From d6001097a9751bd9211eb52f940e282ead026a32 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Velad=20Galv=C3=A1n?= <ladvan91@hotmail.com>
Date: Thu, 1 Dec 2022 22:34:34 +0100
Subject: [PATCH] fix(cea): Fix not rendering CEA-608 on encrypted mp4 segments
 (#4756)

Fixes https://github.com/shaka-project/shaka-player/issues/4605

Co-authored-by: Joey Parrish <joeyparrish@google.com>
---
 externs/shaka/mp4_parser.js |  3 +++
 lib/cea/mp4_cea_parser.js   | 53 ++++++++++++++++++++++++++-----------
 lib/util/mp4_box_parsers.js | 24 +++++++++++++++++
 lib/util/mp4_parser.js      | 35 ++++++++++++++++++++++++
 4 files changed, 99 insertions(+), 16 deletions(-)

diff --git a/externs/shaka/mp4_parser.js b/externs/shaka/mp4_parser.js
index 3545bcdf18..ecc300b899 100644
--- a/externs/shaka/mp4_parser.js
+++ b/externs/shaka/mp4_parser.js
@@ -11,6 +11,7 @@
 
 /**
  * @typedef {{
+ *    name: string,
  *    parser: !shaka.util.Mp4Parser,
  *    partialOkay: boolean,
  *    start: number,
@@ -21,6 +22,8 @@
  *    has64BitSize: boolean
  * }}
  *
+ * @property {string} name
+ *   The box name, a 4-character string (fourcc).
  * @property {!shaka.util.Mp4Parser} parser
  *   The parser that parsed this box. The parser can be used to parse child
  *   boxes where the configuration of the current parser is needed to parsed
diff --git a/lib/cea/mp4_cea_parser.js b/lib/cea/mp4_cea_parser.js
index 4869500da7..553407813a 100644
--- a/lib/cea/mp4_cea_parser.js
+++ b/lib/cea/mp4_cea_parser.js
@@ -66,14 +66,7 @@ shaka.cea.Mp4CeaParser = class {
     const trackIds = [];
     const timescales = [];
 
-    // This generates a box-parser callback that simply sets a particular
-    // bitstream format.  It makes the list of codec-signalling boxes below
-    // more compact and readable.
-    const bitstreamFormatSetter = (format) => {
-      return (box) => {
-        this.bitstreamFormat_ = format;
-      };
-    };
+    const codecBoxParser = (box) => this.setBitstreamFormat_(box.name);
 
     new Mp4Parser()
         .box('moov', Mp4Parser.children)
@@ -108,14 +101,21 @@ shaka.cea.Mp4CeaParser = class {
         .fullBox('stsd', Mp4Parser.sampleDescription)
 
         // These are the various boxes that signal a codec.
-        // Use these to set bistreamFormat_.
-        .box('avc1', bitstreamFormatSetter(BitstreamFormat.H264))
-        .box('avc3', bitstreamFormatSetter(BitstreamFormat.H264))
-        .box('hev1', bitstreamFormatSetter(BitstreamFormat.H265))
-        .box('hvc1', bitstreamFormatSetter(BitstreamFormat.H265))
-        // Dobly vision is also H265.
-        .box('dvh1', bitstreamFormatSetter(BitstreamFormat.H265))
-        .box('dvhe', bitstreamFormatSetter(BitstreamFormat.H265))
+        .box('avc1', codecBoxParser)
+        .box('avc3', codecBoxParser)
+        .box('hev1', codecBoxParser)
+        .box('hvc1', codecBoxParser)
+        .box('dvh1', codecBoxParser)
+        .box('dvhe', codecBoxParser)
+
+        // This signals an encrypted sample, which we can go inside of to find
+        // the codec used.
+        .box('encv', Mp4Parser.visualSampleEntry)
+        .box('sinf', Mp4Parser.children)
+        .box('frma', (box) => {
+          const {codec} = shaka.util.Mp4BoxParsers.parseFRMA(box.reader);
+          this.setBitstreamFormat_(codec);
+        })
 
         .parse(initSegment, /* partialOkay= */ true);
 
@@ -338,6 +338,16 @@ shaka.cea.Mp4CeaParser = class {
       }
     }
   }
+
+  /**
+   * @param {string} codec A fourcc for a codec.
+   * @private
+   */
+  setBitstreamFormat_(codec) {
+    if (codec in shaka.cea.Mp4CeaParser.CodecBitstreamMap_) {
+      this.bitstreamFormat_ = shaka.cea.Mp4CeaParser.CodecBitstreamMap_[codec];
+    }
+  }
 };
 
