Sony M25 -> HD-Connect vs. AJA HD10AVA etc.
by Bob Cole
on
Aug 10, 2007 at 3:30:40 am
Trying to solve several problems at once: timecode breaks which interrupt captures in FCP, and improvements to video quality.
1. Timecode Issues: Using FCP with an AJA Kona LHe, ingesting HDV and DVCAM material from a Sony M25 deck, I experience occasional timecode breaks where there shouldn't be any (e.g. in the middle of a shot, on a high-quality tape, where the tape has never been rewound and reviewed in the camera).
2. Video Quality: I've been capturing from the Sony M25 via Firewire for simple edits, and via component->LHe for "real" editing. I'd like the best possible quality, and would prefer to capture via HD-SDI on the Kona LHe. Are there any objective evaluations that show whether the SonyM25 HDMI-to-HD-Connect path is superior to the Sony M25 component-to-AJA HD10AVA?
3. Nano vs. MI: As I understand it, the Nano uses Firewire for deck control, while the HD-Connect MI translates RS422 to Firewire. Would the Nano have the same timecode break trouble I'm having now, due to its reliance on Firewire for deck control? Would the MI's RS422 implementation solve this problem, or is it part of life for anyone who was too cheap to buy the Sony 1500 deck with its built-in RS422?
I'm mainly concerned with capturing from the M25, not laying off to it. Using either the Nano or the MI, Would the HDMI signal from the M25 carry the original camera timecode to the LHe's RS422 input, or would that timecode data have to taken from the Sony M25's Firewire output?
Re: Sony M25 -> HD-Connect vs. AJA HD10AVA etc. by John Schell on Aug 10, 2007 at 3:40:48 pm
Hi Bob,
I believe the HD-Connect MI will solve your issues. Answers to your specific questions:
1. I assume the timecode/deck control comes through 1394 in this case. We haven't done much work with FCP 1394 deck control. I can tell you we've had great success with the HD-Connect MI and RS-422 deck control with the M25 deck (we have that deck here and test regularly).
2. We have a video on our website (http://convergent-design.fileburst.com/AvD.wmv) that shows the difference between analog and HDMI capture (using the HD-Connect MI) with a JVC BR-HD50 deck and a popular HD-SDI/analog capture card. The results with a M25 deck will likely be very similar. The reasons that analog capture is not preferred are the following: loss from digital to analog conversion (in deck), loss from cable (voltage shifts, droops over distance), loss from analog to digital conversion. The effect is color shifts and an overall softening of the video (you'll see this in the comparison footage). Also, HDMI carries video and audio so there is no need for separate paths for video/audio.
3. I would recommend the HD-Connect MI. It does RS-422 to 1394 deck control conversion (RS-422 to your Kona card, 1394 from the MI to the deck). We have done a LOT of work on deck control and timecode issues trying to make it as good as possible. HDMI carries only video/audio, while the 1394 takes care of the timecode/deck control.
Let me know if I can answer any further questions.
Re: Sony M25 -> HD-Connect vs. AJA HD10AVA etc. by Bob Cole on Aug 10, 2007 at 4:02:20 pm
That's a very interesting video. btw, it wouldn't seem to play when I used Firefox, only IE.
Would the HD-Connect MI work for the following task? I have to dub a ton of tapes from HDV to Beta, with the original camera timecode. Could I connect the 9-pin from the HD-Connect MI to the 9-pin on the Sony UVW1800 and access the HDV's timecode? (I know this is more of a Sony UVW1800 question, but anyway...)
Have you actually tested the HD-Connect/M25 with FCP, as far as the interrupted captures? You'd have to capture a tape directly to FCP, find the flukey spot, and then recapture through the HD-Connect.
Re: Sony M25 -> HD-Connect vs. AJA HD10AVA etc. by John Schell on Aug 10, 2007 at 4:52:38 pm
Hi Bob,
Unfortunately, the UVW-1800 to MI RS-422 connection will not work as both RS-422 connections are configured to be the slave. We do make a different converter called HD-Connect LE, which has component and LTC output. The LTC would carry the timecode for the UVW-1800. The LE is a 1394 to HD/SD-SDI/component converter and has a MPEG2 decoder on the board. The MI is an HDMI to HD/SD-SDI converter. HDMI is already uncompressed video/audio so the MI does not have a MPEG2 decoder.
