Audio editing guide

osu!academy covered this in Episode 15: Audio Encoding (4:02). That episode also contains how to install and use Audacity with LAME's .mp3 export ability.

This article serves as guide to help you do minor edits to your audio files for beatmapping purposes. By expanding it, you can help fellow beatmappers to create suitable audio files for any need.

By no means is this the software that you can only use, rather this only lists from those who had added them here. If you know of other tools that could be used and can explain how to use them for the described sections below, please add them.

Audacity

Note: This article uses Audacity 3.4.2.

Audacity is a free, open-source audio editing and recording software. It uses the LAME encoding library to be able to export audio in the MP3 audio format and is built into Audacity on Windows and macOS.

Linux users should refer to the Audacity Reference Manual for more information, as certain Linux distributions may not provide LAME when installing Audacity, but most do provide it.

Lowering Bit Rate

For information on compression in general, see: Compressing files

Install and open Audacity, then follow these steps:

1. Open the .mp3 file that you want to lower the bit rate on.
2. Press Ctrl + Shift + E, or click File -> Export Audio....
3. In Format: select MP3 Files.
4. In the Audio options, change the following settings:

   1. Bit Rate Mode: Preset
   2. Quality: Medium, 145-185 kbps
5. Edit File Name: and Folder: to determine the location and name you want to save the file as.

   • You could also use the Browse... button to navigate.
6. If you would like to edit the metadata of the file, click Edit Metadata....
7. Click OK once done editing metadata.
8. Click Export to export the audio file.

Looping

Install and open Audacity then follow these steps:

1. Open the .mp3 file that you want to loop.
2. Click and drag to highlight the parts you want to loop.

   • Rarely, it would be the start to the end of the music.
   • Sometimes the chorus or refrain is where looping is done best.
3. Press Ctrl + C, or click Edit -> Copy.
4. Find a location for where you can loop the part you have copied.

   • This could be the end of the part you had highlighted.
5. Press Ctrl + V, or click Edit -> Paste.
6. Play through the entire music and make sure that the loop sounds good.
7. Repeat as needed.
8. Export the audio file.

Cropping

Install and open Audacity, then follow these steps:

1. Open the .mp3 file that you want to crop.
2. Click and drag to highlight the parts you want to crop.

   • This should be the long outro that you don't want to map.
3. Press Delete or Ctrl + K, or click Edit -> Delete.
4. Click and drag the last 3 to 5 seconds towards the end.
5. Click Effect -> Fading -> Fade Out.
6. Export the audio file.

mp3DirectCut

Note: This article uses mp3DirectCut 2.36.

mp3DirectCut is a free-to-use audio editing software that can directly edit MP3 files without re-encoding, often preventing loss of quality. It is recommended when needing to raise/lower the volume or crop the audio.

Lowering Bit Rate

Note: A 32-bit library file is needed to use this feature.

1. Open the .mp3 file that you want to lower the bit rate on.
2. Click Settings -> Configuration, or press F11.
3. Go to the Encoder tab.
4. Enable one of available encoding libraries.

   • System: ACM encoding library
   • Lame: The Lame_enc.dll file under the installation directory
5. Change the minimum bitrate to 128 kbit/s, and the maximum to 192 kbit/s.
6. Click Close.
7. Press Ctrl + W, or click File -> Save complete audio....
8. Navigate to the location you want to save the file as.

   • You could rename the file too.
9. Click Save.

Looping

Install and open mp3DirectCut, then follow these steps:

1. Open the .mp3 file that you want to loop.
2. Click and drag to highlight the parts you want to loop.

   • Rarely, it would be the start to the end of the music.
   • Sometimes the chorus or refrain is where looping is done best.
3. Press Ctrl + C, or click Edit -> Copy.
4. Find a location for where you can loop the part you have copied.

   • This could be the end of the part you had highlighted.
5. Press Ctrl + V, or click Edit -> Paste.
6. Play through the entire music and make sure that the loop sounds good.
7. Repeat as needed.
8. Press Ctrl + W, or click File -> Save complete audio....
9. Navigate to the location you want to save the file as.

   • You could rename the file too.
10. Click Save.

Cropping

Install and open mp3DirectCut, then follow these steps:

1. Open the .mp3 file that you want to crop.
2. Click and drag to highlight the parts you want to crop.

   • This should be the long outro that you don't want to map.
3. Press Delete.
4. Click and drag the last 3 to 5 seconds towards the end.
5. Press Ctrl + F, or click Edit -> Simple fade.
6. Press Ctrl + W, or click File -> Save complete audio....
7. Navigate to the location you want to save the file as.

   • You could rename the file too.
8. Click Save.

Adjusting the Volume

Install and open mp3DirectCut, then follow these steps:

1. Open the .mp3 file that you want to adjust.
2. Press Ctrl + A to select all.
3. Press Ctrl + G, or click Edit -> Level....
4. Check the Lock Sliders checkbox.
5. Take the left slider and lower it.

   • The dB (decibels) you set it to will vary, just try various volumes until you get it right.
6. When you are satisfied, press OK.
7. Press Ctrl + W, or click File -> Save complete audio....
8. Navigate to the location you want to save the file as.

   • You could rename the file too.
9. Click Save.