10.28.2004 11:42 AM
Ups and downs of conversion face stations in an HD world

As the transition from analog to digital broadcasting continues, stations must grapple with several new issues, not the least of which is when and how to approach creation and presentation of locally originated material in HD.

Network shows in HD are relatively simple to pass along, but what issues must be considered to stitch together locally originated material in a mixed HD and SD environment?

High Definition Technology Update turned to Paul Turner at Omneon Video Networks for some insight.

HDTU: What is your perspective on television stations' transition from SD to HD?

Turner: It is reality that stations have been transmitting SD material for a very long time and probably have built up a pretty significant amount of inventory on the SD front that they are going to want to preserve.

As a manufacturer, we have to recognize it. It used to be that the hardware is king. Now, the material is king. The material in house is king, especially as you transition your broadcasts over to HD. So there’s a strong need to retain the value of that stored material.

On top of that is that you have to transmit digital right now.

HDTU: True, stations must transmit digital now, but the real problems arise when stations consider HD. What’s driving HD at stations?

Turner: Business pressures are forcing people to go to HD. You have to find a business reason to transmit HD, and that reason is competition. HD lets stations differentiate themselves.

If you did simply go HD, you would be abandoning a huge portion of your audience and that is an important issue. So, the reality is that most stations are looking to continue to provide SD material and provide a ghost copy that plays out HD so they don’t have to do extra work for HD.

HDTU: How are stations currently addressing their HD and SD requirements?

Turner: Right now, stations are generating SD and sending it out on an HD channel. So, they need upconversion so they can take it out of their station as both SD and HD. Server manufacturers are migrating upconversion into their existing SD servers.

It’s up to the station's general manager and chief engineer to decide whether to use a server with an integral upconverter or use a stand-alone upconverter to feed the HD channel. They must weigh the quality of upconversion and ease of maintainability versus cost and complexity.

For the most part, upconversion in a server will work great, and that’s the issue that the station must weigh. Each will have its own opinion on where the upconversion should happen. Using an external upconverter to achieve a pristine signal comes with a price.

HDTU: What will be the impact of broader audience migration to HD?

Turner: Moving forward, more and more material will come in HD, and at some point a station will have to produce HD news or other material itself. What you are going to see at that point will be a demand for downconversion. Stations will want to leverage that material for the SD audience for the same reasons we discussed in upconversion.

As we move forward, there will be significant demand for downconversion. And manufacturers will have to move it back to the server. Why is that, you may ask?

The answer is channel branding. If the logo is burned in, the station will be hard pressed to re-brand it and get revenue as a separate channel.

Another point is the need to have both resolutions coexist on one time line in a server. You want two outputs for every playout channel from a server: one for HD and one for SD. You want the server channel to play it out in both resolutions. As a broadcaster, you really don’t want to be concerned about what resolution each clip originated in. You want to feed both outputs from one time line so the automation chain is playing with only one time line.

Tell us what you think!

HDTU invites response from our readers. Please submit your comments to editor@broadcastengineering.com. We’ll follow up with your comments in an upcoming issue.

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