25fps>29.97fps?

[pijetro]

Most guides explain 25fps>24fps.
What about 25fps>29.97fps?

Here's what I did so far. Frameserve video stream from 25fps to 29.97fps to CCE. Ripped MP3 into .wav with 41000 sample and 16 bit rate. So far so good.Video shouldn't be a problem. How do I convert audio to match from 25fps to 29.97fps. If I simply convert audio to .mp2 and mux, then I'm assuming I'll get mismatch.

Can somebody tell me how to do the math for audio shrink (not stretch) and what program? Or should I follow the guide http://forum.vcdhelp.com/userguides/78178.php ?

[Bel]

Audio should not be a problem, assuming the framerate conversion is done properly. After all, the total video length remains the same regardless of how many frames play per second, as should the audio length. If you remux the new video with the old audio, it should still be in sync.

[wildcatfan]

Most guides explain 25fps>24fps.
What about 25fps>29.97fps?

Here's what I did so far. Frameserve video stream from 25fps to 29.97fps to CCE. Ripped MP3 into .wav with 41000 sample and 16 bit rate. So far so good.Video shouldn't be a problem. How do I convert audio to match from 25fps to 29.97fps. If I simply convert audio to .mp2 and mux, then I'm assuming I'll get mismatch.

Can somebody tell me how to do the math for audio shrink (not stretch) and what program? Or should I follow the guide http://forum.vcdhelp.com/userguides/78178.php ?

If you do it this way it will work but will be jerky though as the it will duplicate frames (or worse shorten the play time of the video so it doesn't match the audio). The way it should be done (assuming it is was originally from film stock, ie most movies but not tv shows) is to convert the video to 23.976 fps then slow the audio down by the same amount (with cooledit or some other audio editor that lets you slow the audio without changing pitch) this will give you ntsc film that can be used directly for vcd (its supported) or you can use pulldown to get a playback rate of 29.97 if making an svcd. This is actually the inverse of how pal vcds are made from film stock. Hope this helps.

[z0nk]

/edit
read the post wrong

[ya_jai]

Why do ppl need to convert frame rate of one format to another format ( PAL to NTSC or NTSC PAL). I don't really get it when almost every stand alone player can handel any type of VCD/SVCD. I never have and problem playing PAL vcd/svcd in my APEX, btw I live in US which use NTSC format and I also sent some of my home-made vcd (ntsc format) to Thailand which use PAL and all my friends can play my VCD without a single problem.

IMO, converting frame rate, you will never get a perfect vcd/svcd, you wil face either jerking or out of sync issue, one or another or in worst case you'll have them both

[pijetro]

Okay, i was correct in assuming video would shrink.

Solution opened up video stream in WMP and looked at total time.

Opened up cool edit (trial version) and went to the time pitch>stretch options, and typed in the same length in seconds. Grabbed the new .wav file and made into an MP2 with toolame. Muxed the video and audio in Tmpgenc.

Perfect.

As for the reason for conversion. Didn't know that DVD players could magically switch from 25fps to 29.97fps. If that's the case, I'll never convert again. I received a 25fps divx. and needed to make it an VCD for NTSC display. If anybody has better suggestions, please answer back.

Thanx!!!!!!!!!!!

[reman]

You do not need to convert from 23 or 25 or 29 to any other fps rate if your DVD player supports the fps the file is in. However, there are APEX players, for example the 1500, that will not play most 23fps videos. Search APEX on www.kvcd.net.

I do convert 23fps movies into 29fps movies and found no audio issues. There should not be any since the audio is added on top of the converted movie so if a 23fps movie is 60min so is the audio and when converted the movie is still 60 min. You are adding 6 frames per second and it is not the last frame of each second. The added frames are spaced out so your eyes do not see it.

Good luck!
reman

[bugster]

Guys, Converting PAL-> NTSC is not usually necessary because most PAL equipment (TV's and DVD players) handle NTSC fine (PAL DVD players often output PAL 60 when given a DVD disc, most PAL TV's will accept a NTSC signal). However, I think I am correct in saying that in the USA, the homeland of NTSC, support for PAL amongst TV's is very poor. Therfore many poor americans downloading movies from the net have to convert Pal to NTSC to make them watchable on their DVD/TV setup.

