Recording a Live Session

In this tutorial, you’ll learn how to record and play back an application in real time using Chaos Visual Debugger (CVD). Unlike recording to file, recording a live session can be done locally (on your machine) or remotely (over a network). This is useful for live debugging on the fly but also saves the recording as a .utrace file for you to review and share later on.

Record Live Sessions

In this section you’ll learn how to record a PIE session using the Local Editor target preset, and the process to record all other target types.

Local Editor

To record and play back a live PIE session on a local or a remote machine, follow these steps:

1. In CVD, toggle the data channels you want to record.

   

2. In Unreal Editor, click the Play button in the main toolbar to begin a PIE session. You can start the PIE session before or after beginning a recording in CVD

   

3. Since the Local Editor target is already selected by default, you can begin the recording by clicking Record Live Session. While recording, this button turns into a red recording icon.

   

4. To stop recording, highlight the recording icon and click the red square icon. This process outputs a single .utrace file.

   

   If you are currently recording, you can quit an existing PIE session and begin a new one — CVD automatically connects to it.

All Other Targets

To record and playback a game client, server, or packaged build on a local or remote machine, follow these steps:

1. Verify that your target application or applications are running.

2. Toggle the data channels you want to record.

   

3. To select a target to record, in CVD’s main toolbar, click the Session Target dropdown menu and choose your target.

   

4. To begin a recording, in CVD’s main toolbar, click Record Live Session. While recording, this button turns into a red recording icon.

   

5. To stop recording, highlight the recording icon and click the red square icon. This process outputs one or more .utrace files.

   

(Legacy) Record a Live Session with the Command Line Interface

We recommend using CVD’s UI to start and end recordings, however, you can use the command line to record PIE sessions, game clients and servers, and packaged builds. The session can be local (on the same workstation or even in the same PIE instance) or over the network.

Enable a Data Channel

1. To modify data channels, open the command line in the target application. In a packaged build, press Backtick (`).

2. Enter the following console command, making sure to replace [newstate] with true or false and [channelname] with the desired data channel:

     p.Chaos.VD.SetCVDDataChannelEnabled [newstate] [channelname]

    For example:

   

3. Press Enter to execute the command.

Enable Multiple Data Channels

You can enable or disable multiple channels by listing them, separated by commas. The following example enables the PostIntegrate and Scene Queries channels:

p.Chaos.VD.SetCVDDataChannelEnabled true SceneQueries,PostIntegrate

Enable Predefined Data Channels

If you want to launch a game client or server with a predefined set of enabled channels, add the following command line argument:

CVDDataChannelsOverride=[ChannelName1,ChannelName2]

The following example enables the Integrate and Scene Queries channels:

CVDDataChannelsOverride=SceneQueries,PostIntegrate

Start a Recording Using the Command Line

1. To start a recording, open the command line.

2. If you are working on a local machine, type the following command and press Enter to execute it:

   p.Chaos.StartVDRecording Server

   

   If you are working on a remote machine, type the following command and press Enter to execute it:

   p.Chaos.StartVDRecording Server [YOURWORKSTATIONIP]

3. In CVD’s main toolbar, click Connect To Session. In the Live Session Browser, next to Selected Live Session, select the available live session running on the local trace store. 

4. (Optional) If you’re connecting to multiple targets, from the Connection Mode dropdown menu, select Multi Source.

   

5. Click Connect to Session (in the Live Session Browser dialog). When the recording begins, the string Chaos Visual Debugger recording in progress… displays on screen.

   

6. To stop a recording, open the command line. If you’re working on a local machine, type the following command and press Enter:

   p.Chaos.StopVDRecording Server

   

   If you’re working on a remote machine, type:

   p.Chaos.StopVDRecording Server [YOURWORKSTATIONIP]

Next Up

In the next tutorial, you’ll learn how to locate your .utrace files and play back your recordings.

Playback in Chaos Visual Debugger

Play back recordings in Chaos Visual Debugger.