StreamLabs ALPHA SDI Capture / Playout Card with SDK

StreamLabs ALPHA SDI Capture / Playout Card with SDK
Stream ALPHA SDI is a multi-functional video card, which is able to substitute several devices in a studio at a time. Besides the primary function of graphics overlaying on transmitted digital signal of SDI format or its output for external mixer, the video card may converse analog signal to digital SDI format of video signal and work as frame-grabber and video sequence-grabber.

Stream ALPHA SDI works with 8- and 10-bit serial component SDI input signal and 10-bit - output signal, in accordance with CCIR656 and SMPTE259m instructions. At signal passing through the board all service information is kept, and sound packs may be either kept or replaced depending on the required conditions. In the input signal error check with calculation of checksum under EDH technique is performed. At output, EDH packs are always generated anew according to SMPTE165 instruction.

The board works in external synchronization mode, which is performed on the input video signal. If at the output is only computer graphics, synchronization signal Black burst may be sent to the main input or to optional analog one. At external synchronization absence internal generator is used.

For use of the described devices in combination with external mixer having DSK input (Down Stream Key), key signal output (of alpha channel) is specially designed in analog and digital format. Board setup program allows setting both positive and negative delay of key signal in relation to the output graphics within broad range.

At switching off computer power supply or at BYPASS mode activating inputs and outputs of all devices form a circle through relay, and 75 Ohm load is switched off. During power supply switching off and also initialization no distortions of the transmitted signal take place at the output.

For output of computer graphics the video card memory buffer is used of 720x576 points size for 50 Hz video systems and 720x480 points for 60 Hz systems. Each point has 32-bit representation, 24 bits of which are used for representation of its color (16 mln. shades), and 8 bits - for specification of one of 256 transparency degrees (alpha channel). Although the component of points color of computer graphics has 24 bits in its presentation (8x8x8), at mixing representation of 30 bits (10x10x10) is used, i.e. if the input signal was a 10-bit one, it will remain such at output after mixing.

The memory used for graphics buffer, and also data throughput of PCI bus of modern computers allow to refresh entirely its content in real time without loss of pictures, transmitting uncompressed image (32 bit/pixel) together with the sound component.

Video card Stream ALPHA SDI besides the digital serial input is also equipped with analog inputs - YUV/RGB, S-Video and a composite input. It also may generate analog signals YUV/RGB regardless of input used at the output simultaneously with SDI signal.

For generation of signals at analog outputs 10-bit digital to analog converter with fourfold oversampling is used. It allows obtaining of their HF noise total filtration without additional reduction of channel signal output brightness bandwidth.

Compatible Software:
- Alpha Pro 2.0
- TELE 2.2
- TELE 2.2 Info


8- and 10-bit serial video component SDI signal, full compliance with CCIR656 and SMPTE259m recommendations.

Two options in video signal synchronization: the analog Black Burst or SDI video.

Output SDI and analog key-signal to support external video mixer equipped by DSK input.

Automatic pass-through mode.

Live mode video mixer and display on RGB monitor, composition of source video signal and computer graphics, animation and text data without pre-processing.

Analog YUV/RGB, S-Video, and Composite video inputs and outputs.


In the Box

- Stream ALPHA SDI Board
- SDK (Software Development Kit)


Compatible Products