HD Sequence to SD Delivery

[Michael Gissing]

[Dave Beaty] “Doing a realtime downconvert won’t work for us.”

The Decklink real time downconvert is not good enough in my opinion. My preference is to stay HD and output to HDCam and then send to a facility with a Teranex or equivalent to make the SD digi.

I have also dropped the HD sequence as a nest in a 10 bit SD uncompressed sequence and rendered. Slow but looked OK. I also had some zoomed up SD material but it looked correct without any adjustments in the SD sequence.

I suggest doing a short test with HD and zoomed SD material to check this.

[Walter Biscardi]

[Dave Beaty] “Does that workflow seem OK?”

Do you have access to a facility that has an AJA Kona card? That downconvert is completely pristine broadcast quality as we use it often to make BetaSP masters from our HD timelines.

Otherwise I would lay out to DVCPro HD or HDCAM and take that master to a Post House for a hardware downconversion through something like a Terranex.

I don’t think FCP does all that great of a job rendering a downconvert.

Walter Biscardi, Jr.
https://www.biscardicreative.com
HD Editorial & Animation for Broadcast and independent productions.

All Things Apple Podcast! https://cowcast.creativecow.net/all_things_apple/index.html

Read my blog! https://blogs.creativecow.net/WalterBiscardi

[Chris Borjis]

[Michael G] “The Decklink real time downconvert is not good enough in my opinion.”

is your decklink doing a hardware or software convert?

my multibridge extreme does it in both and the hardware downconversion is quite excellent. software of course is aliased and completely unacceptable, not even sure why they offer it.

[Peter Dewit]

I’ve never found any combination within FCP to make HDV convert well at all. Spiut out an HD version to tape. if you want you might want to try to re-digitze that tape using the deck’s internal downconverter. I’ve had decent luck doing this with HDV footage in the past. not perfect but sure looked better than what FCP did.

[Chris Borjis]

you can get a fabulous down conversion (if you don’t mind the wait) if you export through quicktime conversion.

It has options to format the image for 4:3 or 16:9 and adding bars as well.

I did this for a spot delivered on betasp that originated from HDV. It looked awesome when it was aired.

[Dave Beaty]

We have Multibridge Pro’s here, but I don’t know if the RT down converts are as good as Kona. We do have one suite with a Kona LH board.

I want to try the render to SD method, so I can preserve the stock footage which we will be redigitizing as NTSC. The master has to be NTSC so, I’m thinking I can work on getting the stock footage cropped to match the 16:9 HD in an NTSC sequence without scaling up.

I’ll have to do some tests with FCPro’s scaled HDV as see how it looks output SDI. I’m dissapointed that FCPro can’t scale down HD footage with good results.

The Multibridge downconvert looks great but some HD images shimmer when they have lots of fine detail or horizontal lines.

Dave Beaty
Dreamtime Entertainment
1625 SE 46th St
Cape Coral FL 33904
239-549-4081
800-446-7575
dave@dreamtimeentertainment.com
http://www.dreamtimeentertainment.com

[Dave Beaty]

I figured out why there is a problem with 720p30 down converts in FCPro. It’s the way the sequence is adding interlacing to the progressive footage even though is SHOULD just flag both fields as the same, it doesn’t do that and creates a jagged edge or aliasing.

Good news, I did tests this morning using Media Manager to Recompress the HDV material into a new SD timeline. The results are startling.

First I copied and pasted the 720p30 HD edited clips into an Uncompressed NTSC 8 sequence and rendered. Looks terrrible. Lot’s of aliasing on all edges. Shimmers and looks soft.

Next, I used media manager to copy and recompress all clips into a new uncompressed NTSC sequence. Looks good with no aliasing. Switching between the recompressed project and the original down converted sequence with HD clips showed noticeable differences. The recompressed SD sequence looked much better.

But then I had a thought, perhaps the problem FCPro has dealing with 720p HDV has to do with the interlace vs progressive timelines. I changed the original problem sequence to none for interlacing in the sequence settings and the problem dissapears.

That fixed the shots with aliasing and it was now a carbon copy of the recompressed sequence when I switched back and forth.

But the issue isn’t solved. Now the problem is with source NTSC material that IS interlaced. You can’t put this material into the non-interlaced timeline without it looking terrible. So, for now, recompressing is the only answer for mixed format down conversions.

Dave B

Dave Beaty
Dreamtime Entertainment
1625 SE 46th St
Cape Coral FL 33904
239-549-4081
800-446-7575
dave@dreamtimeentertainment.com
http://www.dreamtimeentertainment.com