capture from tape play back using HDMI versus firewire... at DVinfo.net

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Sony HVR-V1 / HDR-FX7
Pro and consumer versions of this Sony 3-CMOS HDV camcorder.


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Old May 13th, 2007, 09:13 AM   #1
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capture from tape play back using HDMI versus firewire...

Correct me and fill me in please... This is NOT regarding live capture into computer, this IS regarding taped footage.

HDV is 4:2:0, so if i record to tape, and then capture footage via firewire into FCP it's regular HDV (i think)...

OR

If I were to instead, capture from tape, using HDMI and BM Intensity, is the quality going to be better or the same as the firewire capture? Or is there a quality increase similar to using SDI and how it decompresses the codec? or what???

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Old May 13th, 2007, 09:39 AM   #2
 
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There is a difference in decompression of the HDV content if it's managed at the camcorder vs the NLE, yes. Whether it's significant or not is a personal opinion not easily quantified. I like the chromasmoothing that CineForm applies, for instance. I also like the chromasmoothing is applied when using BMD and HDMI capture. But it couldn't be quantified as "10% better" IMO.
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Old May 13th, 2007, 09:51 AM   #3
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You'll also need something like DeckLink's Intensity:

http://decklink.com/products/intensity/

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Old May 13th, 2007, 12:12 PM   #4
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Douglas,
Is the HDMI/BM Intensity workflow decompressing the footage from tape playback - in other words is it truly an uncompressed capture into an nle?
And is this a cleaner decompression than a software decompression offered via an nle render (FCP)? Or is that what you were referring to above?

(again, not interested in a live out, which bypasses the hdv codec, only interested in what's happening from the tape)

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Old May 13th, 2007, 01:20 PM   #5
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What about transport control? Does the HDMI interface include transport control? I think I heard someone at Decklink say you can control via Firewire, but capture via HDMI.
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Old May 13th, 2007, 01:49 PM   #6
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Check out the specs:

http://decklink.com/products/intensity/techspecs/

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Old May 13th, 2007, 04:04 PM   #7
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Thanks. That's where I saw the control via FireWire in the Intensity specs. Anyone out there tried it?
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Old May 13th, 2007, 06:33 PM   #8
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I see one useful outcome of capturing from tape via HDMI: you can ingest the clips as "uncompressed" (although the usual uncompressed quality wont be there) and use these "uncompressed" files in the NLE to avoid the annoyingly long processing times characteristic for HDV native editing.
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Old May 13th, 2007, 07:01 PM   #9
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Quote:
Originally Posted by Zsolt Gordos View Post
... and use these "uncompressed" files in the NLE to avoid the annoyingly long processing times characteristic for HDV native editing.
What "long" processing times? Playback is real-time with HDV. Multi-stream RT is better with HDV than "lossless" compression codecs because these require high-bandwidth disk systems -- often RAIDs. Real uncompressed requires RAID.

CineForm gets its RT power -- only in Premiere -- because they provide their own FX engine.

If you are talking about export -- that's got nothing to do with HDV. (Playback is real-time with HDV.) It's the encode time of the codec you are using.

And, if you use any AVID NLE you get Smart GOP Splicing so you may be able to avoid conforming on export.
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Old May 13th, 2007, 07:08 PM   #10
 
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Processing times=render time (some may refer to rendering as "encoding" yet "encoding" in current industry jargon is relegated to highly compressed web formats, although the word could be applied accurately to any compressed format).
I may be incorrect, but believe this is what Zsolt is referring to.

Realtime playback of HDV is *entirely* CPU dependent. Uncompressed formats don't suffer the challenges of decoding, but rather bring in its own problems via throughput/resource availablility.

Cineform gets its horsepower due to it being a lesser compression than native HDV, and being optimized to work in Sony Vegas and Adobe Premiere.
Adobe Premiere has an additional advantage with Cineform, as Cineform is able to access the Adobe Premiere HAL.
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Old May 13th, 2007, 08:37 PM   #11
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Quote:
Originally Posted by Douglas Spotted Eagle View Post
Processing times=render time (some may refer to rendering as "encoding" yet "encoding" in current industry jargon is relegated to highly compressed web formats, although the word could be applied accurately to any compressed format).
I may be incorrect, but believe this is what Zsolt is referring to.

Adobe Premiere has an additional advantage with Cineform, as Cineform is able to access the Adobe Premiere HAL.
Encoding is the term generally applied to inter-frame compression (compression expressed in bit-rate reduction). The fact some might see the term applied to the web is a side-effect of inter-frame compression being used on the web.

Compression is the term generally applied to intra-frame compression (compression expressed as a compression ratio).

