#!/usr/bin/env python3 """Encode one scene to the DLX bitstream, at a chosen quality profile. python3 tools/encoder/encode.py [--profile scsi] [--lam N] [--fps 12] [--preview out.png] [--fixed-lam] [--rc-floor profile|open] Rate control is ON by default: lam is bisected per frame under a leaky bucket so the profile's bitrate is a ceiling rather than an average hope. `--fixed-lam` restores session 5's behaviour, which overshoots by 18-34% on sustained action (FINDINGS 25.3). `--rc-floor` picks the quality floor: `profile` (default) never spends more than the fixed-lam profile would, so it can only ever help; `open` lets quiet frames spend the whole allowance and lands the mean ON target. Container (little-endian is WRONG here -- the 68000 is big-endian, so every multi-byte field is big-endian and the decoder can read it with a plain move.w): header, 32 bytes 0 'DLX2' magic ('DLX1' = the same, unaligned; still read) 4 u16 width, u16 height 8 u16 fps, u16 nframes 12 u16 k1, u16 k4 codebook sizes 16 u32 palette offset (256 * 3 bytes, RGB888 -- the player converts to the X68000's GRB555 at load time) 20 u32 cb1 offset (k1 * 16 bytes of palette indices) 24 u32 cb4 offset (k4 * 4 bytes) 28 u32 frames offset then, per frame, each record starting on a 4-BYTE BOUNDARY (0-3 zero pad bytes before it; a 68000 takes an address error, not a slow read, on an odd `move.l` -- FINDINGS 28.3): u32 payload length, then ceil(nblocks*2/8) bytes of 2-bit mode headers, MSB-first, block raster order then payloads in block order: V1 -> 1 byte, V4 -> 4 bytes, RAW -> 16 bytes Codebooks are emitted as palette INDICES, not pixels. The player expands them once at load time into word-per-pixel form so the blitter can movem them straight into GVRAM -- k1=1024 costs 1024*16*2 = 32 KB of the 2 MB. """ import argparse, struct, sys, os sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) import numpy as np import vq as VQ, vq_hybrid as H, ratectl as RC # Measured on the emulated 68000, FINDINGS 24. Instruction cycles against # zero-wait-state memory, so these are floors, not hardware predictions. BLIT_PCT = 53.6 # V1: compose in RAM, then a row-linear movem.l blit DIRECT_PCT = 76.6 # V4: write every block straight into GVRAM CROSSOVER_PCT = 100 * BLIT_PCT / DIRECT_PCT def pack_modes(mode): """2 bits per block, MSB-first -- cheap for the 68000 to shift out.""" n = len(mode) out = bytearray((n * 2 + 7) // 8) for i, m in enumerate(mode): out[i // 4] |= (int(m) & 3) << (6 - 2 * (i % 4)) return bytes(out) def frame_payload(mode, l1, l4g, src_idx, nbx): body = bytearray() for b, mo in enumerate(mode): if mo == 1: body += _idx(l1[b]) elif mo == 2: for j in range(4): body += _idx(l4g[b][j]) elif mo == 3: by, bx = divmod(b, nbx) body += src_idx[by*4:by*4+4, bx*4:bx*4+4].tobytes() return bytes(body) def _idx(v): """codebook index: 1 byte if it fits, else big-endian u16. k>256 means 2-byte indices -- decided once by the header, not per block.""" v = int(v) return bytes([v]) if _IDX_BYTES == 1 else struct.pack(">H", v) _IDX_BYTES = 1 def main(): global _IDX_BYTES ap = argparse.ArgumentParser() ap.add_argument("frames_dir"); ap.add_argument("out") ap.add_argument("--profile", choices=list(RC.PROFILES), default="scsi") ap.add_argument("--lam", type=float, default=None) ap.add_argument("--fps", type=int, default=12) ap.add_argument("--iters", type=int, default=16) ap.add_argument("--fixed-lam", action="store_true", help="disable rate control (session 5 behaviour)") ap.add_argument("--rc-floor", choices=("profile", "open"), default="profile", help="quality