종료 코드는 네가 던진 것보다 좁은 질문에 답해

# INTENT ONLY - this is what most pipelines do
def encode(src: Path, dst: Path) -> Path:
    subprocess.run([FFMPEG, "-i", str(src), *PROFILE, str(dst)], check=True)
    return dst        # exit 0. we know nothing about dst.


# RESULT - open the artifact and ask what it actually is
def encode_checked(src: Path, dst: Path, expect_s: float) -> Path:
    subprocess.run([FFMPEG, "-i", str(src), *PROFILE, str(dst)], check=True)

    got = probe_duration(dst)                       # measured, not computed
    if abs(got - expect_s) > 0.05:
        raise BadEncode(f"{dst.name}: {got:.2f}s, expected {expect_s:.2f}s")

    streams = probe_streams(dst)                    # enumerated, not assumed
    if [s["codec_type"] for s in streams] != ["video", "audio"]:
        raise BadEncode(f"{dst.name}: unexpected stream layout {streams}")

    return dst

# The 25x-too-long clip passed the first version and fails the second
# on its first assertion - with the actual number in the message.

# WEAK: a help listing may be a static table compiled in,
# not a reflection of what this build can actually run.
ffmpeg -h filter=somefilter        # "supported" proves little

# STRONG: render one frame through it and see.
ffmpeg -v error -f lavfi -i color=c=black:s=64x64:d=1 \
       -vf "somefilter=..." -frames:v 1 -f null - \
  && echo "actually works in THIS build"

# Same principle as measuring output: a system's report about
# itself is a claim. Exercise the capability instead.