Game Boy Sound Effect Studio

Notes:

A similar software (but without wave RAM editing) to run directly on your device (or emulator) can be found in GBDK’s example. If you don't want to build it yourself, there's a repository with the binary.
The download feature produces a WAV file with the Game Boy's digital output at its native sample rate (1 MiHz for duty, 2 MiHz for wave, 512 KiHz for noise), which is non-standard for the WAV format. You will likely need professional audio software to open the file, e. g. Audacity.
Hovering the keyboard keys displays the name of a note. For the wave channel, this and the displayed frequency only apply if the wave RAM samples go up and down exactly twice (each).
The keyboard uses the correct periods, whereas most Game Boy software and references use incorrect values for C♯3, D3, G3, A3, C5 and C♯8.
Assembly output does not contain the writes to rNR5x.
Any change implicitly triggers the channel.

DIV\SHIFT	0	1	2	3	4	5	6	7	8	9	10	11	12	13
0	524288	262144	131072	65536	32768	16384	8192	4096	2048	1024	512	256	128	64
1	262144	131072	65536	32768	16384	8192	4096	2048	1024	512	256	128	64	32
2	131072	65536	32768	16384	8192	4096	2048	1024	512	256	128	64	32	16
3	87381.3	43690.6	21845.3	10922.6	5461.3	2730.6	1365.3	682.6	341.3	170.6	85.3	42.6	21.3	10.6
4	65536	32768	16384	8192	4096	2048	1024	512	256	128	64	32	16	8
5	52428.8	26214.4	13107.2	6553.6	3276.8	1638.4	819.2	409.6	204.8	102.4	51.2	25.6	12.8	6.4
6	43690.6	21845.3	10922.6	5461.3	2730.6	1365.3	682.6	341.3	170.6	85.3	42.6	21.3	10.6	5.3
7	~37449.1	~18724.6	~9362.3	~4681.1	~2340.6	~1170.3	~585.1	~292.6	~146.3	~73.1	~36.6	~18.3	~9.1	~4.6

Created by daid, extended by numma_cway. Find this on GitHub!