diff --git a/cista/preview.py b/cista/preview.py
index ad007b1..bc65f2a 100644
--- a/cista/preview.py
+++ b/cista/preview.py
@@ -6,7 +6,6 @@ import urllib.parse
 from pathlib import PurePosixPath
 from urllib.parse import unquote
 from wsgiref.handlers import format_date_time
-
 import av
 import av.datasets
 import fitz  # PyMuPDF
@@ -36,13 +35,13 @@ async def preview(req, path):
     etag = config.derived_secret(
         "preview", rel, stat.st_mtime_ns, quality, maxsize, maxzoom
     ).hex()
-    savename = PurePosixPath(path.name).with_suffix(".webp")
+    savename = PurePosixPath(path.name).with_suffix(".avif")
     headers = {
         "etag": etag,
         "last-modified": format_date_time(stat.st_mtime),
         "cache-control": "max-age=604800, immutable"
         + ("" if config.config.public else ", private"),
-        "content-type": "image/webp",
+        "content-type": "image/avif",
         "content-disposition": f"inline; filename*=UTF-8''{urllib.parse.quote(savename.as_posix())}",
     }
     if req.headers.if_none_match == etag:
@@ -83,7 +82,7 @@ def process_image(path, *, maxsize, quality):
         logger.error(f"Error rotating preview image: {e}")
     # Save as webp
     imgdata = io.BytesIO()
-    img.save(imgdata, format="webp", quality=quality, method=4)
+    img.save(imgdata, format="avif", quality=quality, method=4)
     return imgdata.getvalue()
 
 
@@ -94,48 +93,48 @@ def process_pdf(path, *, maxsize, maxzoom, quality, page_number=0):
     zoom = min(maxsize / w, maxsize / h, maxzoom)
     mat = fitz.Matrix(zoom, zoom)
     pix = page.get_pixmap(matrix=mat)
-    return pix.pil_tobytes(format="webp", quality=quality, method=4)
+    return pix.pil_tobytes(format="avif", quality=quality, method=4)
 
 
 def process_video(path, *, maxsize, quality):
-    with av.open(str(path)) as container:
-        stream = container.streams.video[0]
-        stream.codec_context.skip_frame = "NONKEY"
-
-        # Updated side data access for newer av versions
-        rot = 0
-        try:
-            # Try newer API first
-            if hasattr(stream, "side_data") and stream.side_data:
-                display_matrix = stream.side_data.get("DISPLAYMATRIX")
-                if display_matrix:
-                    rot = (
-                        display_matrix.rotation
-                        if hasattr(display_matrix, "rotation")
-                        else 0
-                    )
-        except (AttributeError, KeyError):
-            # Fallback for older API or missing side data
-            rot = 0
-
-        container.seek(container.duration // 8)
-        try:
-            frame = next(container.decode(stream))
-            img = frame.to_image()
-        except StopIteration:
-            # If no frame found, try from beginning
-            container.seek(0)
-            frame = next(container.decode(stream))
-            img = frame.to_image()
-
-        del stream
-
-    img.thumbnail((maxsize, maxsize))
+    frame = None
     imgdata = io.BytesIO()
-    if rot and rot != 0:
-        img = img.rotate(-rot, expand=True)  # Negative rotation for correct orientation
-    img.save(imgdata, format="webp", quality=quality, method=4)
-    del img
+    with (
+        av.open(str(path)) as container,
+        av.open(imgdata, "w", format="avif") as ocontainer,
+    ):
+        istream = container.streams.video[0]
+        istream.codec_context.skip_frame = "NONKEY"
+        container.seek((container.duration or 0) // 8)
+        for frame in container.decode(istream):
+            if frame.dts is not None:
+                break
+        else:
+            raise RuntimeError("No frames found in video")
+
+        # Resize frame to thumbnail size
+        if frame.width > maxsize or frame.height > maxsize:
+            scale_factor = min(maxsize / frame.width, maxsize / frame.height)
+            new_width = int(frame.width * scale_factor)
+            new_height = int(frame.height * scale_factor)
+            frame = frame.reformat(width=new_width, height=new_height)
+
+        ostream = ocontainer.add_stream("av1", options={"quality": str(quality)})
+        assert isinstance(ostream, av.VideoStream)
+        ostream.width = frame.width
+        ostream.height = frame.height
+        icc = istream.codec_context
+        occ = ostream.codec_context
+
+        # Copy HDR metadata from input video stream
+        occ.color_primaries = icc.color_primaries
+        occ.color_trc = icc.color_trc
+        occ.colorspace = icc.colorspace
+        occ.color_range = icc.color_range
+
+        ocontainer.mux(ostream.encode(frame))
+        ocontainer.mux(ostream.encode(None))  # Flush the stream
+
     ret = imgdata.getvalue()
     del imgdata
     gc.collect()