Getting to grips with HDV's higher quality

John Poore · August 2nd, 2005, 05:28 PM

Interesting. There might indeed be a difference with the Z1 vs FX1. It would be good to test this, it's been discussed before without conclusion here.

Anhar - I know what you're getting at there. i've seen that method being posted somewhere before. i think there are other steps involved as well. But we're simply interested in camera conversion direct to DV sd.

Steve Crisdale · August 2nd, 2005, 08:15 PM

Quote:

Originally Posted by Boyd Ostroff

Yes the Z1 does 1080/60i, 1080/50i, 480i, 576i, 480p and 576p. This makes me wonder if there's something different about how the different models downconvert HDV to DV as well...

And what about the capabilities and settings of the display device that the stuff is being viewed on?

We all assume it's being viewed on correctly set-up and appropriate display devices.

Now I'm sure I'll get flamed badly for mentioning it; by those who are offended that I have, but for those who are all excited about what HDV can do for them - whether it be downconverting to SD for superior results from the higher rez image, or getting 16:9 or whatever... The results aren't going to magically appear on the display stuff you got for SD material.

Tommy James · August 2nd, 2005, 09:26 PM

What I am wondering is that in this day and age who wants to downconvert HDV video ? When I watch the news I want to see the news in high definition not crummy standard definition. If you downconvert HDV you might as well shoot in black and white. When color cameras where first introduced did people ask how good where these color cameras for producing black and white footage ? When motion picture cameras were first invented did people wonder how good a still picture these cameras could make? What amazes me is that since the 1950's we are still stuck with the same 480 lines of resolution. Had there not been a great depression television would have boomed in the 1930s and we would have had only 300 lines of resolution as standard definition for the next 100 years. During these last 50 years there has been many oppurtunities for picture quality improvement but the increases in bandwidth went to more programming choices not to any improvement in picture quality. Most people vehemenently resist change so high definition no matter how good it is will always face fierce opposition by people who are unwilling to change.

Steven Gotz · August 2nd, 2005, 09:38 PM

I shoot and edit HDV. I show HDV to the majority of the people who see my videos. But now and then, I need to export to a standard DVD. It happens. It is annoying, but some people just don't have HDTV yet, so recommending a AVeL Linkplayer2 just isn't an option.

Boyd Ostroff · August 2nd, 2005, 09:42 PM

I shot a couple tests and here are my first impressions. These were exported from the FCP Timeline with Quicktime conversion as JPEG's at highest quality. The only alteration to the images was stretching the PAL to 1024x576 and the NTSC to 854x480.

NTSC Test: http://www.greenmist.com/hdv/NTSC-lake.jpg

If I enlarge to 200% in Photoshop I can see a definite improvement in the downsampled HDV compared to straight DVCAM clip. Take a look at the treeline against the sky and the dead twigs, they are sharper. Not a big difference, but it's there. Also notice the color is a bit different, but I didn't change any settings. This might just be due to rapidly changing light around sunset, but they were shot within one minute of each other. Playing the clip in motion makes the difference in sharpness pretty noticeable to me.

PAL Test: http://www.greenmist.com/hdv/PAL-lake.jpg

These two are much closer together, as I suspected. I still think the HDV downconverted image is slightly better, but the difference is subtle. Playing the clip in motion seems to favor the downconverted version to my eyes. But I can understand why the BBC didn't think the difference was significant in PAL mode.

I don't know why you are seeing inferior results with the downsampled HDV John, I certainly don't see it here. Perhaps the FX1 and Z1 really do use a different approach to downconversion?

As far as how I viewed these (aside from Photoshop), I have a Samsung 22" HD LCD monitor (1280x720) which I connected to the camera's component output. Looking at the native HDV clip compared to any of the DV clips shows a huge difference in resolution. After watching in HDV the DV clip looks out of focus. This was a good test for me since I enjoy shooting scenery like this. It helps convince me that I need to gear up to start working directly with HDV and forget about all this downconversion stuff :-)

I also watched the clips in the FCP canvas at 100% on my Apple 23" Cinema Display. With all the switching between 50i, 60i, DV and HDV I was having a hard time keeping the camera and FCP settings correct, and I started to have problems monitoring over firewire. It's getting late, so I'll take a closer look at all this tomorrow, and will try to put some other examples online.

