AC3 sound and choppy video

[mmjb4500]

First I'd like to say thank you to all the comments and suggestions at this forum. The advice here has helped me greatly. I've ripped 15 movies so far. All have looked great, but I have had a few file size problems. Big Deal.

My problem is I can't figure out how to encode with AC3 5.1 digital sound. I can mux the sound afterwards in Nandub, but the picture then becomes choppy (as in a cheap video card. Know what I mean?). What I do is, let's say the AC3 file is 350 meg. I'll set the video to be a filesize of 1040 megs. Then dub the AC3 track in. Sounds great................BUT CHOPPY video. Is there a site or could someone in there most experienced wisdom PLEASE help me. I can get (for free) an endless supply of DVD's to rip. I would love to have AC3 sound as I have an Audigy MP3 SC hooked up to a Harman Kardon AVR220 DTS amp. HELP!!!!!!!!!!!!!

[theReal]

Try different interleave settings - the defaults from Nandub are good for mp3, not for AC3.
For me, 160ms preload and 160ms interleave works fine, there are other good values in the Audio FAQ.
Also remember to set these interleave values again when you cut the file with Nandub.

[mmjb4500]

I tried instead of saving, but to do a two pass. It seemed to work for a 540 meg vid file. I will try it on a larger file tomorrow. Thanx for the reply.

[theReal]

I tried instead of saving, but to do a two pass.:confused:

This has nothing to do with two-pass encoding. First, you encode the video without audio, then you mux it with the AC3: Open the encoded video in Nandub, set video processing to "direct stream copy", then add the audio and set the correct interleaving values, also set the audio processing to "direct stream copy". Now you can save the video file (should be very quick, around 3000 fps, because it is a direct stream copy)

[MvB]

Try virtualdub-ac3 and an interleave setting of 60ms instead of 160ms.
that worked fine for me. With nandub i always had problems.

[theReal]

This is from the Audio FAQ (http://forum.doom9.org/showthread.php?s=&threadid=18318) __What interleave settings should I use to mux my AC3 in NanDub? This is by far the most difficult task for some people. It seems as though we can't have a magic set of numbers that will work for everyone. This is mostly trial and error in order to find the right values. So below is a few common interleave settings for muxing AC3 (preferably using NanDub)-



code:--------------------------------------------------------------------------------
90ms/90ms
120ms/120ms
500ms/128ms
500ms/64ms
160ms/160ms (Works well for 5.1 384kbps)
128ms/128ms (Works well for 5.1 448kbps)
96ms/96ms
80ms/80ms (Works well for 2.0 192kbps)
64ms/64ms
250ms/64ms
160ms/60ms
160ms/2frames
500ms/3frames
--------------------------------------------------------------------------------


First value above is for preload. Some users have reported choppy playback if using the NanDub default 500/1frame setting. There has been some discussion in the forums and the general consensus for most users is that the values must be multiples of 32(i.e. 64, 96 or 128). One of the values above should work but it will take some patience testing them.

Also worth noting, Acaila kindly pointed out that certain interleave values above might only work for a specific AC3 bitrate. A 448kbps AC3 seems to work nicely with a 64ms/64ms setting but audio drop outs might occur with this setting. I tested 96ms/96ms and 128ms/128ms and they both worked very well on a Fortissmo II and TB Santa Cruz card. For a 384kbps AC3, try an interleave of 160ms/160ms.

[mmjb4500]

Ok, I have it worked out. Now when I try to split the file the sound goes choppy or the video is choppy. Any help?

[theReal]

when splitting the video, you have to set the interleave values again, otherwise the Nandub defaults are used.

[mmjb4500]

I've done that, but the sound is either screwed or the video is choppy. This only happens in AC3. The settings I used were 128 ms, 128 ms and 400 ms delay.

EDIT

I figured it out. Thanx everyone.