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fix(render): detect portrait sources that carry rotation metadata #109

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fix(render): detect portrait sources that carry rotation metadata #109

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26 changes: 22 additions & 4 deletions helpers/render.py
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Original file line number Diff line number Diff line change
Expand Up @@ -132,15 +132,33 @@ def is_hdr_source(video: Path) -> bool:


def is_portrait_source(video: Path) -> bool:
"""Return True if the video's height > width (portrait / vertical)."""
"""Return True if the video displays taller than wide (portrait / vertical).

Phone cameras store vertical footage as a landscape stream plus a rotation
entry. ffmpeg auto-rotates on decode, so the displayed dimensions -- not the
stored ones -- decide which axis to scale by.
"""
try:
out = subprocess.run(
["ffprobe", "-v", "error", "-select_streams", "v:0",
"-show_entries", "stream=width,height",
"-of", "csv=p=0", str(video)],
"-show_entries", "stream=width,height:stream_side_data=rotation:stream_tags=rotate",
"-of", "json", str(video)],
capture_output=True, text=True, check=True,
)
w, h = map(int, out.stdout.strip().split(","))
stream = json.loads(out.stdout)["streams"][0]
w, h = int(stream["width"]), int(stream["height"])

rotation = 0
for side_data in stream.get("side_data_list", []):
if "rotation" in side_data:
rotation = int(side_data["rotation"])
break
else:
# ffmpeg < 5 exposes the display matrix as a stream tag instead.
rotation = int(stream.get("tags", {}).get("rotate", 0))

if rotation % 180 != 0:

@cubic-dev-ai cubic-dev-ai Bot Jul 16, 2026 •
edited
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P2: Non-right-angle rotation metadata is classified as portrait, so slightly rotated landscape sources can take the portrait scaling path. Limit the swap to 90°/270° rotations, which are the only cases that exchange axes.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At helpers/render.py, line 160:

<comment>Non-right-angle rotation metadata is classified as portrait, so slightly rotated landscape sources can take the portrait scaling path. Limit the swap to 90°/270° rotations, which are the only cases that exchange axes.</comment>

<file context>
@@ -132,15 +132,33 @@ def is_hdr_source(video: Path) -> bool:
+            # ffmpeg < 5 exposes the display matrix as a stream tag instead.
+            rotation = int(stream.get("tags", {}).get("rotate", 0))
+
+        if rotation % 180 != 0:
+            w, h = h, w
         return h > w
</file context>
Suggested change
if rotation % 180 != 0:
if rotation % 180 == 90:
Fix with cubic

w, h = h, w
return h > w
except Exception:
return False
Expand Down