Conforming is used by some to define the encoding process. This leaves the word render for the calculation of FX.

With AVID Smart GOP Splicing, there is no "conform" time if no FX are used. Conform only occurs in the areas where there are FX. Even better, where there are no FX, the original bits are exported with no decode/recode cycle. (Just like DV.) This puts the same bits back to tape as were on the source tape. (Except two GOPS at cuts.)

Since HDV export is the first step in going to BD or HD DVD, this is a huge time saver for anyone working with HDV. It also can deliver maximum quality.

HAL is Hardware Abstraction Layer. By using it, CineForm replaces Premiere FX code with their own FX code that have been written to work optimally with CFHD and Intel. So when you see CineForm's amazing multi-stream RT demos, you ONLY get this performance with Premiere. CineForm also brings 2-3 pulldown removal to Premiere for 24p editing.
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Old May 13th, 2007, 08:50 PM   #12
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so, in essence, HDMI capture from TAPE, is very similar to being a poor man's SDI - is this a correct analogy...

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Old May 13th, 2007, 09:23 PM   #13
 
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Quote:
Originally Posted by Steve Mullen View Post
Since HDV export is the first step in going to BD or HD DVD, this is a huge time saver for anyone working with HDV. It also can deliver maximum quality.

.
There is no point in ever rendering/conforming/processing/exporting to HDV/.m2t file format output for delivery to BD or HD DVD.
A-.m2t is not a native-supported format in either HD playback system
B-rendering/conforming/processing/exporting is an additional compression step that I'm sure everyone recognizes the perils of performing. There simply is no need. Some applications do require an export, while most applications allow direct output of MPEG2, AVCHD, or VC1 directly from the timeline.
This is ALWAYS the best option. Otherwise, titles, graphics, and other 4:4:4 content on the timeline becomes 4:2:0 and is subsequently recompressed, and that's without mentioning the losses incurred in rendering an MPEG format to yet another more highly compressed format.
Every editor in the world (I believe) is well-informed when it comes to the subject of recompression and highly compressed source content.

"Compression," while being an accurate descriptor, is never used in the professional editing world. The term "render" on the other hand, is very commonly used when discussing output/export/mastering. As a great example, simply search this site for the term "render" and then again for "compress video." Do the same with Google. "Render" is the nomenclature used by professionals and consumers alike. I'm sure you're familiar with the common lingo of the industry?

Lonnie, HDMI is often referred to as "poor man's SDI" as it's quite similar to SDI for in-studio/capture/acquisitional use, but could never be used effectively in the field due to not only lack of cable length capability, but also weakness in the connector, and lack of ability to lock it down.
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Old May 14th, 2007, 05:03 PM   #14
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Those of us who have actually been burning hi-def optical discs know that because HDV is simply a "brand name" for MPEG-2 and MPEG-2 is what's used on BD and HD DVD, we can simply "export" HDV and -- with the correct application -- burn a disc. These discs will have menus, etc. And, except for the menus -- no recompression of the HDV is performed. The TS is simply repacked as PS.

And, if you use Avid NLE's, Smart GOP Splicing, can mean no "conforming" during .MT2 export!

Sony's BD burners also have a FireWire input that supports direct burning of HDV to BD -- obviously without menus.

And, we understand that BD and HD DVD use 4:2:0 sampling so exporting to HDV is the same thing as exporting to MPEG-2 at 4:2:0. Only the name is different.

And, of course, we understand that since exporting to HDV is the same as exporting to MPEG-2 -- there are no "extra" compression steps: camera encode, NLE decode, NLE encode, disc decode.

We also understand this can be done very cheaply -- no need for some expensive app to make hi-def discs. Spend $60 and you are in business.

No need to buy a $750 burner, either. Burn to red-laser discs. The 25Mbps of HDV is a perfect match -- although some NLEs let you tweek the "HDV" data rate so you can increase this to 29Mbps.

In the real world folks burn hi-def discs using HDV. And, unless one has a need to believe in the "extra" quality of inputting via HD-SDI or HDMI -- just stay with i.LINK. You are working with an under $5K HD camera who's own problems far out-weigh the issues of what type of xfer is used. So we are back on topic.
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Last edited by Steve Mullen; May 14th, 2007 at 08:51 PM.
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Old May 14th, 2007, 08:38 PM   #15
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In this months DV mag, there is a review for the Black Magic HDMI card, and the reviewer says unless you are going LIVE out of the camera with HDMI into the computer, then you are better off just staying native HDV. This is in regards to quality of the image.

If you don't want to deal with long render times and other issues that have to do with HDV, then using HDMI in to another codec or uncompressed FROM TAPE is the next best option. In terms of picture quality from tape, go HDV native over firewire.
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