222 lines
6.9 KiB
GDScript
222 lines
6.9 KiB
GDScript
extends Node
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signal audio_samples_loaded
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var has_loaded_audio_samples := false
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const BGM_NUM := 70
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const BGM_LOOKUP := 0x043B97
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const INST_NUM := 35
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const INST_BRR_LOOKUP := 0x043C6F
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const INST_LOOP := 0x043CD8
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const INST_SR := 0x043D1E
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const INST_ADSR := 0x043D64
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const SFX_NUM := 8
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const SFX_BRR_SPC_TABLE := 0x041F4F + 2 # (first two bytes are the length of 0x0020 = 32 bytes = 4*8)
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const SFX_BRR_START := 0x041E3F + 2 # First two bytes are the length of the block, 0x010E = 270 bytes = 16 BRR packets = 480 samples
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const SFX_ADSR := 0x041F71
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const SFX_SR := 0x041F83
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var bgm_tracks = []
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var instrument_samples = []
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var sfx_samples = []
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func read_rom_address(rom: File) -> int:
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# Read a 3-byte little-endian address and wrap the bank to ROM space
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return rom.get_16() + ((rom.get_8() & 0x3F) << 16)
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const MAX_15B = 1 << 15
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const MAX_16B = 1 << 16
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func unsigned16_to_signed(unsigned):
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return (unsigned + MAX_15B) % MAX_16B - MAX_15B
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func get_reference_pitch_samplerate(tuning1: int, tuning2: int = 0) -> int:
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# This is non-trivial and subject to change
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var pitch_scale = tuning1/256.0 + tuning2/65536.0
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if tuning1 < 0x80:
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pitch_scale += 1.0
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return int(pitch_scale * 36000)
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# return (unsigned16_to_signed(pitch) + 0x8000) * 32000/4096
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func process_sample(mantissa: int, exponent: int) -> int:
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# For filter arithmetic the samples need to be in signed form.
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# Sign-extend
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if mantissa >= 8:
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mantissa |= 0xFFF0
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if exponent > 12:
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exponent = 12
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var unsigned = (mantissa << exponent) & 0xFFFF
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return unsigned16_to_signed(unsigned)
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func decode_brr(data: PoolByteArray):
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# Decodes a single 9byte BRR packet
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var exponent := data[0] >> 4
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var filter_designation := (data[0] >> 2) & 0x03
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var loop := bool(data[0] & 0x02)
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var end := bool(data[0] & 0x01)
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var samples := PoolIntArray()
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for i in range(1, 9):
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var b := data[i]
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samples.append(process_sample(b >> 4, exponent))
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samples.append(process_sample(b & 0x0F, exponent))
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return [samples, loop, end, filter_designation]
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func clamp_short(i: int) -> int:
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if i < -0x8000:
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return -0x8000
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if i > 0x7FFF:
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return 0x7FFF
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return i
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func make_sample(rom: File, size: int, sample_rate: int) -> AudioStreamSample:
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var audio := AudioStreamSample.new()
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audio.mix_rate = sample_rate
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audio.stereo = false
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audio.set_format(AudioStreamSample.FORMAT_16_BITS)
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if (size % 9) != 0:
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print_debug('Oh no! An instrument sample has an invalid size of %d! at $%06X' % [size, rom.get_position()-2])
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return audio
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var num_packets := size/9
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var samples = PoolIntArray([0, 0]) # Start with two zero samples for filter purposes, strip them from the actual output
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var i := 2
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for pkt in num_packets:
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var data = decode_brr(rom.get_buffer(9))
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samples.append_array(data[0])
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#var loop = data[1]
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var end = data[2]
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var filter = data[3]
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match filter:
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1:
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for j in range(samples.size()-16, samples.size()):
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samples[j] = clamp_short(samples[j] + (samples[j-1]*15)/16)
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2:
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for j in range(samples.size()-16, samples.size()):
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samples[j] = clamp_short(samples[j] + (samples[j-1]*61)/32 - (samples[j-2]*15)/16)
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3:
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for j in range(samples.size()-16, samples.size()):
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samples[j] = clamp_short(samples[j] + (samples[j-1]*115)/64 - (samples[j-2]*13)/16)
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if end:
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# print('End flag on packet')
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break
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# Convert int array to byte array
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var audio_data = PoolByteArray()
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for j in range(2, samples.size()):
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var b = samples[j]
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audio_data.append(b & 0xFF)
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audio_data.append(b >> 8)
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audio.data = audio_data
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return audio
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func get_inst_sample_data(rom: File, id: int) -> AudioStreamSample:
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rom.seek(INST_SR + (id*2))
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var tuning1 := rom.get_8()
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var tuning2 := rom.get_8()
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var sample_rate := get_reference_pitch_samplerate(tuning1)
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rom.seek(INST_LOOP + (id*2))
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var loop_start_packet := rom.get_16()/9 # Note that Instrument $1F Steel Guitar has a length of $088B but a loop point of $088D which is 243.22... packets. Luckily it doesn't matter.
