Converting 5.1 Ac3 from Pal to NTSC...

[KillerBear]

I have an XVid which has a 5.1 AC3 as the sound. The framerate of this file is 25 fps.
I need to get it to NTSC, converting the video is no problem (I am well aware of the features of VDub)... BUT I have never converted an AC3... any ideas? any tools I dont know about?

Thanks...

Oh, as a side question, what is the best way to convert video/sound to NTSC that have very strange framerates. I have some avi's that have like 14 fps and crap like that.... anyone?
Thanks...

[redwudz]

I'm afraid I have been doing PAL > NTSC conversions the easy way: VSO DivxToDvd. I don't think it does AC3 5.1 sound, though. Just AC3 2 channel.

For the files I have, mostly DIVX and XVIDs, it works fine and saves a lot of time and effort.

Someone can probably point you to some guides for a better method to preserve the 5.1 sound and do the odd framerate conversions.

[KillerBear]

I looked at that VSO DivX2DVD... looks very basic, and theres no configuration settings... weird...
I use CCE.... which is great. Like I said, I have no problem encoding the video.. I've just never come across having to change a framerate on an ac3.
Am I going to have to extract all the ac3 channels as WAVs, change the framerate on each of them, then re-encode the ac3????
I sure as hell hope not....

Any ideas????
If that is what I have to end up doing, anyone know of a tool I could do this with (extract each channel from the AC3)???
Maybe the AC3 Machine front-end for Besweet?

Some help would be appreciated

[guns1inger]

Leave it PAL and get a mutli-format player and you'll get the best results. Short of that, you will have to demux the audio back to 6 mono wav files, retime each one to match the new playback time, then re-encode. Surprisingly, no-one appears to have added this feature to any of the besweet front ends yet.

[incredible]

a) Doing it in Besweet by using a preset from 25fps to 23.976fps. BUT reencoding AC3 could be problematic as ac3enc.dll bases on the liba52 core which causes Problems while playback on some SAPs! So u have to test. Otherwise Do decode the 5.1 AC3 using besweet and the 25to23,976 preset and choose 6ch Wav as output which will be encoded to a full compilant AC3 using Softencode. Softencode is no longer available so u have to search for a used software maybe on ebay.

b) Via Avisynth (if you got some skills on avisynth)

Avisource("25fpsXVID",audio=false)
Dgbob(x) # x= Fielddorder 0 or 1
Converttofps(29,97*2)
Separatefields().selectevery(4,0,3).weave()

but this wil result in a fieldblended 29.97 fps Video, means interlaced including its combing artifacts, .... so thats only for NTSC 525 Lines TV target purposes.

[KillerBear]

lol. I have no skills in AviSynth. When I need to use it I use FitCD (the frontend). lol

What I have found when I demuxed the ac3 is that it was not a true 5.1 ac3.. whoever encoded took a mono wave and stuck it in there 6 times!! ha

So I just took one of em and I'm using Adobe Audition to stretch it...
I was also looking at this page: http://neuron2.net/dgpulldown/dgpulldown.html

It looks like an easy way to convert PAL to NTSC just by altering the MPEG2 RFF/TFF flags. That way I dont have to change the audio at all!!! Sweet huh?? Only problem is that this procedure only works with a progressive source... :\ And I dont know how to tell interlaced vs progressive. And if it is interlaced how to de-interlace it....

Any help on that matter?

Thanks guys...

[Abond]

Xvid at 25 fps - well 99.99% it is progressive. You can look for interlaced artefacts in VDub.
How they look like? www.100fps.com is the answer.

[manono]

Hi-

You're starting with an XviD AVI, right? Then almost by definition it's progressive. Just resize to 720x480, adding the black bars if necessary (get the script from FitCD if you don't know how to make it yourself), and then run DGPulldown afterwards. But just to be sure, you could open the AVI in VDubMod and scroll around looking for interlacing/combing.