floor for rate control") ap.add_argument("--bucket-frames", type=int, default=8, help="leaky-bucket depth, in frame budgets") ap.add_argument("--no-cpu-fit", action="store_true", help="drop the per-frame 68000 decode ceiling (session 7 " "behaviour: 31%% of frames on hard content do not fit)") ap.add_argument("--prefill", type=float, default=0.0, help="how full the player's buffer is assumed to be at " "scene start, as a fraction of the bucket (0 = cold " "buffer after a seek, the conservative assumption)") ap.add_argument("--preview") a = ap.parse_args() prof = RC.PROFILES[a.profile] lam = a.lam if a.lam is not None else prof["lam"] k1, k4 = prof["k1"], prof["k4"] _IDX_BYTES = 1 if max(k1, k4) <= 256 else 2 # An explicit --lam is a request for that lam, so it implies --fixed-lam. rc = not (a.fixed_lam or a.lam is not None) lam_lo = lam if a.rc_floor == "profile" else 1.0 # The CPU ceiling is hardware, not taste: without it 31%% of frames on the # worst sustained window do not decode in time on a stock 68000, and with # it that is one frame -- the intra frame -- for 0.26 dB. FINDINGS 31. cyc_budget = None if a.no_cpu_fit else RC.FRAME_CYCLES print(f"profile {a.profile}: {prof['desc']}") if rc: print(f" target {prof['kbps']} KB/s CEILING, rate-controlled: " f"lam bisected per frame in [{lam_lo:g}, {RC.LAM_CLIFF:g}], " f"{a.bucket_frames}-frame bucket") print(f" CPU ceiling: " + (f"mu bisected per frame against " f"{RC.FRAME_CYCLES:,.0f} cycles (12fps, stock 68000)" if cyc_budget else "OFF (--no-cpu-fit)")) else: print(f" target {prof['kbps']} KB/s, FIXED lam={lam} (no rate control)") print(f" k1={k1} k4={k4}, {_IDX_BYTES}-byte indices") m = H.build(a.frames_dir, k1=k1, k4=k4, iters=a.iters) if rc: enc = RC.encode_rate_controlled(m, prof["kbps"], fps=a.fps, bucket_frames=a.bucket_frames, lam_lo=lam_lo, prefill=a.prefill, cycle_budget=cyc_budget) else: enc = H.encode(m, lam=lam) r = H.evaluate(m, enc, fps=a.fps) H_, W_ = m["H"], m["W"]; nbx = W_ // 4 pal, idx = m["pal"], m["idx"] # The encoder hands back the symbols it actually chose. Re-deriving them # here (as session 5 did) is a second chance to disagree with the encoder, # and with per-frame rate control the mode map is no longer reproducible # from a single lam anyway. frames = [] for f, im in enumerate(idx): mode = enc["modes"][f] frames.append(pack_modes(mode) + frame_payload(mode, enc["l1"][f], enc["l4g"][f], im, nbx)) # the rate controller budgets exactly these bytes -- if that ever drifts # from the container, every bitrate figure below is fiction assert len(frames[-1]) == enc["sizes"][f], (f, len(frames[-1]), enc["sizes"][f]) palette = m["pal"][:256] if len(palette) < 256: palette = np.vstack([palette, np.zeros((256 - len(palette), 3), np.uint8)]) pal_b = palette.astype(np.uint8).tobytes() cb1_b = m["cb1"].astype(np.uint8).tobytes() cb4_b = m["cb4"].astype(np.uint8).tobytes() off_pal = 32 off_cb1 = off_pal + len(pal_b) off_cb4 = off_cb1 + len(cb1_b) off_frm = off_cb4 + len(cb4_b) # DLX2: every frame record starts on a 4-byte boundary, including the # first. Payload lengths are arbitrary, so end-to-end records land on odd # addresses -- and `move.l (a0)+` at an odd address is an ADDRESS ERROR on # a 68000, not a slow read. It vectors into the IPL and looks exactly like # an infinite loop (FINDINGS 28.3). tools/bench/prep_dlx.py has been # realigning at load time; the container now carries it. tbl_pad = -off_frm % 4 off_frm += tbl_pad hdr = (b"DLX2" + struct.pack(">HHHHHH", W_, H_, a.fps, len(idx), k1, k4) + struct.pack(">IIII", off_pal, off_cb1, off_cb4, off_frm)) assert