From 7cebd6f02087d02e2762a44c52dcb04e552d882f Mon Sep 17 00:00:00 2001
From: Koushik Dutta <koushd@gmail.com>
Date: Mon, 9 May 2022 09:47:31 -0700
Subject: [PATCH] common: sdp parsing should handle default audio type

---
 common/src/rtsp-server.ts |  5 ++---
 common/src/sdp-utils.ts   | 16 ++++++++++++++--
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/common/src/rtsp-server.ts b/common/src/rtsp-server.ts
index cd3281b21..e73879ef7 100644
--- a/common/src/rtsp-server.ts
+++ b/common/src/rtsp-server.ts
@@ -9,7 +9,6 @@ import tls from 'tls';
 import { BASIC, DIGEST } from 'http-auth-utils/dist/index';
 import crypto from 'crypto';
 import { timeoutPromise } from './promise-utils';
-import { sleep } from './sleep';
 
 export const RTSP_FRAME_MAGIC = 36;
 
@@ -617,7 +616,7 @@ export class RtspServer {
                 control: msection.control,
                 protocol: 'udp',
                 destination: parseInt(rtp),
-                codec: msection.codec || (msection.type === 'audio' ? 'pcm' : undefined),
+                codec: msection.codec,
             }
         }
         else if (transport.includes('TCP')) {
@@ -629,7 +628,7 @@ export class RtspServer {
                     control: msection.control,
                     protocol: 'tcp',
                     destination: low,
-                    codec: msection.codec || (msection.type === 'audio' ? 'pcm' : undefined),
+                    codec: msection.codec,
                 }
             }
         }
diff --git a/common/src/sdp-utils.ts b/common/src/sdp-utils.ts
index 0e7f683d9..c8e3d885f 100644
--- a/common/src/sdp-utils.ts
+++ b/common/src/sdp-utils.ts
@@ -163,6 +163,7 @@ const artpmap = 'a=rtpmap:';
 export function parseMSection(msection: string[]) {
     const control = msection.find(line => line.startsWith(acontrol))?.substring(acontrol.length);
     const rtpmap = msection.find(line => line.startsWith(artpmap))?.toLowerCase();
+    const mline = parseMLine(msection[0]);
 
     let codec: string;
     if (rtpmap?.includes('mpeg4')) {
@@ -171,6 +172,12 @@ export function parseMSection(msection: string[]) {
     else if (rtpmap?.includes('opus')) {
         codec = 'opus';
     }
+    else if (rtpmap?.includes('pcma')) {
+        codec = 'pcm_alaw';
+    }
+    else if (rtpmap?.includes('pcmu')) {
+        codec = 'pcm_ulaw';
+    }
     else if (rtpmap?.includes('pcm')) {
         codec = 'pcm';
     }
@@ -180,8 +187,13 @@ export function parseMSection(msection: string[]) {
     else if (rtpmap?.includes('h265')) {
         codec = 'h265';
     }
+    else if (!rtpmap && mline.type === 'audio') {
+        // ffmpeg seems to omit the rtpmap type for pcm alaw when creating sdp?
+        // is this the default?
+        codec = 'pcm_alaw';
+    }
 
-    let direction: string;
+        let direction: string;
     for (const checkDirection of ['sendonly', 'sendrecv', 'recvonly', 'inactive']) {
         const found = msection.find(line => line === 'a=' + checkDirection);
         if (found) {
@@ -191,7 +203,7 @@ export function parseMSection(msection: string[]) {
     }
 
     return {
-        ...parseMLine(msection[0]),
+        ...mline,
         fmtp: parseFmtp(msection),
         lines: msection,
         contents: msection.join('\r\n'),