PAL speed-up: 24fps to 25fps video, how?

[JoachimS]

Hi there,

I frequently come across some NTSC-film (24fps roughly) footage that I am trying to convert to 25fps.

What I want to do is the following:

1) Separate or demux video and audio tracks and save them in two files, I know how to do that
2) Speed-up the Video to 25fps without re-encoding, making it play faster/shorter by 4%
3) Scale the Audio to match the shorter playing time of the Video, maybe with pitch adjustment, I know how to do that
4) Authoring, I know how to do that

I don't know how to do step 2, anyone?

[mats.hogberg]

AVIFrate if it's AVI, DVDPatcher if it's mpg2
<edit>Damned - didn't realize it was a Mac question. Sorry.</edit>

/Mats

[JoachimS]

Hm, they are not for the Mac.

[terryj]

JoachimS,
Your question is posted in the MAC forum.
If this isn't a Mac related question
(such as "...and how do I accomplish my post on a Mac?")
then it should be moved to the Advanced Conversion forum.
I'll ping a Mod to do so.....

[JoachimS]

I surely have a Mac in front of me.

The post should stay where it is.

[mats.hogberg]

Thought so too - That's why I left it in place.

/Mats

[Herve]

Speed-up the Video to 25fps without re-encoding, making it play faster/shorter by 4%

you didn't say what codec / container do you want to use...

bye

[JoachimS]

Currently I have H264 Video and AAC audio in an mp4 container.

I want to make a DVD from it.

If I go the straight way through reencoding, I have stutter every second.

[Herve]

eseaiest way: MovieConverter ... the soft in my sign

other soluces:
- ugly hack (like the dvdpatcher soft if I well understood what I readed): use pulldownX to reconstruct gop and do bull***t with headers as describe in its tuto (with an hex editor you can manipulate headers too, maybe with mydvdedit too - I didn't try such ugly hack)
Only advantage: speed
disadvantages: all others (and compatibility with dvd players too)

- reencoding: decode each image of the stream, break stream, rebuild with groups of 25 images per second, scale and encode.
Every command line tool and a fifo can do it
(PS: only for streams with progressive contents, interlaced streams are more complicated to handle)
Advantage: resulting quality
disadvantage: speed (it's an re-encoding): a DVD conversion from NTSC film<->PAL take almost 5*real time -on my old computer PPC 867Mhz*2- for audio (synch+ac3) & video.

PS: for audio, Audacity can scale and correct pitch (not very friendly nor speed, but I did it with it ...some years ago)
PSS: if your stream comes from satellite and you're satisfy with my soft, contact me directly (I have a newer version to decode broadcast h264, and I don't have ntsc stream to test).
bye

[terryj]

I surely have a Mac in front of me.

@ joachim:



didn't think to mention that fact in your OP eh?

[mats.hogberg]

Posting in the Mac forum is usually enough indication of what computer system is in front of the OP...

/Mats

[tomlee59]

There's also a "computer details" button you can click on if you're really curious or unsure. Takes less time to do this than to post an unhelpful and unnecessarily snide comment to the OP.

Joachim -- changing the audio speed is not hard, and in fact you have several options. My favorite is Audacity (which Herve already mentioned), which is not only free, but highly functional. You can even change the duration of the audio track without changing any pitches, so if you are one of those who is bothered by even a 4% shift in pitch, Audacity's "tempo change" tool is for you. So after you've demuxed into elementary streams, take the audio track and adjust its duration using the tempo change tool. You will have to specify duration quite accurately, of course, since even a 100ms error will be noticeable (and 200ms will be intolerable).

[terryj]

to all:
--first, if you read his post third down, he said it wasn't for the mac.
His details I checked BEFORE I posted my comment fourth one down,
right below his

Hm, they are not for the Mac.

post.


my kick in the face from the computer I stand by, due to his third post.
*shrugs*
plain and simple if he didn't say what he said in third post
...but I digress. I don't claim to be a mind reader, only I read what someone posted publicly and albeit confusingly?

and second, you know there's no love lost between me & you tomlee.
*shrugs*

[tomlee59]

terryj, read the entire thread, and you'll see that his "they are not for the mac" is a reference to the preceding mention of non-mac tools by mats. Reading before posting can be a useful habit to acquire.

If you don't have something useful to contribute, you should just refrain from posting. But you seem to have a bad habit of belittling and bossing folks about.

[mats.hogberg]

@terryj & tomlee59:If you have some issue to solve between the two of you, please do so someplace else. Keep this thread on topic, thank you.

/Mats

[terryj]

noted mats.

[JoachimS]

Hello Herve,

thanks for the link, I downloaded the converter app and I'll try it over the weekend.

Hope the others around here could calm down again....