This is an experimental implementation of Wi-Fi Display (aka Miracast).
The application will stream the selected monitor if the mutter screencast portal is available. If it is unavailable, a fallback to X11 based frame grabbing will happen. As such, it should work fine in almost all setups.
To get audio streaming, you need to change the audio output in pulseaudio to use the created "Network-Displays" sink.
To use it, you will need:
To build it locally:
meson
meson build
on the cloned repositorymeson install
on the build
folder created by mesonThe following devices have been tested:
For testing purposes you can run with NETWORK_DISPLAYS_DUMMY=1 set. In that case, a dummy sink will be provided that allows connecting on localhost using any RTSP capable client to test WFD streaming.
You can connect to rtsp://localhost:7236/wfd1.0 then.
Appropriate video/audio encoders will be selected automatically. You should
also get a notification if codecs are missing and an offer to automatically
install these. To debug the codecs themselves, you can modify the default
choice by setting the NETWORK_DISPLAYS_H264_ENC
and NETWORK_DISPLAYS_AAC_ENC
environment variables and specifying the gstreamer element to use (if
supported and detected). Run with G_MESSAGES_DEBUG=all
to see the selection
at work during connection establishment.
P2P WiFi/WiFi Direct and the mechanism to establish a connection is a relatively complicated process that can fail in a number of different ways and stages.
As a first step, you should run with G_MESSAGES_DEBUG=all
to get a better
idea when the failure happens. Your TV/Display may also give an indication
about the progress. Much of the information is also displayed in the UI, but
might only be visible for a very short period of time.
The first required step is successful discovery of the remote device. This step can already be problematic sometimes. Confirm the following, each ensuring that support exists:
Run gnome-network-displays
with G_MESSAGES_DEBUG=all
. This will print
a lot more information. Theoretically it may be that we see the device, but
think that it is not WiFi Display capable (e.g. because the wpa_supplicant
support is missing, see further below). Look out for the following messages:
WFDP2PRegistry: Got NMClient
:
The connection to NetworkManager works.WFDP2PRegistry: Found a new device, creating provider
:
This means that we have a seemingly usable P2P device installed.WFDP2PProvider: Ignoring peer "XX:XX:XX:XX:XX" (Y) as it has no WFDIEs set
:
This means there is a P2P device, but it does not seem to support WiFi
Display. It may also mean that wpa_supplicant
is not complied with
the required support, see below.WFDP2PProvider: Found a new sink with peer X on device Y
:
The device has been found, everything should be good.nmcli device
shows your WiFi device and a corresponding p2p-dev-X
device.
If you do not see your WiFi device, then NetworkManager is probably not
managing it for some reason. Both the main WiFi device and the P2P device
need to be managed by NetworkManager.
iw dev
should show an Unnamed/non-netdev interface
device with type
P2P-device
.
If this is not the case, then the device is likely unsupported.
One example of this are legacy wext
drivers, which may support P2P
operation, but are not (and will not be) supported by this software.
NetworkManager only support P2P operation together with wpa_supplicant
.
The use of iwd
is currently not supported and you may have enabled it
in NetworkManager.
If NetworkManager does not even show a device, then, as root, run
gdbus call --system --dest fi.w1.wpa_supplicant1 --object-path /fi/w1/wpa_supplicant1 --method org.freedesktop.DBus.Properties.Get fi.w1.wpa_supplicant1 Capabilities
This should output something like (<['ap', 'ibss-rsn', 'p2p', 'pmf', 'mesh', 'ft', 'sha384']>,)
.
Make sure that p2p
is listed here. If it is not, then wpa_supplicant
was
compiled without P2P WiFi support (CONFIG_P2P
).
If a device is shown, but it does not work, then, as root, run
gdbus call --system --dest fi.w1.wpa_supplicant1 --object-path /fi/w1/wpa_supplicant1 --method org.freedesktop.DBus.Properties.Get fi.w1.wpa_supplicant1 WFDIEs
If this runs successfully, it'll return (<@ay []>,)
. This answer will be
longer when we try to connect to a device, but only at that point.
If it shows an error, then your wpa_supplicant
was compiled without
WiFi Display support (CONFIG_WIFI_DISPLAY
).
If everything looks good, but you still can't find the TV, then please try the following:
gdbus call --system --dest fi.w1.wpa_supplicant1 --object-path /fi/w1/wpa_supplicant1 --method org.freedesktop.DBus.Properties.Set fi.w1.wpa_supplicant1 WFDIEs "<@ay [0x00, 0x00, 0x06, 0x00, 0x90, 0x1c, 0x44, 0x00, 0xc8]>"
Doing this will set the WFD Information Elements earlier in the process. It should not make a difference. But if it does, then some bigger changes will be needed.
iw phy phyX interface add mon0 type monitor
ip link set mon0 up
Then connect to it using wireshark
. You may need to disable your normal
WiFi connection and change the channel using iw dev
. Explaining the details
is out of scope for this document.
When you click on the TV, the first step is to establish a WiFi P2P connection. Check whether you see the message:
Got state change notification from streaming sink to state ND_SINK_STATE_WAIT_P2P
[...]
Got state change notification from streaming sink to state ND_SINK_STATE_WAIT_SOCKET
If you see both of these messages, then we have successfully created a P2P Group.
What happens next is that both side will configure their network. Then the TV
will establish a connection to gnome-network-displays
.
Things could go wrong here:
dnsmasq
At this point the IP link is there. You can do the following:
The low level link is established (i.e. a P2P network device has been created). This means, to debug further, we can montior this network device and see what is happening. We should see a DHCP handshake to configure the network, and then an attempt to establish an RTSP connection.
The easiest way to do this is to have wireshark
running. Then, right after
clicking on the TV, the P2P device will show up in the list. Quickly start a
capture on it.
Alternatively, use a script like the following (as root):
interface=""; while [ -z "$interface" ]; do interface=$( ls /sys/class/net/ | grep -- p2p- ); sleep 0.1; done; echo $interface; tcpdump -i "$interface" -w /tmp/p2p-connection-dump.pcap
And then open the created dump file /tmp/p2p-connection-dump.pcap
in Wireshark.
Not all devices are compliant, and the standard is a bit odd. If you have problems where the stream seems to start, but then does not work or stop after a while.
Try the following:
G_MESSAGES_DEBUG=all
and check if you see something that is wrong.
Note that certain warnings are expected.tcpdump
/wireshark
capture (see above) and check whether
you see something weird in the RTSP stream.GST_DEBUG=*:5
, but is generally
harder to pin point. Try it a few times, and check if the problem persists.