Douglas Spotted Eagle · August 2nd, 2005, 09:45 PM

Steven has it like most folks do. There are very limited choices as of right now, for HD to the masses. Avelink, Buffalo, Windows Media HD, Nero Digital/AVC. So, a lot of folks have no choice but to downsample.

Boyd Ostroff · August 2nd, 2005, 09:45 PM

Oh, one other curious thing. Look closely at the top of the downconverted images. The NTSC one has a black line at the top of the frame. The PAL one has a black line at the top, a normal line, then a white line below that.

Interesting...

John Poore · August 3rd, 2005, 05:22 AM

Boyd, can you host a couple of JPEGS for me from my test? You'll see my results, I was looking for sharpness of detail? Like what you've shown here there is a subtle difference in the two, I am interested to see what others think?

Richard Entwistle · August 3rd, 2005, 05:35 AM

Quote:

Originally Posted by John Poore

... ... Like what you've shown here there is a subtle difference in the two, I am interested to see what others think?

John, Boyd,

I am confused! All images (the four halves) look the same to me! I see the same ripples on the water. Exact same tree/twig formations. So how can they be shot at different times?

Have you stitched same frames together in error? Or am I doing something incredibly stupid. :)

Just back from my own testing of HDV vs DV. My method was to shoot several scenes, with and without motion, using HDV record for a minute, then switching to DV SP (to keep tape speed same) for another minute. Pans and close ups. Buildings, buses, and park lake/trees.

To view results, I simply attached an s-video lead from Z1 to my Sony SD widescreen monitor and rolled the tape. With my commentary and the Z1 switching display, I focussed on looking for artifacts and fine detail in the resultant SD signal that switched between HDV and DV recorded footage.

Result: The HDV recorded images via s-video are definitely clearer than the DV recorded images. So much so, I have to agree with Spot's comments. Fine detail like Chinese Banyan tree hanging roots from afar are clear in HDV->DV and woolly in DV. Fine shadows of the roots on a bridge are visible in HDV and absent in DV. And so on. Motion artifacts appear the same. Nothing abnormal, and nothing to worry about.

So, I will be sticking with HDV recording (DigitalMaster tape) and getting myself an HDV player as soon as I can afford one. :)

Steven White · August 3rd, 2005, 06:15 AM

I've done a few experiments on the subject.

DV vs HDV -> DV (in camera or otherwise)

Shooting DV in camera results in the uncompressed original data being downsampled and compressed via the DV codec. For producing "DV footage", this result should be the best, because the MPEG-2 compression is avoided entirely. The key here is that this statement applies to "DV footage" only... not "SD" footage. This is difficult to test perfectly without two cameras in perfect alignment and a perfect beam splitter. Since "perfect" is a bit of a stretch, then any error in the experiment would likely over-ride the conclusions.

In my opinion, if you want DV footage out - you should shoot HDV and down-convert in camera to DV. While there might not be a significant gain in image quality, you at least have a higher quality master for later.

HDV -> 4:4:4 uncompressed SD vs HDV -> DV

Converting HDV via software tools to 4:4:4 yeilds the best result, short of recording an uncompressed HD signal directly. The difference between the 4:4:4 colourspace of a software downsampled image and the 4:1:1 DV is quite noticable. While it's difficult to detect without knowing what you're looking for, watching the 4:4:4 SD play it's immediately obvious which is better. Furthermore, the added DV compression, appearing in the form of mosquito noise and other artifacts is apparant with inspection.

