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[Proposal] Beatmapset's Audio File Must Be CBR mp3

posted
Total Posts
17
ailv
403 posts
Joined August 2015
Topic Starter
ailv

Proposal wrote:

A beatmapset's audio file must use the .mp3 file format and have a constant bit rate of no greater than 192kbps. This ensures that the audio file will be compatible across a range of platforms and does not cause issues in osu!.


Currently osu supports wav, ogg, and mp3 files, for an audio track, but mp3 has been the only one used. This formalizes the container format allowed for use in ranking, which may not be clear otherwise.

mp3 is an optimal choice due to it's compatibility, relatively low file size, and relative accessibility and prevalent use.

This rule also prevents VBR files from being used, which has issues regarding differing offsets, and audio delay, along with some incompatibility with the editor.

This also includes the following rule currently in the RC:

RC wrote:

A beatmapset's audio file must be no higher than 192kbps. Variable bit rate songs must average at 192kbps or lower.


The proposal catches and limits the CBR to a limit of 192kbps and as such the current RC can be removed for this one.
anna apple
1,256 posts
Joined March 2014
anna apple
can you speak non audiophile words, wat is cbr and vbr
ailv
403 posts
Joined August 2015
Topic Starter
ailv
cbr = constant bit rate, vbr = variable bit rate. CBR is already written out as constant bit rate explicitly in the rule.
Ikikaera
149 posts
Joined January 2014
Ikikaera
CBR = Constant Bitrate
VBR = Variable Bitrate

VBR basically lowers the bitrate when there's less going on in the song while CBR keeps it constant throughout.
This helps a lot for saving filesize but osu or rhythm games in general don't really like those kinda files.
pimp
1,417 posts
Joined April 2010
pimp
don't see any reason to oppose this


additionally....
since peppy told us not to be looking at spectros then we should at least add back the 128kbps minimum bitrate because if we don't have a minimum allowed bitrate in the rc then we are allowed to use whatever bitrate we want that's bellow 192, so even "youtube rips" are acceptable currently as long as the bitrate is not upscaled and you can't really force mappers to replace the youtube rips since they can just claim they are keeping it to reduce filesize.

we should have a rule that can be relevant for most songs (128kbps min ~ 192kbps max), not to change it completely just because of some isolated cases like jumping jack flash. also there are more efficient ways to reduce beatmap file size than checking spectrogram and messing with mp3 bitrates.

btw people generally try to use the highest allowed bitrate mp3, i'm assuming we are getting so many DQ's for mp3 bitrate upscaled to 192kbps lately because mappers forgot (or never knew) that 128kbps mp3 are rankeable.
Last edited by pimp , edited 1 time in total.
Ikikaera
149 posts
Joined January 2014
Ikikaera
Tbh this line in the RC "A song's audio file must be of reasonable quality. Try to find the highest quality source file available rather than ripping a file from a streaming video website. Songs should be normalized to their original release volumes." still discourages youtube rips.
pimp
1,417 posts
Joined April 2010
pimp
forgot about this one somehow :?
but you can still get a good quality mp3 and reduce the bitrate to bellow 128 with the current rule.
ailv
403 posts
Joined August 2015
Topic Starter
ailv

pimp wrote:

forgot about this one somehow :?
but you can still get a good quality mp3 and reduce the bitrate to bellow 128 with the current rule.


then it would no longer be of a reasonable quality
pimp
1,417 posts
Joined April 2010
pimp
according to what? peppy removed the 16khz minimum frequency and the 128kbps minimum bitrate is no longer in the rc.
ailv
403 posts
Joined August 2015
Topic Starter
ailv

pimp wrote:

according to what? peppy removed the 16khz minimum frequency and the 128kbps minimum bitrate is no longer in the rc.


to your ears, its left for the bng to decide, using their ears and listening to the song