len(hdr) == 32, len(hdr) frm_pad = 0 with open(a.out, "wb") as fh: fh.write(hdr); fh.write(pal_b); fh.write(cb1_b); fh.write(cb4_b) fh.write(b"\0" * tbl_pad) for i, p in enumerate(frames): fh.write(struct.pack(">I", len(p))); fh.write(p) if i + 1 < len(frames): # nothing follows the last record n = -(4 + len(p)) % 4 fh.write(b"\0" * n); frm_pad += n total = os.path.getsize(a.out) vid = sum(len(p) + 4 for p in frames) + frm_pad print(f" wrote {a.out}: {total} B " f"(header+tables {total-vid} B, video {vid} B)") print(f" DLX2 4-byte record alignment: {frm_pad} B over {len(frames)} frames " f"({frm_pad/len(frames):.2f} B/frame = {frm_pad/len(frames)*a.fps:.0f} B/s)") print(f" {vid/len(idx):.0f} B/frame -> {vid/len(idx)*a.fps/1024:.1f} KB/s video" f" + {RC.AUDIO_KBPS} KB/s audio = {vid/len(idx)*a.fps/1024+RC.AUDIO_KBPS:.1f} KB/s") print(f" PSNR {r['psnr']:.2f} dB palette ceiling {r['pal']:.2f} dB " f"loss {r['loss']:.2f} dB") print(f" modes: SKIP {r['skip']:.1f}% V1 {r['v1']:.1f}% " f"V4 {r['v4']:.1f}% RAW {r['raw']:.1f}%") if rc: rr = RC.summarise(m, enc, prof["kbps"], fps=a.fps) lm = enc["lam"] print(f" rate control: per-frame budget {enc['budget']:.0f} B, " f"bucket {enc['cap']:.0f} B ({a.bucket_frames} frames), " f"prefill {100*a.prefill:.0f}%") print(f" lam: min {lm.min():.1f} median {rr['lam_med']:.1f} " f"p90 {rr['lam_p90']:.1f} max {rr['lam_max']:.1f}") print(f" frames over the per-frame budget (banked by the bucket): " f"{rr['over']:.0f}%") print(f" frames that could not fit even at the lam={RC.LAM_CLIFF:g} " f"cliff: {rr['overrun']}/{len(lm)}") # PER-FRAME DECODE COST, from the measured per-mode block costs # (FINDINGS 28.2, vq_hybrid.cycles). The mean cannot answer this: a scene # cut is ~100% non-SKIP and a held frame near 0%, so their mean describes # no real frame. What matters is how many frames MISS, and by how much. # # This replaces the per-frame blit-vs-direct path choice that used to be # printed here. That plan is withdrawn -- mixing the two paths displays # stale pixels on 70 of 120 frames, and there was never a crossover to # begin with, because the compose path pays the blit ON TOP of decoding. # FINDINGS 28.1/28.4. The player has one path and no reference frame. ns = np.array([100 * (mm != 0).mean() for mm in enc["modes"]]) cyc = np.array([H.cycles(mm) for mm in enc["modes"]]) pct = 100 * cyc / RC.FRAME_CYCLES miss = int((pct > 100).sum()) print(f" non-SKIP blocks/frame: median {np.median(ns):.1f}% " f"p90 {np.percentile(ns, 90):.1f}% max {ns.max():.1f}%") print(f" decode cost: median {np.median(pct):.1f}% " f"p90 {np.percentile(pct, 90):.1f}% max {pct.max():.1f}% " f"of a {a.fps}fps frame") print(f" frames that do NOT decode in time: {miss}/{len(pct)} " f"({100*miss/len(pct):.0f}%)" + (f" -- worst {pct.max():.1f}%" if miss else "")) if rc and cyc_budget: rr2 = RC.summarise(m, enc, prof["kbps"], fps=a.fps) print(f" mu: median {rr2['mu_med']:.4f} max {rr2['mu_max']:.3f} " f"frames needing any mu at all: {int((enc['mu'] > 0).sum())}/{len(pct)}") print(f" frames that cannot fit even at mu={RC.MU_CLIFF:g} " f"(emitted late on purpose): {rr2['late']}") if a.preview: from PIL import Image f = len(idx) // 2 gap = np.full((H_ * 3, 4, 3), 40, np.uint8) st = np.concatenate([VQ.zoom(m["rgb"][f], 3), gap, VQ.zoom(pal[idx[f]], 3), gap, VQ.zoom(pal[enc["recon"][f]], 3)], axis=1) Image.fromarray(st).save(a.preview) print(f" preview -> {a.preview} (source | palette ceiling | decoded)") if __name__ == "__main__": main()