[Bug] Fix libopus warning during build: "No bit rate set. Defaulting to 96000 bps."

During the build process, when running ffmpeg from the Makefile to convert audio files to Opus format, the following warning appears: [libopus @ 0x...] No bit rate set. Defaulting to 96000 bps. This warning occurs because the encoder’s bitrate was not explicitly set, so it defaults to 96 kbps automatically.

Why This Matters

  • Unspecified bitrate causes ambiguity: Without explicitly setting bitrate, the encoder’s behaviour depends on internal defaults, which may not be optimal for our target platform (Nintendo 3DS).

  • Performance and file size impact: The 3DS has limited CPU and memory resources. Defaulting to 96 kbps can increase decoding load and file size unnecessarily.

  • Control over audio quality and size: Setting the bitrate explicitly ensures consistent audio quality, better file size management, and reduces CPU usage during playback.

Fix Summary Added explicit -b:a 64k flag to ffmpeg commands in the build script to set audio bitrate to 64 kbps, which is a balanced choice for the 3DS:

  • Reduces CPU decoding requirements.

  • Saves storage space.

  • Maintains acceptable audio quality for app music.

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