ScummVM tools question (audio compression)

monkeyman · Post by **monkeyman** » Thu Jan 10, 2008 9:50 pm

Hiya,

I'm trying to extract some of The Dig's in-game music. I found a utility in the tools, compress_scumm_bun, that can get the music clips out of the DIGMUSIC.BUN file. Unfortunately it then immediately deletes them

but a quick source change fixed that.
I now have over 500MB worth of WAV clips (22kHz, 16bit) that I am trying to encode to MP3.

compress_scumm_bun actually does the encoding already, but to rather low quality MP3 files: VBR between 56 and 64 kb/s.

My question is just whether there is any reason for these low default settings? Did someone perform a listening test or is the aim just to save lots of space?

Thanks in advance.

spookypeanut · Post by **spookypeanut** » Fri Jan 11, 2008 12:26 am

Don't forget we're working with 22k audio, not 44k (like CDs). That means that half the bitrate will retain the same quality (i.e. 56/64 kb/s is equivalent to compressing a CD at 112/128 kb/s)
Are the samples compressed (in a lossy way) inside the BUN file? If so, probably a little pointless using v high bitrates...

clem · Post by **clem** » Fri Jan 11, 2008 2:19 pm

I'd also expect them to be mono instead of stereo (as you'd expect from music), which would further reduce the bitrate needed

can't check from here though

monkeyman · Post by **monkeyman** » Sun Jan 13, 2008 6:25 am

spookypeanut wrote: Are the samples compressed (in a lossy way) inside the BUN file? If so, probably a little pointless using v high bitrates...

I don't know, but it sure looks like it: the original DIGMUSIC.BUN is about 250MB, whereas the WAV files amount to just over 550MB. I don't suppose any lossless compression could account for this 50%+ size decrease, could it?

monkeyman · Post by **monkeyman** » Sun Jan 13, 2008 6:26 am

clem wrote:I'd also expect them to be mono instead of stereo (as you'd expect from music), which would further reduce the bitrate needed

can't check from here though

No, they're definitely stereo (just checked on my headphones

)

fingolfin · Post by **fingolfin** » Sun Jan 13, 2008 12:34 pm

BUN files are indeed already compressed, using the "IMC" codec, a variant of IMA (see http://www.multimedia.cx/simpleaudio.html and http://wiki.multimedia.cx/index.php?tit ... dio_Codecs).

monkeyman · Post by **monkeyman** » Sun Jan 13, 2008 7:50 pm

Thanks for the info Fingolfin,
Hope this is not a stupid question but I'm assuming IMC is a lossless compression?

SithlordDK · Post by **SithlordDK** » Mon Jan 14, 2008 9:55 am

Wahh!! I wanna extract the DIGMUSIC.BUN file too

!

Noelemahc · Post by **Noelemahc** » Mon Jan 14, 2008 10:54 am

SithlordDK wrote:Wahh!! I wanna extract the DIGMUSIC.BUN file too !

Then do so. For crying out loud, ScummRevisited2 has been out for several years now, but nobody seems to know of its existence.

monkeyman · Post by **monkeyman** » Mon Jan 14, 2008 7:22 pm

ScummRev will not extract the music from DIGMUSIC.BUN, unfortunately (tried with both v2 and v5).

The only ways I found to get the tracks out of the BUN file are with the Dig Music Player, or using compress_scumm_bun.exe from the ScummVM tools.

Noelemahc · Post by **Noelemahc** » Mon Jan 14, 2008 7:47 pm

Which is kinda weird, since I remember quite clearly I've used ScummRev to tear up my copies of DIG, CoMI and FT for the music tracks I've liked. Hmmm. Gotta go check if that was actually the case.

SithlordDK · Post by **SithlordDK** » Tue Jan 15, 2008 9:28 am

monkeyman wrote:ScummRev will not extract the music from DIGMUSIC.BUN, unfortunately (tried with both v2 and v5).

The only ways I found to get the tracks out of the BUN file are with the Dig Music Player, or using compress_scumm_bun.exe from the ScummVM tools.

Thanks for that link! I tried it also with ScummRev before and it didn't work.

monkeyman · Post by **monkeyman** » Sun Jan 20, 2008 9:48 pm

Well if anyone's interested.... I finally managed to put the entire ingame soundtrack online, here:
http://www.megaupload.com/?d=Q2WRPK6T

Files were extracted from DIGMUSIC.BUN, joined up using foobar2000, renamed to the non-truncated track labels, and finally encoded with LAME.

Have fun.