From 1da96f6d694ae215b28754160c34ebe332a51625 Mon Sep 17 00:00:00 2001
From: Vanilagy <1696106+Vanilagy@users.noreply.github.com>
Date: Thu, 19 Mar 2026 12:25:19 +0100
Subject: [PATCH] Add displayAspectWidth/displayAspectHeight only when they are
 necessary

---
 src/isobmff/isobmff-demuxer.ts   | 14 +++++++++++---
 src/matroska/matroska-demuxer.ts | 14 +++++++++++---
 src/mpeg-ts/mpeg-ts-demuxer.ts   | 10 ++++++++--
 test/browser/par.test.ts         |  4 ++--
 4 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/src/isobmff/isobmff-demuxer.ts b/src/isobmff/isobmff-demuxer.ts
index e247193..d52e160 100644
--- a/src/isobmff/isobmff-demuxer.ts
+++ b/src/isobmff/isobmff-demuxer.ts
@@ -2947,15 +2947,23 @@ class IsobmffVideoTrackBacking extends IsobmffTrackBacking implements InputVideo
 				this.internalTrack.info.av1CodecInfo = firstPacket && extractAv1CodecInfoFromPacket(firstPacket.data);
 			}
 
-			return {
+			const config: VideoDecoderConfig = {
 				codec: extractVideoCodecString(this.internalTrack.info),
 				codedWidth: this.internalTrack.info.width,
 				codedHeight: this.internalTrack.info.height,
-				displayAspectWidth: this.internalTrack.info.squarePixelWidth,
-				displayAspectHeight: this.internalTrack.info.squarePixelHeight,
 				description: this.internalTrack.info.codecDescription ?? undefined,
 				colorSpace: this.internalTrack.info.colorSpace ?? undefined,
 			};
+
+			if (
+				this.internalTrack.info.width !== this.internalTrack.info.squarePixelWidth
+				|| this.internalTrack.info.height !== this.internalTrack.info.squarePixelHeight
+			) {
+				config.displayAspectWidth = this.internalTrack.info.squarePixelWidth;
+				config.displayAspectHeight = this.internalTrack.info.squarePixelHeight;
+			}
+
+			return config;
 		})();
 	}
 }
diff --git a/src/matroska/matroska-demuxer.ts b/src/matroska/matroska-demuxer.ts
index 28106c9..37a601d 100644
--- a/src/matroska/matroska-demuxer.ts
+++ b/src/matroska/matroska-demuxer.ts
@@ -2430,7 +2430,7 @@ class MatroskaVideoTrackBacking extends MatroskaTrackBacking implements InputVid
 				firstPacket = await this.getFirstPacket({});
 			}
 
-			return {
+			const config: VideoDecoderConfig = {
 				codec: extractVideoCodecString({
 					width: this.internalTrack.info.width,
 					height: this.internalTrack.info.height,
@@ -2453,11 +2453,19 @@ class MatroskaVideoTrackBacking extends MatroskaTrackBacking implements InputVid
 				}),
 				codedWidth: this.internalTrack.info.width,
 				codedHeight: this.internalTrack.info.height,
-				displayAspectWidth: this.internalTrack.info.squarePixelWidth,
-				displayAspectHeight: this.internalTrack.info.squarePixelHeight,
 				description: this.internalTrack.info.codecDescription ?? undefined,
 				colorSpace: this.internalTrack.info.colorSpace ?? undefined,
 			};
+
+			if (
+				this.internalTrack.info.width !== this.internalTrack.info.squarePixelWidth
+				|| this.internalTrack.info.height !== this.internalTrack.info.squarePixelHeight
+			) {
+				config.displayAspectWidth = this.internalTrack.info.squarePixelWidth;
+				config.displayAspectHeight = this.internalTrack.info.squarePixelHeight;
+			}
+
+			return config;
 		})();
 	}
 }
diff --git a/src/mpeg-ts/mpeg-ts-demuxer.ts b/src/mpeg-ts/mpeg-ts-demuxer.ts
index be61c08..42ee52e 100644
--- a/src/mpeg-ts/mpeg-ts-demuxer.ts
+++ b/src/mpeg-ts/mpeg-ts-demuxer.ts
@@ -1514,10 +1514,16 @@ class MpegTsVideoTrackBacking extends MpegTsTrackBacking implements InputVideoTr
 			}),
 			codedWidth: this.elementaryStream.info.width,
 			codedHeight: this.elementaryStream.info.height,
-			displayAspectWidth: this.elementaryStream.info.squarePixelWidth,
-			displayAspectHeight: this.elementaryStream.info.squarePixelHeight,
 			colorSpace: this.elementaryStream.info.colorSpace,
 		};
+
+		if (
+			this.elementaryStream.info.width !== this.elementaryStream.info.squarePixelWidth
+			|| this.elementaryStream.info.height !== this.elementaryStream.info.squarePixelHeight
+		) {
+			this.decoderConfig.displayAspectWidth = this.elementaryStream.info.squarePixelWidth;
+			this.decoderConfig.displayAspectHeight = this.elementaryStream.info.squarePixelHeight;
+		}
 	}
 
 	override getCodec(): VideoCodec {
diff --git a/test/browser/par.test.ts b/test/browser/par.test.ts
index 744999d..0f04c53 100644
--- a/test/browser/par.test.ts
+++ b/test/browser/par.test.ts
@@ -87,8 +87,8 @@ test('Pixel aspect ratio transcode conversion', async () => {
 	expect(mp4.snapshot.squarePixelHeight).toBe(mp4.snapshot.codedHeight);
 	expect(mp4.snapshot.displayWidth).toBe(mp4.snapshot.codedWidth);
 	expect(mp4.snapshot.displayHeight).toBe(mp4.snapshot.codedHeight);
-	expect(mp4.snapshot.decoderDisplayAspectWidth).toBe(mp4.snapshot.codedWidth);
-	expect(mp4.snapshot.decoderDisplayAspectHeight).toBe(mp4.snapshot.codedHeight);
+	expect(mp4.snapshot.decoderDisplayAspectWidth).toBeUndefined();
+	expect(mp4.snapshot.decoderDisplayAspectHeight).toBeUndefined();
 
 	expect(mp4.snapshot.codedWidth).toBe(source.squarePixelWidth);
 	expect(mp4.snapshot.codedHeight).toBe(source.squarePixelHeight);