Let ffprobe pipe data to stdin

packages/transcode/analyze.test.ts

@@ -4,8 +4,7 @@ import { getVideoDimensions } from './analyze.ts';
 
 Deno.test('getVideoDimensions', async () => {
   const uri = new URL('./buckbunny.mp4', import.meta.url);
-
-  const dimensions = await getVideoDimensions(uri.href);
+  const dimensions = await getVideoDimensions(uri);
 
   assertEquals(dimensions, { width: 1920, height: 1080 });
 });

packages/transcode/analyze.ts

@@ -1,7 +1,9 @@
 import { ffprobe } from './ffprobe.ts';
 
-export async function getVideoDimensions(path: string): Promise<{ width: number; height: number } | null> {
-  const stream = ffprobe(path, {
+export async function getVideoDimensions(
+  input: URL | ReadableStream<Uint8Array>,
+): Promise<{ width: number; height: number } | null> {
+  const stream = ffprobe(input, {
     'v': 'error',
     'select_streams': 'v:0',
     'show_entries': 'stream=width,height',

packages/transcode/ffprobe.test.ts

@@ -3,6 +3,21 @@ import { assertEquals } from '@std/assert';
 import { ffprobe } from './ffprobe.ts';
 
 Deno.test('ffprobe', async () => {
+  await using file = await Deno.open(new URL('./buckbunny.mp4', import.meta.url));
+
+  const stream = ffprobe(file.readable, {
+    'v': 'error',
+    'select_streams': 'v:0',
+    'show_entries': 'stream=width,height',
+    'of': 'json',
+  });
+
+  const { streams: [dimensions] } = await new Response(stream).json();
+
+  assertEquals(dimensions, { width: 1920, height: 1080 });
+});
+
+Deno.test('ffprobe from file', async () => {
   const uri = new URL('./buckbunny.mp4', import.meta.url);
 
   const stream = ffprobe(uri, {

packages/transcode/ffprobe.ts

@@ -6,19 +6,45 @@ export interface FFprobeFlags {
   [key: string]: string | undefined;
 }
 
-export function ffprobe(path: URL | string, flags: FFprobeFlags): ReadableStream<Uint8Array> {
+export function ffprobe(input: URL | ReadableStream<Uint8Array>, flags: FFprobeFlags): ReadableStream<Uint8Array> {
   const args = [];
 
   for (const [key, value] of Object.entries(flags)) {
     if (typeof value === 'string') {
-      args.push(`-${key}`, value);
+      if (value) {
+        args.push(`-${key}`, value);
+      } else {
+        args.push(`-${key}`);
+      }
     }
   }
 
-  args.push(path instanceof URL ? path.href : path);
+  if (input instanceof URL) {
+    args.push('-i', input.href);
+  } else {
+    args.push('-i', 'pipe:0');
+  }
+
+  // Spawn the FFprobe process
+  const command = new Deno.Command('ffprobe', {
+    args,
+    stdin: input instanceof ReadableStream ? 'piped' : 'null',
+    stdout: 'piped',
+  });
 
-  const command = new Deno.Command('ffprobe', { args, stdout: 'piped' });
   const child = command.spawn();
 
+  // Pipe the input stream into FFmpeg stdin and ensure completion
+  if (input instanceof ReadableStream) {
+    input.pipeTo(child.stdin).catch((e: unknown) => {
+      if (e instanceof Error && e.name === 'BrokenPipe') {
+        // Ignore. ffprobe closes the pipe once it has read the metadata.
+      } else {
+        throw e;
+      }
+    });
+  }
+
+  // Return the FFmpeg stdout stream
   return child.stdout;
 }