Abond beat me to it. Hi Abond

[Abond]

Hi, manono .

[KillerBear]

So are some formats progressive and some are interlaced?
I dont get it... how can I tell by looking at the file which it is?
And when I open it in VDubMod, and if I find these artifacts, what do I do?

If I have an interlaced source, what do I use to de-interlace?
------

Anyways, back to my xvid.. I'm going to go with the DGPulldown method (that way I dont have to screw around with the audio). So first I need to resize my PAL source to 720 x 480. So I load up FitCD and make a script. Then just to make sure it looks ok, I load the script into Windows Media Player... I have the original PAL source and the NTSC script loaded in the que right under each other... and the times are different!
The PAL source is 2:10:13, and the script I just made is 2:15:46. If I encode this script I'm going to have to encode the audio anyways because already it will be out of sync.
How can I resize the PAL source without changing the length of the movie?

[manono]

Hi-

Make sure that the script you're going to use for DGPulldown later on doesn't have AssumeFPS(23.976) in it. If it's there, remove it. When you told FitCD you were going to convert from PAL to NTSC, it added that line to slow it down to NTSC speed. When using DGPulldown that's not necessary, as the whole point is to avoid reencoding the audio.

So are some formats progressive and some are interlaced?

Most can be both, but for AVI they're almost always progressive. If you open the AVI in VDub and still see interlacing lines/combing, it usually means that the original encoder didn't know what he was doing, and you may as well throw it away, as in most cases the fields have already been destroyed and it can't be fixed/deinterlaced.

If I have an interlaced source, what do I use to de-interlace?

If the source is a DVD, and the destination format is AVI, you either ForceFILM in DGIndex, IVTC it, or you deinterlace it. That's for NTSC only. Most PAL DVD sources are already progressive. If the source is a DVD and the destination format is also DVD, you either ForceFILM it, IVTC it, or you leave it alone. Again, NTSC only.

To deinterlace, when using AviSynth to frameserve, you use one of the many AviSynth deinterlacers, such as TDeint, KernelDeint, or FieldDeinterlace. For the best combination of speed and quality, KernelDeint is probably the way to go. TDeint can be better, but it's slower.

And if you're going to continue to use AviSynth, I'd suggest you put in some time to learn it. It'll be worth it to you in the end. A good place to start is http://www.avisynth.org/

[KillerBear]

Thanks.. that helps alot.

[digitalfreaknyc]

My question is similar in that I DO want to change from PAL to NTSC and slow it down. So I want to use DGPulldown (which gave me really good results already).

1) is there a way to resize to 720x480 without re-encoding (like if i used tmgenc or other)?

2) have we found a way to stretch 5.1 ac3 from pal to ntsc without breaking out each of the wav files?

[KillerBear]

I'm pretty sure you have to re-encode to re-size it. As for stretching the AC3..... I havent heard of anything, but there may be a way. Like in some audio editing programs you might be able to do it... Adobe Audition, Sonar... that kinda thing.....

[digitalfreaknyc]

Adobe Audition won't play ANY AC3s right now.

If one were to break up the 5.1 track into separate tracks...how would one do it? and then join them back together?

[mats.hogberg]

1) is there a way to resize to 720x480 without re-encoding (like if i used tmgenc or other)?
2) have we found a way to stretch 5.1 ac3 from pal to ntsc without breaking out each of the wav files?

To the best of my (limited) knowledge:
1) No
2) No

/Mats

[guns1inger]

The payware version of DivxtoDVD supports multi-channel audio, although I haven't tested format conversion with 5.1 audio yet. It certainly retains 5.1 audio for straight conversions.

[mats.hogberg]

It certainly retains 5.1 audio for straight conversions.

Well, that's about the easiest task there is for an encoder....

/Mats

[digitalfreaknyc]

Pretty easy. just have to separate each track...use adobe to stretch...combine back together to ac3. haven't done it yet though.