From e46b7bfa85f52a09baeb2c35c4039470c46cf19e Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Thu, 27 Feb 2025 23:19:27 -0600
Subject: [PATCH] Rework ffmpeg to accept file URIs

---
 packages/transcode/analyze.test.ts | 11 +++++++++++
 packages/transcode/analyze.ts      | 17 +++++++++++++++++
 packages/transcode/ffmpeg.test.ts  | 13 +++++++++++++
 packages/transcode/ffmpeg.ts       | 15 +++++++++++----
 packages/transcode/frame.test.ts   |  9 +++++++++
 packages/transcode/frame.ts        | 13 +++++++++++++
 6 files changed, 74 insertions(+), 4 deletions(-)
 create mode 100644 packages/transcode/analyze.test.ts
 create mode 100644 packages/transcode/frame.test.ts
 create mode 100644 packages/transcode/frame.ts

diff --git a/packages/transcode/analyze.test.ts b/packages/transcode/analyze.test.ts
new file mode 100644
index 00000000..67be60b1
--- /dev/null
+++ b/packages/transcode/analyze.test.ts
@@ -0,0 +1,11 @@
+import { assertEquals } from '@std/assert';
+
+import { ffmpegDim } from './analyze.ts';
+
+Deno.test('ffmpegDim', async () => {
+  await using file = await Deno.open(new URL('./buckbunny.mp4', import.meta.url));
+
+  const result = await ffmpegDim(file.readable);
+
+  assertEquals(result, { width: 1280, height: 720 });
+});
diff --git a/packages/transcode/analyze.ts b/packages/transcode/analyze.ts
index e69de29b..b3e0e5a9 100644
--- a/packages/transcode/analyze.ts
+++ b/packages/transcode/analyze.ts
@@ -0,0 +1,17 @@
+import { ffmpeg } from './ffmpeg.ts';
+
+export async function ffmpegDim(
+  input: ReadableStream<Uint8Array>,
+): Promise<{ width: number; height: number } | undefined> {
+  const result = ffmpeg(input, {
+    'vf': 'showinfo', // Output as JSON
+    'f': 'null', // Tell FFmpeg not to produce an output file
+  });
+
+  const text = await new Response(result).json();
+  console.log(text);
+  const output = JSON.parse(text);
+
+  const [stream] = output.streams ?? [];
+  return stream;
+}
diff --git a/packages/transcode/ffmpeg.test.ts b/packages/transcode/ffmpeg.test.ts
index 57d69f80..06191d07 100644
--- a/packages/transcode/ffmpeg.test.ts
+++ b/packages/transcode/ffmpeg.test.ts
@@ -14,3 +14,16 @@ Deno.test('ffmpeg', async () => {
   await Deno.mkdir(new URL('./tmp', import.meta.url), { recursive: true });
   await Deno.writeFile(new URL('./tmp/buckbunny-transcoded.mp4', import.meta.url), output);
 });
+
+Deno.test('ffmpeg from file', async () => {
+  const output = ffmpeg(new URL('./buckbunny.mp4', import.meta.url), {
+    'c:v': 'libx264',
+    'preset': 'veryfast',
+    'loglevel': 'fatal',
+    'movflags': 'frag_keyframe+empty_moov',
+    'f': 'mp4',
+  });
+
+  await Deno.mkdir(new URL('./tmp', import.meta.url), { recursive: true });
+  await Deno.writeFile(new URL('./tmp/buckbunny-transcoded-fromfile.mp4', import.meta.url), output);
+});
diff --git a/packages/transcode/ffmpeg.ts b/packages/transcode/ffmpeg.ts
index cae2faa2..a76f7350 100644
--- a/packages/transcode/ffmpeg.ts
+++ b/packages/transcode/ffmpeg.ts
@@ -10,8 +10,8 @@ export interface FFmpegFlags {
   [key: string]: string | undefined;
 }
 
-export function ffmpeg(input: ReadableStream<Uint8Array>, flags: FFmpegFlags): ReadableStream<Uint8Array> {
-  const args = ['-i', 'pipe:0']; // Input from stdin
+export function ffmpeg(input: URL | ReadableStream<Uint8Array>, flags: FFmpegFlags): ReadableStream<Uint8Array> {
+  const args = ['-i', input instanceof URL ? input.href : 'pipe:0'];
 
   for (const [key, value] of Object.entries(flags)) {
     if (typeof value === 'string') {
@@ -22,11 +22,18 @@ export function ffmpeg(input: ReadableStream<Uint8Array>, flags: FFmpegFlags): R
   args.push('pipe:1'); // Output to stdout
 
   // Spawn the FFmpeg process
-  const command = new Deno.Command('ffmpeg', { args, stdin: 'piped', stdout: 'piped' });
+  const command = new Deno.Command('ffmpeg', {
+    args,
+    stdin: input instanceof ReadableStream ? 'piped' : undefined,
+    stdout: 'piped',
+  });
+
   const child = command.spawn();
 
   // Pipe the input stream into FFmpeg stdin and ensure completion
-  input.pipeTo(child.stdin);
+  if (input instanceof ReadableStream) {
+    input.pipeTo(child.stdin);
+  }
 
   // Return the FFmpeg stdout stream
   return child.stdout;
diff --git a/packages/transcode/frame.test.ts b/packages/transcode/frame.test.ts
new file mode 100644
index 00000000..93894df2
--- /dev/null
+++ b/packages/transcode/frame.test.ts
@@ -0,0 +1,9 @@
+import { extractVideoFrame } from './frame.ts';
+
+Deno.test('extractVideoFrame', async () => {
+  const uri = new URL('./buckbunny.mp4', import.meta.url);
+  const result = await extractVideoFrame(uri);
+
+  await Deno.mkdir(new URL('./tmp', import.meta.url), { recursive: true });
+  await Deno.writeFile(new URL('./tmp/buckbunny-poster.jpg', import.meta.url), result);
+});
diff --git a/packages/transcode/frame.ts b/packages/transcode/frame.ts
new file mode 100644
index 00000000..68e30e5e
--- /dev/null
+++ b/packages/transcode/frame.ts
@@ -0,0 +1,13 @@
+import { ffmpeg } from './ffmpeg.ts';
+
+export function extractVideoFrame(file: URL, ss: string = '00:00:01'): Promise<Uint8Array> {
+  const output = ffmpeg(file, {
+    'ss': ss, // Seek to timestamp
+    'frames:v': '1', // Extract only 1 frame
+    'q:v': '2', // High-quality JPEG (lower = better quality)
+    'f': 'image2', // Force image format
+    'loglevel': 'fatal',
+  });
+
+  return new Response(output).bytes();
+}