenton_Net]

Hi Adam,

Thanks for your comments. About encoding, I do it all the time, so im pretty fluent with it. And about IVTC, that was one of the first things I did.

But thats not the problem. After I reconstruct the Interlaced screens so I have a progressive source, the framerate seems to still be 29fps. Almost as if they did a real intraced encode at 29fps, and not a pulldown. This is not unusual im sure, but im not sure how (if Possible) I can change the 29fps movie to 23fps without studdering or audio streching to get my
20% bitrate back.

[adam]

I don't understand what you mean when you say that it seems as if its still at 29.97fps. If you tell the encoder to encode at 23.976fps than it WILL be. How can it seem to be anything else?

Do what I said, set the output to 23.976fps and 3:2 pulldown while playback. On the advanced tab double click the IVTC option and set it to run while encoding. Encode it. Multiplex the resulting video stream with your audio using bbmpeg and watch your mpg using a software dvd player (not media player.) If it looks ok then your done. Your file is encoded at 23.976 and you have saved %20 of your bitrate. If its jumpy or you can still see interlacing than IVTC did not work properly. You can try doing it manually in TMPGenc (scroll through frame by frame looking for the pattern then applying it to all....and pray the pattern doesnt change )

More than likley if IVTC doesnt work then your material didn't originate as film. Encode it at 29.97fps interlaced and move on.

[afreitas]

If Im sure my video is 29.97fps Interlaced (From a camcorder) would it be still possible to IVTC it?

How do they produce film with 23.976fps? Are there camcorders that can record at others fps??

Just another newbie question

[therick]

The BEST way to do IVTC is using AVISynth and Decomb...look them up on google...

[wildcatfan]

If Im sure my video is 29.97fps Interlaced (From a camcorder) would it be still possible to IVTC it?

How do they produce film with 23.976fps? Are there camcorders that can record at others fps??

Just another newbie question

No it wouldn't if you record interlaced it is interlaced forever.... Interlacing isn't the same as pulldown. in pulldown you repeat some fields, interlacing interlaces every single frame. And to answer your question they get 23.976 (actually 24, they slow it down a tick later) by using film not video tape at all.