prosolis
e00264a058
The open risk since session 2 was "a sustained action sequence could still break the bitrate", with every clip measured so far being 1.2-1.7 s. Closed by measurement rather than by sampling clips by hand. 07_motion_survey.py scans a whole stream at 96x72 for the hottest sliding window of inter-frame difference. On 00223 the spread between the quietest and hottest sustained 10 s windows is 10.6x, which is the argument for not eyeballing it. Hottest is t=539.4s, the Singe endgame. There, with the fixed lam the CLI uses, sasi overshoots 110 -> 129.6 KB/s (+18%) and scsi 280 -> 373.8 KB/s (+34%). Rate control moves from "insurance, not a fix" to required, and is promoted above the full-disc survey. The bus is not broken -- 381.6 KB/s still fits the 488 KB/s figure -- so FINDINGS 21 survives, at 78% of the pipe instead of a comfortable margin. Three further corrections fall out: - The two largest streams on the disc are bonus material. 00216 is the feature with a burned-in commentary PiP; 00215 is the commentary. 00223 is the clean 9.4 min. A size-ranked survey would have encoded live action. - On hard content the 256-colour scene palette (31.33 dB) binds well before the X68000 display (40.81 dB); scsi is already within 0.51 dB of it. - FINDINGS 24.5's architecture question resolves to "both paths, chosen per frame": 30-53% of frames sit above the 70% crossover. Picking per frame costs a median 37.0% of the frame budget and caps at 53.6%. Reporting for this is wired into encode.py, which previously only printed a mean over all frames -- the one statistic that cannot answer a per-frame question. extract.py takes optional start/dur; 08_mode_map.py renders source | decoded | block-mode map to .webm. Claude-Session: https://claude.ai/code/session_01194oWYW8DQXK1SZ2DnChW6
48 lines
2.1 KiB
Python
48 lines
2.1 KiB
Python
#!/usr/bin/env python3
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"""Extract decimated frames from a Blu-ray .m2ts into 256x192 PNGs.
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Source is 1920x1080 (16:9). The arcade original is 4:3, so we CENTER-CROP to
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1440x1080 by default -- see docs/STATUS.md open question on framing.
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"""
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import subprocess, sys, os, shutil
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STREAM_DIR = "/media/reala-misaki/BDROM/BDMV/STREAM"
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W, H = 256, 192
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def duration(path):
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out = subprocess.check_output(["ffprobe","-v","error","-show_entries",
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"format=duration","-of","csv=p=0",path], text=True)
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return float(out.strip())
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def extract(stream, outdir, fps=12, mode="crop", start=None, dur=None):
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src = f"{STREAM_DIR}/{stream}.m2ts"
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total = duration(src)
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if start is None: start = 0.0
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if dur is None: dur = total - start
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shutil.rmtree(outdir, ignore_errors=True); os.makedirs(outdir)
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if mode == "crop": # 4:3 centre crop, arcade framing
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vf = f"crop=1440:1080:240:0,hqdn3d=4:3:0:0,scale={W}:{H}:flags=lanczos"
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elif mode == "squash": # full 16:9 squeezed into 4:3
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vf = f"hqdn3d=4:3:0:0,scale={W}:{H}:flags=lanczos"
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elif mode == "wide": # 16:9 preserved, letterboxed later
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vf = f"hqdn3d=4:3:0:0,scale={W}:144:flags=lanczos"
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else: raise ValueError(mode)
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vf = f"fps={fps}," + vf
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subprocess.check_call(["ffmpeg","-v","error","-ss",str(start),"-t",str(dur),
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"-i",src,"-vf",vf,"-vsync","0",f"{outdir}/f%04d.png","-y"])
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n = len(os.listdir(outdir))
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print(f"{stream}: dur={total:.2f}s -> {n} frames @{fps}fps ({mode})")
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return n
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if __name__ == "__main__":
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# extract.py <stream> <outdir> [fps] [mode] [start_s] [dur_s]
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# start/dur matter for the long streams: 00223 is 9.4 min and the parts
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# that stress the codec are a few seconds each (tools/analysis/07 finds
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# them). Without them a survey silently averages action into idle scenes.
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stream, outdir = sys.argv[1], sys.argv[2]
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fps = int(sys.argv[3]) if len(sys.argv) > 3 else 12
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mode = sys.argv[4] if len(sys.argv) > 4 else "crop"
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start = float(sys.argv[5]) if len(sys.argv) > 5 else None
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dur = float(sys.argv[6]) if len(sys.argv) > 6 else None
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extract(stream, outdir, fps, mode, start, dur)
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