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var lookup_offset := INST_BRR_LOOKUP + (id*3)
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rom.seek(lookup_offset)
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var brr_offset := read_rom_address(rom)
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rom.seek(brr_offset)
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var size := rom.get_16()
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var num_samples := (size/9)*16
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var audio := make_sample(rom, size, sample_rate)
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audio.loop_mode = AudioStreamSample.LOOP_FORWARD
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audio.loop_begin = loop_start_packet * 16 # Each 9byte packet is 16 samples
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audio.loop_end = num_samples-1
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# print_debug('Loaded instrument #%02X with lookup offset $%06X, BRR data offset $%06X, length $%04X (%f packets, %d samples) and loop point %d samples' % [id, lookup_offset, brr_offset, size, size/9.0, num_samples, audio.loop_begin])
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return audio
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func load_sfx_samples_data(rom: File):
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var sample_rates = []
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rom.seek(SFX_SR)
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for i in SFX_NUM:
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var tuning1 := rom.get_8()
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var tuning2 := rom.get_8()
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sample_rates.append(get_reference_pitch_samplerate(tuning1))
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var brr_spc_addrs = []
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var brr_spc_loop_addrs = []
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rom.seek(SFX_BRR_SPC_TABLE)
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for i in SFX_NUM:
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brr_spc_addrs.append(rom.get_16())
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brr_spc_loop_addrs.append(rom.get_16())
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var brr_spc_start = brr_spc_addrs[0]
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for i in SFX_NUM:
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brr_spc_addrs[i] += SFX_BRR_START - brr_spc_start
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for i in SFX_NUM:
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rom.seek(brr_spc_addrs[i])
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# print('Loading sfx sample #%X with BRR data offset $%06X' % [i, rom.get_position()])
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sfx_samples.append(make_sample(rom, 900, sample_rates[i])) # Use 900 as a limit, it won't be hit, parser stops after End packet anyway
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# print('size of %d samples' % sfx_samples[i].data.size())
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# Called when the node enters the scene tree for the first time.
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func load_samples(rom: File):
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pass
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load_sfx_samples_data(rom)
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for i in INST_NUM:
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instrument_samples.append(get_inst_sample_data(rom, i))
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func get_song_data(rom: File, id: int):
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var lookup_offset := BGM_LOOKUP + (id*3)
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rom.seek(lookup_offset)
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var offset := read_rom_address(rom)
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var bank := offset & 0xFF0000
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rom.seek(offset)
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var _block_size := rom.get_16() # Unused since we pull the individual tracks
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var track_ptrs = []
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for i in 10:
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var a := bank + rom.get_16()
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if a < offset:
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a += 0x010000 # Bank shift
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track_ptrs.append(a)
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if track_ptrs[0] != track_ptrs[1]:
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print('Master is not channel 1, interesting', track_ptrs)
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var tracks = []
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for i in range(1, track_ptrs.size()-1):
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var length = track_ptrs[i+1] - track_ptrs[i]
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tracks.append(rom.get_buffer(length))
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return tracks
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func load_bgms(rom: File):
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for i in BGM_NUM:
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bgm_tracks.append(get_song_data(rom, i))
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var player := AudioStreamPlayer.new() # Make one for each channel, later
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func play_sample(id: int):
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print('Playing sample #%02X' % id)
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player.stream = instrument_samples[id]
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player.play()
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func play_sfx(id: int):
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print('Playing sample #%02X' % id)
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player.stream = sfx_samples[id]
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player.play()
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func parse_rom(rom: File):
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load_samples(rom)
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#load_bgms(rom)
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has_loaded_audio_samples = true
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emit_signal('audio_samples_loaded')
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func _ready() -> void:
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add_child(player)
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# Called every frame. 'delta' is the elapsed time since the previous frame.
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#func _process(delta: float) -> void:
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# pass
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