Actually use a waveform instead of the frequency data

src/components/views/voice_messages/Waveform.tsx

@@ -0,0 +1,48 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from "react";
+import {IRecordingUpdate, VoiceRecorder} from "../../../voice/VoiceRecorder";
+import {replaceableComponent} from "../../../utils/replaceableComponent";
+import {arrayFastResample, arraySeed} from "../../../utils/arrays";
+import {percentageOf} from "../../../utils/numbers";
+
+interface IProps {
+    heights: number[]; // percentages as integers (0-100)
+}
+
+interface IState {
+}
+
+/**
+ * A simple waveform component. This renders bars (centered vertically) for each
+ * height provided in the component properties. Updating the properties will update
+ * the rendered waveform.
+ */
+@replaceableComponent("views.voice_messages.Waveform")
+export default class Waveform extends React.PureComponent<IProps, IState> {
+    public constructor(props) {
+        super(props);
+    }
+
+    public render() {
+        return <div className='mx_Waveform'>
+            {this.props.heights.map((h, i) => {
+                return <span key={i} style={{height: h + '%'}} className='mx_Waveform_bar' />;
+            })}
+        </div>;
+    }
+}