Files
ComfyAssets-ComfyUI_PromptM…/py/api/thumbnail_encode.py
T
Vito Sansevero dc8b86751e feat(thumbnails): thumbnail format, quality and size as server settings
Thumbnail format (webp default, jxl, jpeg), quality (1-100, default 80)
and size limit (128-2048 px, default 512) are server settings in the
config.json thumbnails section, saved with the settings revision. The
never-read gallery thumbnail_size is gone: older saves wrote its unused
default 256 into config.json.

One module names previews (<stem>_thumb.webp/.jxl/.jpg) and finds the
preview a source owns, preferring the configured format; legacy names
are still found. The encoder module writes every preview atomically and
verifies it decodes. JPEG XL needs no new dependency: Pillow (natively
or with pillow_jxl), ffmpeg with libjxl, or cjxl; without one the
settings refuse jxl (400 jxl-unavailable) and GET says why. Encoder
processes are tracked, bounded and killed at shutdown.
2026-10-24 12:41:06 -07:00

404 lines
13 KiB
Python
Raw Blame History

This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
"""Thumbnail encoders (#317): every preview file is written here.
``write_thumbnail(frame, dst, settings)`` encodes a prepared frame
(``thumbnail_frame``: the first frame, RGB, fitted inside the edge) in the
configured format into a hidden temp sibling, closes it, verifies that it
decodes, and renames it over ``dst`` (``os.replace``), so a reader never sees
a partial file and a failure keeps the old preview. ``guard()`` is asked just
before the rename (automatic previews' holds, #249).
Formats: WebP (Pillow, ``method=4``) and JPEG (Pillow, ``optimize``) always
work. JPEG XL needs no new dependency; the first encoder found is used:
1. Pillow, natively or through the ``pillow_jxl`` plugin (imported when
installed: ``pip install pillow-jxl-plugin``), given the quality itself;
2. ffmpeg built with ``libjxl`` (``-distance``), fed a PNG on stdin;
3. ``cjxl`` from libjxl (``-d``), fed a temp PNG that is closed first.
Quality maps to a JPEG XL distance with libjxl's own
``JxlEncoderDistanceFromQuality``: ``0.1 + (100 - q) * 0.09`` from 30 up
(q80 → d1.9, q85 → d1.45, q90 → d1.0), the quadratic below 30, and q100 →
d0.1 (a preview is never lossless). Pillow's plugin applies the same mapping
inside libjxl. Detection is cached (``detect_jxl_encoder(refresh=True)``
probes again). If JPEG XL is configured but no encoder is left at write
time, that file is written as WebP and the fallback is logged once.
Encoder processes (and ffmpeg's video frames, images.py) go through
``run_encoder``: tracked, bounded by a timeout, and killed by
``shutdown_encoders()`` at the app's cleanup, after which none starts.
"""
import importlib
import io
import os
import shutil
import subprocess # nosec B404 - fixed argv lists, never a shell
import threading
from pathlib import Path
from PIL import Image
try:
from ...utils.logging_config import get_logger
except ImportError: # tests import the package top-level
from utils.logging_config import get_logger
logger = get_logger("prompt_manager.thumbnails")
PILLOW_JXL_FORMAT = "JXL"
JXL_UNAVAILABLE = (
"No JPEG XL encoder found. Install pillow-jxl-plugin "
"(pip install pillow-jxl-plugin), ffmpeg built with libjxl, or cjxl from "
"libjxl, then restart ComfyUI."
)
# Seconds an encoder process may run (ffmpeg's video frame shares it).
ENCODE_TIMEOUT = 30
PROBE_TIMEOUT = 10
JXL_EFFORT = 7
WEBP_METHOD = 4
JXL_SIGNATURES = (b"\xff\x0a", b"\x00\x00\x00\x0cJXL \r\n\x87\n")
_NO_WINDOW = getattr(subprocess, "CREATE_NO_WINDOW", 0)
class PreviewWriteHeld(Exception):
"""A preview write stopped before its rename: ``guard()`` said no (#249)."""
# The result error of a write held before its rename (never remembered).
PREVIEW_HELD = "Preview writes are held while another job runs"
class ThumbnailVerifyError(RuntimeError):
"""The encoded preview did not decode; it was never renamed in."""
class EncoderFailed(RuntimeError):
"""An encoder process failed or wrote nothing."""
class EncoderClosed(RuntimeError):
"""The app is shutting down: no encoder process runs any more."""
