From bc7ec5dcaf44a8eed228a738fb30393a572c75a2 Mon Sep 17 00:00:00 2001
From: Nikola Novakovic <nikola@tandem.chat>
Date: Fri, 26 Mar 2021 09:35:22 -1000
Subject: [PATCH] Add support for choosing preferred video codec profile (#183)

---
 decs.d.ts     |  1 +
 src/stream.ts | 30 +++++++++++++++++++++++++-----
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/decs.d.ts b/decs.d.ts
index 3de73779..f5488364 100644
--- a/decs.d.ts
+++ b/decs.d.ts
@@ -99,6 +99,7 @@ interface RTCDtlsTransport {
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtpcodeccapability
 interface RTCRtpCodecCapability {
   mimeType: string;
+  sdpFmtpLine?: string;
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtpheaderextensioncapability
diff --git a/src/stream.ts b/src/stream.ts
index c1818fa5..df4c0db6 100644
--- a/src/stream.ts
+++ b/src/stream.ts
@@ -109,6 +109,7 @@ export interface Constraints extends MediaStreamConstraints {
   codec: string;
   simulcast?: boolean;
   sendEmptyOnMute?: boolean;
+  preferredCodecProfile?: string;
 }
 
 const defaults = {
@@ -253,11 +254,30 @@ export class LocalStream extends MediaStream {
     if ('setCodecPreferences' in transceiver) {
       const cap = RTCRtpSender.getCapabilities(kind);
       if (!cap) return;
-      const selCodec = cap.codecs.find(
-        (c) =>
-          c.mimeType.toLowerCase() === `video/${this.constraints.codec.toLowerCase()}` ||
-          c.mimeType.toLowerCase() === `audio/opus`,
-      );
+
+      let selCodec: RTCRtpCodecCapability | undefined;
+      if (this.constraints.preferredCodecProfile && kind === 'video') {
+        const allCodecProfiles = cap.codecs.filter((c) => c.mimeType.toLowerCase() === `video/${this.constraints.codec.toLowerCase()}`);
+        if (!allCodecProfiles) {
+          return;
+        }
+        selCodec = allCodecProfiles.find(
+          (c) =>
+            c.sdpFmtpLine &&
+            c.sdpFmtpLine?.indexOf(`profile-level-id=${this.constraints.preferredCodecProfile}`) >= 0
+        );
+        if (!selCodec) {
+          // get first one
+          selCodec = allCodecProfiles[0];
+
+        }
+      } else {
+        selCodec = cap.codecs.find(
+          (c) =>
+            c.mimeType.toLowerCase() === `video/${this.constraints.codec.toLowerCase()}` ||
+            c.mimeType.toLowerCase() === `audio/opus`
+        );
+      }
       if (selCodec) {
         transceiver.setCodecPreferences([selCodec]);
       }