From 9f3fb46d371d52f58bc9a7fc5beefe51890879ed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Velad=20Galv=C3=A1n?= <alvaro.velad@mirada.tv>
Date: Thu, 13 Jan 2022 23:07:35 +0100
Subject: [PATCH] feat: Allow WebP and AVIF image streams (#3856)

Fixes: #3845
---
 lib/util/stream_utils.js | 101 ++++++++++++++++++++++++++++++---------
 1 file changed, 79 insertions(+), 22 deletions(-)

diff --git a/lib/util/stream_utils.js b/lib/util/stream_utils.js
index ca32535840..3ed813b9a6 100644
--- a/lib/util/stream_utils.js
+++ b/lib/util/stream_utils.js
@@ -406,7 +406,7 @@ shaka.util.StreamUtils = class {
     shaka.util.StreamUtils.filterManifestByCurrentVariant(
         currentVariant, manifest);
     shaka.util.StreamUtils.filterTextStreams_(manifest);
-    shaka.util.StreamUtils.filterImageStreams_(manifest);
+    await shaka.util.StreamUtils.filterImageStreams_(manifest);
   }
 
 
@@ -761,37 +761,57 @@ shaka.util.StreamUtils = class {
    * @param {shaka.extern.Manifest} manifest
    * @private
    */
-  static filterImageStreams_(manifest) {
-    // Filter image streams.
-    manifest.imageStreams = manifest.imageStreams.filter((stream) => {
-      // TODO: re-examine this and avoid allow-listing the MIME types we can
-      // accept.
-      const validMimeTypes = [
-        'image/svg+xml',
-        'image/png',
-        'image/jpeg',
-      ];
-      const Platform = shaka.util.Platform;
-      // Add webp support to popular platforms that support it.
-      const webpSupport = Platform.isWebOS() ||
-                          Platform.isTizen() ||
-                          Platform.isChromecast();
-      if (webpSupport) {
-        validMimeTypes.push('image/webp');
+  static async filterImageStreams_(manifest) {
+    const imageStreams = [];
+    for (const stream of manifest.imageStreams) {
+      const mimeType = stream.mimeType;
+      if (!shaka.util.StreamUtils.supportedImageMimeTypes_.has(mimeType)) {
+        const minImage = shaka.util.StreamUtils.minImage_.get(mimeType);
+        if (minImage) {
+          // eslint-disable-next-line no-await-in-loop
+          const res = await shaka.util.StreamUtils.isImageSupported_(minImage);
+          shaka.util.StreamUtils.supportedImageMimeTypes_.set(mimeType, res);
+        } else {
+          shaka.util.StreamUtils.supportedImageMimeTypes_.set(mimeType, false);
+        }
       }
-      // TODO: add support to image/webp and image/avif
-      const keep = validMimeTypes.includes(stream.mimeType);
+
+      const keep =
+          shaka.util.StreamUtils.supportedImageMimeTypes_.get(mimeType);
 
       if (!keep) {
         shaka.log.debug('Dropping image stream. Is not supported by the ' +
                         'platform.', stream);
+      } else {
+        imageStreams.push(stream);
       }
+    }
+    manifest.imageStreams = imageStreams;
+  }
 
-      return keep;
+  /**
+   * @param {string} minImage
+   * @return {!Promise.<boolean>}
+   * @private
+   */
+  static isImageSupported_(minImage) {
+    return new Promise((resolve) => {
+      const imageElement = /** @type {HTMLImageElement} */(new Image());
+      imageElement.src = minImage;
+      if ('decode' in imageElement) {
+        imageElement.decode().then(() => {
+          resolve(true);
+        }).catch(() => {
+          resolve(false);
+        });
+      } else {
+        imageElement.onload = imageElement.onerror = () => {
+          resolve(imageElement.height === 2);
+        };
+      }
     });
   }
 
-
   /**
    * @param {shaka.extern.Stream} s0
    * @param {shaka.extern.Stream} s1
@@ -1445,3 +1465,40 @@ shaka.util.StreamUtils.DecodingAttributes = {
   POWER: 'powerEfficient',
   BANDWIDTH: 'bandwidth',
 };
+
+/**
+ * @private {!Map.<string, boolean>}
+ */
+shaka.util.StreamUtils.supportedImageMimeTypes_ = new Map()
+    .set('image/svg+xml', true)
+    .set('image/png', true)
+    .set('image/jpeg', true)
+    .set('image/jpg', true);
+
+/**
+ * @const {string}
+ * @private
+ */
+shaka.util.StreamUtils.minWebPImage_ = 'data:image/webp;base64,UklGRjoAAABXRU' +
+    'JQVlA4IC4AAACyAgCdASoCAAIALmk0mk0iIiIiIgBoSygABc6WWgAA/veff/0PP8bA//LwY' +
+    'AAA';
+
+/**
+ * @const {string}
+ * @private
+ */
+shaka.util.StreamUtils.minAvifImage_ = 'data:image/avif;base64,AAAAIGZ0eXBhdm' +
+    'lmAAAAAGF2aWZtaWYxbWlhZk1BMUIAAADybWV0YQAAAAAAAAAoaGRscgAAAAAAAAAAcGljd' +
+    'AAAAAAAAAAAAAAAAGxpYmF2aWYAAAAADnBpdG0AAAAAAAEAAAAeaWxvYwAAAABEAAABAAEA' +
+    'AAABAAABGgAAAB0AAAAoaWluZgAAAAAAAQAAABppbmZlAgAAAAABAABhdjAxQ29sb3IAAAA' +
+    'AamlwcnAAAABLaXBjbwAAABRpc3BlAAAAAAAAAAIAAAACAAAAEHBpeGkAAAAAAwgICAAAAA' +
+    'xhdjFDgQ0MAAAAABNjb2xybmNseAACAAIAAYAAAAAXaXBtYQAAAAAAAAABAAEEAQKDBAAAA' +
+    'CVtZGF0EgAKCBgANogQEAwgMg8f8D///8WfhwB8+ErK42A=';
+
+/**
+ * @const {!Map.<string, string>}
+ * @private
+ */
+shaka.util.StreamUtils.minImage_ = new Map()
+    .set('image/webp', shaka.util.StreamUtils.minWebPImage_)
+    .set('image/avif', shaka.util.StreamUtils.minAvifImage_);