# ── temp files ───────────────────────────────────────────────────────
def temp_sibling(dst, tag="part"):
"""Hidden temp path next to *dst* that keeps its extension."""
dst = Path(dst)
token = f"{os.getpid()}-{threading.get_ident()}"
return dst.with_name(f".{dst.stem}.{tag}-{token}{dst.suffix}")
def replace_unless_held(tmp, dst, guard=None):
"""Rename *tmp* over *dst*, unless ``guard()`` is false (PreviewWriteHeld)."""
if guard is not None and not guard():
raise PreviewWriteHeld(PREVIEW_HELD)
os.replace(tmp, dst)
def _unlink_quietly(path):
try:
Path(path).unlink()
except FileNotFoundError:
pass
except OSError as exc:
logger.debug(f"Could not remove temp file {Path(path).name}: {exc}")
# ── encoder processes ────────────────────────────────────────────────
_process_lock = threading.Lock()
_processes = set()
_closed = False
def run_encoder(cmd, *, input=None, timeout=ENCODE_TIMEOUT, track=None):
"""Run *cmd* (a fixed argv) with *input* on stdin; returns a
CompletedProcess with bytes output.
The process is tracked so ``shutdown_encoders`` can kill it; past
*timeout* it is killed and TimeoutExpired raised. After the shutdown
nothing starts (EncoderClosed). ``track(process)`` sees it too.
"""
with _process_lock:
if _closed:
raise EncoderClosed("Encoders are shut down")
process = subprocess.Popen( # nosec B603 - fixed argv, no shell
cmd,
stdin=subprocess.PIPE if input is not None else subprocess.DEVNULL,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
creationflags=_NO_WINDOW,
)
with _process_lock:
_processes.add(process)
closed = _closed
try:
if closed:
process.kill()
if track is not None:
track(process)
try:
out, err = process.communicate(input=input, timeout=timeout)
except subprocess.TimeoutExpired:
process.kill()
process.communicate()
raise
finally:
with _process_lock:
_processes.discard(process)
closed = _closed
if closed:
raise EncoderClosed("Encoder stopped by the shutdown")
return subprocess.CompletedProcess(cmd, process.returncode, out, err)
def shutdown_encoders():
"""Kill every running encoder process; none starts afterwards."""
global _closed
with _process_lock:
_closed = True
running = list(_processes)
for process in running:
try:
process.kill()
except OSError:
pass
def reset_encoders():
"""Allow encoders again and forget the detection (tests, a reload)."""
global _closed, _detected, _fallback_logged
with _process_lock:
_closed = False
with _detect_lock:
_detected = _UNSET
_fallback_logged = False
# ── JPEG XL detection ────────────────────────────────────────────────
_UNSET = object()
_detect_lock = threading.Lock()
_detected = _UNSET
_fallback_logged = False
def _pillow_jxl_format():
"""Pillow's JPEG XL format id when it can save one, else None."""
try:
native = Image.registered_extensions().get(".jxl")
except Exception:
native = None
if native and native in Image.SAVE:
return native
return PILLOW_JXL_FORMAT if PILLOW_JXL_FORMAT in Image.SAVE else None
def _pillow_can_save_jxl():
if _pillow_jxl_format():
return True
try:
importlib.import_module("pillow_jxl")
except Exception:
return False
return _pillow_jxl_format() is not None
def _pillow_decodes_jxl():
try:
native = Image.registered_extensions().get(".jxl")
except Exception:
native = None
return bool(native and native in Image.OPEN) or PILLOW_JXL_FORMAT in Image.OPEN
def _ffmpeg_has_libjxl():
"""Whether the ffmpeg on PATH lists the ``libjxl`` encoder."""
if not shutil.which("ffmpeg"):
return False
try:
done = run_encoder(
["ffmpeg", "-hide_banner", "-encoders"], timeout=PROBE_TIMEOUT
)
except (OSError, subprocess.SubprocessError, EncoderClosed):
return False
listing = done.stdout
if isinstance(listing, bytes):
listing = listing.decode("utf-8", "replace")
return any(
len(line.split()) > 1 and line.split()[1] == "libjxl"
for line in listing.splitlines()
)
def _detect():
if _pillow_can_save_jxl():
return "pillow"
if _ffmpeg_has_libjxl():
return "ffmpeg"
if shutil.which("cjxl"):
return "cjxl"
return None
def detect_jxl_encoder(refresh=False):
"""``pillow``, ``ffmpeg``, ``cjxl`` or None (cached; blocking on a probe)."""
global _detected
with _detect_lock:
if refresh or _detected is _UNSET:
_detected = _detect()
return _detected
def encoder_status():
"""Which formats can be written now (``GET /prompt_manager/settings``)."""
encoder = detect_jxl_encoder()
return {
"webp": {"available": True},
"jpeg": {"available": True},
"jxl": {
"available": encoder is not None,
"encoder": encoder,
"reason": None if encoder is not None else JXL_UNAVAILABLE,
},
}
def jxl_distance(quality):
"""libjxl's distance for a 1–100 quality (q100 gives 0.1, never lossless)."""
