Framerate Question: 23.976 or 29.97 for a 25 FPS PAL movie?
 

I am encoding Spanish movies, and they are in 25 FPS. The problem arises when encoding, if going down to 23.976 in TMPEG the result is that the movements are not even, that is for example, provided the camera is panning a landscape, the movement is not smooth. It is more or like it goes at a certain speed, suddenly slows down for a very short moment and then goes fast again (I shall mention that "fast" is the normal speed of the movie).

This happens all the lenght of the movie. Sometimes it is not noticeable, but most of the time it is.

I have solved the issue by encoding to 29.97 FPS, but I get an important decrease in CQ values required to fit a (for example 14.7 to 16.9 for Scooby Doo).

I would like to know if this problem is related to TMPEG, and thus if it can be solved by changing framerate in the avisynth script (or perhaps with VirtualDub) instead of specifying the encoding framerate in the soft.

Any help or hint will be great.

Many thanks in advance.

Gaudi

Hi Gaudi,

If your source is 25fps, encode at 25fps.
Don't use other frame rates different than your target :)

-kwag

Well, you are right, but the problem is that my DVD, a Philips DVD 703 recognizes the format as per framerate. So, I have to encode the movie with the PAL template.

But for some strange reason, its PAL format is not compatible at all with TV sets here in Argentina, so I have to use it in NTSC.

Then, a PAL encoded movie will not show correctly in this DVD.

Despite the fact that I shouldn´t do transcoding, what would you suggest?

Thanks again.

Hi Gaudi,

That should only apply to DVDs. I can only play NTSC DVDs on my players. But I can play any VCD, either NTSC or PAL. This should apply to any NTSC DVD player capable of playing VCD.
Have you tried burning a PAL VCD and playing it on your DVD player :?: It should play :)

-kwag

Mine will play them, but it crops off the extra horizontal lines :x.

Uhh!, then I guess you will have to do some fps conversion 8O
Maybe using Telecide and Decimate to bring it down to 24fps, and then re-encoding the audio with CoolWave or something like that to correct for the new fps :idea: . But that's a hell of a job :roll:

-kwag

Thanks kwag and SansGrip for the answers.
I will give it a try again.

But as far as I remember, when playing a PAL VCD, the image is black and white, as with the old TV sets.

Aparently the DVD internally switches to PAL, and that is why it does not work.

I think I will have to continue loosing the extra quality (which is around 20%) to be able to see the movies properly. At least until I buy a new DVD.

Ah, it doesn't matter. I very rarely need to play any PAL VCDs :).

I don´t think audio will be a problem. With my current encodings, the framerate of the movie changes, but the length is preserved, and the audio has its own length, which in turn is the same of the movie. After multiplexed again, the sync is still correct (at least using the method I use).

Could you give me further info or some place to visit and read about those two tools: Telecide and Decimate.

Wouldn´t the Avisynth filter "ConvertFPS" do?

Thanks again.

Gaudi

PS: by the way, how to erase the "Quote:" text from the quote? Is there any other tool to quote?

Your best bet is to convert from 25fps to 23.976fps using AssumeFPS in Avisynth. This will not alter the frame count of the source material, but will cause it to play 1fps slower. TV broadcasters in Europe often use the reverse method to show 24fps movies.

You may now have an issue with audio sync, but that can be corrected either by using the sync_audio parameter with AssumeFPS (which will alter the sample rate of the audio to be in sync, but unfortunately the pitch of the audio will change slightly too) or you can use a tool such as Wave Length Adjust (available from Doom9's download page) to change the length of the audio without changing the pitch.

Definitely the PAL mode does not work with this DVD.
Tried a PAL SVCD and it is black and white.

Will check out this solution.
I am using ACP program to encode the movies. As the audio will be extracted from the avi using virtualdub (which is out of the range of the avisynth script), should I do that manually?

I'm not sure what you mean by "out of the range of the avisynth script".

I am sorry, I meant that the script generated in ACP is only used for video. So, if assuming a different framerate for the movie, the audio will have a different lenght as stated by SansGrip.
SO, I thought that pehaps VirtualDub had some framerate conversion that will also be applicable to audio, and then, I could use it while extracting audio to avoid any further processing of it (avoiding having to use Cooledit or other audio editor to regain sync).
In that case, the automation of ACP will not be useful and I would have to extract the audio "manually".

Up to know, I am finishing now Scooby Doo, with the ConvertFPS(23.976) command in the script. Will see what comes out in a few hours. Perhaps this filter does not alter significantly the movie quality and can be used for transcoding movies.

I don't believe it does. AFAIK VirtualDub's frame rate conversion is fairly unsophisticated, more akin to "decimating" than converting.

ConvertFPS works, but you might notice "ghosting" because of how it works (it blends certain frames into one in order to achieve smooth playback).

If you're satisfied with the output from ConvertFPS, by all means use it. If not, try AssumeFPS and changing the length of the audio manually.

After some encoding, I have found that the best to do is to assume FPS. It does not add a considerable ammount of time to the movie (about 3.8 minutes to a 90 minutes movie).

And I have found that the audio part is very very simple to solve, and the pitch and quality is affected very little or none.

Just use this in your bsweet command line:

BeSweet.exe -core( -input Audio.wav -output audio.mp2 -logfile audio.log ) -ota( -g max -r 25000 23976 -shibatch( --rate 44100 ) ) -2lame( -e -b 128 -m s )

This extra command performs a framerate conversion, with no need for extra software (i.e. Cooledit, Soundforge or others).

The resulting movie preserves the sync.

Hope this helps for others with same problem.

Gaudi

Try to switch your DVD player to "RGB only" output... When I view NTSC Discs on my Standalone, (PAL here), it's Black and White too, except I make the output for the TV RGB...
see if that helps. I don't think you need to change the framerate at all...
Just switch it to PAL and RGB...

Thanks Gaudi,

I was just about to go go looking for that besweet command, you saved me some time.

You are very welcome. That is what are we here for.

I would like to try that option. But where do am I supposed to find it. I own a Philips DVD 703, and can not find it under the menu. Could it be that my DVD does not support RGB only?

Many thanks.


Gaudi

maybe......maybe could be the sub oscilator of croma
(don't know the name in english) oscilator of 3,58Mhz
(or 4,??? for pal-g..don't remember)
of the tv or dvd out ( a little) of adjust and the "color killer"
in the tv cut the color.

:wink:

Thanks for the reply, but honestly, I could not understand you.

I am looking for some clean and easy solution for watching PAL VCDs on my standalone DVD.

If not possible, I will continue reencoding the movies to NTSC.

Thanks