FlowCaster creates an Open I/O board in Avid creative software like Media Composer. As a virtual video board, it can send the same high quality audio, video and captions from a real or virtual machine to wherever you are doing your creative work for output on a 'third monitor'. This signal can be received by free software, like VLC and the Haivision Pro Player, or by dedicated Drastic receivers for more features, like FlowCaster for IOS and Android, videoQC for Windows, macOS and Linux, or a variety of hardware decoders from AJA, Haivision and others. This article demonstrates configuring FlowCaster in Avid Media Composer.
Avid Media Composer
To configure FlowCaster in Avid Media Composer, you first have to enable it on the timeline. Find the Open IO output button just above the timeline.
To enable it, right click on it and select FlowCaster. If FlowCaster is already selected, you can just left click on the button.
Once enabled, the button will flash a red double arrow to indicate it is sending to FlowCaster.
When enabled, a new menu under Tools will be available called Video Output Tool.
Click on this to bring up the FlowCaster Configuration Dialog.
FlowCaster Configuration Dialog
SRT Caller - this uses SRT to call out to a remote device. The IP and port for this protocol in URL should be the remote device's IP address and selected port.
SRT Listener - this uses SRT to listen on your local machine. The IP must be one of the IPs on your machine, and you must select a port to receive on.
SRT Rendezvous - this mode uses the external, internet IP to connect through local NAT routers. Here it should be the internet facing IP of the remote device. On that device's config, it should be your internet facing remote IP. To determine each computer’s IP address: (Windows Terminal: ipconfig, Mac/Linux Terminal: ifconfig or Control Panel)
RTP - the IP and Port for this mode can be the remote device, or a multicast address (239.x.x.x) that both the sender and receiver are set to.
UDP - the IP and Port for this mode can be the remote device, or a multicast address (239.x.x.x) that both the sender and receiver are set to.
RTMP - the URL for this mode will consist of the remote server, followed by the remote key For instance, with YouTube.com, the address would be rtmp://a.rtmp.youtube.com/live2, and the key would be provided by YouTube and look something like this j2br-3t45-b6ck-s9h9-5dcy, so the URL would be rtmp://a.rtmp.youtube.com/live2/j2br-3t45-b6ck-s9h9-5dcy.
NDI - for NDI, the URL would be a unique name, that NDI will combine with the computer name, to create a fully qualified name you can use to connect to the stream.
WHIP - uses WebRTC to call out to the Whip server that sends out WebRTC sessions to all the clients
WebRTC/FlowCaster.live - integrates one or more FlowCaster signals into a group chat
BLS - provides an HTTP server/file that allows a browser to directly display the audio and video
Normally the IP and Port or a fully qualified URL, depending on the Transmit Type setting. Below are some typical examples
SRT Caller: 10.0.0.60:5000
SRT Listener: 10.0.0.238:5000
SRT Rendezvous: 126.96.36.199:5000
Latency is the number of milliseconds to give the signal to recover packets. This is for SRT. The lower this number, the closer to real time the monitor will be. The larger, the more room it will have to recover any lost packets. It is recommended this be the RTT (round trip time) between the two devices plus 20 milliseconds
SRT supports end to end encryption. Setting this to 128 or 256 will cause all the data to be encrypted, use the Password below.
If encryption above is set to 128 or 256, then this password will be used to encrypt the signal, and it must be used on the receiving device for it to be able to decrypt the signal.
If your protocol/transmit type require authentication, this is the user name that will be used in that authentication.
If your protocol/transmit type supports multiple stream sets, this will specify which one you are sending.
What compression to use to send the stream. FlowCaster supports h.264, h.265/HEVC and JPEG 2000, but the receiver must also support them for the monitor to work. If you are unable to see the signal in the receiver, start with h.264 8 bit 4:2:0 and then work up from there to see what the receiver supports. videoQC supports all the codecs.
This is the internal structure of the compression. Three modes are supported.
- IBBP - this has the highest quality, but the longest latency
- IPPP - this has the best compromise between quality and latency
- IIII - this has the shortest latency, but the worst quality
The kilobit rate to encode the video within. For instance, 2 mbs (megabits) would be 2000 kbs (kilobits).
Receiver Supports HDR Signalling
If your receiving software supports HDR Signalling, checking the checkbox will enable sending any local HDR signalling to the remote monitor.
FlowCaster supports 5 audio modes
- Stereo - just the first stereo pair
- Stereo Mix - mix all available channels to a stereo pair
- 4 channels - send the first four channels
- 8 channels - send the first eight channels
- 16 channels - send the first sixteen channels
A path and filename to a file to place on the output as a watermark. This would normally be a 32 bit PNG file with Alpha. The "..." button will bring up a file browse dialog to allow you to select a file from your local file system. The two numbers separated by a comma and the x and y start position of the watermark on the output signal in pixels.
Once the OK button is clicked, FlowCaster will reset its output to match the new setup. This may take a few seconds before you see the changes on the receiver.
There is a Quick Overview video located here.