video: libmediadec and playmov

assets/disk0/tvdos/include/mediadec_ipf.mjs

@@ -0,0 +1,181 @@
+/*
+ * mediadec_ipf.mjs — legacy MOV / iPF backend for the mediadec library.
+ *
+ * Ported from assets/disk0/tvdos/bin/playmv1.js.  Decodes iPF1 / iPF1a /
+ * iPF2 / iPF2a / iPF1-delta video packets straight to the 4bpp display planes
+ * (the proven, fast path), plus MP2 and raw-PCM audio and the background-colour
+ * packet.  Presents at decode time (so blit() is a no-op); bias lighting is a
+ * separate player-driven stage via the bias() method; the ASCII path reads the
+ * planes back via common.sampleGrayScreen.
+ */
+
+const WIDTH = 560
+const HEIGHT = 448
+const FBUF_SIZE = WIDTH * HEIGHT
+
+function create(magic, sr, fileLength, opts, common) {
+    const audioR = common.makeAudioRouter(sr)
+
+    // Header (after the 8-byte magic): w, h, fps, frameCount, queue info.
+    let width = sr.readShort()
+    let height = sr.readShort()
+    let fps = sr.readShort(); if (fps == 0) fps = 9999
+    const FRAME_COUNT = sr.readInt() % 16777216
+    sr.readShort()                 // skip unused
+    sr.readShort()                 // audioQueueInfo (unused for playback)
+    sr.skip(10)
+
+    graphics.setGraphicsMode(4)
+    graphics.clearPixels(255)
+    graphics.clearPixels2(240)
+
+    const FRAME_TIME = 1.0 / fps
+    const applyBias = common.makeBias(width, height, 4)
+
+    const ipfbuf = sys.malloc(FBUF_SIZE)
+
+    const info = {
+        format: 'ipf', width: width, height: height, fps: fps,
+        totalFrames: FRAME_COUNT, hasAudio: true, hasSubtitles: false,
+        isInterlaced: false, colourSpace: 'YCoCg', graphicsMode: 4, isStill: false
+    }
+
+    // No subtitles in iPF; expose an inert state object for the uniform API.
+    const subtitle = { visible: false, text: "", position: 0, useUnicode: false, dirty: false }
+
+    let akku = FRAME_TIME
+    let lastT = sys.nanoTime()
+    let doFrameskip = true
+    let autoBg = true
+    let framesRead = 0
+    let frameCount = 0
+    let paused = false
+
+    function setBackgroundPacket() {
+        autoBg = false
+        let rgbx = sr.readInt()
+        graphics.setBackground((rgbx & 0xFF000000) >>> 24, (rgbx & 0x00FF0000) >>> 16, (rgbx & 0x0000FF00) >>> 8)
+    }
+
+    function step() {
+        const now = sys.nanoTime()
+        if (paused) { lastT = now; return { type: 'idle' } }
+        akku += (now - lastT) / 1000000000.0
+        lastT = now
+
+        if (sr.getReadCount() >= fileLength) return { type: 'eof' }
+        if (akku < FRAME_TIME) return { type: 'idle' }
+
+        // Drain accumulated time into a frame budget (frameskip drops late frames).
