Request: Make encoder options configurable at runtime

[Venryx]

Is there any way to customize the bitrate for the Opus encoding?

I'd like to use this library to record speech to a file, however some recordings might be long, so the user may want to lower the bit-rate/quality to reduce the resulting file-size.

[Venryx]

It looks like the file here contains the configuration for the Opus encoder: https://github.com/kbumsik/opus-media-recorder/blob/master/src/OpusEncoder.js

If so, I guess this issue is changing from asking:
Old: "How do you configure the Opus encoder?"
New: "Request: Make encoder options configurable at runtime"

[Venryx]

Hmm. I changed that constant, however now the assert at this location is failing: https://github.com/kbumsik/opus-media-recorder/blob/master/src/ContainerInterface.cpp#L20

Is updating ContainerInterface.cpp to support other sample rates an easy task, or does it take substantial rewriting?

I'd need it to support a sampling rate of 16000 to send the resulting Opus audio to the DialogFlow api: https://cloud.google.com/dialogflow/docs/reference/rpc/google.cloud.dialogflow.v2#google.cloud.dialogflow.v2.AudioEncoding

[Venryx]

For others coming across this issue, I ended up solving the problem by using the opus-recorder library.

The API is maybe not quite as nice, but it has more configuration options, including the one I need (sample rate).

Here is the code I used, which works with uploading to DialogFlow:

function RecordFor10SecondsThenTranscribe() {
	var options = {
		monitorGain: 0,
		recordingGain: 1,
		numberOfChannels: 1,
		//encoderSampleRate: 48000,
		encoderSampleRate: 16000,
		originalSampleRateOverride: 16000, // necessary due to Google bug? (https://github.com/chris-rudmin/opus-recorder/issues/191#issuecomment-509426093)
		encoderPath: "/FromNodeModules/encoderWorker.min.js",
	};

	this.micRecorder = new Recorder(options);
	this.micRecorder.onstart = ()=>console.log("Recorder is started");
	this.micRecorder.onstop = ()=>console.log("Recorder is stopped");
	this.micRecorder.onpause = ()=>console.log("Recorder is paused");
	this.micRecorder.onresume = ()=>console.log("Recorder is resuming");
	this.micRecorder.ondataavailable = async typedArray=>{
		console.log("Data received");
		const audioData = new Blob([typedArray], {type: "audio/ogg"});
		const audioDataStr = await BlobToString(audioData, "readAsDataURL");
		const audioDataStr_trimmed = audioDataStr.replace(/^data:.+?base64,/, "");

		// this sends the audio-data to Google's servers for transcription
		const text = await ConvertSpeechToText(audioDataStr_trimmed);
		console.log(`Got speech!: ${text}`);
	};

	this.micRecorder.start(); // start recording (and conversion/encoding to ogg)
	await SleepAsync(10000); // wait 10 seconds (to let it pick up speech)
	this.micRecorder.stop(); // stop recorder, triggering "ondataavailable" listener
}

export function BlobToString(blob: Blob, readAsFuncName = "readAsText" as "readAsBinaryString" | "readAsDataURL" | "readAsText") {
	return new Promise((resolve, reject)=>{
		const reader = new FileReader();
		reader.addEventListener("loadend", e=>resolve(reader.result as string));
		reader[readAsFuncName](blob);
	}) as Promise<string>;
}