Converting PAL->NTSC can be done but can be tricky, especially regarding sync issues and smooth playback. I can't claim to have done this, never having had the need, but would expect things to be easier converting from PAL's 25fps to NTSCfilm at 23.97 fps and then applying 3:2 pulldown, rather than trying to convert to 29.97fps.

[Xesdeeni]

The two DVD players I've used to view PAL videos here in the NTSC-land do only a fair job of playing them. But they don't do a good job.

From pure observation, and guessing at the rest, it looks like they do the following:

1. Throw out one field entirely, leaving 25, 288-line frames per second.
2. Use the VCD scaler built-in to interpolate the 288-lines to 576 lines.
3. Use the letterbox scaler built-in to convert the 576 lines to 432 lines. (a 16:9 PAL video is not letterboxed when converted, so the converter must already be in use)
[2 and 3 above may be reversed]
4. Skip a frame about once a second to adjust the 25fps to 24fps.

Again, this is just from observation, but one thing I'm sure of is that they throw out one field, reducing the vertical resolution by 1/2, and making the resulting image a bit short and fat.

So although I can watch my PAL DVDs, I'm working on converting them at present. The guides indicate how to convert a PAL movie to NTSC, but I'm mostly interested in video rather than films so far.

Unfortunately the conversion of video takes quite a while so far. On my 1.1GHz Athlon, each 30-minute episode of the British comedy I'm working on now has been taking 13-14 hours to convert.

Thanks to open-source, I was able to convert a VirtualDub plugin to an AVISynth plugin that uses YUV instead of RGB, and I was able to cut that time down to 6-7 hours, yesterday. I think I can make a few more changes that may cut out an hour or two more. And I think using CCE would help speed things up as well.

Maybe once I'm finished, with the help of people on VCDHelp.com, I'll be able to create a "PAL DVD9 to NTSC DVD*R, including original menus and extras" guide.

Xesdeeni

[banjazzer]

Opened up cool edit (trial version) and went to the time pitch>stretch options, and typed in the same length in seconds. Grabbed the new .wav file and made into an MP2 with toolame. Muxed the video and audio in Tmpgenc.

Presuming you were starting with a DivX I think maybe the correct way would be to first convert the framerate to 23.976fps and stretch the wav. Then use the NTSC template with 3:2 pulldown. NTSC(film) and PAL can be interconverted by adjusting the overall length, but an NTSC movie should be the same length as an NTSC(film) movie, but with added fields.

[pijetro]

Thank you bugster and banjazzer. Your answers helped me out.

As for converting 25fps to 24fps, how do you derive your audio time. Do you do what I did, and see what the new video length is, and then apply that same number into your time>stretch option in cool edit? Back to my original question of how does everyone else do the math in regards to audio stretch?

As for banjazzer, I guess instead of removing one frame, and then applying pulldown, I must have removed the middle man and gone straight for the 29.97fps encode (frameserve via Vdub). I'm lucky, because it worked, with no jittery playback like everyone says I should get.

Hope it's the last time I have to write back on the subject.( It's like beating a dead horse).

Thanx everybody!!!!

[banjazzer]

As for converting 25fps to 24fps, how do you derive your audio time. Do you do what I did, and see what the new video length is, and then apply that same number into your time>stretch option in cool edit? Back to my original question of how does everyone else do the math in regards to audio stretch?

Hopefully in a properly encoded file the audio and video are exactly the same length, although I have come across a few that are not. 8) In Soundforge when converting from NTSC(film) to PAL I generally input the original wav and shrink it to the length of the video after it has been converted to 25fps, as you have done. The percentange shrinkage is retained in Soundforge, so in subsequent processing I no longer need to enter a new length. I see at the moment it shows 95.91% of the original. It should theoretically be 23.976/25*100 = 95.904%, but it's close enough to give excellent results.