ffcine-core 0.4.0

ffcine core types: errors, colour spaces, 3D LUTs, media info, 2D geometry, param tracks and expressions
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#!/usr/bin/env python3
"""Regenerates ffmpeg_eval.json: each row is [ours, ffmpeg's spelling, av_expr_eval's value].

Run from the dev shell (it needs libavutil):
    nix develop -c python3 crates/ffcine-core/src/anim/testdata/gen_ffmpeg_eval.py
Variables: t = 1.25. The test (`anim::tests::matches_av_expr_eval`) needs no libav.
"""
import ctypes, ctypes.util, json, math, os, subprocess, sys

ROWS = [
    # Functions, spelled the same in both.
    "if(1, 2, 3)", "if(0, 2, 3)", "if(0, 2)", "if(5, 2)", "ifnot(0, 2, 3)", "ifnot(1, 2)",
    "ifnot(0, 2)", "lt(1, 2)", "lt(2, 1)", "lt(2, 2)", "lte(2, 2)", "lte(3, 2)", "gt(3, 2)",
    "gt(2, 2)", "gte(2, 2)", "gte(1, 2)", "eq(2, 2)", "eq(2, 3)", "not(0)", "not(2)",
    "between(2, 1, 3)", "between(1, 1, 3)", "between(3, 1, 3)", "between(4, 1, 3)",
    "clip(5, 0, 3)", "clip(-1, 0, 3)", "clip(1.5, 0, 3)", "min(3, -2)", "max(3, -2)",
    "abs(-2.5)", "floor(-2.5)", "floor(2.5)", "ceil(-2.5)", "ceil(2.1)", "round(2.5)",
    "round(-2.5)", "round(2.4)", "trunc(-2.7)", "trunc(2.7)", "mod(7, 3)", "mod(-7, 3)",
    "mod(7, -3)", "mod(7.5, 2)", "mod(-0.5, 1)", "sqrt(2)", "pow(2, 10)", "pow(2, 0.5)",
    "exp(1)", "log(10)", "sin(1)", "cos(1)", "tan(1)", "asin(0.5)", "acos(0.5)", "atan(1)",
    "atan2(1, 2)", "atan2(-1, -2)", "hypot(3, 4)", "squish(0.3)", "squish(-1)", "gauss(0.5)",
    "gauss(0)", "lerp(1, 3, 0.25)", "lerp(2, -2, 1.5)", "PI", "E", "PHI",
    # Precedence and the operators ffmpeg shares.
    "1 + 2 * 3", "(1 + 2) * 3", "10 - 4 - 3", "64 / 4 / 2", "2 * 3 / 4", "-2^2", "2^-1",
    "-(3 - 5)", "2 ^ 0.5 * 2", "--3", "+3", "1e3 + 2.5e-1", "t * 2", "sin(t) + cos(t)^2",
    "if(lt(t, 4.7), 0, -1080 * (t - 4.7) / 0.4)", "1 - clip((t - 0.6) / 0.4, 0, 1)",
]
# Ours, ffmpeg's spelling: what ffmpeg has only as a function.
PAIRS = [
    ("7 % 3", "mod(7, 3)"), ("-7 % 3", "mod(-7, 3)"), ("7.5 % 2", "mod(7.5, 2)"),
    ("1 < 2", "lt(1, 2)"), ("2 <= 2", "lte(2, 2)"), ("3 > 4", "gt(3, 4)"),
    ("4 >= 4", "gte(4, 4)"), ("2 == 2", "eq(2, 2)"), ("2 != 2", "not(eq(2, 2))"),
    ("!0", "not(0)"), ("!3", "not(3)"), ("1 && 0", "not(not(1))*not(not(0))"),
    ("0 || 2", "not(not(0) * not(2))"), ("1 ? 2 : 3", "if(1, 2, 3)"),
    ("0 ? 2 : 3", "if(0, 2, 3)"), ("sign(-3)", "sgn(-3)"), ("sgn(2)", "sgn(2)"),
    ("sign(0)", "sgn(0)"), ("1 + 2 < 4", "lt(1 + 2, 4)"),
    ("t < 2 && t > 1 ? t * 10 : -1", "if(lt(t, 2) * gt(t, 1), t * 10, -1)"),
]

def libavutil():
    out = subprocess.run(["pkg-config", "--libs-only-L", "libavutil"], capture_output=True,
                         text=True).stdout.split()
    for d in [o[2:] for o in out if o.startswith("-L")]:
        for f in sorted(os.listdir(d)):
            if f.startswith("libavutil.so"):
                return os.path.join(d, f)
    return ctypes.util.find_library("avutil")

lib = ctypes.CDLL(libavutil())
lib.av_version_info.restype = ctypes.c_char_p
names = (ctypes.c_char_p * 2)(b"t", None)
values = (ctypes.c_double * 1)(1.25)

def ev(s):
    r = ctypes.c_double()
    rc = lib.av_expr_parse_and_eval(ctypes.byref(r), s.encode(), names, values, None, None,
                                    None, None, None, 0, None)
    if rc < 0:
        sys.exit(f"ffmpeg rejected {s!r}: {rc}")
    assert math.isfinite(r.value), s
    return r.value

rows = [[s, s, ev(s)] for s in ROWS] + [[a, b, ev(b)] for a, b in PAIRS]
doc = {"ffmpeg": lib.av_version_info().decode(), "vars": {"t": 1.25}, "rows": rows}
here = os.path.dirname(os.path.abspath(__file__))
with open(os.path.join(here, "ffmpeg_eval.json"), "w") as f:
    f.write('{"ffmpeg": %s, "vars": {"t": 1.25}, "rows": [\n' % json.dumps(doc["ffmpeg"]))
    f.write(",\n".join("  " + json.dumps(r) for r in rows))
    f.write("\n]}\n")