1 files changed, 90 insertions, 0 deletions
diff --git a/node_modules/prism-media/src/opus/OggOpus.js b/node_modules/prism-media/src/opus/OggOpus.js
new file mode 100644
index 0000000..9a938cd
--- /dev/null
+++ b/node_modules/prism-media/src/opus/OggOpus.js
@@ -0,0 +1,90 @@
+const { Transform } = require('stream');
+
+const OGG_PAGE_HEADER_SIZE = 26;
+const STREAM_STRUCTURE_VERSION = 0;
+
+const OGGS_HEADER = Buffer.from('OggS'.split('').map(x => x.charCodeAt(0)));
+const OPUS_HEAD = Buffer.from('OpusHead'.split('').map(x => x.charCodeAt(0)));
+const OPUS_TAGS = Buffer.from('OpusTags'.split('').map(x => x.charCodeAt(0)));
+
+class OggOpusTransform extends Transform {
+  constructor() {
+    super();
+    this._remainder = null;
+    this._head = null;
+  }
+
+  _transform(chunk, encoding, done) {
+    if (this._remainder) {
+      chunk = Buffer.concat([this._remainder, chunk]);
+      this._remainder = null;
+    }
+
+    while (chunk) {
+      try {
+        const result = this.readPage(chunk);
+        if (result) chunk = result;
+        else break;
+      } catch (err) {
+        this.emit('error', err);
+      }
+    }
+    this._remainder = chunk;
+    done();
+  }
+
+  /**
+   * Reads a page from a buffer
+   * @param {Buffer} chunk The chunk containing the page
+   * @returns {boolean|Buffer}
+   */
+  readPage(chunk) {
+    if (chunk.length < OGG_PAGE_HEADER_SIZE) {
+      return false;
+    }
+    if (!chunk.slice(0, 4).equals(OGGS_HEADER)) {
+      throw Error(`capture_pattern is not ${OGGS_HEADER}`);
+    }
+    if (chunk.readUInt8(4) !== STREAM_STRUCTURE_VERSION) {
+      throw Error(`stream_structure_version is not ${STREAM_STRUCTURE_VERSION}`);
+    }
+
+    const pageSegments = chunk.readUInt8(26),
+      table = chunk.slice(27, 27 + pageSegments);
+
+    let sizes = [], totalSize = 0;
+
+    for (let i = 0; i < pageSegments;) {
+      let size = 0, x = 255;
+      while (x === 255) {
+        x = table.readUInt8(i);
+        i++;
+        size += x;
+      }
+      sizes.push(size);
+      totalSize += size;
+    }
+
+    if (chunk.length < 27 + pageSegments + totalSize) {
+      return false;
+    }
+
+    let start = 27 + pageSegments;
+    for (const size of sizes) {
+      const segment = chunk.slice(start, start + size);
+      const header = segment.slice(0, 8);
+      if (this._head) {
+        if (header.equals(OPUS_TAGS)) this.emit('opusTags', segment);
+        else this.push(segment);
+      } else if (header.equals(OPUS_HEAD)) {
+        this._head = segment;
+      } else {
+        throw Error(`Invalid segment ${segment}`);
+      }
+      start += size;
+    }
+    return chunk.slice(start);
+  }
+}
+
+module.exports = OggOpusTransform;