Panasonic Voice Recorder Triple Rate Codec Decoder (for VM1 files) - uses LuaJIT FFI to call native code

panasonic_trc_vm1_decoder.lua

-- saved at 12000Hz, 16 bit PCM, little endian

local vcName = "SD_VC001"
local folder = "SD_VOICE/"..vcName

ffi=require'ffi'

ffi.cdef [[
    void vInitDecoder(void);
    void vDecode(uint8_t* param_1,uint8_t *param_2);
    void vSet_volume(uint32_t param_1,uint32_t param_2);
]]

function fileExists(name) local f = io.open(name,"rb") if f ~= nil then io.close(f) return true else return false end end
 

local trc = ffi.load("trcL.dll")

local rawMetadataF = io.open(folder.."/SD_VOICE.TKM","rb")
local rawMetadata = rawMetadataF:read("*a")
rawMetadataF:close()
local metadata = {}
for entry in rawMetadata:gmatch("TRC_HQ_(%d+/%d+/%d+ %d+%:%d+)\\TRC") do
    metadata[#metadata + 1] = entry
end

local clk = os.clock()
local fileIdx = 1
while true do
    trc.vInitDecoder()
    trc.vSet_volume(0x400,0x40)

    local input = ffi.new("uint8_t[?]",8192)
    local output = ffi.new("uint8_t[?]",8192)

    local infile = io.open(string.format(folder.."/MOB%03d.VM1",fileIdx),"rb")
    if infile == nil then print("Job complete!") break end
    local outfileName = string.format("output/OUT_"..vcName.."_MOB%03d.pcm",fileIdx)
    local outfile = io.open(outfileName,"wb")
    print(string.format("Processing file "..folder.."/MOB%03d.VM1 (%s)",fileIdx,metadata[fileIdx] or "???"))
    local curFileMetadata = metadata[fileIdx]
    fileIdx = fileIdx + 1

    -- Dump first 512 bytes
    infile:read(512)

    local complete_input = {}
    local len = 0
    while true do
        local b = infile:read(1)
        if b == nil then break end
        complete_input[len] = string.byte(b)
        len = len + 1
    end

    infile:close()

    local loc = 0
    while true do
        local cancel = false

        -- fill frame buffer
        for i=1,0x200 do
            if complete_input[i-1 + loc] == nil then cancel = true break end
            input[i-1] = complete_input[i-1 + loc]
        end
        if cancel then break end
        loc = loc + 0x200

        local remaining = 0x200
        local cur_loc = 0
        while remaining >= 0x18 do
            local bytesPerFrameRef = 0x18
            if fin then break end

            local cur_input = ffi.cast("uint8_t*",input) + cur_loc

            local bVar1 = bit.band(cur_input[0], 0xc0)
            local ok = false
            if (bVar1 == 0) or (bVar1 == 0x40) then
                ok = true
            else
                bytesPerFrameRef = 8

                if bVar1 == 0x80 then
                    ok = true
                end
            end

            if ok then
                trc.vDecode(output,cur_input)

                for i=1,0x140 do
                    outfile:write(string.char(output[i-1]))
                end

                bytesPerFrameRef = 0x18
            end

            cur_loc = cur_loc + bytesPerFrameRef
            remaining = remaining - bytesPerFrameRef

        end

        if (os.clock() - clk) > 1 then
            print(string.format("Decoding %.02f%%...",loc / #complete_input * 100))
            clk = os.clock()
        end
    end

    outfile:close()

    local niceOutFile = curFileMetadata or outfileName:gsub("%.pcm$","")
    niceOutFile = niceOutFile:gsub("[/:]","-")
    while fileExists("output/"..niceOutFile..".mp3") do niceOutFile = niceOutFile.."-copy" end
    print("ffmpeg -f s16le -ar 12k -ac 1 -i "..outfileName.." \"output/"..niceOutFile..".mp3\"")
    os.execute("ffmpeg -f s16le -ar 12k -ac 1 -i "..outfileName.." \"output/"..niceOutFile..".mp3\"")
end