Fix AVC software decoder sometimes dropping B-frames (fixes #488)

test/browser/media-sinks.test.ts

@@ -1,9 +1,13 @@
 import { expect, test } from 'vitest';
 import { Input } from '../../src/input.js';
-import { UrlSource } from '../../src/source.js';
+import { BufferSource, 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';
+import { AudioSampleSink, VideoSampleSink } from '../../src/media-sink.js';
+import { Output } from '../../src/output.js';
+import { MpegTsOutputFormat } from '../../src/output-format.js';
+import { BufferTarget } from '../../src/target.js';
+import { Conversion } from '../../src/conversion.js';
 
 // https://github.com/Vanilagy/mediabunny/issues/370
 test('Negative audio timestamps are preserved', async () => {
@@ -24,3 +28,61 @@ test('Negative audio timestamps are preserved', async () => {
 		break;
 	}
 });
+
+test('No B-frames are skipped when software-decoding AVC', async () => {
+	using input = new Input({
+		source: new UrlSource('/missing-reorder-metadata-v1.mp4'),
+		formats: ALL_FORMATS,
+	});
+
+	const track = await input.getPrimaryVideoTrack();
+	assert(track);
+
+	const sink = new VideoSampleSink(track, {
+		hardwareAcceleration: 'prefer-software',
+	});
+	let count = 0;
+
+	// eslint-disable-next-line @typescript-eslint/no-unused-vars
+	for await (using sample of sink.samples()) {
+		count++;
+	}
+
+	expect(count).toBe(48);
+});
+
+test('No B-frames are skipped when software-decoding AVC, Annex B edition', async () => {
+	using input = new Input({
+		source: new UrlSource('/missing-reorder-metadata-v1.mp4'),
+		formats: ALL_FORMATS,
+	});
+
+	// Force Annex B by converting to MPEG-TS
+	const output = new Output({
+		format: new MpegTsOutputFormat(),
+		target: new BufferTarget(),
+	});
+
+	const conversion = await Conversion.init({ input, output, copy: { mode: 'forced' } });
+	await conversion.execute();
+
+	using newInput = new Input({
+		source: new BufferSource(output.target.buffer!),
+		formats: ALL_FORMATS,
+	});
+
+	const track = await newInput.getPrimaryVideoTrack();
+	assert(track);
+
+	const sink = new VideoSampleSink(track, {
+		hardwareAcceleration: 'prefer-software',
+	});
+	let count = 0;
+
+	// eslint-disable-next-line @typescript-eslint/no-unused-vars
+	for await (using sample of sink.samples()) {
+		count++;
+	}
+
+	expect(count).toBe(48);
+});