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The Moog
22nd October 2002, 12:09
Hi there,
I have encoded quite a few movies using XMPEG and DivX 5.02, but when I watch them the soundtrack is really quiet, even with the volume turned right up on WMP and on the TV. I was just wondering if there was any way that I could extract the soundtrack from the AVI, amplify it and put it back without having to re-encode the video (as that part is OK!), or are the two streams intrinsically linked to one another? Thanks for any help,

The Moog

bb
22nd October 2002, 14:31
You didn't say which audio compression you used, so I assume MP3 (maybe VBR). You can open your AVI in NanDub, then File / Save WAV to get the MP3 file (having a WAV header, and a .WAV extension, if you didn't change it).

Use a tool capable of changing the volume in your MP3 file without re-encoding (I think there are tools like "MP3 normalize" or similar).

Then open your AVI again (if you closed it in the meantime), and mux the files again using NanDub. Choose the MP3 file under the audio options. Make sure you selected "Direct stream copy" under both, Video and Audio. Then File / Save AVI.

bb

manono
22nd October 2002, 14:40
Hi-

You can boost the volume without removing the audio, with the DeDynamic Filter (http://www.doom9.org/Soft21/Audio/dedynamic02.zip). But if you prefer to take the audio and work on it, then open the .avi in Nandub, set Audio and Video to Direct Stream Copy, and then File-Save WAV to strip out the Audio. Then when done, rename the extension (to .mp3, for example).

Edit-you beat me to it, bb-I got interrupted while replying.:)

The Moog
22nd October 2002, 15:17
Sorry,

I used MP3 compression at 128kb/s. Thanks for both the replies, I'll give it a go!

The Moog

The Moog
22nd October 2002, 15:46
Hi again,

I have downloaded Nandub, pulled the MP3 audio track out of the avi and saved it. What is the best tool to use to normalise it? I have looked in the downloads section of Doom9.net and there doesn't seem to be anything there to do MP3's, and I have had a quick search elsewhere with no luck. Also, will there be any problems with syncing between the soundtrack and the video when the MP3 is put back into the avi? Thanks for all the help,

The Moog

OvERaCiD23
22nd October 2002, 19:57
You'll want to use BeSweet for the audio. Download the latest BeSweet and then the GUI for it from the downloads section. read the guides on the site as well. your process will be a bit different since you're only re-encoding the the MP3 (not AC3 ~> MP3), mainly just easier. if you don't want to do all of this, use DeDynamic in playback (much easier IMO).

manono
22nd October 2002, 21:25
Hi-

From the Audio FAQ (http://forum.doom9.org/showthread.php?s=&threadid=7633) in the Audio Forum (always a good source when you have audio questions):

14) Can i raise up the volume of an mp3 without doing decode,normalize,encode?
Yes, there are few programs that offer this, check MP3 Gain (http://www.geocities.com/mp3gain/) & MP3 Trim (http://www.logiccell.com/~mp3trim/), for instance.Be careful with MP3 Gain. It will make it as loud as you want, but it's real easy to get clipping (distortion) in the louder passages.

jggimi
22nd October 2002, 22:41
BSPlayer has the DeDynamic filter "built-in". You can turn in on from the Preferences....Audio tab.

The Moog
23rd October 2002, 00:06
Thanks for all the help guys,
I will take a look at each of these options and see which one suits me the best. Cheers again!

The Moog

bb
23rd October 2002, 11:28
Originally posted by OvERaCiD23
You'll want to use BeSweet for the audio
Although BeSweet is an excellent tool, do not use it in this special case, because re-encoding decreases the quality. Use the recommended MP3 Gain instead.

bb

DSPguru
23rd October 2002, 19:22
Originally posted by bb
Although BeSweet is an excellent tool, do not use it in this special case, because re-encoding decreases the quality. Use the recommended MP3 Gain instead.in fact, i have already implemented the loseless gain assertion on mp3 in BeSplit, but i just fail to find the time to pack a release..

bb
24th October 2002, 06:42
Originally posted by DSPguru
in fact, i have already implemented the loseless gain assertion on mp3 in BeSplit, but i just fail to find the time to pack a release..
DSPguru, again you succeed in surprising me. :)

bb

lovecraft25
24th October 2002, 10:16
@The Moog

Hello,

It's a well known problem of FlaskMPEG/XMPEG : the audio is always soooo weak...
You should encode your video & your audio separately, by example :
you encode the video stream with XMPEG and you encode the audio stream with HeadAC3he or BeSweet (the sound will be very fine !)
and then you mux the two together with VirtualDub/NanDub.
To do that, you have first to demux the AC3 track from the VOBs...

A+

DSPguru
26th October 2002, 09:01
Originally posted by lovecraft25
To do that, you have first to demux the AC3 track from the VOBs...no, he doesn't have to ;)
BeSweet offers a direct VOB->MP3 conversion.

@bb
BeSplit v0.9b3 can now be found on my beta page (http://dspguru.notrace.dk/beta.html).
it's bundled with BeSliced v0.3 and it has a nice feature in the menu - Normlize+Header - for normalizing and adding wave header (for muxing in vbdub) in a single process.

in fact, BeSplit can also remove bogus wave header, fix corrupted stream, normalize, cut a stream to slices and add wave header to each one of them - all in a single process.

bb
28th October 2002, 08:51
@DSPguru:
Great, thank you very much. I'll test it as soon as I get the time. And report back, of course. This week I have a lot of things to do, so this may take a while...

bb

DaveQB
30th October 2002, 11:50
dunno if i am looking at this too simply but i use Virtual Dub and under Audio select > Volume
and then up it to its highest settings (something like 965%)

sounds comes out just right at the end of encoding

hope this helps ... :confused: