Capturing Intermediate Output in C# PowerShell CmdLet using yt-dlp

Question

Capturing Intermediate Output in C# PowerShell CmdLet using yt-dlp

Will Pittenger 311

How can intermediate status messages be displayed to the user and logged while executing the yt-dlp command in a C# CmdLet? I've created a System.Diagnostics.Process to execute yt-dlp, but I need to provide it access to the console for real-time output, similar to running it directly from the command line. Using Host.UI.WriteLine may strip colors, and I need to ensure that yt-dlp's dynamic updates to the console are visible. Additionally, I need to capture any JSON output that yt-dlp generates before it completes, which I believe will be in Standard Output. How can this be achieved?

Anonymous

Hi @Will Pittenger ,Welcome to Microsoft Q&A,

Have you seen the sample code in the related links? Try the code below and give me feedback.

using System;
using System.Diagnostics;
using System.Text;

public void RunYtDlp()
{
    // Set up the process start info
    var startInfo = new ProcessStartInfo
    {
        FileName = "yt-dlp",                     // Path to yt-dlp executable
        Arguments = "--your-arguments-here",     // Your arguments, e.g. URL, --dump-json, etc.
        UseShellExecute = false,                 // Must be false to redirect output
        CreateNoWindow = false,                  // Show a window if needed
        RedirectStandardOutput = true,           // Capture stdout (for JSON)
        // Leave StandardError not redirected so it goes directly to the console
    };

    var process = new Process { StartInfo = startInfo };

    // StringBuilder to accumulate JSON output (if needed)
    var jsonOutput = new StringBuilder();

    // Attach an asynchronous handler for stdout
    process.OutputDataReceived += (sender, e) =>
    {
        if (e.Data != null)
        {
            // Log or process the JSON output here
            jsonOutput.AppendLine(e.Data);
            // You can also write to a log file or update your UI here.
        }
    };

    // Start the process
    process.Start();

    // Begin reading stdout asynchronously
    process.BeginOutputReadLine();

    // Wait for yt-dlp to exit
    process.WaitForExit();

    // Now jsonOutput.ToString() contains the captured JSON output.
    // You can process it as needed.
    Console.WriteLine("Captured JSON output:");
    Console.WriteLine(jsonOutput.ToString());
}

Will Pittenger 311 Reputation points

2025-02-17T04:44:29.76+00:00

That's what I know. But it'd probably skip those intermediate lines unless those are in Standard Out with the JSON. Then I'd have to figure out where the JSON starts.
Will Pittenger 311 Reputation points

2025-02-18T00:24:03.4833333+00:00

I needed a translator for that as I don't know Japanese. Seems to be as follows

By default, yt-dlp outputs progress information (including dynamic updates and colors) to standard error and JSON to standard output, making it easy to separate the two outputs. Do not redirect standard error.

Please note I need errors too. But that's an interesting detail I was unaware of.

Anonymous

Hi @Will Pittenger ,

Try reading Standard Output asynchronously to capture JSON.

var startInfo = new ProcessStartInfo
{
FileName = "yt-dlp",
Arguments = "--your-json-arguments", // Use --dump-json or --print-json arguments
UseShellExecute = false,
CreateNoWindow = false,
RedirectStandardOutput = true, // Capture JSON output
// Do not redirect StandardError, let it write directly to the console
};

Will Pittenger 311 Reputation points

2025-02-19T09:35:16.56+00:00

I'm intending to experiment with that, but I don't know if actual errors in the Standard Error stream will be handled correctly or how well the colors output by yt-dlp will be preserved. Plus, what happens when yt-dlp updates the download progress line?
Anonymous

2025-02-20T02:14:25.96+00:00

Please give us a reply after experimenting. In addition, yt‑dlp is not a Microsoft product, and we are not responsible for supporting and maintaining it.
Will Pittenger 311 Reputation points

2025-02-20T02:17:13.77+00:00

I understand you wouldn't support yt-dlp. It just happens to be what I'd be calling.
Anonymous

2025-02-20T02:22:52.5966667+00:00

If you need to find support for yt-dlp, you will need to go to the relevant forums.
Will Pittenger 311 Reputation points

2025-02-20T02:24:21.4766667+00:00

I don't appear to need support with it, but I do talk with them on Discord.

