48 Hour Film Project and HDV downconversion

GregFlowers wrote on 7/24/2006, 1:18 PM

I just finished the Asheville 48 Hour Film Project, which is a competition to create a 4-7 minute short film over the course of a weekend. I have an FX1 and normally I would shoot hdv and downconvert to dv on the fly because time is very much of the essence in this competition.

My short this year was very simple and I had plenty of time to edit so I went hdv all of the way so I would have a high resolution master. I captured with Connect HD on the default settings and edited on my laptop. No color correction performed, just a semitransparent fake news emblem was placed in the bottom right corner. I rendered to the NTSC widescreen DV 60i template except I changed rendering quality from the default "Good" to "Best". It took 3 hours and 11 min to render a 6 min 48 sec clip. I had plenty of time so no problem.

I must have done something wrong somewhere because the resulting dv downconverted file looked bad. Not just subtley different but considerably worse. There was clear macroblocking and rough aliased edges that are not there when the original HDV footage is downconverted in camera and viewed via s-video on the same standard def CRT set. This was apparent on the printed to tape dv version I had to turn in.

I had done 60i HDV to SD 24p mpeg2 conversion in Vegas with very good results previously so I was surprised that HDV downconverted to 60i dv did not look better. I know the process has been discussed ad nausem here and I thought I had the procedure down perfect.

The things I 100% know for sure is that I did shoot HDV to start with, I captured using the default Connect HD settings with no conversions except to 1080i Cineform, used the 1080i Cineform intermediate setting in Vegas, and rendered to the default widescreen NTSC dv template with quality changed from "Good" to "Best". I even went back again last night and rerendered the file with the "Best" setting just to make sure - the results were the same.

I think the next step for me is to render the HDV original to 1080i mt2 and print back to tape. Then view it in HD and standard def with in camera conversion to make sure the original HDV file does not contain any anomolies.

Has anyone had any problems with their HDV to DV downconversion that can see what I might be screwing up. I know Vegas should do at least as good if not better than the in-camera conversion but I can't pinpoint my error.

Comments

Spot|DSE wrote on 7/24/2006, 1:28 PM

No problems with the conversion, but it's possible you had a project setting that was off or something along those lines?
Can you render/print to the FX1, then downconvert in cam hardware at capture for the DVD burn?

fldave wrote on 7/24/2006, 2:12 PM

HDV 1080-60i Project properties? I always have Full resolution quality Best; motion blur set to Gaussian; Deinterlace = Blend. Not that they all come into play here, but I haven't had your problem with these settings.

Now with MPEG2 output, there is a quality setting on the video tab, 0-31. I always use 31, set to max.

GregFlowers wrote on 7/24/2006, 2:31 PM

Thanks for the replies fellows. The project settings are as follows: HDV 1080-60i (1440x1080, 29.970 fps)
field order: upper field first
Full resolution rendering quality = Best
Motion blur type = Gaussian
Deinterlace method = Blend fields

The short had to be turned in on mini dv tape in sd. They did not want a dvd. So I rendered to the NTSC Widescreen DV template with video rendering quality at "Best". There was no mpeg2 conversion, only widescreen DV avi so I could print back to mini dv tape. I rendered as 60i, with no 24p conversion. I will go and render it as an sd 60i mpeg2 video to see if the quality changes.

fldave wrote on 7/24/2006, 2:45 PM

Clarification, please: what looked bad, your video itself, or the fake news emblem? Was the emblem an image, or generated/text?

If text, I always follow the "twice the size of your project" recommendation. It downsizes nicely.

winrockpost wrote on 7/24/2006, 3:17 PM

If you are delivering on sd mini dv, just let the cam convert. no use going through all the extra steps and possible problems.
my 2 cents

GregFlowers wrote on 7/24/2006, 3:37 PM

fldave,
The entire video looked pretty bad. It will still be viewable, but will likely look bad when projected on a full sized movie screen in front of a sell-out audience. It looked similar to how poorly mastered dvd does, with macroblocking and roughened edged, especially in darker areas. Also other compression-looking artifacts as well. Not acceptable and not subtle either. A non-videophile could easily tell. Not crisp and clear like good dv looks like or like what the original hdv did when viewed on an SD CRT set via svideo.

Winrock, I agree in retrospect that i'd have been much better off letting the camera do the downconversion, but I had the time and I liked the idea of havind an HDV master. I figured the downconvert to widescreen dv would be painless and super sharp. I am downconverting to sd mpeg2 now at best quality (31) to compare to the .avi version to the mpeg2 version. I'll post with my findings in a little while.

winrockpost wrote on 7/24/2006, 3:46 PM

, understand completely wanting that hdv master, some day we are are going to use those sob"s, i do the same thing.

best of luck !

fldave wrote on 7/24/2006, 3:46 PM

You said that you did no color correction. Any other effects or pan/crop? Something is definitely not set up right if your preview window looks a lot better than your final output. I downconvert HDV timeline to DV frequently (hobby, not job).

