# Can't preview camera in a WEB session while using a mobile

**URL:** <https://devforum.zoom.us/t/cant-preview-camera-in-a-web-session-while-using-a-mobile/126547>\
**Category:** Video SDK\
**Tags:** video-sdk\
**Created:** [February 11, 2025, 8:10pm UTC](https://devforum.zoom.us/t/cant-preview-camera-in-a-web-session-while-using-a-mobile/126547 "2025-02-11T20:10:01Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Simas](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/simas/32/58649_2.png) [@Simas](https://devforum.zoom.us/u/Simas)\
**Post date:** [February 11, 2025, 8:10pm UTC](https://devforum.zoom.us/t/cant-preview-camera-in-a-web-session-while-using-a-mobile/126547/1 "2025-02-11T20:10:01Z")

</div>

Hello,  
We have a web application running on Nuxt with Zoom video sdk version 2.1.5 implemented.

We want to allow our users to preview their camera **inside a session** with or without camera enabled and separated away from other remote participants. We tried two approaches, which both succeeded for desktops, but failed for mobiles.

First, we tried to accomplish it with `ZoomVideo.localVideoTrack`, but after we started to receive different, unexpected results on mobile devices we changed local camera preview functionality with `stream.previewVirtualBackground` (we pass undefined for imageUrl parameter). The second approach does not show us any exclusive error. Here is a function that we use for handling local participant after he joins the session:

```auto
    async function handleLocalParticipantConnected(participant: ZoomParticipant): Promise<void> {
        try {
            const { cameras } = await fetchDevices()

            const camera: DeviceData | undefined = cameras.find(camera => camera.id === devices.camera.id) || cameras?.[0]

            if (devices.camera.enabled) {
                try {
                    if (!camera?.id)
                        throw new Error('Unable to detect camera')

                    await stream!.startVideo({
                        cameraId: camera.id,
                        virtualBackground: virtualBackground.value, /* this is either { imageUrl: 'blur' } or undefined determined by stream!.isSupportVirtualBackground() */
                    })
                } catch (error) {
                }
            }

            const previewVideoElement: VideoPlayer = document.querySelector('video-player#local-video')!

            const promise = stream!.previewVirtualBackground(previewVideoElement, undefined)

            alert('before promise')

            promise
                .then((result) => {
                    alert('promise resolved')
                }).catch((error) => {
                    alert('promise error')
                })
                .finally(() => {
                    alert('promise finally')
                })

                try {
                    await stream!.startAudio({
                        mute: !devices.microphone.enabled,
                        microphoneId: devices.microphone.enabled ? (devices.microphone.id || undefined) : undefined,
                        speakerId: devices.speakers.id || undefined,
                    })
                } catch(e) {}
            // }
        } catch(error) { console.log('local participant connection error ' + error)}

    }

```

In this function you can find `alert()` which we use for debugging purposes. For desktops we receive “promise resolved” and “promise finally” alerts and camera preview works fine, but for mobile devices we do not receive neither of alerts declared in `then()`, `catch()` or `finally()` blocks.

While troubleshooting, I opened Chrome dev tools and entered responsive mode with desktop-sized window and it failed to show camera preview also. For me, it looks like that user agent has something to do with this.

Is there a mistake that I made in this code or did I misunderstood which function should be used for previewing local camera inside a session?

Thank you!

---

<div class="post-metadata">

**Author:** ![vic.yang](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/vic.yang/32/24656_2.png) [@vic.yang](https://devforum.zoom.us/u/vic.yang)\
**Post date:** [February 12, 2025, 9:06am UTC](https://devforum.zoom.us/t/cant-preview-camera-in-a-web-session-while-using-a-mobile/126547/2 "2025-02-12T09:06:47Z")

</div>

Hey @Simas

Thanks for your feedback.

> We want to allow our users to preview their camera **inside a session** with or without camera enabled and separated away from other remote participants.

Are you referring to previewing self-video in session without sending the video to remote users?

If so, `stream.previewVirtualBackground` is not applicable, as this function also applies to the stream sent to remote users.

Regarding your observations on the mobile platform, as described, this function is intended for previewing the virtual background. However, virtual background support is not yet available on mobile.

If you only need to display self-video on the page, simply call `stream.startVideo` and attach the video accordingly.

Thanks  
Vic