1 answer

Your answer

Anonymous

2025-02-17T03:08:32.5366667+00:00

Hi @Will Pittenger ,Welcome to Microsoft Q&A,

Have you seen the sample code in the related links? Try the code below and give me feedback.

using System; using System.Diagnostics; using System.Text; public void RunYtDlp() { // Set up the process start info var startInfo = new ProcessStartInfo { FileName = "yt-dlp", // Path to yt-dlp executable Arguments = "--your-arguments-here", // Your arguments, e.g. URL, --dump-json, etc. UseShellExecute = false, // Must be false to redirect output CreateNoWindow = false, // Show a window if needed RedirectStandardOutput = true, // Capture stdout (for JSON) // Leave StandardError not redirected so it goes directly to the console }; var process = new Process { StartInfo = startInfo }; // StringBuilder to accumulate JSON output (if needed) var jsonOutput = new StringBuilder(); // Attach an asynchronous handler for stdout process.OutputDataReceived += (sender, e) => { if (e.Data != null) { // Log or process the JSON output here jsonOutput.AppendLine(e.Data); // You can also write to a log file or update your UI here. } }; // Start the process process.Start(); // Begin reading stdout asynchronously process.BeginOutputReadLine(); // Wait for yt-dlp to exit process.WaitForExit(); // Now jsonOutput.ToString() contains the captured JSON output. // You can process it as needed. Console.WriteLine("Captured JSON output:"); Console.WriteLine(jsonOutput.ToString()); }
Will Pittenger 311 Reputation points

2025-02-17T04:44:29.76+00:00

That's what I know. But it'd probably skip those intermediate lines unless those are in Standard Out with the JSON. Then I'd have to figure out where the JSON starts.
Will Pittenger 311 Reputation points

2025-02-18T00:24:03.4833333+00:00

I needed a translator for that as I don't know Japanese. Seems to be as follows

By default, yt-dlp outputs progress information (including dynamic updates and colors) to standard error and JSON to standard output, making it easy to separate the two outputs. Do not redirect standard error.

Please note I need errors too. But that's an interesting detail I was unaware of.
Anonymous

2025-02-19T09:31:55.86+00:00

Hi @Will Pittenger ,

Try reading Standard Output asynchronously to capture JSON.

var startInfo = new ProcessStartInfo { FileName = "yt-dlp", Arguments = "--your-json-arguments", // Use --dump-json or --print-json arguments UseShellExecute = false, CreateNoWindow = false, RedirectStandardOutput = true, // Capture JSON output // Do not redirect StandardError, let it write directly to the console };
Will Pittenger 311 Reputation points

2025-02-19T09:35:16.56+00:00

I'm intending to experiment with that, but I don't know if actual errors in the Standard Error stream will be handled correctly or how well the colors output by yt-dlp will be preserved. Plus, what happens when yt-dlp updates the download progress line?
Anonymous

2025-02-20T02:14:25.96+00:00

Please give us a reply after experimenting. In addition, yt‑dlp is not a Microsoft product, and we are not responsible for supporting and maintaining it.
Will Pittenger 311 Reputation points

2025-02-20T02:17:13.77+00:00

I understand you wouldn't support yt-dlp. It just happens to be what I'd be calling.
Anonymous

2025-02-20T02:22:52.5966667+00:00

If you need to find support for yt-dlp, you will need to go to the relevant forums.
Will Pittenger 311 Reputation points

2025-02-20T02:24:21.4766667+00:00

I don't appear to need support with it, but I do talk with them on Discord.

Answer 1

Bruce (SqlWork.com) 77,686 Volunteer Moderator

You redirect standard output and error to streams to capture them. See

https://learn.microsoft.com/en-us/dotnet/api/system.diagnostics.process.standardoutput?view=net-9.0

Will Pittenger 311 Reputation points

2025-02-16T18:26:41.56+00:00

The problem is how to catch all lines it outputs. It seems to have a way to send lines to the console that bypass at least PowerShell redirection. Second, even if the redirected Standard Output stream contains the messages, it might also have JSON at the end. I want to capture the JSON separately.
Anonymous

2025-02-17T09:22:51.3533333+00:00

By default, yt-dlp outputs progress information (including dynamic updates and colors) to standard error and JSON to standard output, making it easy to separate the two outputs. Do not redirect standard error.

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Capturing Intermediate Output in C# PowerShell CmdLet using yt-dlp

1 answer

Your answer