63 lines
2.4 KiB
TypeScript
63 lines
2.4 KiB
TypeScript
|
/** Containers the backend accepts, in the order we prefer to record them. */
|
||
|
|
const PREFERRED_MIME_TYPES = [
|
||
|
|
'audio/webm;codecs=opus',
|
||
|
|
'audio/webm',
|
||
|
|
'audio/mp4',
|
||
|
|
'audio/aac',
|
||
|
|
'audio/ogg;codecs=opus',
|
||
|
|
'audio/ogg',
|
||
|
|
] as const;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Pick a container this browser can record AND the backend accepts.
|
||
|
|
*
|
||
|
|
* Chrome and Android produce webm/opus; Safari and iPad produce mp4/aac. Both go to the
|
||
|
|
* vendor unmodified, so there is no transcode step — but the choice still has to be made
|
||
|
|
* at record time, and `isTypeSupported` is missing entirely on older Safari.
|
||
|
|
*/
|
||
|
|
export function pickRecordingMimeType(): string | null {
|
||
|
|
if (typeof MediaRecorder === 'undefined') return null;
|
||
|
|
if (typeof MediaRecorder.isTypeSupported !== 'function') {
|
||
|
|
// Safari <14.1 shipped MediaRecorder without the feature check; let it choose.
|
||
|
|
return '';
|
||
|
|
}
|
||
|
|
for (const type of PREFERRED_MIME_TYPES) {
|
||
|
|
if (MediaRecorder.isTypeSupported(type)) return type;
|
||
|
|
}
|
||
|
|
return null;
|
||
|
|
}
|
||
|
|
|
||
|
|
/** `audio/webm;codecs=opus` → `webm`, which is what the API's `format` field wants. */
|
||
|
|
export function mimeTypeToFormat(mimeType: string): string {
|
||
|
|
const base = mimeType.split(';')[0]?.trim().toLowerCase() ?? '';
|
||
|
|
const subtype = base.startsWith('audio/') ? base.slice('audio/'.length) : base;
|
||
|
|
// Safari/iOS records `audio/mp4`, but the transcription endpoint's documented container
|
||
|
|
// list names m4a, not mp4. Same container; send the name the vendor documents, so iPad
|
||
|
|
// recordings do not fail while Chrome's webm works.
|
||
|
|
if (subtype === 'x-m4a' || subtype === 'm4a' || subtype === 'mp4') return 'm4a';
|
||
|
|
if (subtype === 'mpeg') return 'mp3';
|
||
|
|
return subtype || 'webm';
|
||
|
|
}
|
||
|
|
|
||
|
|
/** Blob → base64 without the `data:` prefix, which the API does not want. */
|
||
|
|
export async function blobToBase64(blob: Blob): Promise<string> {
|
||
|
|
const buffer = await blob.arrayBuffer();
|
||
|
|
let binary = '';
|
||
|
|
const bytes = new Uint8Array(buffer);
|
||
|
|
// Chunked to avoid blowing the argument limit on a two-minute recording.
|
||
|
|
const chunkSize = 0x8000;
|
||
|
|
for (let i = 0; i < bytes.length; i += chunkSize) {
|
||
|
|
binary += String.fromCharCode(...bytes.subarray(i, i + chunkSize));
|
||
|
|
}
|
||
|
|
return btoa(binary);
|
||
|
|
}
|
||
|
|
|
||
|
|
export function isMediaRecorderSupported(): boolean {
|
||
|
|
return (
|
||
|
|
typeof window !== 'undefined' &&
|
||
|
|
typeof MediaRecorder !== 'undefined' &&
|
||
|
|
typeof navigator !== 'undefined' &&
|
||
|
|
Boolean(navigator.mediaDevices?.getUserMedia)
|
||
|
|
);
|
||
|
|
}
|