fix(station): decode wav chunks to speaker samples

Bump the station build to v1.0.2 and decode streamed WAV chunks into PCM samples on the client before feeding playAudioAll/playAudio, while keeping the HQ WAV path as a fallback for decode failures.

station_broadcast.lua

@@ -2,7 +2,7 @@
 -- ============================================================================
 -- 1. Configuration & Constants
 -- ============================================================================
-local APP_VERSION_TEXT = "v1.0.1"
+local APP_VERSION_TEXT = "v1.0.2"
 
 local CONFIG = {
     CLOUD_URL = "ws://stabadmin.fse-media.group",
@@ -665,6 +665,117 @@ local function decodePcmS8Chunk(chunk)
     return samples
 end
 
+local function readU16LE(data, offset)
+    local a, b = string.byte(data, offset, offset + 1)
+    if not a or not b then return nil end
+    return a + b * 256
+end
+
+local function readS16LE(data, offset)
+    local val = readU16LE(data, offset)
+    if not val then return nil end
+    if val >= 32768 then
+        val = val - 65536
+    end
+    return val
+end
+
+local function readU32LE(data, offset)
+    local a, b, c, d = string.byte(data, offset, offset + 3)
+    if not a or not b or not c or not d then return nil end
+    return a + b * 256 + c * 65536 + d * 16777216
+end
+
+local function clampSample8(val)
+    if val > 127 then return 127 end
+    if val < -128 then return -128 end
+    return val
+end
+
+local function decodeWavChunkToSamples(chunk)
+    if type(chunk) ~= "string" or #chunk < 44 then
+        return nil, "wav chunk too short"
+    end
+    if chunk:sub(1, 4) ~= "RIFF" or chunk:sub(9, 12) ~= "WAVE" then
+        return nil, "invalid wav header"
+    end
+
+    local offset = 13
+    local audioFormat, channels, sampleRate, bitsPerSample
+    local dataOffset, dataSize
+
+    while offset + 7 <= #chunk do
+        local chunkId = chunk:sub(offset, offset + 3)
+        local chunkSize = readU32LE(chunk, offset + 4)
+        if not chunkSize then break end
+        local payloadOffset = offset + 8
+        if chunkId == "fmt " and chunkSize >= 16 then
+            audioFormat = readU16LE(chunk, payloadOffset)
+            channels = readU16LE(chunk, payloadOffset + 2)
+            sampleRate = readU32LE(chunk, payloadOffset + 4)
+            bitsPerSample = readU16LE(chunk, payloadOffset + 14)
+        elseif chunkId == "data" then
+            dataOffset = payloadOffset
+            dataSize = chunkSize
+            break
+        end
+        offset = payloadOffset + chunkSize
+        if chunkSize % 2 == 1 then
+            offset = offset + 1
+        end
+    end
+
+    if audioFormat ~= 1 then
+        return nil, "unsupported wav format " .. tostring(audioFormat)
+    end
+    if channels ~= 1 and channels ~= 2 then
+        return nil, "unsupported channels " .. tostring(channels)
+    end
+    if bitsPerSample ~= 8 and bitsPerSample ~= 16 then
+        return nil, "unsupported bits " .. tostring(bitsPerSample)
+    end
+    if not dataOffset or not dataSize or dataOffset + dataSize - 1 > #chunk then
+        return nil, "invalid wav data chunk"
+    end
+
+    local frameSize = channels * (bitsPerSample / 8)
+    if frameSize <= 0 then
+        return nil, "invalid frame size"
+    end
+
+    local samples = {}
+    local sampleIndex = 1
+    local endOffset = dataOffset + dataSize - frameSize
+
+    for pos = dataOffset, endOffset, frameSize do
+        local mixed = 0
+        for ch = 0, channels - 1 do
+            local sampleOffset = pos + ch * (bitsPerSample / 8)
+            local sampleValue
+            if bitsPerSample == 8 then
+                local raw = string.byte(chunk, sampleOffset)
+                sampleValue = (raw or 128) - 128
+            else
+                sampleValue = readS16LE(chunk, sampleOffset) or 0
+                if sampleValue >= 0 then
+                    sampleValue = math.floor(sampleValue / 256)
+                else
+                    sampleValue = math.ceil(sampleValue / 256)
+                end
+            end
+            mixed = mixed + sampleValue
+        end
+        samples[sampleIndex] = clampSample8(math.floor(mixed / channels))
+        sampleIndex = sampleIndex + 1
+    end
+
+    return samples, nil, {
+        channels = channels,
+        bitsPerSample = bitsPerSample,
+        sampleRate = sampleRate or 0
+    }
+end
+
 local function areHqSpeakersBusy(speakers)
     for _, sp in ipairs(speakers) do
         local playing = false
@@ -971,12 +1082,29 @@ function Audio.playWavStreamItem(item)
         local chunk = source()
         if chunk == nil then break end
         if type(chunk) == "string" and #chunk > 0 then
+            local samples, err, meta = decodeWavChunkToSamples(chunk)
+            if samples and #samples > 0 then
+                Utils.log("INFO", string.format(
+                    "Decoded WAV chunk: bytes=%d samples=%d rate=%d ch=%d bits=%d",
+                    #chunk,
+                    #samples,
+                    tonumber(meta and meta.sampleRate) or 0,
+                    tonumber(meta and meta.channels) or 0,
+                    tonumber(meta and meta.bitsPerSample) or 0
+                ))
+                if not playChunkOnSpeakers(samples, CONFIG.AUDIO_VOLUME, playSeq) then
+                    Audio.stop("current")
+                    return
+                end
+            else
+                Utils.log("WARN", "WAV chunk decode failed, falling back to HQ path: " .. tostring(err))
                 if not pushWavChunkToSpeakers(chunk, playSeq) then
                     Audio.stop("current")
                     return
                 end
             end
         end
+    end
 
     while areHqSpeakersBusy(Peripherals.speakers) do
         if shouldStop(playSeq) then