cherrypick(release-1.4): check for ffmpeg only when starting screencast (microsoft#3893)

- PR microsoft#3874 SHA: e5c6b19

References microsoft#3845

Author: aslushnikov

package-lock.json

@@ -14,13 +14,14 @@
  * limitations under the License.
  */
 
-import { launchProcess } from '../processLauncher';
 import { ChildProcess } from 'child_process';
-import { Progress, runAbortableTask } from '../progress';
-import * as types from '../types';
-import * as path from 'path';
 import * as os from 'os';
+import * as path from 'path';
 import { assert } from '../../utils/utils';
+import { launchProcess } from '../processLauncher';
+import { Progress, runAbortableTask } from '../progress';
+import * as types from '../types';
+import { spawnAsync } from '../validateDependencies';
 
 const fps = 25;
 
@@ -59,10 +60,16 @@ export class VideoRecorder {
 
     let ffmpegPath = 'ffmpeg';
     const binPath = path.join(__dirname, '../../../third_party/ffmpeg/');
-    if (os.platform() === 'win32')
+    if (os.platform() === 'win32') {
       ffmpegPath = path.join(binPath, os.arch() === 'x64' ? 'ffmpeg-win64.exe' : 'ffmpeg-win32.exe');
-    else if (os.platform() === 'darwin')
+    } else if (os.platform() === 'darwin') {
       ffmpegPath = path.join(binPath, 'ffmpeg-mac');
+    } else {
+      // Look for ffmpeg in PATH.
+      const {code, error} = await spawnAsync(ffmpegPath, ['-version'], {});
+      if (code !== 0 || error)
+        throw new Error('ffmpeg not found.\nInstall missing packages with:\n    sudo apt-get install ffmpeg');
+    }
     const { launchedProcess, gracefullyClose } = await launchProcess({
       executablePath: ffmpegPath,
       args,

src/server/chromium/videoRecorder.ts

@@ -112,8 +112,6 @@ async function validateDependenciesLinux(browserPath: string, browser: BrowserDe
   }
   for (const dep of (await missingDLOPENLibraries(browser)))
     missingDeps.add(dep);
-  for (const dep of (await missingSystemBinaries(browser)))
-    missingDeps.add(dep);
   if (!missingDeps.size)
     return;
   // Check Ubuntu version.
@@ -233,17 +231,7 @@ async function missingDLOPENLibraries(browser: BrowserDescriptor): Promise<strin
   return libraries.filter(library => !isLibraryAvailable(library));
 }
 
-async function missingSystemBinaries(browser: BrowserDescriptor): Promise<string[]> {
-  if (browser.name !== 'chromium')
-    return [];
-  // Look for ffmpeg in PATH.
-  const {code, error} = await spawnAsync('ffmpeg', ['-version'], {});
-  if (code !== 0 || error)
-    return ['ffmpeg'];
-  return [];
-}
-
-function spawnAsync(cmd: string, args: string[], options: any): Promise<{stdout: string, stderr: string, code: number, error?: Error}> {
+export function spawnAsync(cmd: string, args: string[], options: any): Promise<{stdout: string, stderr: string, code: number, error?: Error}> {
   const process = spawn(cmd, args, options);
 
   return new Promise(resolve => {
@@ -436,6 +424,4 @@ const MANUAL_LIBRARY_TO_PACKAGE_NAME_UBUNTU: { [s: string]: string} = {
   // and if it's missing recommend installing missing gstreamer lib.
   // gstreamer1.0-libav -> libavcodec57 -> libx264-152
   'libx264.so': 'gstreamer1.0-libav',
-  // Required for screencast in Chromium.
-  'ffmpeg': 'ffmpeg',
 };