An demonstration of software-vs-in-camera down conversion is given below. Note that differences in colour are due to the handling of the different YUV colourspaces of DV and HDV (YUV.6xx vs. YUV.7xx):
http://s94963366.onlinehome.us/HDRFX1/softvincam.bmp (2 MB)

-Steve

Boyd Ostroff · August 3rd, 2005, 06:19 AM

Not sure what you mean Richard? I shot each clip for 60 seconds, one after the other. I kept the exposure and everything else the same. There was no wind so the water was still. I don't think you're seeing any ripples in the water, it was calm. Those are lily pads in the distance and some sort of other "stuff" in the foreground. Nope, these are definitely the correct frames stitched together. These are static shots - your test using motion is a good idea though.

I enlarged a section of each using photoshop to help compare:

http://www.greenmist.com/hdv/NTSC-lake-200.jpg
http://www.greenmist.com/hdv/PAL-lake-200.jpg

There really isn't a huge difference in the NTSC clips, but I think the downconverted one is a little better. When I play them in motion this is noticeable. The differences in the PAL clips are pretty subtle. However if you look at both of those links side by side it definitely shows the advantage of PAL vs NTSC in terms of resolution. You can see more twigs in the PAL version.

John - sure, send me your clips and I'll put them online.

Boyd Ostroff · August 3rd, 2005, 06:29 AM

That's interesting Steven. I don't see much difference in your two examples but as you say, it probably shows up better in motion. There's noticeable interlace in these - were they handheld maybe? It would be interesting to compare these with a frame grab from the component output in 480p mode. I wish I had a way to capture from component because I see a big quality difference shooting HDV and downconverting the component to either 480p or 576p.

I'm also unclear as to whether they was any final determination about the component output. I was assuming that it's HDV compressed when set to 1080i, but DSE and others have implied that you get superior results when capturing uncompressed HD from component.

John Poore · August 3rd, 2005, 07:19 AM

Here's my experiment with a PAL FX1 using in-camera convert. In both cases the bottom half is HDV, and the top is DV. What do you guys think?

http://www.greenmist.com/hdv/poore/hdv-dv%20testing.jpg
http://www.greenmist.com/hdv/poore/hdv-dv.jpg

And my thanks to Boyd for kindly hosting this.

Boyd Ostroff · August 3rd, 2005, 07:25 AM

Well the differences are subtle, and maybe a little inconsistent between different parts of the images. With this sort of complex texture I suspect that the MPEG compression might be taking its toll on the HDV image. In the second link I can see a lot of "blockiness" in the lower (HDV) part.

Augusto Manuel · August 3rd, 2005, 11:06 AM

The only way you really can compare footage and analize the quality of a video image is using a professional industrial critical monitor. Using web images or consumer even plasma monitors to do so does not make much sense. People are getting sloppy when analizing things these days. About the downconverted footage being superior to SD DV footage, it is cut and clear. Just get an 8045Q monitor or larger (rent one if you dont have one) and observe the difference.

My two cents.

August 2nd, 2005, 09:38 PM	#19
Steven Gotz Trustee Join Date: May 2002 Location: Clermont, FL Posts: 1,520	I shoot and edit HDV. I show HDV to the majority of the people who see my videos. But now and then, I need to export to a standard DVD. It happens. It is annoying, but some people just don't have HDTV yet, so recommending a AVeL Linkplayer2 just isn't an option. __________________ Steven Gotz http://www.stevengotz.com

August 2nd, 2005, 09:45 PM	#21
Douglas Spotted Eagle VASST Join Date: Jan 2004 Location: Stockton, UT Posts: 5,648	Steven has it like most folks do. There are very limited choices as of right now, for HD to the masses. Avelink, Buffalo, Windows Media HD, Nero Digital/AVC. So, a lot of folks have no choice but to downsample. __________________ Douglas Spotted Eagle/Spot Author, producer, composer Certified Sony Vegas Trainer http://www.vasst.com

August 2nd, 2005, 05:28 PM	#16
John Poore Regular Crew Join Date: Nov 2004 Location: Johannesburg Posts: 107	Interesting. There might indeed be a difference with the Z1 vs FX1. It would be good to test this, it's been discussed before without conclusion here. Anhar - I know what you're getting at there. i've seen that method being posted somewhere before. i think there are other steps involved as well. But we're simply interested in camera conversion direct to DV sd.

