perf: Init source buffers synchronously

lib/media/media_source_engine.js

@@ -320,72 +320,6 @@ shaka.media.MediaSourceEngine = class {
     p.resolve();
   }
 
-  /**
-   * Checks if a certain type is supported.
-   *
-   * @param {shaka.extern.Stream} stream
-   * @param {shaka.util.ManifestParserUtils.ContentType} contentType
-   * @return {!Promise<boolean>}
-   */
-  static async isStreamSupported(stream, contentType) {
-    if (stream.createSegmentIndex) {
-      await stream.createSegmentIndex();
-    }
-    if (!stream.segmentIndex) {
-      return false;
-    }
-    if (stream.segmentIndex.isEmpty()) {
-      return true;
-    }
-    const MimeUtils = shaka.util.MimeUtils;
-    const TransmuxerEngine = shaka.transmuxer.TransmuxerEngine;
-    const ContentType = shaka.util.ManifestParserUtils.ContentType;
-    const StreamUtils = shaka.util.StreamUtils;
-    const seenCombos = new Set();
-    // Check each combination of mimeType and codecs within the segment index.
-    // Unfortunately we cannot use fullMimeTypes, as we ALSO need to check the
-    // getFullTypeWithAllCodecs (for the sake of the transmuxer) and we have no
-    // way of going from a full mimeType to a full mimeType with all codecs.
-    // As this function is only called in debug mode, a little inefficiency is
-    // acceptable.
-    for (const ref of stream.segmentIndex) {
-      const mimeType = ref.mimeType || stream.mimeType || '';
-      let codecs = ref.codecs || stream.codecs || '';
-      // Optimization for the case where the codecs and mimetype of the stream
-      // match the reference.
-      if (mimeType == stream.mimeType && codecs == stream.codecs) {
-        continue;
-      }
-      // Don't check the same combination of mimetype + codecs twice.
-      const combo = mimeType + ':' + codecs;
-      if (seenCombos.has(combo)) {
-        continue;
-      }
-      seenCombos.add(combo);
-      if (contentType == ContentType.TEXT) {
-        const fullMimeType = MimeUtils.getFullType(mimeType, codecs);
-        if (!shaka.text.TextEngine.isTypeSupported(fullMimeType)) {
-          return false;
-        }
-      } else {
-        if (contentType == ContentType.VIDEO) {
-          codecs = StreamUtils.getCorrectVideoCodecs(codecs);
-        } else if (contentType == ContentType.AUDIO) {
-          codecs = StreamUtils.getCorrectAudioCodecs(codecs, mimeType);
-        }
-        const extendedMimeType = MimeUtils.getExtendedType(
-            stream, mimeType, codecs);
-        const fullMimeType = MimeUtils.getFullTypeWithAllCodecs(
-            mimeType, codecs);
-        if (!shaka.media.Capabilities.isTypeSupported(extendedMimeType) &&
-            !TransmuxerEngine.isSupported(fullMimeType, stream.type)) {
-          return false;
-        }
-      }
-    }
-    return true;
-  }
-
   /**
    * Returns a map of MediaSource support for well-known types.
    *
@@ -554,8 +488,7 @@ shaka.media.MediaSourceEngine = class {
    *
    * @param {!Map<shaka.util.ManifestParserUtils.ContentType,
    *               shaka.extern.Stream>} streamsByType
-   *   A map of content types to streams.  All streams must be supported
-   *   according to MediaSourceEngine.isStreamSupported.
+   *   A map of content types to streams.
    * @param {boolean=} sequenceMode
    *   If true, the media segments are appended to the SourceBuffer in strict
    *   sequence.
@@ -602,8 +535,7 @@ shaka.media.MediaSourceEngine = class {
 
     for (const contentType of streamsByType.keys()) {
       const stream = streamsByType.get(contentType);
-      // eslint-disable-next-line no-await-in-loop
-      await this.initSourceBuffer_(contentType, stream, stream.codecs);
+      this.initSourceBuffer_(contentType, stream, stream.codecs);
       if (this.needSplitMuxedContent_) {
         this.queues_.set(ContentType.AUDIO, []);
         this.queues_.set(ContentType.VIDEO, []);
@@ -623,17 +555,11 @@ shaka.media.MediaSourceEngine = class {
    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
    * @param {shaka.extern.Stream} stream
    * @param {string} codecs
-   * @return {!Promise}
    * @private
    */
-  async initSourceBuffer_(contentType, stream, codecs) {
+  initSourceBuffer_(contentType, stream, codecs) {
     const ContentType = shaka.util.ManifestParserUtils.ContentType;
 
-    goog.asserts.assert(
-        await shaka.media.MediaSourceEngine.isStreamSupported(
-            stream, contentType),
-        'Type negotiation should happen before MediaSourceEngine.init!');
-
     if (contentType == ContentType.AUDIO && codecs) {
       codecs = shaka.util.StreamUtils.getCorrectAudioCodecs(
           codecs, stream.mimeType);
@@ -660,8 +586,8 @@ shaka.media.MediaSourceEngine = class {
             ContentType.VIDEO, (codecs || '').split(','));
         if (audioCodec && videoCodec) {
           this.needSplitMuxedContent_ = true;
-          await this.initSourceBuffer_(ContentType.AUDIO, stream, audioCodec);
-          await this.initSourceBuffer_(ContentType.VIDEO, stream, videoCodec);
+          this.initSourceBuffer_(ContentType.AUDIO, stream, audioCodec);
+          this.initSourceBuffer_(ContentType.VIDEO, stream, videoCodec);
           return;
         }
         const transmuxerPlugin = shaka.transmuxer.TransmuxerEngine
@@ -1519,8 +1445,7 @@ shaka.media.MediaSourceEngine = class {
    * @param {string} codecs
    * @param {!Map<shaka.util.ManifestParserUtils.ContentType,
    *               shaka.extern.Stream>} streamsByType
-   *   A map of content types to streams.  All streams must be supported
-   *   according to MediaSourceEngine.isStreamSupported.
+   *   A map of content types to streams.
    *
    * @return {!Promise}
    */
@@ -2363,8 +2288,7 @@ shaka.media.MediaSourceEngine = class {
 
       for (const contentType of streamsByType.keys()) {
         const stream = streamsByType.get(contentType);
-        // eslint-disable-next-line no-await-in-loop
-        await this.initSourceBuffer_(contentType, stream, stream.codecs);
+        this.initSourceBuffer_(contentType, stream, stream.codecs);
       }
       const audio = streamsByType.get(ContentType.AUDIO);
       if (audio && audio.isAudioMuxedInVideo) {