Receiving T2-MI

T2-MI (DVB-T2 Modulator Interface) is a way to carry a whole DVB-T2 multiplex inside an MPEG-TS stream. Broadcasters use it to deliver terrestrial multiplexes to DVB-T2 transmitters, usually over satellite.

In a T2-MI stream the TV channels are not regular programs. The whole DVB-T2 multiplex is packed into a single PID as data, so a normal scan does not find any channels. Astra unpacks T2-MI and gives you the channels inside.

Reception works in two steps:

1. Receive the stream that carries T2-MI: from a DVB adapter or from a UDP source
2. Create a virtual MPTS adapter that unpacks T2-MI and provides the channels

Configure the DVB adapter

Skip this step if the T2-MI stream comes to your server over UDP, for example from a satellite receiver.

Click “New Adapter” in the main menu and configure the adapter as usual: type, frequency, polarization, symbol rate, and other parameters. Read more: DVB Adapters.

Two settings are important for T2-MI:

• Budget Mode: turn it on in the Advanced options. Budget mode disables hardware PID filtering, so Astra receives the whole transponder from the adapter, including the PID with T2-MI data
• ID: you need this identifier in the next step. Set your own ID, or copy the generated one after you save the adapter

Click Apply to save the adapter. In this setup the DVB adapter only delivers the transponder. The channels from the T2-MI stream are added later, from the virtual adapter.

Find the T2-MI PID

In most networks T2-MI data is carried in PID 4096. To check which PID your transponder uses, open the DVB adapter settings and press Scan.

You can also check the source in the console with the MPEG-TS Analyzer. For a UDP source:

astra --analyze udp://239.255.1.1:1234

For a DVB transponder, turn the adapter off in Astra first, because two processes cannot use the same tuner:

astra --analyze 'dvb://#adapter=0&type=s2&tp=11044:V:43200'

Read more about the DVB parameters: Extended Address Format.

Create the virtual adapter

Click “New Adapter” in the main menu again and set the following options:

• Name: any name that helps you find the adapter later
• Virtual: select the MPTS option
• Address: address of the T2-MI source with the T2-MI options

For a DVB adapter from the previous step:

dvb://a001#t2mi=0&t2mi_pid=4096

For a T2-MI stream that comes over UDP:

udp://239.255.1.1:1234#t2mi=0&t2mi_pid=4096

Replace:

• a001 with the ID of your DVB adapter, or 239.255.1.1:1234 with the address and port of your UDP stream
• t2mi=0 with the number of the T2-MI stream you need, if it is not 0
• t2mi_pid=4096 with the PID that carries T2-MI data, if it is not 4096

Click Apply to save the adapter, then press Scan. Astra unpacks the T2-MI stream and shows the list of channels. Select the channels you need and press Apply to add them.

T2-MI options

• t2mi=number: number of the T2-MI stream to unpack. One PID can carry several T2-MI streams. They are numbered from 0
• t2mi_pid=number: PID that carries T2-MI data. Usually 4096

Set both options in the same address.

If the scan finds no channels

• Check the signal quality on the DVB adapter
• Check that Budget Mode is on in the DVB adapter settings
• Check that the adapter ID in the address is the same as the ID of the DVB adapter
• Check the T2-MI PID and the T2-MI stream number

More information: Troubleshooting DVB Adapters