August 2nd, 2005, 09:26 PM	#18
Tommy James suspended -- contact admin Join Date: May 2005 Posts: 214	What I am wondering is that in this day and age who wants to downconvert HDV video ? When I watch the news I want to see the news in high definition not crummy standard definition. If you downconvert HDV you might as well shoot in black and white. When color cameras where first introduced did people ask how good where these color cameras for producing black and white footage ? When motion picture cameras were first invented did people wonder how good a still picture these cameras could make? What amazes me is that since the 1950's we are still stuck with the same 480 lines of resolution. Had there not been a great depression television would have boomed in the 1930s and we would have had only 300 lines of resolution as standard definition for the next 100 years. During these last 50 years there has been many oppurtunities for picture quality improvement but the increases in bandwidth went to more programming choices not to any improvement in picture quality. Most people vehemenently resist change so high definition no matter how good it is will always face fierce opposition by people who are unwilling to change.

August 2nd, 2005, 09:42 PM	#20
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,802	I shot a couple tests and here are my first impressions. These were exported from the FCP Timeline with Quicktime conversion as JPEG's at highest quality. The only alteration to the images was stretching the PAL to 1024x576 and the NTSC to 854x480. NTSC Test: http://www.greenmist.com/hdv/NTSC-lake.jpg If I enlarge to 200% in Photoshop I can see a definite improvement in the downsampled HDV compared to straight DVCAM clip. Take a look at the treeline against the sky and the dead twigs, they are sharper. Not a big difference, but it's there. Also notice the color is a bit different, but I didn't change any settings. This might just be due to rapidly changing light around sunset, but they were shot within one minute of each other. Playing the clip in motion makes the difference in sharpness pretty noticeable to me. PAL Test: http://www.greenmist.com/hdv/PAL-lake.jpg These two are much closer together, as I suspected. I still think the HDV downconverted image is slightly better, but the difference is subtle. Playing the clip in motion seems to favor the downconverted version to my eyes. But I can understand why the BBC didn't think the difference was significant in PAL mode. I don't know why you are seeing inferior results with the downsampled HDV John, I certainly don't see it here. Perhaps the FX1 and Z1 really do use a different approach to downconversion? As far as how I viewed these (aside from Photoshop), I have a Samsung 22" HD LCD monitor (1280x720) which I connected to the camera's component output. Looking at the native HDV clip compared to any of the DV clips shows a huge difference in resolution. After watching in HDV the DV clip looks out of focus. This was a good test for me since I enjoy shooting scenery like this. It helps convince me that I need to gear up to start working directly with HDV and forget about all this downconversion stuff :-) I also watched the clips in the FCP canvas at 100% on my Apple 23" Cinema Display. With all the switching between 50i, 60i, DV and HDV I was having a hard time keeping the camera and FCP settings correct, and I started to have problems monitoring over firewire. It's getting late, so I'll take a closer look at all this tomorrow, and will try to put some other examples online.

August 3rd, 2005, 05:22 AM	#23
John Poore Regular Crew Join Date: Nov 2004 Location: Johannesburg Posts: 107	Boyd, can you host a couple of JPEGS for me from my test? You'll see my results, I was looking for sharpness of detail? Like what you've shown here there is a subtle difference in the two, I am interested to see what others think?

