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87 lines
4.5 KiB
JavaScript
87 lines
4.5 KiB
JavaScript
/*
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* mediadec.mjs — the all-in-one media-decoding library for TVDOS movie players.
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*
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* One simple public API, three internal backends (iPF/MOV, TEV, TAV/TAP),
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* sharing the front-end utilities in mediadec_common.mjs. Used by playmov.js.
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*
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* const mediadec = require("mediadec")
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* const dec = mediadec.open("A:\\film.tav", { interactive: true })
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* while (true) {
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* const ev = dec.step() // [backend] decode the next due frame to RAM
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* if (ev.type === 'eof') break
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* if (ev.type !== 'frame') { sys.sleep(1); continue }
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* dec.blit() // [draw] upload the RAM frame to the screen
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* // ...or in ASCII mode (no upload): dec.sampleGray(buf,w,h); aa.render/flush
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* // ...or grab the frame yourself: sys.peek(dec.frameBuffer + ...)
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* }
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* dec.close()
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*
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* step() decodes the next due frame into a generic RAM RGB888 buffer (exposed as
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* .frameBuffer); the caller decides what to do with it — upload it with .blit(),
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* sample it for ASCII, or read it directly. (iPF is the exception: it decodes
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* straight to the 4bpp display planes, so .frameBuffer is 0 and .sampleGray/.blit
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* operate on the planes — see mediadec_ipf.mjs.)
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*
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* The decoder object every backend returns exposes a uniform interface:
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* .info {format,width,height,fps,totalFrames,hasAudio,hasSubtitles,
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* isInterlaced,colourSpace,graphicsMode,isStill}
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* .step() -> { type:'frame'|'idle'|'eof'|'newfile'|'error', frameCount }
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* .frameBuffer RAM RGB888 address of the current frame (0 for iPF; see above)
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* .frameWidth/.frameHeight dimensions of the frame in .frameBuffer
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* .blit() upload the current RAM frame to the screen (adapter)
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* .sampleGray(dst,w,h) fill an ASCII brightness buffer from the RAM frame
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* .sampleColour(dst,w,h) fill a per-cell RGB buffer (w*h*3) from the RAM frame
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* .subtitle {visible,text,position,useUnicode,dirty} (resolved by the lib)
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* .pause(b)/.isPaused() .setVolume(v)/.getVolume()
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* .seekSeconds(n) .cue(d) .cues
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* .frameCount .currentTimecodeNs .videoRate .frameMode [.qY/.qCo/.qCg]
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* .close()
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*/
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// NOTE: every require() below is deliberately made at call time (inside open()),
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// never at module top level. TVDOS's require() loads a module by eval()-ing it,
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// and requiring one module *while another module is still being eval()-ed* nests
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// the evals — which can collide on the loader's `let exports` binding and throw
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// "Identifier 'exports' has already been declared" at load, breaking every file.
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// Keeping requires at runtime means each is a single, non-nested eval.
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// Open a movie file: sniff the magic, then hand off to the matching backend.
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// `opts` (all optional): interactive, debugMotionVectors, enableDeblocking,
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// enableBoundaryAwareDecoding, deinterlaceAlgorithm, filmGrainLevel.
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function open(fullPathStr, opts) {
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opts = opts || {}
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const common = require("mediadec_common")
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// IMPORTANT: query the file size via files.open() BEFORE preparing seqread.
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// On the real disk driver both share the drive's serial port, so a files.open()
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// *after* seqread.prepare() clobbers the read position and the first readBytes()
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// returns driver leftovers (the size as an ASCII string) instead of the file's
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// bytes — which made every file fail the magic check. Every original player
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// reads the size first, then prepares seqread.
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const fileLength = files.open(fullPathStr).size
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const sr = common.openSeqread(fullPathStr)
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const magic = common.readMagic(sr)
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const fmt = common.detectFormat(magic)
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con.clear()
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con.curs_set(0)
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switch (fmt) {
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case 'mov': return require("mediadec_ipf").create(magic, sr, fileLength, opts, common)
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case 'tev': return require("mediadec_tev").create(magic, sr, fileLength, opts, common)
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case 'tav': return require("mediadec_tav").create(magic, sr, fileLength, opts, common, false)
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case 'tap': return require("mediadec_tav").create(magic, sr, fileLength, opts, common, true)
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case 'ucf':
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throw Error("UCF cue files are not directly playable; play the TAV stream they index")
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default:
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throw Error("Unrecognised movie file (magic: " + magic.map(b => b.toString(16)).join(' ') + ")")
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}
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}
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exports = {
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open: open,
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// Lazy require so this module never requires another at load time (see note above).
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detectFormat: function (magic) { return require("mediadec_common").detectFormat(magic) }
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}
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