A song reeconded that far down in terms of kbps will lack high end and sound awful. Spectrums and hard kbps and hz limits are not suitable for deterministically telling what is higher quality, which is why the other rule is written the way it is, so that you use your ears to determine if it is an acceptable quality.
Last edited by ailv , edited 1 time in total.
pimp
1,417 posts
Joined April 2010
pimp
mp3 quality shouldn't be treated like something subjective... for the amount of mp3 dq's you can say that BN's have different opinions regarding mp3 quality and/or they don't have good enough headsets to even notice the difference.

usually when i compare the mp3 from those disqualified maps i hear minimal difference or none. i'm sure that my ears are fine i just don't have high quality headset for now (and i don't think it's fair to expect BN's to spend a lot of money with headsets).

if bellow 128kbps results on bad quality then 128kbps should be in the rc as the minimum allowed.
alternatively the rule could be rewritten so 192kbps is the only rankeable bitrate unless there is no good quality mp3 available like in jumpin' jack flash.
ailv
403 posts
Joined August 2015
Topic Starter
ailv

pimp wrote:

mp3 quality shouldn't be treated like something subjective... for the amount of mp3 dq's you can say that BN's have different opinions regarding mp3 quality and/or they don't have good enough headsets to even notice the difference.


Mp3 quality is inherently somewhat subjective, it's not like you can look at a spectrum and tell if it's high quality or not, and there's no real tangible way aside from listening to tell if it sounds good/bad. Of course BN's will have differing opinions regarding mp3 quality. If a BN doesn't have a good quality headset, and someone else that does, provides a better mp3, that works fine. It is unreasonable to expect everyone to have high level audiophile set ups, or potentially even decent monitors, but other people playing the map shouldn't need to listen to poor audio quality, just because some BN or mapper was too lazy to improve it.

pimp wrote:

usually when i compare the mp3 from those disqualified maps i hear minimal difference or none. i'm sure that my ears are fine i just don't have high quality headset for now (and i don't think it's fair to expect BN's to spend a lot of money with headsets).


Same as above, but keep in mind the vast majority of the dq's that have happened are on extremely bad mp3s that while you may not be able to hear, most people can.

pimp wrote:

if bellow 128kbps results on bad quality then 128kbps should be in the rc as the minimum allowed.
alternatively the rule could be rewritten so 192kbps is the only rankeable bitrate unless there is no good quality mp3 available like in jumpin' jack flash.


Please see https://osu.ppy.sh/community/forums/topics/923648, where this topic has been discussed already.
pimp
1,417 posts
Joined April 2010
pimp
messing with original the rule was a mistake to begin with, the rule was perfectly fine the way it was, the problem is that some people made the mistake of not taking the time to find decent quality mp3 for their maps and upscaled it to max allowed bitrate.

there is no need for this to be subjective because nothing can go wrong if you get a good quality mp3 and change the bitrate to 128~192 with a decent program, the old rule had nothing to do with people not following these simple steps correctly...
and like i said before, i wouldn't bother about the rare cases where a good quality mp3 for the song doesn't exist but this could have a guideline for it as mentioned in the op post from the thread you linked.

actually i'll just wait until your proposal is finalized and will make this an individual proposal
pishifat
osu! Paragon
3,812 posts
Joined August 2013
pishifat

ailv wrote:

This rule also prevents VBR files from being used, which has issues regarding differing offsets, and audio delay, along with some incompatibility with the editor.


can i get a source on this
ailv
403 posts
Joined August 2015
Topic Starter
ailv
Discussion with pishi and input from ppy has resulted in decisions to fix poor VBR support if they appear, as of now VBR should be bugless and thus that can be removed.

Proposal wrote:

A beatmapset's audio file must use the .mp3 file format and have an average bit rate of no greater than 192kbps. This ensures that the audio file will be compatible across a range of platforms.


the wording "average bit rate" encompasses both cbr and vbr files, since cbr will have up to a constant 192.
pishifat
osu! Paragon
3,812 posts
Joined August 2013
pishifat
https://github.com/ppy/osu-wiki/pull/2453 will be pending for a few days for last minute input
pishifat
osu! Paragon
3,812 posts
Joined August 2013
pishifat
merged
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