cant get full HDV quality out of the HD100
 

1. I've been producing a couple of music videos with the HD101, doing both the filming and editing. I shot the first in HDV 24p, and the second in HDV 25p. During editing I noticed in both videos, that dark backgrounds (flat and larger areas) become blocky. I also noticed that on closeups, human skin lost some texture. All in all it looked like the footage was compressed heavily. I am a Avid 5.2 user, and since Avid does not support the HD100-series (yet), I captured the footage with Ulead Mediastudio 8 (into mpeg2) and converted that into uncompressed quicktime with the dv codec using ProCoder 2. I then imported the uncompressed clips into Avid.

I thought it might have been my workflow of capturing/converting the footage, BUT, when I connected my cam straight to a external monitor, the footage still had some compressed artifacts in it, not as bad as the edited footage, but just doesn't look as clear as lets say dv.

Now, I'm pretty new at using the HD101 camera, so I thought maybe I am doing something wrong on the settings of the cam. F.ex does skin detection, low f.stop, low lights,, shutter speed, zoom etc cause lower quality on the footage? Or is it just the mpeg2 conversion that causes this? I thought HDV would regardless be clearer than DV, specially after downconversion.

2. When capturing HDV, the resolution is 1280x720, so by converting the footage to 720x576 (in PAL land), I have converted it to SD, right?

3. On the HD101 you can choose to shoot between HDV-HD25p and HDV-SD50p. I understand one shoots at 50p the other 25p, but why are they both HDV, when the 50p says SD?

Sorry if I ask wierd questions, but I'm a fairly new HD100/101 user.

- Nima

Not as clear as DV?
You must have a defective camera, although I've never heard of this problem before.

You just bought this camera, right?
Send it back for another.

In reply to 2 and 3:

2: Yes, your footage is now SD.

3: HDV-HD25P is 1280x720 25 progressive frames per second encoded in HDV (mpeg 2). HDV-SD50P is 720x576 50 progressive frames per second encoded in HDV (mpeg 2). This in comparison to DV: 720x576 50i - 50 fields per second. Obviously, with DV encoding and 50 fields per second, you can encode progressively, but only at a rate of 25 frames per second. In order to fit the extra 25 frames per second of HDV-SD50P onto tape, it has to be compressed more, so it is compressed in HDV and not DV.

Tim:

Thanks for the answers.

On subject 2. Is there any difference in quality when converting hdv to sd with computer software rather than downconverting internally on a camera (f.ex Sony) or via the HD100 Component/Composite output?

subject 3. So if you wanted to f.ex film a footage that you wanted to do slow-mo in post, the HDV-50p would be a better choice? Also, would the HDV50p almost compare to Canon XL1's 50 full frame mode (but whereas Canon's is dv)

- Nima

>Is there any difference in quality when converting
>hdv to sd with computer software rather than
>downconverting internally on a camera

Most definitely. When you downconvert to SD in camera (which you can't do with the HD100), you downconvert to DV, which means losing a lot of color resolution.

As far as the second question, I am unfamiliar with the XL1's 50 frame mode. If you were shooting a standard def project and needed slow motion, shooting in HDV-SD50p would be an excellent idea. Just conform it to 25 fps and you have 50% slomo. If you were shooting for an HD project, HDV-SD50p would have to be uprezzed and things might get a little soft. Not sure how acceptable this would be since I haven't really tried it.

For HD slomo, the Panasonic HVX is a better tool.

So by downconverting from hdv to dv uncompressed quicktime, with computer software (Procoder/Sorensen Squeeze etc) you don't lose quality?

of course you can lose quality plus you re-compressing the footage into another compression codec (mp2) before going to uncompressed.

You should capture the footage properly into the computer then convert to the highest quality codec you can edit with. The best solution would be to capture, convert to uncompressed, downsample to the size you want then edit in a codec that your sytem can handle. Remember that when you size something down, not all conversions are equal. You need to use a high quality code for this, if you do it with more re-compressing you are just going compound any artifacts that exist.

Listen to Tim.

And remember SD and DV are not the same thing.

