Video mixing and switching is commonly used in film production, broadcast trucks/vans, medical imaging consoles, surveillance monitoring and post-production studios. Over the recent years, these have moved away from being pure hardware solutions towards being highly programmable. Embedded platforms provide the right trade-off between performance and flexibility.
Let us understand how.
A typical KxM digital video switcher/mixer receives K inputs and generates M outputs.
- Each of the K audio video inputs is either uncompressed/raw (HDMI®, HD-SDI, 3G-SDI, etc.) or compressed/encoded streams (received as unicast/multicast stream over IP network).
- Each of the M audio video outputs is either uncompressed/raw (HDMI®, HD-SDI, 3G-SDI, etc.) or compressed/encoded (recorded to SD Card/SATA/network storage, streamed over IP network).
As some of the key audio video processing steps between input and output, a typical video mixer implements the following:
- Switching any input to any output with the minimal switching latency
Composition of two or more video inputs to generate any video output (with configurable dimensions, transparency, position and z-ordering of overlay)
- Mixing of two or more audio inputs to generate any audio output (with configurable mixing weights)
Independent overlay of text, graphics and images for each video output
Maintaining perfect synchronization across input/output channels during composition and switching
The media flow for such a 2×2 video mixer/switcher is illustrated below. Realizing a mixer/switcher therefore hinges on finding the right embedded platform to do justice to both composition & compression functions, while keeping the design complexity low.
- Multi-channel switching/mixing for uncompressed as well as compressed audio/video inputs.
- 3D graphics acceleration using SGX544 (dual core) and 2D graphics acceleration using GC320, enabling rich overlay (text, graphics), video composition (with alpha-blending) and pre-processing (de-noising, contrast enhancement, etc.).
- Optimized device drivers for low latency operation, enabling frame level synchronization.
- Seamless support for video mixing/switching of progressive and interlaced video formats.
- Hardware accelerated video resizing and de-interlacing.
- Hardware accelerated high quality video encode/decode up to Full-HD (1080p60) for recording (SATA, SD Card, USB 3.0/2.0) or streaming (wired/wireless).
- ARM Cortex™ A15 or C66x DSP based high-fidelity audio encode/decode.
- High DDR3 throughput to support bandwidth intensive graphics operations.
- Optimized media pipelines & framework based on Ittiam’s patented Adroit software architecture.
- Standards compliant encoding/decoding, streaming and recording.