Fix decoded audio always starting at 0, fix startTimestamp=0 for ranged media iterators (fixes #370)

test/browser/media-sinks.test.ts

@@ -0,0 +1,26 @@
+import { expect, test } from 'vitest';
+import { Input } from '../../src/input.js';
+import { UrlSource } from '../../src/source.js';
+import { ALL_FORMATS } from '../../src/input-format.js';
+import { assert } from '../../src/misc.js';
+import { AudioSampleSink } from '../../src/media-sink.js';
+
+// https://github.com/Vanilagy/mediabunny/issues/370
+test('Negative audio timestamps are preserved', async () => {
+	using input = new Input({
+		source: new UrlSource('/edts.mp4'),
+		formats: ALL_FORMATS,
+	});
+
+	const track = await input.getPrimaryAudioTrack();
+	assert(track);
+
+	expect(await track.getFirstTimestamp()).toBeLessThan(0);
+
+	const sink = new AudioSampleSink(track);
+
+	for await (using sample of sink.samples()) {
+		expect(sample.timestamp).toBe(await track.getFirstTimestamp());
+		break;
+	}
+});