Tim Gray: SD and DV - not equal. Got it.

Tim Holtermann: I usually capture HDV with CapDVHS, and use Procoder to convert and downsize the HDV into Quicktime Movie uncompressed quicktime 720x576. I've been testing the Quicktime Target with the Avid DNxHD codec (720p/25 8bit) aswell, but it seems like the Quicktime Movie uncompressed comes out best. Does this make sense, or is another codec usually used for optimal results (for quality, not saving hdd space)?

You really can't do better than uncompressed, but editing it isn't always easy. I'd say you may want to convert to uncompressed at full HD before downsizing. Not sure what happens when you downconvert directly from HD to Uncompressed DV at the same time. It would take some experimenting.

Hi Tim. There will obviously be a loss of spatial resolution going from HDV to DV, but I thought that for a PAL system the colour resolution is not going to suffer since they are both 4:2:0?

Richard

I'm not really familiar with PAL that much. In fact I am just sorting out this color business myself. From the numbers they sound the same. 4:2:0 is 4:2:0, right? I think (correct me if I'm wrong) that the PAL 4:2:0 is different from the MPEG2 4:2:0. I don't really know.

Maybe one of the PAL guys can chime in.

Nima the problems you are experiencing almost certainly relate back to your workflow. As you have noted Avid does not fully support 720P25 yet so you need to go through an intermediate codec. Everything here is a compromise: Even if Avid did support it, editing in HDV uses MPEG 2, so working directly with HDV is CPU intensive as each block of 6 frames has to be decoded to and re-encoded to make a simple cut. Downcoverting to SD relies on the quality of your conversion software.

I believe the best workflow would be to convert the .ts file from CapVHS into another HD codec - in Avid's case DnxHD. Avid then allows you to drop clips or even edited timelines into a an SD project timeline. That way you have an HD master and an SD master. You should also save time on your conversion as there is no spatial conversion.

The bad news - this won't work completely on Xpress Pro HD yet. The DnxHD 720P25 codec is the 60Mb 8bit version which isn't supported on Xpress Pro. However 720P24 which is available should work in the 60 and 90Mbit versions (8 and 10bit). Your only other oprion on the Avid is to use DVCProHD codec. If you want to go down the Vegas or PremierePro route then Cineform offers an excellent solution at a reasonable price.

Re: your original question about MPEG artifacts, I would suspect your monitor before anything else - monitors usually pre-process the signal unless they can display 1280 x 720 natively - most of the low-end processors built into monitors introduce there own artifacts when they scale and compress the original signal. The HD100 series camera have the most robust MPEG compression scheme of all 3 hi-end HDV camera's on the market although you can still get errors, they should be less noticeable on this cam.

John

When I capture with CapDVHS, I can only save the file as .mpg and not .ts. Do the different file formats make any difference? I'm just trying to capture as close as native quality. Maybe there are some settings I overlooked that can makes CapDVHS save files in .ts... Also, do you think CapDVHS is a appropiate tool to use for capture for professional products that will be broadcasted? If no, what other tools would be appropiate?

As with the conversion of the dnxhd codecs, is it as simple as using lets say Canopus Procoder, selecting the target Quicktime Movie, selecting Avid dnxhd codec with the 720p 23.976 90 10bit (since Avid doesn't support 720p 25)?
1. does the 23.976 on the codec effect the framerate in any way (since my original footage is 25fps)?
2. will 720p 23.976 90 10bit give better image quality than the 720p 23.976 90/60 8bit?
3. because the end result will have to be SD, should I do the HD-SD downconversion during this same process of Avid dnxhd codec conversion? (downing from 1280x720 to 720x576)

Would you say this workflow is sufficient for achieving broadcast quality?

About the mpeg artifacts/monitor issue, I also think it's the monitor at blame, but I think lowering the detail level on the cam during the next shoot might help some too, as I understood after reading some posts.

The term "broadcast quality" has lost its meaning a long time ago...:-) Just remember those cell phone videos aired after the London subway bombing. "Broadcast quality" is directly related to content... other than that, the term has little meaning.