Broadcast Engineering - February 2009 - (Page 37)

Feature Managing aFD Figure 5. AFD insertion in live control room upconversion devices allow for this and will help to ensure that the AFD code will be available throughout the facility. Despite best efforts to encode program-specific AFD codes, mechanisms should be put into place to ensure that a default AFD code is automatically inserted into video streams when authored AFD data is not present. This is best handled close the final distribution point out of the facility as shown in Figure 8. Conclusion Proper aspect ratio management will be critical for preserving cre- Figure 6. AFD insertion during ingest operation Distribution and AFD preservation As discussed in the previous section, ensuring that AFD data is encoded on final versions of content is the first important step Figure 7. File-based AFD insertion in establishing a successful AFD-driven process. Ensuring that the AFD data is preserved through the downstream signal path within the broadcast facility is just as critical. AFD data in accordance with SMPTE 2016 is carried in the VANC of SDI Figure 8. Downstream AFD paths video signals. Specific attention should be paid toward ensur- AFD data to be followed plant-wide. ing all downstream video processing This will be essential for quality consystems (e.g. video routers, switchers, trol and troubleshooting throughout DAs and frame syncs) will reliably the signal path. pass VANC data uncorrupted. The 3. Avoid multiple AFD codes. For any following recommendations should AFD inserting system that is implemented, specific care should be taken also be considered: 1. Focus on HD signals. System de- to avoid the introduction of multiple signs should be focused on carriage AFD codes in a single video stream. of AFD data in the HD-SDI signals This can cause adverse affects in many for the purposes of downconversion AFD supported systems. to SD. Most legacy SD devices have 4. Insert AFD on upconversion. SD been found to strip out any VANC originated content must go through data present in the video signal, so an upconversion process before besystem designs should not rely on ing inserted into a facility’s HD distribution path. Where possible, the AFD data within SD signals. 2. Select video line location. Select a proper AFD code should be inserted specific video line location to carry at the point of upconversion. Many ative control of programming after the DTV transition. Using AFD technology can improve the capability for program providers to deliver content to their audience exactly as they intend. AFD will not solve all of the aspect ratio challenges, but existing technical solutions have been proven to be successful at providing the flexibility needed by broadcasters. As AFD usage expands and technology solutions mature, more advanced uses are sure to emerge. BE Clarence Hau is director of systems engineering at NBC-Universal. This article is based on a paper he presented at the SMPTE 2008 Technical Conference. February 2009 | broadcastengineeringworld.com 37 http://www.broadcastengineeringworld.com

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Broadcast Engineering - February 2009 Contents Viewing the Slowdown in 3-D Examine Workflows Tapeless Technology Digital Audio 24p and 25p Judder Video Routing: A Look at What's Next Managing AFD The Right Connections Solid State Logic's AWS 900+ SE and More... Advertisers Index

Broadcast Engineering - February 2009

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