+        let frameUnit = 0
+        while (akku >= FRAME_TIME) { akku -= FRAME_TIME; frameUnit += 1 }
+        if (!doFrameskip) frameUnit = 1
+
+        let displayed = false
+        while (frameUnit >= 1 && sr.getReadCount() < fileLength) {
+            let packetType = sr.readShort()
+
+            if (0xFFFF === packetType) {            // sync — one frame boundary
+                frameUnit -= 1
+            }
+            else if (0xFEFF === packetType) {       // explicit background colour
+                setBackgroundPacket()
+            }
+            else if (packetType < 2047) {           // video
+                if (packetType == 4 || packetType == 5 || packetType == 260 || packetType == 261) {
+                    let decodefun = (packetType > 255) ? graphics.decodeIpf2 : graphics.decodeIpf1
+                    let payloadLen = sr.readInt()
+                    if (framesRead >= FRAME_COUNT) return { type: 'eof' }
+                    framesRead += 1
+                    let gz = sr.readBytes(payloadLen)
+                    if (frameUnit == 1) {
+                        gzip.decompFromTo(gz, payloadLen, ipfbuf)
+                        decodefun(ipfbuf, common.DISP_RG, common.DISP_BA, width, height, (packetType & 255) == 5)
+                        audioR.fire()
+                        displayed = true
+                        frameCount += 1
+                    }
+                    sys.free(gz)
+                }
+                else if (packetType == 516) {       // iPF1-delta
+                    doFrameskip = false
+                    let payloadLen = sr.readInt()
+                    if (framesRead >= FRAME_COUNT) return { type: 'eof' }
+                    framesRead += 1
+                    let gz = sr.readBytes(payloadLen)
+                    if (frameUnit == 1) {
+                        gzip.decompFromTo(gz, payloadLen, ipfbuf)
+                        graphics.applyIpf1d(ipfbuf, common.DISP_RG, common.DISP_BA, width, height)
+                        audioR.fire()
+                        displayed = true
+                        frameCount += 1
+                    }
+                    sys.free(gz)
+                }
+                else {
+                    throw Error(`Unknown iPF video packet type ${packetType} at ${sr.getReadCount() - 2}`)
+                }
+            }
+            else if (4096 <= packetType && packetType <= 6143) {   // audio
+                let readLength = (packetType >>> 8 == 17)
+                    ? common.MP2_FRAME_SIZE[(packetType & 255) >>> 1]
+                    : sr.readInt()
+                if (readLength == 0) throw Error("iPF audio read length is zero")
+                if (packetType >>> 8 == 17) {        // MP2
+                    audioR.ensureMp2()
+                    sr.readBytes(readLength, audioR.sndBase - 2368)
+                    audio.mp2Decode()
+                    audio.mp2UploadDecoded(0)
+                }
+                else if (packetType == 0x1000 || packetType == 0x1001) {   // raw PCM
+                    audioR.rawPcm(readLength)
+                }
+                else {
+                    throw Error(`iPF audio packet type ${packetType} at ${sr.getReadCount() - 2}`)
+                }
+            }
+            else {
+                // Unknown — stop to avoid desync (matches old players' break).
+                return { type: 'eof' }
+            }
+        }
+
+        return displayed ? { type: 'frame', frameCount: frameCount } : { type: 'idle' }
+    }
+
+    // The frame is already on the display planes (decoded there in step()), so
+    // presenting is a no-op. Bias lighting is a separate, player-driven stage
+    // (bias() below) and is skipped when an explicit background packet disabled it.
+    function blit() { }
+
+    // Frame is already on the display planes, so the player can sample the screen.
+    function sampleGray(dst, w, h) { common.sampleGrayScreen(width, height, dst, w, h, 4) }
+
+    return {
+        info: info,
+        subtitle: subtitle,
+        get frameCount() { return frameCount },
+        get currentTimecodeNs() { return Math.floor(frameCount * (1000000000.0 / fps)) },
+        get videoRate() { return 0 },
+        get frameMode() { return ' ' },
+        cues: [],
+
+        step: step,
+        blit: blit,
+        bias() { if (autoBg) applyBias() },   // skipped when an explicit bg packet set the colour
+        sampleGray: sampleGray,
+        pause(p) { paused = p; if (p) audioR.stop(); else { audioR.resume(); lastT = sys.nanoTime() } },
+        isPaused() { return paused },
+        setVolume(v) { audioR.setVolume(v) },
+        getVolume() { return audioR.getVolume() },
+        seekSeconds(_n) { /* iPF has no index; seeking unsupported */ },
+        cue(_d) { /* no cues */ },
+
+        close() {
+            sys.free(ipfbuf)
+            audioR.close()
+        }
+    }
+}
+
+exports = { create }