fix: make the fmtp params could be munged in firefox (#12)

* fix: make the fmtp params could be munged in firefox

* fix: change the params type in FmtpLine and fmtParams type in CodecInfo as map

Co-authored-by: Brown Zhang <weizha2@example.com>

cspell.json

@@ -44,6 +44,7 @@
     "ndarray",
     "Onnx",
     "onnxruntime",
+    "packetization",
     "prettierignore",
     "raddr",
     "remb",
@@ -52,14 +53,14 @@
     "rtcpfb",
     "rtpmap",
     "sandboxed",
+    "SAVPF",
     "sdp",
     "sdps",
+    "SSDK",
     "ssrcs",
-    "TIAS",
     "tfjs",
+    "TIAS",
     "toffset",
-    "SAVPF",
-    "SSDK",
     "trackingid",
     "transcoding",
     "transpiled",

src/lines/fmtp-line.spec.ts

@@ -0,0 +1,70 @@
+import { parseFmtpParams } from './fmtp-line';
+
+describe('parseFmtpParams', () => {
+  it('normal case', async () => {
+    expect.hasAssertions();
+    const expectedValue = {
+      'level-asymmetry-allowed': '1',
+      'max-br': '1000000',
+      'max-dpb': '63600',
+      'packetization-mode': '1',
+      'profile-level-id': '420034',
+    };
+    let fmtpParams = parseFmtpParams(
+      'level-asymmetry-allowed=1;max-br=1000000;max-dpb=63600;packetization-mode=1;profile-level-id=420034'
+    );
+    expect(Object.fromEntries(fmtpParams)).toStrictEqual(expectedValue);
+    fmtpParams = parseFmtpParams(
+      'a=fmtp:97 level-asymmetry-allowed=1;max-br=1000000;max-dpb=63600;packetization-mode=1;profile-level-id=420034' // real Safari case.
+    );
+    expect(Object.fromEntries(fmtpParams)).toStrictEqual(expectedValue);
+  });
+  it('exceptional case', async () => {
+    expect.hasAssertions();
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;max-br=1000000max-dpb=63600;packetization-mode=1;profile-level-id=420034' // only lack semicolon
+      );
+    }).toThrow(Error);
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;max-br=max-dpb=63600;packetization-mode=1;profile-level-id=420034' // lack semicolon and value
+      );
+    }).toThrow(Error);
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;max-br;max-dpb=63600;packetization-mode=1;profile-level-id=420034' // lack semicolon, value and equals sign
+      );
+    }).toThrow(Error);
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;max-br=1000000;;max-dpb=63600;packetization-mode=1;profile-level-id=420034' // lack semicolon, value,  equals sign and key
+      );
+    }).toThrow(Error);
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;max-br=;max-dpb=63600;packetization-mode=1;profile-level-id=420034' //  only lack value
+      );
+    }).toThrow(Error);
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;max-br;max-dpb=63600;packetization-mode=1;profile-level-id=420034' //  lack value and equals sign
+      );
+    }).toThrow(Error);
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;=1000000;max-dpb=63600;packetization-mode=1;profile-level-id=420034' //  only lack key
+      );
+    }).toThrow(Error);
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;=;max-dpb=63600;packetization-mode=1;profile-level-id=420034' //  lack key and value
+      );
+    }).toThrow(Error);
+    expect(() => {
+      parseFmtpParams(
+        'level-asymmetry-allowed=1;=max-dpb=63600;packetization-mode=1;profile-level-id=420034' //  lack key, value and semicolon
+      );
+    }).toThrow(Error);
+  });
+});

src/lines/fmtp-line.ts

@@ -17,6 +17,36 @@
 import { NUM, REST } from '../regex-helpers';
 import { Line } from './line';
 
