more movie format experimentations

assets/disk0/encodemovmjpg.js

@@ -0,0 +1,55 @@
+
+const FBUF_SIZE = 560*448
+let infile = sys.malloc(120000) // somewhat arbitrary
+
+let outfilename = exec_args[1]
+
+if (!outfilename) return 1
+
+function appendToOutfile(bytes) {
+    filesystem.open("A", outfilename, "A")
+    filesystem.writeBytes("A", bytes)
+}
+
+function appendToOutfilePtr(ptr, len) {
+    filesystem.open("A", outfilename, "A")
+    dma.ramToCom(ptr, 0, len)
+}
+
+// write header to the file
+let headerBytes = [
+    0x1F, 0x54, 0x53, 0x56, 0x4D, 0x4D, 0x4F, 0x56, // magic
+    0x30, 0x02, // width (560)
+    0xC0, 0x01, // height (448)
+    0x1E, 0x00, // FPS (30)
+    0x34, 0x00, 0x00, 0x00, // frame count (52)
+    0x10, 0x00, // type 16 frames
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 // reserved
+]
+
+filesystem.open("A", outfilename, "W")
+filesystem.writeBytes("A", headerBytes)
+
+for (let f = 1; f <=52; f++) {
+    let fname = `/movtestimg/${(''+f).padStart(3,'0')}.jpg`
+    filesystem.open("A", fname, "R")
+    let fileLen = filesystem.getFileLen("A")
+    dma.comToRam(0, 0, infile, fileLen)
+
+
+    print(`Encoding frame ${f}...`)
+
+    let frameSize = [
+        (fileLen >>> 0) & 255,
+        (fileLen >>> 8) & 255,
+        (fileLen >>> 16) & 255,
+        (fileLen >>> 24) & 255
+    ]
+
+    appendToOutfile(frameSize)
+    appendToOutfilePtr(infile, fileLen)
+
+    print(` ${fileLen} bytes\n`)
+}
+
+sys.free(infile)