if quality >= 100:
return 0.1
if quality >= 30:
return 0.1 + (100 - quality) * 0.09
return 53.0 / 3000.0 * quality * quality - 23.0 / 20.0 * quality + 25.0
# ── frames and writers ───────────────────────────────────────────────
def thumbnail_frame(img, edge):
"""The first frame of *img* as RGB, fitted inside ``edge`` x ``edge``."""
try:
img.seek(0)
except (EOFError, AttributeError, ValueError):
pass
try:
img.draft("RGB", (edge, edge)) # JPEG: decode at a reduced scale
except (AttributeError, ValueError, OSError):
pass
frame = img.convert("RGB") if img.mode != "RGB" else img.copy()
frame.thumbnail((edge, edge), Image.Resampling.LANCZOS)
return frame
def _png_bytes(img):
buffer = io.BytesIO()
img.save(buffer, "PNG", compress_level=1)
return buffer.getvalue()
def _write_webp(img, tmp, settings, track):
img.save(tmp, "WEBP", quality=settings.quality, method=WEBP_METHOD)
def _write_jpeg(img, tmp, settings, track):
img.save(tmp, "JPEG", quality=settings.quality, optimize=True)
def _check(done, tmp, name):
if done.returncode != 0 or not Path(tmp).is_file():
detail = (done.stderr or b"")[-300:]
if isinstance(detail, bytes):
detail = detail.decode("utf-8", "replace")
raise EncoderFailed(f"{name} could not encode the preview: {detail.strip()}")
def _write_jxl(img, tmp, settings, track):
encoder = detect_jxl_encoder()
distance = f"{jxl_distance(settings.quality):.2f}"
if encoder == "pillow":
img.save(
tmp,
_pillow_jxl_format() or PILLOW_JXL_FORMAT,
quality=min(settings.quality, 99),
effort=JXL_EFFORT,
num_threads=1,
)
return
if encoder == "ffmpeg":
cmd = [
"ffmpeg", "-v", "error", "-f", "png_pipe", "-i", "-",
"-frames:v", "1", "-c:v", "libjxl", "-distance", distance,
"-effort", str(JXL_EFFORT), "-f", "image2", "-y", str(tmp),
] # fmt: skip
_check(run_encoder(cmd, input=_png_bytes(img), track=track), tmp, "ffmpeg")
return
if encoder == "cjxl":
source = temp_sibling(Path(tmp).with_suffix(".png"), "src")
try:
with open(source, "wb") as handle:
handle.write(_png_bytes(img))
cmd = ["cjxl", str(source), str(tmp), "-d", distance, "-e", str(JXL_EFFORT)]
_check(run_encoder(cmd, track=track), tmp, "cjxl")
finally:
_unlink_quietly(source)
return
raise EncoderFailed(JXL_UNAVAILABLE)
_WRITERS = {"webp": _write_webp, "jpeg": _write_jpeg, "jxl": _write_jxl}
def verify_thumbnail(path, fmt):
"""Raise ThumbnailVerifyError unless *path* decodes as a preview.
A JPEG XL file Pillow cannot read (no plugin) is checked by signature.
"""
try:
if fmt == "jxl" and not _pillow_decodes_jxl():
with open(path, "rb") as handle:
head = handle.read(12)
if not head.startswith(JXL_SIGNATURES):
raise ThumbnailVerifyError("The JPEG XL preview has no signature")
return
with Image.open(path) as written:
written.load()
except ThumbnailVerifyError:
raise
except Exception as exc:
raise ThumbnailVerifyError(f"The new preview does not decode: {exc}") from exc
def _jxl_fallback():
"""Log once that JPEG XL previews are being written as WebP."""
global _fallback_logged
with _detect_lock:
first, _fallback_logged = not _fallback_logged, True
if first:
logger.warning(
"JPEG XL is the thumbnail format but no JPEG XL encoder is available "
"any more; previews are written as WebP until one is installed"
)
def write_thumbnail(frame, dst, settings, *, guard=None, track=None):
"""Encode *frame* into *dst* in ``settings``' format; returns the path
written (``.webp`` when JPEG XL fell back). Atomic and verified; raises
PreviewWriteHeld, ThumbnailVerifyError, EncoderFailed, EncoderClosed or
the OSError of the write."""
dst = Path(dst)
fmt = settings.format
if fmt == "jxl" and detect_jxl_encoder() is None:
_jxl_fallback()
fmt, dst = "webp", dst.with_suffix(".webp")
tmp = temp_sibling(dst)
try:
_WRITERS[fmt](frame, tmp, settings, track)
verify_thumbnail(tmp, fmt)
replace_unless_held(tmp, dst, guard)
finally:
_unlink_quietly(tmp)
return dst