intentional dynamic compression for MP3's

squib

Member
2007-07-10 12:52 pm
At risk of asking a heretical question...has anyone else experimented with dynamic compression for ripped (AAC, MP3, etc.) tracks? I've been trying recently to produce separate versions of my small collection of symphonic music for more casual listening in the kitchen. The problem with the originals is the large dynamic range for much of this music makes it difficult to use as background music. Quiet passages are lost when the volume is adjusted to keep the loudest passages from overwhelming conversation (or scaring the wee kiddies). I've grown accustomed to listening to public radio broadcasts of classical music, but lately have found the selections rather off-putting (ie. lots of John Williams and other hollywood soundtracks). The music is being played through a Tivoli PAL radio, so high fidelity in the source is large wasted.

I've tried importing tracks to Audacity and compressing at -12bd and -18db using a 2:1 or 2.5:1 ratio. I'm exporting the processed file as a VBR MP3 (200-250 kbps). Depending on the content of the track, the results have been promising, but I'm curious if anyone else has done this and might offer some tips.

Thanks,
Squib
 

squib

Member
2007-07-10 12:52 pm
graphical example

Here's an example of a track that is rather difficult to manage...

Shostakovich Symphony No. 8 in C minor OP 64 - Largo
 

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squib

Member
2007-07-10 12:52 pm
Thanks for the suggestion, dangus.

It would be handy to have the ipod handle the compression. Creating multiple copies of even a small music library is daunting, and I'd just as soon skip it.

RE: Rockbox. I've been tempted in the past, mostly for Ogg support and because the Apple firmware continues to choke on their own hardware. I have to reset the Ipod at least once a month because it refuses to power down. One hiccup for 3rd party firmware is my DLO HomeDock. I don't think it will get along with RockBox, but I confess I've never looked into it. Looks like I have another date with google!

Thanks again,
Squib
 

error401

Member
2007-03-24 7:54 am
squib said:
One hiccup for 3rd party firmware is my DLO HomeDock. I don't think it will get along with RockBox, but I confess I've never looked into it. Looks like I have another date with google!

Thanks again,
Squib
Audio out should work, but the remote will not. Proprietary Apple Accessory Protocol is completely unimplemented in RockBox, and I don't think they really want it there, since it has been at least partially documented.
 

squib

Member
2007-07-10 12:52 pm
Audio out, but no remote

Alas, for me that's a deal breaker. I don't see much advantage to using the HomeDock if the remote is non-functional.

As a side note: While googling for info on RockBox/DLO compatibility, I bumped into numerous posts from DLO owners complaining that the HomeDock is hosing their Ipods. Perhaps I was too quick to blame apple for my power down problems with my Nano.

I've downloaded a firmware update for the HomeDock and will see if that helps.

Thanks for the info!
 

squib

Member
2007-07-10 12:52 pm
That's what I've been doing so far (see 1st post). I was curious what settings other people have tried, assuming I'm not the only one attempting this...

Audacity does some pretty impressive processing. I've used it in the past to clean up digital rips of obscure music from 20-year old cassettes.

Thanks again for the input!
 

squib

Member
2007-07-10 12:52 pm
rane dc22

Dangus,

I just took a quick peek at the Rane catalog, and sure enough there is a decent looking compressor that would do the trick: (DC22)

However, $300 is more than the Ipod & PAL put together. Given my current needs, I'm going to press on with my Audacity experiments.

If anyone is curious, I'll post back when I have some useful observations on the Audacity compressor settings.

Squib