---
title: Casting (DLNA)
description: Stream to Chromecast and DLNA devices
---

import Callout from "blume/components/content/Callout.astro";
import Steps from "blume/components/content/Steps.astro";
import Step from "blume/components/content/Step.astro";
import Badge from "blume/components/content/Badge.astro";
import Accordion from "blume/components/content/Accordion.astro";
import AccordionItem from "blume/components/content/AccordionItem.astro";

CineWindows can stream media to Chromecast, DLNA-compatible TVs, and UPnP media renderers on your local network. The `CastService` handles device discovery via UPnP SSDP and sends media URLs using SOAP-based AVTransport control.

## How Casting Works

The `CastService` uses UPnP (Universal Plug and Play) to discover and control media renderers:

1. **Discovery** — Sends an SSDP `M-SEARCH` multicast to `239.255.255.250:1900` requesting `MediaRenderer:1` devices
2. **Description** — Devices respond with a description URL; the service fetches the XML and extracts the `friendlyName` and `AVTransport` control URL
3. **Streaming** — Sends the media URL to the device via `SetAVTransportURI` SOAP action, followed by a `Play` command

<Badge variant="default">UPnP AV Transport 1.0</Badge>
<Badge variant="default">SSDP v1.0</Badge>

## Device Discovery

Trigger discovery from the **Cast** dialog (**Media > Cast**). The service broadcasts an `M-SEARCH` request with a 2-second MX (response wait time) and collects responses for 3.5 seconds total. Compatible devices appear in a list as they are found.

### Discovery Process

```
M-SEARCH * HTTP/1.1
HOST: 239.255.255.250:1900
MAN: "ssdp:discover"
MX: 2
ST: urn:schemas-upnp-org:device:MediaRenderer:1
```

The service listens on a UDP socket bound to `QHostAddress::AnyIPv4`. Each response is parsed for the `LOCATION` header, which points to the device's XML description. The description is fetched over HTTP, parsed with `QXmlStreamReader`, and registered if it exposes an `AVTransport` service with a `controlURL`.

### Device Information

Discovered devices provide:

- **Name** — `friendlyName` from the device description (e.g. "Living Room TV", "Office Chromecast")
- **Control URL** — SOAP endpoint for `AVTransport` commands
- **Description URL** — Device description URL for metadata

## Streaming a URL

Once a device is selected, CineWindows sends the media URL to the device via a SOAP XML envelope:

### SetAVTransportURI

```xml
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"
  s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
  <s:Body>
    <u:SetAVTransportURI xmlns:u="urn:schemas-upnp-org:service:AVTransport:1">
      <InstanceID>0</InstanceID>
      <CurrentURI>https://example.com/video.mp4</CurrentURI>
      <CurrentURIMetaData></CurrentURIMetaData>
    </u:SetAVTransportURI>
  </s:Body>
</s:Envelope>
```

### Play

Immediately after the URI is set (on success), the service sends a `Play` SOAP action:

```xml
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"
  s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
  <s:Body>
    <u:Play xmlns:u="urn:schemas-upnp-org:service:AVTransport:1">
      <InstanceID>0</InstanceID>
      <Speed>1</Speed>
    </u:Play>
  </s:Body>
</s:Envelope>
```

> **Info**
>
> The current casting implementation supports **direct HTTP and HTTPS media URLs** only. Local file paths and unsupported protocols will show an error message. The device must be able to reach the URL directly on your network.

## Same-Network Requirement

Both your computer and the casting device must be on the same local network. UPnP SSDP discovery uses multicast (239.255.255.250:1900) which does not route across subnets or through NAT. The media URL must also be accessible from the casting device — local file paths will not work unless served by an HTTP server reachable on the LAN.

## Casting Steps

1. ### Connect Devices to the Same Network

    Ensure your computer and the target device (Chromecast, DLNA TV, etc.) are on the same Wi-Fi or wired network. Devices on separate VLANs or guest networks will not discover each other.

2. ### Open the Cast Dialog

    Click **Media > Cast** from the menu bar or right-click the video and select **Cast**. The Cast dialog opens with a **Discover Devices** button and a device list.

3. ### Discover Devices

    Click **Discover Devices**. The service broadcasts SSDP and lists every found `MediaRenderer` on the network. Discovery runs for ~3.5 seconds. If no devices are found, the dialog shows a "No compatible devices found" message.

4. ### Select a Device

    Click a device name from the list. CineWindows immediately sends the currently-playing media URL to the device.

5. ### Streaming Begins

    The device starts playback. CineWindows shows a confirmation toast. The local player continues playing independently — casting does not stop local playback. Use the device's own controls (remote, TV interface) to pause, seek, or stop.

<Accordion>
<AccordionItem title="Supported Devices">
CineWindows' UPnP implementation is compatible with:

- **Chromecast** (1st, 2nd, 3rd gen, Chromecast Ultra, Chromecast with Google TV)
- **Google Nest Hub** and **Nest Max**
- **DLNA-certified TVs** (Samsung, LG, Sony, Panasonic, Vizio)
- **Game consoles** (PS4, PS5, Xbox One, Xbox Series X/S — DLNA mode)
- **Software renderers** (VLC in renderer mode, Plex, Universal Media Server)

Note that Chromecast requires the media URL to be an HTTP/HTTPS link. Local file paths will not cast to Chromecast devices.
</AccordionItem>
<AccordionItem title="Limitations">
The first release of casting supports:

- **HTTP/HTTPS URLs only** — local files and YouTube links resolved by yt-dlp are not cast directly. To cast YouTube content, use the Chromecast's native YouTube app.
- **No playlist support** — single media URL per cast session
- **No transport monitoring** — CineWindows does not poll the device for playback position or status after casting starts
- **No queuing** — subsequent cast actions replace the current URI

These limitations are expected to be addressed in future releases as the cast service matures.
</AccordionItem>
<AccordionItem title="Troubleshooting">
**No devices found** — Check that all devices are on the same network. Verify UPnP is enabled on the target device (often in network settings). Try disabling and re-enabling the network interface. Some corporate or guest networks block SSDP multicast.

**Device found but cast fails** — Ensure the media URL is accessible from the casting device. Test by opening the URL in a browser on the device. Check that the URL uses HTTP or HTTPS — local files are not supported.

**Playback does not start** — The device may not support the media format. Try a standard MP4 with H.264 video and AAC audio. Some devices require specific container formats.
</AccordionItem>
</Accordion>