[Proposal] scte214 - use supplemental codec instead of base codec if it's supported

src/manifest/representation.ts

@@ -111,6 +111,14 @@ class Representation {
    */
   public codec : string | undefined;
 
+  /**
+   * Supplemental codecs are defined as backwards-compatible codecs enhancing
+   * the experience of a base layer codec
+   */
+  public supplementalCodec?: string | undefined;
+
+
+  public isSupplementalCodecSupported: boolean;
   /**
    * A string describing the mime-type for this Representation.
    * Examples: audio/mp4, video/webm, application/mp4, text/plain
@@ -161,6 +169,10 @@ class Representation {
     this.bitrate = args.bitrate;
     this.codec = args.codecs;
 
+    if (args.supplementalCodecs !== undefined) {
+      this.supplementalCodec = args.supplementalCodecs;
+    }
+
     if (args.isSpatialAudio !== undefined) {
       this.isSpatialAudio = args.isSpatialAudio;
     }
@@ -191,6 +203,15 @@ class Representation {
 
     this.cdnMetadata = args.cdnMetadata;
 
+    if (this.supplementalCodec !== undefined) {
+      const supplementalCodecMimeTypeStr =
+       `${this.mimeType ?? ""};codecs="${this.supplementalCodec ?? ""}"`;
+      const isSupplementalCodecSupported = isCodecSupported(supplementalCodecMimeTypeStr);
+      this.isSupplementalCodecSupported = isSupplementalCodecSupported;
+    } else {
+      this.isSupplementalCodecSupported = false;
+    }
+
     this.index = args.index;
     if (opts.type === "audio" || opts.type === "video") {
       const mimeTypeStr = this.getMimeTypeString();
@@ -210,7 +231,11 @@ class Representation {
    * @returns {string}
    */
   public getMimeTypeString() : string {
-    return `${this.mimeType ?? ""};codecs="${this.codec ?? ""}"`;
+    if (this.isSupplementalCodecSupported) {
+      return `${this.mimeType ?? ""};codecs="${this.supplementalCodec ?? ""}"`;
+    } else {
+      return `${this.mimeType ?? ""};codecs="${this.codec ?? ""}"`;
+    }
   }
 
   /**

src/parsers/manifest/dash/common/parse_representations.ts

@@ -213,6 +213,17 @@ export default function parseRepresentations(
       codecs = codecs === "mp4a.40.02" ? "mp4a.40.2" : codecs;
       parsedRepresentation.codecs = codecs;
     }
+
+    let supplementalCodecs: string | undefined;
+    if (representation.attributes.supplementalCodecs != null) {
+      supplementalCodecs = representation.attributes.supplementalCodecs;
+    } else if (adaptation.attributes.supplementalCodecs != null) {
+      supplementalCodecs = adaptation.attributes.supplementalCodecs;
+    }
+    if (supplementalCodecs != null) {
+      parsedRepresentation.supplementalCodecs = supplementalCodecs;
+    }
+
     if (representation.attributes.frameRate != null) {
       parsedRepresentation.frameRate =
         representation.attributes.frameRate;

src/parsers/manifest/dash/js-parser/node_parsers/Representation.ts

@@ -184,6 +184,10 @@ function parseRepresentationAttributes(
                                  dashName: "qualityRanking" });
         break;
 
+      case "scte214:supplementalCodecs":
+        attributes.supplementalCodecs = attr.value;
+        break;
+
       case "segmentProfiles":
         attributes.segmentProfiles = attr.value;
         break;

src/parsers/manifest/dash/node_parser_types.ts

@@ -232,6 +232,7 @@ export interface IAdaptationSetAttributes {
   segmentAlignment? : number|boolean;
   segmentProfiles? : string;
   subsegmentAlignment? : number|boolean;
+  supplementalCodecs?: string;
   width? : number;
   availabilityTimeComplete?: boolean;
   availabilityTimeOffset?: number;
@@ -271,6 +272,7 @@ export interface IRepresentationAttributes {
   profiles? : string;
   qualityRanking? : number;
   segmentProfiles? : string;
+  supplementalCodecs?: string;
   width? : number;
   availabilityTimeComplete?: boolean;
   availabilityTimeOffset?: number;

src/parsers/manifest/types.ts

@@ -160,6 +160,8 @@ export interface IParsedRepresentation {
   hdrInfo?: IHDRInformation | undefined;
   /** `true` if audio has Dolby Atmos. */
   isSpatialAudio?: boolean | undefined;
+
+  supplementalCodecs? : string | undefined;
 }
 
 /** Every possible types an Adaptation can have. */

test/suppCodec.mpd

@@ -0,0 +1,35 @@
+<?xml version="1.0"?>
+<MPD mediaPresentationDuration="PT12M14S" minBufferTime="PT3.00S"
+  profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static"
+  xmlns="urn:mpeg:dash:schema:mpd:2011"
+  xmlns:scte214="urn:scte:dash:scte214-extensions">
+  <!-- Created with Bento4 mp4-dash.py, VERSION=1.6.0-588 -->
+  <Period>
+    <AdaptationSet lang="en" mimeType="audio/mp4" segmentAlignment="true" startWithSAP="1">
+      <SegmentTemplate duration="3000" initialization="https://www.bok.net/dash/tears_of_steel/cleartext/$RepresentationID$/init.mp4"
+        media="https://www.bok.net/dash/tears_of_steel/cleartext/$RepresentationID$/seg-$Number$.m4f" startNumber="1" timescale="1000" />
+      <Representation audioSamplingRate="44100" bandwidth="132348" codecs="mp4a.40.2" id="audio/en">
+        <AudioChannelConfiguration
+          schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2" />
+      </Representation>
+    </AdaptationSet>
+    <AdaptationSet mimeType="video/mp4" segmentAlignment="true" startWithSAP="1">
+      <SegmentTemplate duration="3000" initialization="https://www.bok.net/dash/tears_of_steel/cleartext/$RepresentationID$/init.mp4"
+        media="https://www.bok.net/dash/tears_of_steel/cleartext/$RepresentationID$/seg-$Number$.m4f" startNumber="1" timescale="1000" />
+      <!-- <Representation bandwidth="686685" codecs="avc1.42C015" frameRate="24" height="214"
+        id="video/1" scanType="progressive" width="512" />
+      <Representation bandwidth="1116150" codecs="avc1.42C016" frameRate="24" height="294"
+        id="video/2" scanType="progressive" width="704" /> -->
+      <Representation bandwidth="686685" codecs="avc1.42C015"
+        scte214:supplementalCodecs="avc1.42C01F" scte214:supplementalProfiles="db1p" frameRate="24"
+        height="214"
+        id="video/3" scanType="progressive" width="512"  />
+      <!-- <Representation bandwidth="1929169" codecs="avc1.42C01F" frameRate="24" height="428"
+        id="video/4" scanType="progressive" width="1024" />
+      <Representation bandwidth="2362822" codecs="avc1.42C01F" frameRate="24" height="482"
+        id="video/5" scanType="progressive" width="1152" />
+      <Representation bandwidth="2470094" codecs="avc1.4D401F" frameRate="24" height="534"
+        id="video/6" scanType="progressive" width="1280" /> -->
+    </AdaptationSet>
+  </Period>
+</MPD>