jalport

Compressing audio file size whilst trying to preserve more quality

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Hi, I'm trying to work out a way to preserve some more quality when I compress to a low bit rate m4a to be used in an online browser game.

Any help would be greatly appreciated for any software oriented musicians! 

Cheers

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Google audio file converters and you'll get a ton of options. I'm on Mac and use one called Switch. Lots of options and works great. I've also used Triumph as well as Soundforge (PC version is better than the Mac one) and have used Audition as well. iZotope's RX is great for this as well but that's probably overkill for what you're after. 

If you're just changing the file and not doing any actual audio processing (i.e. limiting, EQ, clean up, etc) then it's very easy to do and you'll find a ton of options. If you're looking to do a bit more audio processing then you'll need a more specialized program. 

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Thanks for you response, I've been trying out a few different options such as Max and my go-to DAW Logic X, but will definitely check out using switch and Triumph. I have to get iZotope's RX, it's been a long time coming. This particular project I'm working on is extremely limiting on audio file size, we're talking getting a 38mb 7min track down to below 1.6mb :( Complete heresy in other words.

I've experimented with Limiting, compressing and EQ to try to make the potential file size smaller before encoding to m4a, would you have any tips on that side of things?

I think my next steps will be to get iZotope's RX, would you have any suggestions on what to experiment in RX to get the file size as small as possible without it sounding like it's underwater?

Cheers!

 

 

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5 hours ago, jalport said:

Limiting, compressing and EQ to try to make the potential file size smaller

Correct me if I'm wrong, but I would have guessed those things shouldn't have any serious effect on the resulting file size, as far as I'd imagine.  And if the goal is to preserve "quality" of your sound, those steps will absolutely have an audible effect on the end result, as opposed to finding another way to package the audio.

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"Audio compression" and "file compression" are essentially unrelated. Limiting / compression changes the dynamic range of your music (i.e. the spread from the quietest sounds to the lowest sounds) but has no impact on file size afaik.

If you have bad file quality, though, it might be a result of bouncing tracks that haven't been properly metered. Try just dropping your master volume and then doing all your rendering / file conversions. 

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I think your right, It definitely has minimal impact on it if any- but it would be interesting to find out if there's anyone out there who has some clever techniques up their wizard sleeves. Unfortunately the sort of compression rate I've had to use is 60 kbps for an mp4, to reach the sort of file size needed, and crushing my dreams in the process :(

 

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Thanks Will, it was on a bit of whim- I understand they're both very different things but I thought there could be a chance, there wasn't.

Will make sure the metering is right too, thanks for the suggestion!

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Sorry if I confused you. I only mentioned some of the other, more advanced features with audio production, because sometimes a user will want to do some sonic changes while also converting the files themselves. For example, normalize all assets and export them out as an OGG file. 

The sonic changes do nothing to change the file size itself. Just the sonic qualities. 

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It is worth noting that decisions made when mixing and mastering audio can help when crushing it down to a lower bit rate. For example, avoid things like cymbal swells and such that just eat up information in the upper range and sound like total crap when really squashed during data compression. So  you may want to narrow your frequency range some and see how well you can make it sound at a low fidelity. 

RX Advanced has a codec previewer where you can hear the impacts of such data compression while still having options from an audio engineering side. May be worth checking that out. Hope that helps! 

 

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That's a good point to mention on preparing the track in a compositional and mixing sense. I think I'll have to incorporate that into the process. I suppose the advantage of making those changes, is that you can lower the bit rate further whilst avoiding being overwhelmed by chunky bits, and therefore getting the file size smaller as a result. Thanks for the heads up on it not directly affecting file size though!

 

RX does sound decent but I'm feeling intimidated by the huge cost of the advanced version. Do you think the standard version would have enough plugins to help tackle this issue?

Thanks for your help!

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Did you try other codecs, more suitable for lower bitrates?

OGG files was mentioned already, but OGG is just a container. The audio stream would be compressed with specific codec, and Vorbis is typically associated with OGG. It's much better than MP3, but probably not any better than AAC.

But check also if Opus codec is supported by your target platform (still within OGG container). They claim that Opus is much better than the other "general sound compression" competitors at lower bitrates: http://opus-codec.org/comparison/

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Great comment thanks for your suggestion! The issue I've run into with OGG is with wide compatibility on mobile and desktop browsers, I was using this as reference https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats#Browser_compatibility - The current sound implementation process is done using Mozilla webdev to use audio nodes and read from one large sound sheet, in which the code picks out the required sound at different intervals (I don't have much knowledge of this as you can tell)

As it's a html5 game, compatibility is a struggle- and aac in mp4, is the best option I can find for encoding. But I'm lost for a way to improve the quality of mp4s at such a low bit rate. They do sound a lot better than mp3s though.  

 

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Found a great summary for browser specific sound design - 

https://www.gamasutra.com/view/feature/134761/aaalite_audio_design_challenges_.php?page=3

It's a little dated mentioning mp3s over mp4, but had no idea that it's best to start out in as higher sample rate as possible in the DAW, as the codec takes care of bit conversion.

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