 /** @enum {number} */
@@ -346,3 +356,14 @@ shaka.cea.Mp4CeaParser.BitstreamFormat = {
   H264: 1,
   H265: 2,
 };
+
+/** @private {Object.<string, shaka.cea.Mp4CeaParser.BitstreamFormat>} */
+shaka.cea.Mp4CeaParser.CodecBitstreamMap_ = {
+  'avc1': shaka.cea.Mp4CeaParser.BitstreamFormat.H264,
+  'avc3': shaka.cea.Mp4CeaParser.BitstreamFormat.H264,
+  'hev1': shaka.cea.Mp4CeaParser.BitstreamFormat.H265,
+  'hvc1': shaka.cea.Mp4CeaParser.BitstreamFormat.H265,
+  // Dobly vision is also H265.
+  'dvh1': shaka.cea.Mp4CeaParser.BitstreamFormat.H265,
+  'dvhe': shaka.cea.Mp4CeaParser.BitstreamFormat.H265,
+};
diff --git a/lib/util/mp4_box_parsers.js b/lib/util/mp4_box_parsers.js
index 204393c129..6fc41db21f 100644
--- a/lib/util/mp4_box_parsers.js
+++ b/lib/util/mp4_box_parsers.js
@@ -7,6 +7,7 @@
 goog.provide('shaka.util.Mp4BoxParsers');
 
 goog.require('shaka.util.DataViewReader');
+goog.require('shaka.util.Mp4Parser');
 
 shaka.util.Mp4BoxParsers = class {
   /**
@@ -188,6 +189,17 @@ shaka.util.Mp4BoxParsers = class {
       trackId,
     };
   }
+
+  /**
+   * Parses a FRMA box.
+   * @param {!shaka.util.DataViewReader} reader
+   * @return {!shaka.util.ParsedFRMABox}
+   */
+  static parseFRMA(reader) {
+    const fourcc = reader.readUint32();
+    const codec = shaka.util.Mp4Parser.typeToString(fourcc);
+    return {codec};
+  }
 };
 
 
@@ -306,3 +318,15 @@ shaka.util.ParsedTRUNSample;
  * @exportDoc
  */
 shaka.util.ParsedTKHDBox;
+
+/**
+ * @typedef {{
+ *    codec: string
+ *  }}
+ *
+ * @property {string} codec
+ *   A fourcc for a codec
+ *
+ * @exportDoc
+ */
+shaka.util.ParsedFRMABox;
diff --git a/lib/util/mp4_parser.js b/lib/util/mp4_parser.js
index 7d0ebf0818..b21221de3b 100644
--- a/lib/util/mp4_parser.js
+++ b/lib/util/mp4_parser.js
@@ -172,6 +172,7 @@ shaka.util.Mp4Parser = class {
 
       /** @type {shaka.extern.ParsedBox} */
       const box = {
+        name,
         parser: this,
         partialOkay: partialOkay || false,
         version,
@@ -236,6 +237,40 @@ shaka.util.Mp4Parser = class {
   }
 
 
+  /**
+   * A callback that tells the Mp4 parser to treat the body of a box as a visual
+   * sample entry.  A visual sample entry has some fixed-sized fields
+   * describing the video codec parameters, followed by an arbitrary number of
+   * appended children.  Each child is a box.
+   *
+   * @param {!shaka.extern.ParsedBox} box
+   * @export
+   */
+  static visualSampleEntry(box) {
+    // The "reader" starts at the payload, so we need to add the header to the
+    // start position.  The header size varies.
+    const headerSize = shaka.util.Mp4Parser.headerSize(box);
+
+    // Skip 6 reserved bytes.
+    // Skip 2-byte data reference index.
+    // Skip 16 more reserved bytes.
+    // Skip 4 bytes for width/height.
+    // Skip 8 bytes for horizontal/vertical resolution.
+    // Skip 4 more reserved bytes (0)
+    // Skip 2-byte frame count.
+    // Skip 32-byte compressor name (length byte, then name, then 0-padding).
+    // Skip 2-byte depth.
+    // Skip 2 more reserved bytes (0xff)
+    // 78 bytes total.
+    // See also https://github.com/shaka-project/shaka-packager/blob/d5ca6e84/packager/media/formats/mp4/box_definitions.cc#L1544
+    box.reader.skip(78);
+
+    while (box.reader.hasMoreData() && !box.parser.done_) {
+      box.parser.parseNext(box.start + headerSize, box.reader, box.partialOkay);
+    }
+  }
+
+
   /**
    * Create a callback that tells the Mp4 parser to treat the body of a box as a
    * binary blob and to parse the body's contents using the provided callback.