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May 19th, 2007, 08:50 PM | #16 |
Tim...
It might be worthwhile, for some folks, to explain that not all HDMI-DVI converters are created equal. DVI, in itself, will accept either analog(as in VGA) or digital (as in DVI), depending on which pinouts are "hot". But, HDMI will accept digital only. If one attempts, for example, to connect VGA to HDMI with one of these cable adapters, it won't work because HDMI requires a digital input and VGA is analog. |
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May 20th, 2007, 08:47 AM | #17 | |
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May 23rd, 2007, 02:27 PM | #18 | |
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PS 1: anyone looking for an AJA HD10A, please contact me off-line. I've gone to only PC and Mac laptops and have no need of it. PS 2: anyone hear of a HDMI I/O board for a MBP? That's what I need now.
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May 23rd, 2007, 03:27 PM | #19 |
Out of curiousity, I removed the PCB from the box to examine the chips. It has a MYSON MTV230 processor, which, according to the manuf. data sheet is 4 channel 6-bit ADC, which would explain the price difference. There's also a Silicon Image memory chip, SI19030 and an EP901/902 chipset used for the HDMI conversion. It looks like 4:4:4 from the manuf. data, but, I'm unsure of that.
Last edited by Bill Ravens; May 23rd, 2007 at 04:05 PM. |
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May 23rd, 2007, 03:30 PM | #20 |
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i think you will need a HDMI > Firewire converter to record on the DR HD drive.
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May 23rd, 2007, 08:07 PM | #21 |
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Quality Issues
I'm curious to find out if anyone has tried a simple comparison test to see the difference in output resolution quality of HDV vs HD-SDI vs HDMI of the same footage. I bought a BlackMagic Studio card to capture the analogue output from my HD-100 and I'm disappointed with the results. Major resolution loss compared to HDV. I tried to capture from the JVC HD-DVD player DVI outputs to the HDMI input of the BM card but can't get it to work, just to compare the same footage in HDV and HDMI. So I'm back to square one.
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May 24th, 2007, 09:12 AM | #22 |
Doug...
I haven't done the comparison you suggest, but, I can answer your question from some of the data that's published on these formats. Firstly, HDV compressed to m2t and HDMI is 8-bit, 4:2:1 or 4:2:2. HD-SDI is 10-bit, 4:2:2. All HDV cameras are 8-bit. I would expect any 10 bit image to be better than any 8-bit image, primarily in dynamic range. If you're starting with a 720p native video format, HDMI will upscale the image to 1080i,I beleive. So, I would assume any comparison between these digitized formats may be comparing apples to oranges. I would expect HD-SDI to be the best, given a 1080 input signal. Your experience with a softer HDMI image might be related to the rescaling performed by the BMD card. |
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May 24th, 2007, 10:10 AM | #23 | |
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Actually the video quality from HDMI and HD-SDI (from an HDV or AVCHD camera/deck) will be identical. While the HD-SDI signal is indeed 10-bits in resolution, it's effective resoltuion is only 8-bits if the original signal was taken from either an HDV or AVCHD source. All MPEG2 and MPEG4 CODECs only have 8-bits of resolution. HDV and AVCHD are both 8-bit 4:2:0 formats. On decompression, the 4:2:0 color space is expanded to 4:2:2 8-bit. When mapped into an 10-bit HD-SDI stream the lower 2 bits are automatically set to zero. The HDMI stream is normally YCbCr 4:2:2 and can be either 1080i, 720p or 480i/576i. All cameras support their own native resolutions, Sony in particular has built in cross and down-converters to allow 1080i, 720p or SD outputs. We should have an update on our compatibility/capability chart shortly which shows the output options for various cameras and decks. We are working on a comparison video for HDV-> DVD using DV and uncompressed SD workflows. Next week we plan a comparison video on live uncompressed HD vs HDV (from the Canon HV20 and the Sony HC3). The analog vs digital comparison of some JVC footage is available at on our website now. Mike Schell Convergent Design |
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May 24th, 2007, 10:33 AM | #25 | |
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I've seen this comparison before and I thought it was incredible how soft the D to A converter made the image. Could you please post a direct link to this comparison for the benefit of the members here? Thanks,
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May 24th, 2007, 10:48 AM | #26 |
I just downloaded the video so i thought I'd post the link:
http://www.convergent-design.com/MIdownloads.htm#jvc There is a clear difference between the two examples. One is noticeably softer. It's unclear to me, however, which is which. The implication is that the signal captured thru 1394 (after m2t compression) and the Convergent boxes is the sharper signal? How can a clearer signal be achieved from a compressed source? |
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May 24th, 2007, 11:50 AM | #27 | |
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May 24th, 2007, 02:02 PM | #28 | |
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Here's an even more direct link for the analog vs digital comparison: http://convergent-design.fileburst.com/AvD.wmv The analog and digital captures both originate from a compressed HDV tape. But the analog capture (thru the component outputs of the HD50 deck) is softer and shows color shifts due to the bandwidth limitations of the digital to analog converter (in the deck) followed by the analog to digital converter (in the HD-SDI box). The digital capture (HDMI -> HD-SDI) does not suffer from these limitations. Mike Schell |
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May 24th, 2007, 03:15 PM | #29 |
Mike...
ahhh, I understand, now. A signal coming directly from the camera CCD block to the component outs would avoid that extra conversion to analog by the tape deck, not to mention the loss experienced by compression to MPEG2 when it was written to tape; and would, theoretically be better than any of these taped clips. Provided, of course that a suitably fast and large enough uncompressed storage medium could be had. And therein lies HDV's soft spot, a lossless storage medium for approximately the same cost as the camera. Thanx for the explanation. |
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May 24th, 2007, 05:54 PM | #30 |
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Thanks for all your assistance.
The reason I'm asking for the quality Resolution differences between HDV vs HD-SDI vs HDMI is that I'm not made of money. It costs alot just to try something out, and when you find that it doesn't quite give you the results you wanted well you know what I mean. I have a JVC HD-100 and I love the camera, I bought the JVC HD DVD player to view the video on the big screen. The HD Player and the camera can Up-convert the video to 1080I, sometimes that would be nice to capture at 1080I. So I tried the BM card using analog outputs but that doesn't make it in my book. I don't have the JVC HD Tape Deck so I'm looking for some opinions, that might lead me to the next step in my quest. I looked at the analog vs digital comparison video and I found out for myself the hard way that analog is not the way I want to go. Thanks Mike.
I was just hoping that someone may have tried the HDV vs HD-SDI vs HDMI resolution tests to see which format had the highest results. The HDV vs HD-SDI test would be simple, one might take let's say a JVC HD-250 record the HD-SDI to a BM or similiar card, and capture a mt2 file by tape or firewire at the same time. The HDMI test might be harder to do, so Bill have you tried a HDV vs HDMI comparison of your setup to see if your on the right track. |
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