David Heath

Some interesting accounts of new generation codec (DNxHD, JPEG2000, AVC-Intra, and XDCAM-HD422) tests by the EBU at EBU Technical Review , (click on "HDTV production codec tests")

If you're looking for "A is better than B" type conclusions, you'll be disappointed, but it may be worth quoting from the EBU conclusions:

Alister Chapman

An interesting document. In parts of the full report there are some interesting arguments against 10 bit compressed codecs is and the importance of avoiding scaling gets a lot of attention.

Makes me chuckle that the tests center around 1080 production when the EBU have been pushing 720P production.

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Alister Chapman

Producer/Cameraman/Engineer
http://www.ingenioustv.co.uk

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David Heath

I have to disagree Alister - the EBU stance for the last few years has been in favour of progressive video, not interlace, but their big emphasis has been regarding TRANSMISSION, not production, and very clearly 720p/50 v 1080i/25.

I'm pretty sure that when this first became a hot issue (IBC 3 years ago?), they clearly stated that whilst they favoured 720p/50 for transmission, they also felt that future production should ideally be 1080p/50, when the kit became freely available.

What also came clearly across at their presentation two years ago was that they were basing their case on comparisons of how 720p/50 and 1080i/25 stood up to heavy compression for transmission. A question was asked from the floor regarding 1080p/25, and they didn't seem to have an answer, it just didn't seem to have been considered for the trials - which may be seen as surprising as so much currently produced material is precisely that.

My understanding is that broadcasters are tending to currently side with 1080i transmissions as much because they enable 1080p/25 to be transmitted in full resolution (as 1080psf/25), as for actual 1080i/25. For such as a sports only broadcaster, (where 50Hz motion is essential) when the choice really is 720p/50 or 1080i/25, the EBUs stance makes sense. For channels such as BBC-HD, with a large drama content as well as sport, a basic 1080i/25 system able to carry 1080psf/25 makes sense.

But let's look forward to 1080p/50..........

Christopher Drews

Did I miss something? Didn't they say which codec yielded the best results?
Or is it just this blanket statement: Use a codec above 100 megabits per second.
-C

David Heath

No, they didn't say, and I believe quite deliberately:
I suspect it's because it's just not possible to say that "codec A yielded the best results, period" - codec A may be better on some test images, codec B on others, and codec C on a third set.
No, the advice is 50Mbs and above for long-GOP, 100Mbs or above for I-frame only codecs. They also say "All tested codecs have shown quasitransparent quality up to at least 4 to 5 multi-generations..... ", which is quite a vote of confidence in all four. It should also remove any vestiges of doubt about the use of long-GOP codecs for critical work - at least if 50Mbs XDCAM-HD422 is used.