Most of the songs I included in the game (which are all public-domain) have Wikipedia pages about them. And almost every one of those Wikipedia pages has an Ogg recording of that song that is freely available under a license that allows it to be used in an open-source game. Anyway here is a typical comparison:
Gustav Holst's "Mars" movement of "The Planets" symphony:
siege.mid in art directory - 56.8 KB (58,263 bytes)
Ogg file from Wikipedia - 6.95 MB (7,298,204 bytes) - it is possible to re-encode at a lower bitrate if we want smaller filesize though... it is a variable bitrate Ogg file with an average bitrate of 122 kbps... we could re-encode it at the minimum Ogg bitrate of 64 kbps and then the filesize would be about half as big, about 3 and a half megabytes. It would be best to re-encode it as Ogg from a lossless original recording such as a FLAC recording, but re-encoding at such a low bitrate it probably wouldn't really matter either way.
Currently there are 34 MIDI files with a total file size of 1.05 MB (1,107,660 bytes). If compressed into a ZIP file with really good compression, this reduces the file size of the distribution of them to 309 KB (316,745 bytes). Compressing Ogg files in a ZIP file doesn't reduce the size at all, they are merely stored as-is, because Ogg is already a compressed format and you can't compress something that's already compressed.
That covers filesize. As for audio quality, go ahead and listen to the recording from Wikipedia above, it sounds pretty nice.
So the 34 songs range in duration from the shortest one that's 52 seconds long (elections.mid,
the aria Habanera from the opera Carmen by Georges Bizet) to the longest one that's 10 minutes and 10 seconds long (interrogation.mid,
Night on Bald Mountain by Modest Mussorgsky)... both of which are available as public domain recordings on Wikipedia, from the Musopen project... you can listen to them there. The durations of the Ogg versions of both of those on Wikipedia are longer than the MIDI versions.
So the average song is roughly 5 minutes long. At 64 kbps (64 kilobits per second), which is also 8 kiloBYTES per second, 5 minutes, or 300 seconds, comes out to 8 x 300 = 2400 kilobytes for the average Ogg file, about 2.34 megabytes since a megabyte is 1024 kilobytes not 1000. So we'll round this to 2 and 1/3 megabytes (or 7/3 megabytes). Multiplied by 34, this comes out to about 79 megabytes, for all of the music.
So the difference in music size is 1.05 megabytes versus an estimated 79 megabytes for all of the music (if we encode it using the lowest possible bitrate of 64 kbps for Ogg, which still sounds pretty decent).
So including Ogg music for all those songs would make the download size of the game much bigger, it would be 80-something megabytes I estimate. But the music sound quality would sound better.
Anyway I guess you can see why I thought maybe MIDI would be a good format based on disk space concerns, since I thought making the game take up that many megabytes might be controversial. Right now a .ZIP file of the entire game with really good compression, including all the MIDI files, takes up 1.22 MB (1,283,005 bytes), and the entire game, when you extract it onto disk and it's no longer compressed, is 2.92 MB (3,064,271 bytes). So if we add about 79 megabytes to it, well then it'll be many, many times as big. Well OK, 78 megabytes, since we'd subtract 1 megabyte for the MIDI files we're replacing.
But the sound quality would be much nicer if we use Ogg. The only downside is that the download for the game would be many times bigger. I didn't originally use Ogg, but used MIDI instead, because of filesize concerns. But several people have complained about the sound quality of MIDI and said they'd like Ogg better, in the thread about MIDI music. So, those are some basic statistics on the filesize... switching to Ogg would add about 78 megabytes to the size, and that's a rough estimate, it could be lower or higher, that's just the general ballpark estimate. To allow for more uncertainty I'd say it could be anything from 50-100 megabytes and possibly a little over 100 megabytes. But it would sound nicer.
Anyway, you can change your vote on this poll at any time. You aren't stuck with your original vote. In fact I'm going to change my own vote from Ogg Vorbis to MIDI right after I post this, now that I've analyzed this more. Strike that, it appears you can't change your vote on this poll. I tried to enable changing your vote but I guess it didn't work.