+/**
+ * Parse the fmtpParams because SDP has no such util function for that.
+ *
+ * @param fmtpParams -  like `key1=val1;key2=val2;key3=val3".
+ * @returns A JS key-value object.
+ */
+export function parseFmtpParams(fmtpParams: string) {
+  // compatible with Safari, since its `fmtpParams` here contains a prefix as `a=fmtp:{payloadType} `, and separated by space.
+  // eslint-disable-next-line no-param-reassign
+  fmtpParams = fmtpParams.replace(/^a=fmtp:\d+\x20/, '');
+
+  const fmtpObj = new Map<string, string | undefined>();
+
+  // compatible with RED，such as `a=fmtp:121 0/5` in chrome and `a=fmtp:121 0-5` in firefox, which can {@link https://www.rfc-editor.org/rfc/rfc2198}
+  if (/^\d+([/-]\d+)+$/.test(fmtpParams)) {
+    fmtpObj.set(fmtpParams, undefined);
+    return fmtpObj;
+  }
+
+  fmtpParams.split(';').forEach((param) => {
+    const paramArr = param && param.split('=');
+    if (paramArr.length !== 2 || !paramArr[0] || !paramArr[1]) {
+      throw new Error(`Fmtp params is invalid with ${fmtpParams}`);
+    }
+    // eslint-disable-next-line prefer-destructuring
+    fmtpObj.set(paramArr[0], paramArr[1]);
+  });
+  return fmtpObj;
+}
+
 /**
  * Definition of a fmtp attribute line as defined in https://datatracker.ietf.org/doc/html/rfc4566#section-6.
  *
@@ -26,7 +56,7 @@ import { Line } from './line';
 export class FmtpLine extends Line {
   payloadType: number;
 
-  params: string;
+  params: Map<string, string | undefined>;
 
   private static regex = new RegExp(`^fmtp:(${NUM}) (${REST})`);
 
@@ -36,7 +66,7 @@ export class FmtpLine extends Line {
    * @param payloadType - The payload type.
    * @param params - The fmtp parameters.
    */
-  constructor(payloadType: number, params: string) {
+  constructor(payloadType: number, params: Map<string, string | undefined>) {
     super();
     this.payloadType = payloadType;
     this.params = params;
@@ -56,13 +86,21 @@ export class FmtpLine extends Line {
     const payloadType = parseInt(tokens[1], 10);
     const params = tokens[2];
 
-    return new FmtpLine(payloadType, params);
+    return new FmtpLine(payloadType, parseFmtpParams(params));
   }
 
   /**
    * @inheritdoc
    */
   toSdpLine(): string {
-    return `a=fmtp:${this.payloadType} ${this.params}`;
+    const fmtParams = Array.from(this.params.keys())
+      .map((key) => {
+        if (this.params.get(key) !== undefined) {
+          return `${key}=${this.params.get(key)}`;
+        }
+        return `${key}`;
+      })
+      .join(';');
+    return `a=fmtp:${this.payloadType} ${fmtParams}`;
   }
 }

src/model/codec-info.ts

@@ -29,7 +29,7 @@ export class CodecInfo implements SdpBlock {
 
   encodingParams?: string;
 
-  fmtParams: Array<string> = [];
+  fmtParams: Map<string, string | undefined> = new Map();
 
   feedback: Array<string> = [];
 
@@ -57,9 +57,12 @@ export class CodecInfo implements SdpBlock {
       return true;
     }
     if (line instanceof FmtpLine) {
-      this.fmtParams.push(line.params);
-      if (line.params.indexOf('apt') !== -1) {
-        const apt = line.params.split('=')[1];
+      this.fmtParams = new Map([
+        ...Array.from(this.fmtParams.entries()),
+        ...Array.from(line.params.entries()),
+      ]);
+      if (line.params.has('apt')) {
+        const apt = line.params.get('apt') as string;
         this.primaryCodecPt = parseInt(apt, 10);
       }
       return true;
@@ -85,10 +88,9 @@ export class CodecInfo implements SdpBlock {
       lines.push(new RtcpFbLine(this.pt, fb));
     });
     // Now all Fmtp
-    this.fmtParams.forEach((fmt) => {
-      lines.push(new FmtpLine(this.pt, fmt));
-    });
-
+    if (this.fmtParams.size > 0) {
+      lines.push(new FmtpLine(this.pt, this.fmtParams));
+    }
     return lines;
   }
 }