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Use ffprobe and ffmpeg via execa to inspect audio streams and downloaded files during a flow. Both tools are pre-installed on QA Wolf runners. See the ffprobe documentation and ffmpeg documentation for the full list of available flags.

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Examples

Inspect a stream URL 
const { execa } = await import("execa");

const streamUrl = await page.locator("audio").getAttribute("src");

const { stdout } = await execa("ffprobe", [
  "-v", "quiet",
  "-print_format", "json",
  "-show_format",
  "-show_streams",
  "-i", streamUrl,
]);

const metadata = JSON.parse(stdout);
const audioStream = metadata.streams.find((s) => s.codec_type === "audio");

expect(audioStream.codec_name).toBe("aac");
expect(parseInt(metadata.format.bit_rate) / 1000).toBeGreaterThan(100);
Detect silence in a downloaded file 
const { execa } = await import("execa");

const { stderr } = await execa("ffmpeg", [
  "-i", filePath,
  "-af", "silencedetect=n=-50dB:d=1",
  "-f", "null", "-",
]);

if (stderr.includes("silence_start")) {
  throw new Error("Audio file contains silence.");
}
Assert file metadata 
const { execa } = await import("execa");

const { stdout } = await execa("ffprobe", [
  "-v", "error",
  "-show_entries", "format=bit_rate,duration",
  "-show_streams",
  "-of", "json",
  filePath,
]);

const metadata = JSON.parse(stdout);
const audioStream = metadata.streams.find((s) => s.codec_type === "audio");

expect(audioStream.codec_name).toBe("aac");
expect(parseInt(metadata.format.bit_rate) / 1000).toBeGreaterThan(100);

​
When to use

  • Your app streams audio and you need to assert on codec, bitrate, or sample rate.
  • Your app generates or downloads audio files and you need to verify they aren’t silent or corrupted.
  • Your app plays back recordings and you need to confirm the file contains valid audio data.
  • Your test needs to validate audio properties that can’t be asserted through the UI.

​
Full sample test

import { flow, launch } from "@qawolf/flows/web";

export default flow(
  "Validate audio stream",
  "Web - Chrome",
  async ({ page, test }) => {
    await test("navigate to player and assert stream metadata", async () => {
      // Arrange
      await page.goto("https://your-app.com/player");
      await page.locator("audio").waitFor({ state: "attached" });

      // Act
      const { execa } = await import("execa");
      const streamUrl = await page.locator("audio").getAttribute("src");

      const { stdout } = await execa("ffprobe", [
        "-v", "quiet",
        "-print_format", "json",
        "-show_format",
        "-show_streams",
        "-i", streamUrl,
      ]);

      // Assert
      const metadata = JSON.parse(stdout);
      const audioStream = metadata.streams.find((s) => s.codec_type === "audio");

      expect(audioStream).toBeTruthy();
      expect(audioStream.codec_name).toBe("aac");
      expect(parseInt(metadata.format.bit_rate) / 1000).toBeGreaterThan(100);
    });
  },
);
Last modified on May 20, 2026