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Improving compression in HD commercials

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Todd Terry
Improving compression in HD commercials
on Jan 20, 2010 at 3:38:09 pm

Hi gang...

I usually host/haunt other COW forums, but as luck would have it my needs bring me here today...

We're a small production company, most of what we do are broadcast commercials. We have just delivered the very first high-definition :30 television commercial to a station in our area. Until now, the stations here only passed along the networks' HD signals, there was no high-def local origination of programming or commercials. We pushed the envelope and got one of the stations to take one of our spots in HD.

It works pretty well... quite well in fact... but I think it still can be improved. Watching on air from my house, the particular spot we sent looks just a tad "blocky" and compressed at times, mostly coming out of transitions that are within the spot.

We made zillions of test files here, just about every combination of files and settings and kept running to their place to test them (fortunately, the TV station is only a couple of blocks from our studio). In the end we delivered them progressive Mpeg2 files, 29.97fps, 16:9, two-pass variable bit-rate encoding, with a maximum bitrate of 80Mbps and a target bitrate of 70Mbps, M Frames=1, N Frames=1, Closed GOP 0, Macroblock Quantization 10, VBV Buffer Size [2Kbytes] 488, Intra DC Precision 9 Bits.

Mpeg2 seemed to be the best files that play well out of their servers. We tried lots of outputs and combinations.... for example an HD Windows Media9 file looked great... but there were audio issues with it. Their system couldn't handle H.264 files at all.

We are using Adobe Primiere CS3 and CS4 to make these files on two different Matrox AXIO LE systems. When we throw the mastered Mpeg back onto a timeline here and watch it on an HD monitor, it looks great, with none of the artifacting that we see just a little bit of on air.

Any suggestions for improvement?

Much thanks,


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Chris Blair
Re: Improving compression in HD commercials
on Jan 20, 2010 at 4:01:21 pm

Todd,

If they're like every other local station and cable company that we deal with, they're probably recompressing the file on their end. Like you, we've done test after test with local stations and cable outfits. We agree on a file type and settings. Said file looks beautiful here on our monitors, even after it's reimported and recompressed back into our edit system (VelocityQ or Blackmagic/Premiere CS3).

We see the spot air and it looks like dog poop. We call the offending station/cable company. Noboby knows nothing. We dig and dig and dig and FINALLY find someone who knows something, and sure enough the spot has been recompressed for their playback server (even though it was already compatible).

Call them and find out what they're doing to the spot. But good luck in getting them to take what you actually give them and air it "as is."

Chris Blair
Magnetic Image, Inc.
Evansville, IN
http://www.videomi.com


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Todd Terry
Re: Improving compression in HD commercials
on Jan 20, 2010 at 4:09:15 pm

Well, I thought they were taking it "as is," Chris. Maybe not. We'll stand in their master control room and push the "Cue" button on the server screen and supposedly watch it just as it will be transmitted... and it looks great. It's watching a real airing at home that I think could be better. Their engineers have been super helpful to work with, I'll pose those re-compression questions to them.


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Rich Rubasch
Re: Improving compression in HD commercials
on Jan 23, 2010 at 2:50:41 am

I think it kind of works like the old AVID systems. When you imported a Quicktime movie even if it was in the AVID codec, it still created a new file with the AVID codec. I don't think you will EVER be able to just drop a raw file of any codec onto a broadcast server. It will always compress it to the specs of the server, similar to YouTube.

We sent a 25mbps H264 1080 Quicktime movie to our CBS local station and on air I thought it looked pretty darn good....most especially next to all the rest of the standard def local spots! Color matching was darn close to our online monitor and I have a CRT HD TV at home so it was a good test.

Can't believe they couldn't take an H264 but they could take a WMV!



Rich Rubasch
Tilt Media Inc.
Video Production and Post
Owner/President/Editor/Designer/Animator
http://www.tiltmedia.com


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Darren Edwards
Re: Improving compression in HD commercials
on Jan 26, 2010 at 12:48:54 pm

Todd -- in Europe a lot of HDTV (BBC HD, Freeview HD, Sky)
originally shot in 1080p is downrez'd to either 720p or
HDV 1440 for Tx -- the reason being to keep it under around
the 16mb bitrate. Throw in out of date multiplexing and
encoding (broadcaster side) and there could be quite a few
things happening to your commercial pre-Tx affecting its
quality pejoratively.

Thought it was a nice ad, by the way.

D.

youtube.com/darrenpce


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Daniel Low
Re: Improving compression in HD commercials
on Jan 23, 2010 at 3:28:00 pm

It's very likely caused by this process:

http://en.wikipedia.org/wiki/Statistical_multiplexing



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