Now let's consider the Opus codec again, that next-generation codec that there's an experimental branch of SDL2_mixer with support for it. It can still have fairly nice-sounding quality even at very low bitrates, lower than 64 kbps. It supports bitrates as low as 6 kbps. At 6 kbps instead of 64 kbps, to use the most extreme example of a low bitrate to save disk space, Opus would take up about 225 kilobytes for the average 5-minute song, and if you multiply that by 34 songs, you get about 7.5 megabytes. Now that probably wouldn't sound very nice since the bitrate would be extremely low... bitrates that low are just considered suitable for speech, not music. And it would still be several times bigger than the MIDI files which are just 1.05 megabytes. At such a low bitrate it would probably sound worse than them. But Opus audio at 48 kbps sounds pretty decent for music. It would take up 3/4 of the space of 64 kbps Ogg... so instead of being around 80 megs it'd be around 60 megs. Still big though. Plus if we used that experimental branch of SDL2_mixer we'd have to include all the source code for it as part of the source code of Liberal Crime Squad itself or else we'd give people on UNIX-based systems a complete nightmare for compiling.
OK, so Opus would make it much harder to maintain the project with such an unstable untested dependency as that SDL2_mixer unofficial branch and wouldn't offer any major improvement over Ogg Vorbis other than being able to encode at lower bitrates that don't sound as good and if it doesn't sound as good that defeats the whole purpose of using a format that sounds better than MIDI. Let's forget about Opus and just think about it as Ogg Vorbis vs. MIDI. Switching to 64 kbps Ogg Vorbis from MIDI would make the compressed ZIP of the game about 65 times bigger and the uncompressed game after you extract it about 28 times bigger (both being about 80 megabytes). So, is that what we want or not?
Hmm I guess we could also give the MOD format another look, it has full support by SDL2_mixer and comparable filesize and quality to MIDI. The only difficulty with it would be converting all the music to the MOD format, that would be a REAL pain in the buttocks. It would give everything a nice chiptunes-like sound. If you've ever used a crack or keygen to pirate software and it had music playing in the background, those all use the MOD format, so anyone out there involved in software piracy probably knows what MOD music sounds like. Not that I know anything about software piracy myself, I just read that information on Wikipedia, I obviously have no firsthand knowledge of such a thing, I'm a law-abiding citizen, this is just secondhand knowledge from the Wikipedia article about MOD music. Anyway though, I like the sound of MOD music, it would just be a total pain to convert music into the MOD format and take vast, huge amounts of time and effort, and it wouldn't really sound much better than MIDI, and if you're someone who doesn't like chiptunes-type sounds that are all like beeps and boops, it'd actually sound worse to you.
So uhm, let's just stick to Ogg Vorbis versus MIDI like I said originally. If you want the game to be somewhere on the order of 80 megabytes bigger but have nicer sound quality, Ogg Vorbis is your choice. If you're willing to settle for sound quality that isn't as good (but actually can sound pretty good if you install a good MIDI synthesizer on your computer like one that uses SoundFonts), in order to save disk space (and lots of it), well then go for MIDI.
Heh, maybe we could even offer BOTH options to people... so people who want nice sound can have an Ogg Vorbis version of the game, while people who want to save disk space can have a MIDI version of the game, and they'd be offered as separate downloads... naaah, I dunno about that idea, it seems too extreme, to have more than 1 version of the game, one that uses one audio format and one that uses a different audio format, that would mean we'd have to release 2 different editions for each version of the game. It would be a real pain to maintain 2 different versions of the game. Well I have figured out how I could implement the code so it would load Ogg Vorbis versions if they exist and if the right libraries for Ogg Vorbis are present, and use MIDI as a fallback. I could make that change to the code. Then the same code, and same compiled executable of the game would be able to work with either Ogg Vorbis or MIDI files depending on what is in the art directory. Hmm actually that's a pretty good idea, we don't have to make this an either-or, we can offer both options. Ah, I know, I'll change the poll to add that as an option to pick, and vote for it myself.
Oops... I was able to add the option but for some reason it looks like I can't change my vote on the poll. Oh well... I added the option to allow both formats, and then after I couldn't change my vote, I reset the vote counter to zero and I was able to re-vote again. Before I reset the counter there were 2 votes for Ogg Vorbis (me and someone else), and 0 votes for anything else. Now I've reset the counter to zero and changed my vote to "BOTH!". The other person who already voted can also re-vote if they want, now that the poll has an additional option. Unfortunately it looks like people won't be able to change their votes. If you vote one way but then change your mind and want to vote a different way you should post a comment below (luckily you can edit comments).