David Newman wrote on 7/24/2006, 4:47 PM

Sound like you might have messed up the fields, at the is most obvious way to make a downscale look bad, field ordering or blending can cause issues. Do you have it online yet?

I just did the 48Hour film project the weekend before in San Diego. We shot and edited progressive 1080p, and export to 24p anamorphic DVD and it looked great -- we won best cinematography (read my blog and see the movie here -- http://cineform.blogspot.com.) Yet the SD projector in San Diego seemed to do it our field duplication, so I think everyones project only displayed one field. As we shot 1080p, down-res'd to 480p ananmorphic, that was letterboxed to 4x3 (picture is now 360 pixels) and only one of fields displayed. So my 1080p project was displayed at 180 lines vertical --- and it still looked better than the others. :)

David

GregFlowers wrote on 7/24/2006, 5:02 PM

I did no color correction or pan/crop. I did add a semi-transparent "13" in the bottom right hand corner to simulate a news channel logo. Other than that, no changes.

I just finished rendering an sd 60i mpeg2 version of the project. At "Best" it took about 1 hour 15 min for the mpeg2 version vs. 3 hours 11 min for the avi version. The mpeg2 version looked much better than the avi version. Had the avi that I printed to tape and turned in looked as good as the mpeg2 version, I'd have been quite pleased. I also just took the sd mpeg2 that looked good and rendered it to sd widescreen avi. It looked almost just like the sd avi that was downconverted from HDV! Go figure.

Fldave,
Do you downconvert your HDV to sd dv avi or to sd mpeg2. The mpeg2 was fine. The avi version was not.

So so far I have found the following:

-HDV downconverted in Vegas to SD mpeg2 looks very good.

-HDV downconverted from the FX1 on the fly to SD DV AVI looks very good.

-HDV downconverted in Vegas to SD DV AVI looked just okay, but no better than HDV downconverted to SD mpeg2 converted to SD DV AVI looked and inferior to the incamera FX1 conversion.

Now I'm certainly not saying that I may not have made an error in the HDV downconversion to SD DV AVI. But I checked and rendered it twice with exactly the same results. Mabey it has something to do with my specific setup. I may try to replicate the setup on my desktop to see if the results change. I will also try a few other things too. Has anyone else had similar problems or is it just me?

GregFlowers wrote on 7/24/2006, 5:23 PM

Thanks Dan. They wouldn't accept entries on dvd in Asheville, only DV Cam, beta, mini DV, and VHS. I never changed any field settings and the edges didn't have that heavily combed look like reversed fields have. I'm not sure about blending though. I left it at the default "blend fields" for deinterlace method (vs interpolate or none). I do not have it posted anywhere, and I'm not very web savvy in this regard.

It just looks like the SD AVI version has more compression artifacts with macroblocking and sloppy poorly, defined edges. It looks a little like lower resolution video that has been scaled up, like viewing video from the web, but not as severe. Its not horrible or unwatchable, but it was my only dissappointment from the weekend.

The Cineform encoded HDV files are fine I believe and the downconversion to 480/60i mpeg2 I just tested looks quite good, but the 480/60i AVI looks dissappointing to me, and I'm not a huge stickler and I'm not splitting hairs. I will render the Cineform files to m2t and print it back to tape just to confirm.

Most here seem to have no problems converting HDV to SD mpeg2 for dvd. I don't either. But the conversion to SD DV AVI is not of acceptable quality to print back to tape and distribute using that method. Like I said, mabey I'm screwing something up. But everyone seems to be taking about the great quality of the mpeg2 conversion, not the AVI conversion.

fldave wrote on 7/24/2006, 6:11 PM

"Do you downconvert your HDV to sd dv avi or to sd mpeg2. The mpeg2 was fine. The avi version was not"

Both my avis and mpgs look great using Vegas to downconvert from HDV, and as expected, avi is better than mpg. It sounds like maybe the "DV" template you are using is not encoding to the real DV codec. I used to get the same thing you are describing years ago (pre-vegas) with an ancient codec like Cinepak. Can you verify that the template you are using "NTSC DV Widescreen" as the "video format" on the Video tab.

GregFlowers wrote on 7/24/2006, 6:38 PM

fldave,
Thanks for confirming that the downconversion to AVI can and should be of pristine quality. I thought it should. That is why I took the longer route. It does kind of have the look of a video rendered to an inferior codec, or rendered just using the "Good" but not "Best" setting. I will rerender again tonight and triple check all of the settings. I am currently rendering to 1080/60i m2t so I can print back to tape in HDV to my FX1.

farss wrote on 7/24/2006, 9:32 PM

I've had similar problems going from the CF DI to SD AVI when using event pan/crop to zoom in a bit, just tighten up the shot. Results should be perfect SD however major amounts of interlace artifacts creep in and out as the 'zoom' remaps the lines of the interlaced video. Changing the de-interlace method influences the results so I'm wondering if this is the key.
I'd render a short section with fast motion using both de-interlace methods and compare the results.

I doubt this is a CF DI problem as such, just wish I had the time to run definative tests to get to the bottom of these kinds of issues.

Bob.