I started yesterday collecting info about the replaygain stuff, and there are some things to consider IMHO. Here's a quick rundown of what i've found (forgive me for possibly incorrect usage of technical terms):
- If the MC devs decide to utilize "standard" replay gain tags, we could have a conflict with mp3gain. mp3gain writes own tags into the ID3V1 tags (at the "end" of a mp3 file), such as "MP3GAIN_MINMAX", "MP3GAIN_ALBUM_MINMAX", "REPLAYGAIN_ALBUM_GAIN" and a few others. I see a potential problem there with MC overwriting this information for albums that already have been processed with mp3gain.
- foobar 2000 uses ID3V2 tags for replay gain information storage. When using both mp3gain and foobar replay gain analysis on a mp3 file, you end up with different replay gain values in the ID3V1 and ID3V2 tags. This is bad, because the acutal volume values are different, probably because of different ways of determining the volume levels.
Some general thoughts:
- I think there is no such thing as a "general accepted standard" for replay gain. There are some "de-facto standards", but i wouldn't call the handling of replay gain a "standard" per se. The only "real" standard i see is the one implemented by FLAC.
- I can't understand all the fuss about RockBox. I mean, it's a very interesting project, and i appreciate the effort that's put into it. But you have to see what RockBox can do, and what it can't. On the iPod, using RockBox has some major drawbacks. For example. RockBox can't use the "standard" iPod database, which means you either have to build a special database within RockBox based on the file tags, or use a folder/filename based browsing approach. This is a major step backwards from the original iPod design IMHO, and makes RockBox pretty much incompatible with iTunes and MC in terms of database compatibility (think smartlists, for example). Another major RockBox flaw is that is doesn't support power saving functions on many iPod models. This means shorter runtime, and possibly higher strain on the batteries - a large problem IMHO, because it's not easy, and/or expensive to replace the iPod battery. Just have a look at the RockBox website, there are some detailed reports about RockBox' status. For the iPod, i think RockBox is just not "mature" enough yet, and i think it will take a long time before RockBox can be considered a feasible alternative to the original iPod firmware (I've been following RockBox' development for two years now, and it's advancing quite slowly). For other players, the situation might be different. I believe RockBox is more of a toy for experienced users, than a "mainstream" piece of software. It's a bit like Windows vs. Linux, IMHO - the latter holds much promises, but the former is the de-facto standard that can be used easily by "Joe User". I think it would make sense for JRiver to consider if it's worth investing precious development time into a platform that may be used only by a fraction of the potential customers.
My conclusion for the whole replay gain shebang is to use "hard" replay gain. foobar 2000 has a wonderful function where you can apply "hard" replay gain when converting files. The basic workflow is that you first analyze the audio, and apply replay gain tags. After that, you convert the files, and foobar will apply the replay gain settings to the resulting files. This means that, no matter on which device, and with which software you play the files, you will always get a "corrected" volume level. For mp3 files, mp3gain is my tool of choice. Using MC's replay gain functionality is just icing on the cake for me, for playing files in MC. With that approach, i lose an album's "original" volume setting, but i gain complete compatibility for each hard- or software, audio-cd's, and so on.