In Broadcast - May/June 2011 - 39

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Simultaneous Multi-Format Encoding for Efficient Content Repurposing Cont.
• Less equipment – by eliminating the need for separate encoders for each format, multi-forma systems reduce space and power requirements while lowering equipment acquisition costs. • Reduced operational complexity – while separate encoders for each format could be deployed in parallel to achieve simultaneous deliverables, doing so adds to the complexity of the workflow. Automation requirements would increase to ensure that all encoding is perfectly synchronized, while any change to the combinations of desired deliverables may involve rerouting of signals between the encoders and reconfiguration of the settings on multiple systems. • Faster turnaround – systems that support multiple formats but not concurrently can still reduce overall equipment requirements, but require multiple passes from a repeatable source (such as tape) to achieve the desired deliverables. By performing multi-format encodes in a single real-time pass, significant time is saved. • Less wear on supporting equipment – if the source content is tape-based, each additional ingest and encoding pass incurs another complete playout of the tape content, causing additional wear on the deck. • Flexible redeployment – a broadcaster’s encoding needs today may be very different in the notso-distant future, and multi-format systems can easily be redeployed and repurposed. Significant changes in preferred deliverable formats (for example, from On2 VP6 to H.264 on a website) may also be transitioned by offering both formats in parallel on an interim basis to reduce viewer alienation. While all of these benefits are advantageous operationally to the content provider performing the encoding, the speed of turnaround is particularly noteworthy, as it directly extends externally to the provider’s audience. Timely availability of content is critical to audience acquisition and retention. With the vast number of websites and other outlets now available, viewers won’t wait for the clip they want to appear on a specific site – they’ll search for it on other sites instead. Timeliness is particularly significant with news and sports content, but even extends to longer-form content such as episodic series. A viewer who missed an episode of a particular television show is most likely to look for it online within hours of its original debut. If it isn’t available at the time the potential viewer looks, he or she may not come back again – a lost opportunity to engage that audience member. source it must have at least a basic hardware component to interface to analog or SDI sources, but precompression image processing and the actual compression itself may be performed in hardware or software. Systems that rely solely on hardware compression tend to be limited in the breadth of encoding formats they support. The overall number of formats available may be quite limited (sometimes even just one). Even where the hardware supports multiple formats, it may only be able to do one at any given time, requiring reconfiguration to switch formats. Furthermore, while compression formats such as MPEG-2 are relatively mature, more recent formats such as H.264 are still evolving, and new compression formats continue to emerge. While most hardware-centric encoders are firmware-upgradeable with certain extensions of existing formats, more dramatic extensions or completely new formats may require new hardware. As such, these hardware-centric encoders are not well-suited to multi-platform, multi-format applications but may be appropriate for usages targeting a single platform (such as a live satellite channel). Systems that combine hardware and software in a common computing platform offer greater flexibility in the breadth and upgradeability of supported compression and container formats, as enhancements and extensions can be applied through software updates. Beyond the formats themselves, software-centric encoders also provide greater flexibility and robustness in the features surrounding those formats. Examples include automated distribution of the resulting deliverables (such as publishing to a website, or file transfer to distribution partners), branding, and content protection or usage tracking through watermarking and DRM. Optimal effectiveness in multiformat encoding can be achieved through a combination of hardware and software processing. A key step in high-quality encoding is pre-processing – essentially ‘grooming’ the source signal prior to compression. De-interlacing, video noise reduction and filtering are all examples of pre-processing functions that can significantly improve the quality and bandwidth efficiency of the compressed output. From a quality perspective, performing preprocessing in hardware enables the use of more sophisticated algorithms over what could be achieved in real time in software alone. Furthermore, even basic software pre-processing algorithms consume processing time on the host system’s CPUs. By performing the pre-processing in hardware, more CPU processing power is left available for the actual compression, increasing the number of outputs that can be created simultaneously in real time.

Hardware and Software Equation
For an encoding system to ingest content from a live or tape-based

Diagram 2: Combination hardware/ software encoders provide the flexibility of software -- enabling different formats and video processing for each of multiple concurrent real-time outputs – with the quality and performance advantages of hardware for shared pre-processing.

ENCODER SOURCE(S)
VTR
OPERATE MENU SEARCHHOLD PHONES DISP SET BLANK RESET SEARCH+ REW CUE UP STOP FF REC PLAY PAUSE EJECT

OUTPUT(S)
COMPRESSION
H.264 H.264 H.264 720x486 2 Mbps H.264 320x240 600 Kbps VC-1 320x240 600 Kbps Uncompressed 1280x720

HARDWARE
PRE-PROCESSING
(shared de-interlacing, noise reduction, filtering, graphic overlay, etc.)
De-int. Logo Overlay Logo Overlay

PROCESSING
Logo Overlay

SOFTWARE
Watermarking

Watermarking

VC-1
Uncompressed Container Wrapping

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