August 3rd, 2005, 06:15 AM	#25
Steven White Major Player Join Date: Nov 2004 Location: Canada Posts: 547	I've done a few experiments on the subject. DV vs HDV -> DV (in camera or otherwise) Shooting DV in camera results in the uncompressed original data being downsampled and compressed via the DV codec. For producing "DV footage", this result should be the best, because the MPEG-2 compression is avoided entirely. The key here is that this statement applies to "DV footage" only... not "SD" footage. This is difficult to test perfectly without two cameras in perfect alignment and a perfect beam splitter. Since "perfect" is a bit of a stretch, then any error in the experiment would likely over-ride the conclusions. In my opinion, if you want DV footage out - you should shoot HDV and down-convert in camera to DV. While there might not be a significant gain in image quality, you at least have a higher quality master for later. HDV -> 4:4:4 uncompressed SD vs HDV -> DV Converting HDV via software tools to 4:4:4 yeilds the best result, short of recording an uncompressed HD signal directly. The difference between the 4:4:4 colourspace of a software downsampled image and the 4:1:1 DV is quite noticable. While it's difficult to detect without knowing what you're looking for, watching the 4:4:4 SD play it's immediately obvious which is better. Furthermore, the added DV compression, appearing in the form of mosquito noise and other artifacts is apparant with inspection. An demonstration of software-vs-in-camera down conversion is given below. Note that differences in colour are due to the handling of the different YUV colourspaces of DV and HDV (YUV.6xx vs. YUV.7xx): http://s94963366.onlinehome.us/HDRFX1/softvincam.bmp (2 MB) -Steve

August 3rd, 2005, 06:19 AM	#26
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,802	Not sure what you mean Richard? I shot each clip for 60 seconds, one after the other. I kept the exposure and everything else the same. There was no wind so the water was still. I don't think you're seeing any ripples in the water, it was calm. Those are lily pads in the distance and some sort of other "stuff" in the foreground. Nope, these are definitely the correct frames stitched together. These are static shots - your test using motion is a good idea though. I enlarged a section of each using photoshop to help compare: http://www.greenmist.com/hdv/NTSC-lake-200.jpg http://www.greenmist.com/hdv/PAL-lake-200.jpg There really isn't a huge difference in the NTSC clips, but I think the downconverted one is a little better. When I play them in motion this is noticeable. The differences in the PAL clips are pretty subtle. However if you look at both of those links side by side it definitely shows the advantage of PAL vs NTSC in terms of resolution. You can see more twigs in the PAL version. John - sure, send me your clips and I'll put them online.

August 3rd, 2005, 06:29 AM	#27
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,802	That's interesting Steven. I don't see much difference in your two examples but as you say, it probably shows up better in motion. There's noticeable interlace in these - were they handheld maybe? It would be interesting to compare these with a frame grab from the component output in 480p mode. I wish I had a way to capture from component because I see a big quality difference shooting HDV and downconverting the component to either 480p or 576p. I'm also unclear as to whether they was any final determination about the component output. I was assuming that it's HDV compressed when set to 1080i, but DSE and others have implied that you get superior results when capturing uncompressed HD from component.

August 3rd, 2005, 07:19 AM	#28
John Poore Regular Crew Join Date: Nov 2004 Location: Johannesburg Posts: 107	Here's my experiment with a PAL FX1 using in-camera convert. In both cases the bottom half is HDV, and the top is DV. What do you guys think? http://www.greenmist.com/hdv/poore/hdv-dv%20testing.jpg http://www.greenmist.com/hdv/poore/hdv-dv.jpg And my thanks to Boyd for kindly hosting this.

August 3rd, 2005, 07:25 AM	#29
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,802	Well the differences are subtle, and maybe a little inconsistent between different parts of the images. With this sort of complex texture I suspect that the MPEG compression might be taking its toll on the HDV image. In the second link I can see a lot of "blockiness" in the lower (HDV) part.

August 3rd, 2005, 11:06 AM	#30
Augusto Manuel Regular Crew Join Date: Apr 2005 Location: san francisco california Posts: 145	The only way you really can compare footage and analize the quality of a video image is using a professional industrial critical monitor. Using web images or consumer even plasma monitors to do so does not make much sense. People are getting sloppy when analizing things these days. About the downconverted footage being superior to SD DV footage, it is cut and clear. Just get an 8045Q monitor or larger (rent one if you dont have one) and observe the difference. My two cents.