Teranex Mini VS AV?

Hi,

I need to convert 50/60p to 50/60i and I'm trying to figure out if a Teranex Mini will give me the same quality a Teranex AV does?

Specifically a 50p HDMI signal to 50i SDI signal. I need best possible quality and the quality out of the micro converters or other brands (Decimator) isnt enough.

Thanks

And what is it exactly that you find not good enough? Since you only require frame rate conversion I would expect most (all?) products to do the same kind of job. There is no scaling happening so the quality of the video signal is not affected. They are only throwing away frames/lines if you go from progressive to interlaced.

And what is it exactly that you find not good enough? Since you only require frame rate conversion I would expect most (all?) products to do the same kind of job. There is no scaling happening so the quality of the video signal is not affected. They are only throwing away frames/lines if you go from progressive to interlaced.

Yeah in theory you'd expect most mini converters on the market would do a good job of this, but in the real world, they don't. They usually drop the resolution/quality by 50% in my practical experience.

If you want to convert 1080/50-60p to 1080/50-60i and preserve full motion - don't whatever you do buy the Blackmagic UDC range of converters.

They take everything down to 25-30p motion during the conversion between progressive and interlace.

Learned that the hard way. AJA UDCs properly handle 50/60Hz interlaced motion in conversions either way.

I can't comment on Teranex quality.

(BTW - Atem Minis are even worse with 1080i inputs - they take 1080/50i down to 540/25p and then up convert to 1080/50p - so you end up with half rate motion and half resolution.. BMD don't really seem to be that concerned about interlaced content quality.)

If the goal is that odd and even fields are extracted from odd and even frames sans interpolation then the Teranex will perform. What the Teranex will not do is maintain sync. One may start out with odd frames being extracted to odd fields but frame drift will catch up and soon even frames will be extracted to odd fields until it reverts back, and so on. This can be avoided with reference if the HDMI source is so equipped.

Good Luck

If the goal is that odd and even fields are extracted from odd and even frames sans interpolation then the Teranex will perform. What the Teranex will not do is maintain sync. One may start out with odd frames being extracted to odd fields but frame drift will catch up and soon even frames will be extracted to odd fields until it reverts back, and so on. This can be avoided with reference if the HDMI source is so equipped.

Good Luck

Yes - if you aren't genlocked you will inevitably have clock drift and will thus not get a 1:1 frame<->field mapping continuously.

Yes - if you aren't genlocked you will inevitably have clock drift and will thus not get a 1:1 frame<->field mapping continuously.

With the Teranex AV it's always 1:1, there's never interpolation but the frame to field order will change every time a frame is dropped but it's always frame to field.

The OP has never clarified what their actual goal is requiring interlacing. Since there really aren't interlaced displays any longer I'd probably prefer a scheme where every other frame was discarded and the interlaced image was constructed from 29.97p, I suppose it depends what one is after.

Good Luck

Yes - if you aren't genlocked you will inevitably have clock drift and will thus not get a 1:1 frame<->field mapping continuously.

With the Teranex AV it's always 1:1, there's never interpolation but the frame to field order will change every time a frame is dropped but it's always frame to field.

The OP has never clarified what their actual goal is requiring interlacing. Since there really aren't interlaced displays any longer I'd probably prefer a scheme where every other frame was discarded and the interlaced image was constructed from 29.97p, I suppose it depends what one is after.

Good Luck

Going down to 29.97p has a major impact on motion rendition though - you'll losing all >29.97Hz motion detail that is present in both 59.94fps progressive and 29.97fps native interlaced (where fields are captured 1/59.94th second apart)

That's the fundamental problem with the BMD UDC and Atem Mini handling of 1080i - you lose all motion above 29.97/25Hz with interlaced content (sources or destinations with the UDC, sources with the Atem Mini)

AJA's UDC preserves 50 (and 59.94Hz) motion in both directions - if you need to go from 1080p50 to 1080i25 or 1080i25 to 1080p50 with native 50Hz (or similar with 59.94Hz) you get full motion preserved with the AJA UDC. (AJA's UDC is also a lot more expensive - so you are paying for the improved performance)

(The Atem Mini going down to 540p25 from 1080i25 also has an impact if you use cameras with 1080psf outputs, as this drops down to 540p25 resolution too . Tthe Mini basically just discards alternate input fields and scales the resulting 540p25 stream this creates to 1080p25. I tested this pretty extensively when I couldn't believe how bad the 1080i handling on the Atem was since it claimed 1080i input compatibility. Sure it'll accept the 1080i signal - but the quality is unusable)