better compression for GIFs
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esef committed
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eac6dbda3a
commit
0b5ba6511e
1 file changed
+152
-13
+152
-13
@@ -18,8 +18,11 @@ FFPROBE = shutil.which("ffprobe")
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MAX_CONVERTED_BYTES = 8 * 1024 * 1024 # bigger than this, discord rejects it
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_GIF_FILTER = ("fps=15,scale=320:-1:flags=lanczos,split[s0][s1];"
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"[s0]palettegen[p];[s1][p]paletteuse")
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class _Oversize:
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__slots__ = ("size",)
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def __init__(self, size: int):
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self.size = size
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_lottie_state = None # None = not yet checked
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@@ -96,8 +99,12 @@ def _decoder_args(in_suffix: str) -> list[str]:
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async def _convert(data: bytes, in_suffix: str, out_suffix: str,
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args, timeout: float):
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"""Shared conversion body. Returns bytes, or None if it did not work out."""
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args, timeout: float, max_bytes: int = MAX_CONVERTED_BYTES):
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"""Shared conversion body.
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Returns bytes, `_OVERSIZE` if the encode worked but blew the budget, or
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None if it genuinely failed.
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"""
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if not FFMPEG:
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return None
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src = dst = None
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@@ -111,9 +118,10 @@ async def _convert(data: bytes, in_suffix: str, out_suffix: str,
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log.debug("ffmpeg rc=%s: %s", code, out.decode(errors="replace")[:300])
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return None
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size = os.path.getsize(dst)
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if size > MAX_CONVERTED_BYTES:
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log.info("converted media too large (%d bytes) — keeping original", size)
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return None
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if size > max_bytes:
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log.debug("encode over budget: %.2f MB > %.2f MB",
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size / 1048576, max_bytes / 1048576)
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return _Oversize(size)
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with open(dst, "rb") as handle:
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return handle.read()
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except Exception as exc:
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@@ -129,18 +137,149 @@ async def to_animated_webp(data: bytes, in_suffix: str = ".webm"):
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GIF only has on/off transparency, which is what haloed every sticker edge.
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"""
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return await _convert(
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out = await _convert(
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data, in_suffix, ".webp",
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["-c:v", "libwebp_anim", "-pix_fmt", "yuva420p", "-lossless", "0",
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"-q:v", "70", "-loop", "0", "-an", "-fps_mode", "passthrough"],
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timeout=45.0)
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if isinstance(out, _Oversize):
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log.info("animated webp too large — keeping original")
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return None
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return out
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async def to_gif(data: bytes, in_suffix: str = ".mp4"):
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"""Convert a silent clip to a looping GIF (Discord autoplays these)."""
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return await _convert(data, in_suffix, ".gif",
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["-filter_complex", _GIF_FILTER, "-loop", "0"],
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timeout=45.0)
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def _gif_filter(fps=None, width=None, per_frame=True, dither="sierra2_4a"):
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pre = []
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if fps:
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pre.append(f"fps={fps}")
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if width:
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# min() so we never upscale something already smaller than the cap
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pre.append(f"scale='min({width},iw)':-1:flags=lanczos")
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prefix = ",".join(pre) + "," if pre else ""
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if per_frame:
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gen = "palettegen=stats_mode=single:reserve_transparent=0"
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use = f"paletteuse=new=1:dither={dither}"
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else:
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gen = "palettegen=stats_mode=diff"
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use = f"paletteuse=dither={dither}"
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return f"{prefix}split[s0][s1];[s0]{gen}[p];[s1][p]{use}"
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# Quality ladder, best first. Each rung gives up the least it can:
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# per-frame palette -> global palette -> cheaper dither -> framerate -> size.
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# Dither drops before framerate deliberately: dithering breaks up LZW runs, so
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# it costs more bytes than resolution does. Measured on a 6s 640x480 clip,
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# sierra2_4a -> bayer:5 went 13.8 MB -> 8.4 MB with no visible loss in motion.
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# The last rung is the old hardcoded behaviour, kept as a floor, not a default.
