audio sync

[deadbeet]

i have changed frame rate of film to 25 from 23, xtracted audio . but dont know enough to change audio to match new frame rate.please help

[Vejita-sama]

https://www.videohelp.com/forum/viewtopic.php?t=150581&highlight=assumefps

Normally I use avisynth's "assumefps" command to do this, see the above link and do some more forum searchs for more detail. It's really pretty easy:

1) Use avisynth to frameseve to encoder. Will convert from 25fps to 23.976fps

2) Run pulldown to convert to 29.97fps

3) Author as normal

[deadbeet]

thanxs 4 looking ,changed frame rate to 25 fps to play on my dvd player.but cant get audio to match new frame rate. can any one help?

[antoniosgubba]

Use Goldwave's Time Warp function.....work out the length you need to stretch the audio to then just enter the time and it will stretch (or compress) the audio to that time. If you're going from 23.976fps to 25fps then you need to multiply the original time in seconds by 0.95904 to get the new time to stretch to (the ratio of 23.976 to 25).

Just remember to always calculate audio times in seconds only before multiplying...then convert back to hours/mins/seconds before inputting the new time into Goldwave....Goldwave will show you the exact time of the original audio (to within 1000th second) when you open it....use this figure...don't be tempted to round it to the nearest second or you will get sync problems.

Example:

if goldwave says the audio is 01:35:45.345 (1 hour 35 mins 45.345 secs) you need to convert this to seconds only:

5745.345 seconds

then 5745.344 multilpied by 0.95904 becomes 5510.016 seconds

Now convert back to hours/mins/secs...becomes 01:31:50.016

Enter this new time into the Time warp feature.

Save the WAV and you can then use it with your 25fps video, and the audio will be perfectly in sync.

[deadbeet]

great thanks for the help

[deadbeet]

thanxs 4 help it worked great. thanxs for time to write it all down and go into detail .now ive got no more sleepless nights.