In this guide, I'm going to tell you on how to use the Custom BGM function in the game.

A few things to note:

• The music files has to be in the .mp3 format.
  
• Some default music (such as the main title menu music) cannot be changed. (That requires some modding to the game files.)
  
• Due to platform differences, the music files won't play in the game on Steam Deck.

Before that, a word of warning: Because it is possible to use licensed music and songs through the Custom BGM function, you will likely to run a risk of having your gameplay video(s) taken down by the video streaming service if you use licensed tracks through the Custom BGM function in the gameplay video(s). If you want to use the licensed tracks in the gameplay video, do it at your own risk.

As aforementioned, the music files has to be in the .mp3 format. The game will load the music files if the files were encoded in the correct settings.

The correct settings for the .mp3 files that can be use in the game are:

• Sampling frequencies has to be either 32000Hz, 44100Hz or 48000Hz.
  
• The usable bitrates are 96kbps, 112kbps, 128kbps, 160kbps, 192kbps, 224kbps, 256kbps and 320kbps. It is recommend to have the .mp3 files encoded using Constant Bitrate (CBR) instead of Variable Bitrate (VBR).

Once you prepared the music files you want to use, copy and paste them into the 'SRWMUSIC' folder which is usually located at where the game is installed. The default location is '(directory of steam install)\Steam\steamapps\common\SRW30\SRWMUSIC'

To access the Custom BGM function, go to the System menu, and choose either 'Combat BGM Assignment' or 'Default BGM Subsitution' which in under the System Setting 2 tab in the System menu.

Note that the Custom BGM function can be only accessible while in intermission or during stages, and cannot be accessed direct from the start menu right after starting up the game.

For this section of the guide, the 'Default BGM Subsitution' option will be used.

To load the music files:

• Within the Default BGM Subsitution menu, choose any default music.
  
• From the select music menu, press key 1 (on keyboard) or Square (on DualShock 4 and DualSense) to switch from the game's built-in BGM list to 'Build/Owned' music list.
  
• Within the 'Build/Owned' music list, press key 0 (on keyboard) or Option (on DualShock 4 and DualSense) to load the music files
  
• Optionally, you can normalize the music files' volumes and assign Series tag to them.

*Note: Within the 'Build/Owned' music list, you can filter the music files by either Artists, Albums or Series Tags (if you had assigned one to the tags). To do this, press Q or E (on keyboard) or L1 or R1 (On DualShock 4 and DualSense) to switch the filter. By default, the game won't filter the music file list.

There are two ways for the music files to be used in the game.

A. Default BGM Subsitution
This option replace the default BGMs with the custom music. To do this:

• Select 'Default BGM Subsitution' within the System menu (located under System setting 2)
  
• Within the Default BGM Subsitution menu, choose any default music you want to replace.
  
• From the select music menu, press key 1 (on keyboard) or Square (on DualShock 4 and DualSense) to switch from the game's built-in BGM list to 'Build/Owned' music list.
  
• Choose the music file in the list and choose 'Select music'.

The default music is now replaced by the custom music you provided.

B. Combat BGM Assignment
This option allows you to replace individual combat unit's music with custom music. To do this:

• Select 'Combat BGM Assignment' within the System menu (located under System setting 2). From the list, select the unit.
  
• Choose a music slot, either the <theme song> or any of the weapons.
  
• From the select music menu, press key 1 (on keyboard) or Square (on DualShock 4 and DualSense) to switch from the game's built-in BGM list to 'Build/Owned' music list.
  
• Choose the music file in the list and choose 'Select music'.
  
• Optionally, you can quickly change all the music slots in a unit to one custom music by pressing key 0 (on keyboard) or Option (on DualShock 4 and DualSense) while the selected music slot (with custom music assigned) is highlighted.

Note that it is always best to make changes to unit's music while in intermission, as doing so while in stages will only shows the units that were deployed in the stages.

Unique to the PC version of the game, the game will stutters (with the sound playing normally) for a little moment whenever a custom music is loaded. This is more noticeable when a custom music is loaded while a video (Usually combinations or launching sequences) is playing.

There you have it. I hope those guidelines will help you to setting up the custom music in the game.

If you find any error in the guideline, please point them out in the comment section.