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_GIF_TIERS = (
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dict(fps=None, width=None, per_frame=True, dither="sierra2_4a"),
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dict(fps=None, width=None, per_frame=False, dither="sierra2_4a"),
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dict(fps=None, width=None, per_frame=False, dither="bayer:bayer_scale=5"),
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dict(fps=24, width=None, per_frame=False, dither="bayer:bayer_scale=5"),
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dict(fps=20, width=720, per_frame=False, dither="bayer:bayer_scale=5"),
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dict(fps=20, width=560, per_frame=False, dither="bayer:bayer_scale=5"),
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dict(fps=15, width=420, per_frame=False, dither="bayer:bayer_scale=5"),
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dict(fps=15, width=320, per_frame=False, dither="bayer:bayer_scale=5"),
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)
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_GIF_BYTES_PER_PXFRAME = 0.03
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GIF_ATTEMPT_TIMEOUT = 120.0 # native-res per-frame palettes are not fast
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GIF_TOTAL_BUDGET = 240.0 # ceiling across the whole ladder
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async def probe_video(data: bytes, suffix: str = ".mp4"):
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"""-> (width, height, duration, fps), or None if ffprobe cannot say."""
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if not FFPROBE:
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return None
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src = None
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try:
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src = await asyncio.to_thread(_write_temp, data, suffix)
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code, out = await _run([
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FFPROBE, "-v", "error", "-select_streams", "v:0", "-show_entries",
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"stream=width,height,avg_frame_rate:format=duration",
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"-of", "default=noprint_wrappers=1:nokey=0", src,
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], timeout=15.0)
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if code != 0:
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return None
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fields = dict(
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line.split("=", 1)
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for line in out.decode(errors="replace").splitlines() if "=" in line)
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width = int(fields.get("width", 0))
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height = int(fields.get("height", 0))
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duration = float(fields.get("duration", 0) or 0)
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num, _, den = fields.get("avg_frame_rate", "0/0").partition("/")
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fps = float(num) / float(den) if float(den or 0) else 0.0
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if not (width and height and duration > 0 and fps > 0):
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return None
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return width, height, duration, fps
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except Exception as exc:
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log.debug("video probe failed (%s) — trying every tier", exc)
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return None
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finally:
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await asyncio.to_thread(_unlink, src)
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def _tier_cost(tier) -> float:
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return 1.0 if tier["dither"].startswith("sierra") else 0.61
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def _pixel_frames(tier, probed):
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if not probed:
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return None
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width, height, duration, fps = probed
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out_w = min(tier["width"], width) if tier["width"] else width
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out_h = height * (out_w / width)
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out_fps = min(tier["fps"], fps) if tier["fps"] else fps
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return out_w * out_h * duration * out_fps * _tier_cost(tier)
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async def to_gif(data: bytes, in_suffix: str = ".mp4",
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max_bytes: int = MAX_CONVERTED_BYTES):
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if not FFMPEG:
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return None
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probed = await probe_video(data, in_suffix)
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loop = asyncio.get_running_loop()
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started = loop.time()
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rate = _GIF_BYTES_PER_PXFRAME # refined once this clip tells us better
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for index, tier in enumerate(_GIF_TIERS):
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weighted = _pixel_frames(tier, probed)
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if weighted and weighted * rate > max_bytes:
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continue
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remaining = GIF_TOTAL_BUDGET - (loop.time() - started)
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if remaining <= 5.0:
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log.info("gif ladder out of time after tier %d", index)
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break
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try:
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out = await _convert(
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data, in_suffix, ".gif",
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["-filter_complex", _gif_filter(**tier), "-loop", "0"],
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timeout=min(GIF_ATTEMPT_TIMEOUT, remaining),
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max_bytes=max_bytes)
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except asyncio.TimeoutError:
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continue # too slow at this quality, drop a rung
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if isinstance(out, bytes):
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log.info("gif tier %d: fps=%s width=%s per_frame=%s -> %.2f MB",
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index, tier["fps"] or "native", tier["width"] or "native",
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tier["per_frame"], len(out) / 1048576)
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return out
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if out is None:
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# a real ffmpeg failure — every other tier reads the same input
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log.debug("gif encode failed outright at tier %d — giving up", index)
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return None
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if weighted:
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rate = max(rate, out.size / weighted * 0.9)
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log.info("no gif tier fit under %.1f MB — keeping original",
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max_bytes / 1048576)
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return None
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# ── lottie (.tgs animated stickers) ────────────────────────────────────────
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