feat: add disableTwcc helper function

cspell.json

@@ -67,6 +67,7 @@
     "trackingid",
     "transcoding",
     "transpiled",
+    "twcc",
     "typedoc",
     "ufrag",
     "ulpfec",

src/munge.spec.ts

@@ -1,6 +1,12 @@
 import * as fs from 'fs';
 import { AvMediaDescription, CodecInfo, Sdp } from './model';
-import { removeCodec, retainCandidates, retainCodecs } from './munge';
+import {
+  removeCodec,
+  retainCandidates,
+  retainCodecs,
+  disableRtcpFbValue,
+  disableTwcc,
+} from './munge';
 import { parse } from './parser';
 
 /**
@@ -31,6 +37,29 @@ const validateOfferCodecs = (offer: Sdp): boolean => {
   return true;
 };
 
+/**
+ * Check that the sdp offer contains rtcpFbValue or not.
+ *
+ * @param offer - The {@link Sdp} or {@link AvMediaDescription} to validate.
+ * @param rtcpFbValue - The rtcp-fb value to check.
+ * @returns True if the offer contains rtcp-fb value.
+ */
+const checkOfferContainsRtcpFeedbacks = (
+  offer: Sdp | AvMediaDescription,
+  rtcpFbValue: string
+): boolean => {
+  let bContains = false;
+  const mediaDescriptions = offer instanceof Sdp ? offer.avMedia : [offer];
+  mediaDescriptions.forEach((av: AvMediaDescription) => {
+    av.codecs.forEach((ci: CodecInfo) => {
+      if (ci.feedback.includes(rtcpFbValue)) {
+        bContains = true;
+      }
+    });
+  });
+  return bContains;
+};
+
 describe('munging', () => {
   describe('removeCodec', () => {
     it('should remove codecs correctly when passing in an SDP', () => {
@@ -119,4 +148,47 @@ describe('munging', () => {
       });
     });
   });
+
+  describe('disableRtcpFbValue', () => {
+    it('should remove rtcp feedback correctly when passing in an SDP', () => {
+      expect.hasAssertions();
+      const offer = fs.readFileSync('./src/sdp-corpus/offer_with_rtcp_feedback.sdp', 'utf-8');
+      const parsed = parse(offer);
+
+      disableRtcpFbValue(parsed, 'transport-cc');
+      expect(checkOfferContainsRtcpFeedbacks(parsed, 'transport-cc')).toBe(false);
+      expect(checkOfferContainsRtcpFeedbacks(parsed, 'goog-remb')).toBe(true);
+    });
+    it('should remove rtcp feedback correctly when passing in an AvMediaDescription', () => {
+      expect.hasAssertions();
+      const offer = fs.readFileSync('./src/sdp-corpus/offer_with_rtcp_feedback.sdp', 'utf-8');
+      const parsed = parse(offer);
+
+      parsed.avMedia
+        .filter((av) => av.type === 'audio')
+        .forEach((av) => {
+          disableRtcpFbValue(av, 'transport-cc');
+          expect(checkOfferContainsRtcpFeedbacks(av, 'transport-cc')).toBe(false);
+        });
+      expect(checkOfferContainsRtcpFeedbacks(parsed, 'transport-cc')).toBe(true);
+      expect(checkOfferContainsRtcpFeedbacks(parsed, 'goog-remb')).toBe(true);
+    });
+  });
+
+  describe('disableTwcc', () => {
+    it('should remove rtcp feedback correctly when passing in an AvMediaDescription', () => {
+      expect.hasAssertions();
+      const offer = fs.readFileSync('./src/sdp-corpus/offer_with_rtcp_feedback.sdp', 'utf-8');
+      const parsed = parse(offer);
+
+      parsed.avMedia
+        .filter((av) => av.type === 'audio')
+        .forEach((av) => {
+          disableTwcc(av);
+          expect(checkOfferContainsRtcpFeedbacks(av, 'transport-cc')).toBe(false);
+        });
+      expect(checkOfferContainsRtcpFeedbacks(parsed, 'transport-cc')).toBe(true);
+      expect(checkOfferContainsRtcpFeedbacks(parsed, 'goog-remb')).toBe(true);
+    });
+  });
 });

src/munge.ts

@@ -17,13 +17,14 @@
 import { AvMediaDescription, CodecInfo, MediaDescription, Sdp } from './model';
 
 /**
- * Disable an rtcp-fb value from all media blocks in the given SDP.
+ * Disable an rtcp-fb value from the media blocks in the given SDP or audio/video media description.
  *
- * @param sdp - The SDP from which to filter an rtcp-fb value.
+ * @param sdpOrAv - The {@link Sdp} or {@link AvMediaDescription} from which to filter an rtcp-fb value.
  * @param rtcpFbValue - The rtcp-fb value to filter.
  */
-export function disableRtcpFbValue(sdp: Sdp, rtcpFbValue: string) {
-  sdp.avMedia.forEach((media: AvMediaDescription) => {
+export function disableRtcpFbValue(sdpOrAv: Sdp | AvMediaDescription, rtcpFbValue: string) {
+  const mediaDescriptions = sdpOrAv instanceof Sdp ? sdpOrAv.avMedia : [sdpOrAv];
+  mediaDescriptions.forEach((media: AvMediaDescription) => {
     media.codecs.forEach((codec: CodecInfo) => {
       // eslint-disable-next-line no-param-reassign
       codec.feedback = codec.feedback.filter((fb) => fb !== rtcpFbValue);
@@ -40,6 +41,15 @@ export function disableRemb(sdp: Sdp) {
   disableRtcpFbValue(sdp, 'goog-remb');
 }
 
+/**
+ * Disable REMB from all media blocks in the given SDP.
+ *
+ * @param sdpOrAv - The {@link Sdp} or {@link AvMediaDescription} from which to filter TWCC.
+ */
+export function disableTwcc(sdpOrAv: Sdp | AvMediaDescription) {
+  disableRtcpFbValue(sdpOrAv, 'transport-cc');
+}
+
 /**
  * Remove the codec with the given name (as well as any secondary codecs associated with
  * it) from the media blocks in the given SDP or audio/video media description.