We have tested long captures using the M25/MI and FCP (1 hour) without issue. We have not captured the same tape using 1394 though.
Re: Sony M25 -> HD-Connect vs. AJA HD10AVA etc. by Bob Cole on Aug 11, 2007 at 4:56:15 am
[John Schell]"The LE is a 1394 to HD/SD-SDI/component converter and has a MPEG2 decoder on the board. The MI is an HDMI to HD/SD-SDI converter. HDMI is already uncompressed video/audio so the MI does not have a MPEG2 decoder."
Thanks John. Compared to the LE, with its more convoluted path and the MPEG2 decoder, would HDMI->MI->HD/SDI have a cleaner video signal?
Firewire is digital, so how can the MI improve on it? by Bob Cole on Aug 13, 2007 at 2:42:56 am
On the FCP Forum, Dan Sparks observes that his video looks better ingested via the HD-Connect MI, and Chris Poisson replies, "Although I have not done your test with a split screen, or ingested HDV via SDI, from everything I have read here and elsewhere, find it hard to believe there could be any quality difference at all between SDI and FireWire ingest. How can that be?"
Good question, and it's probably better asked here: if they're both digital, what would be the source of any difference between the FireWire->FCP and HDMI->HDConnectMI->Blackmagic or Kona->FCP paths?
I have read that many people don't like to use Firewire to carry their video, but I've never really understood this issue.
Re: Firewire is digital, so how can the MI improve on it? by John Schell on Aug 13, 2007 at 2:45:04 pm
Hi Bob,
Not all MPEG2 decoders are made equal. The hardware decoder in the camera/deck may produce better/worse video than the software decoder on the computer. We have not done much testing on this as quality is quite subjective.
There is one thing that we have seen that will produce better video. Error correction information available on the tape is used by the camera/deck when decoding the video. This error correction info is not available to the MPEG2 decoder on the computer as it is not transmitted over 1394. Use a cheap tape and its easy to see.
The reason people don't use the 1394 transport is for editing. HDV video is long GOP MPEG2 and quite difficult to edit and each frame is not independent. Renders take a very long time and result in 2nd generation compression and the associated quality loss. Editing in an I-frame codec is much easier for the NLE to handle as each frame is independent. No need to recreate the GOP structure on a render as only the frame that needs to be rendered is touched (not the surrounding 15 frames as well).
You can go to an I-frame codec (like Prores) and still do firewire capture. It takes longer because you must ingest (1 X time) and then software render to the appropriate codec (~1 X time). You would spend about 2 hours for each hour of video. If you start with HD-SDI, the conform to an I-frame codec is done as you capture, so the total is 1 hour for each hour of video.
The other advantage of the HDMI approach is in live captures. During a live shoot, the video out the HDMI has very little latency (in the micro seconds) and has not been compressed. It gives you the best quality that the camera can generate given the optics, CCDs/CMOS, etc. This is great for green screen work as you get the full color samples (4:2:2 vs 4:2:0). Also recall that HD-SDI can go 100 meters versus HDMI (~10 meters) and firewire (~10 meters).
Hopefully this helps. Let me know if I can answer any further questions.
Re: Firewire is digital, so how can the MI improve on it? by Michael Palmer on Aug 14, 2007 at 9:38:59 pm
As John has said quality is subjective and it is my opinion that the HDMI port on the M25 creates the best image possible from HDV tape because it rebuilds the image from 1440x1080 to a 1920x1080 4:2:2 uncompressed signal and also uses error control to eliminate tape dropouts. This frees the editor to go into any format they wish in real time. My HD-Connect MI allows me to control this signal into my Kona LHe from SD 4:3, 1080i and 720p using the control software. I think this is the best way to work with HDV.
Anybody around Baltimore-DC have one? by Bob Cole on Aug 21, 2007 at 10:05:48 pm
The demo on the website is impressive, but the equipment involved isn't the same as what I'm using. I'd really like to see this for myself, with something similar to what I'm using: HDV footage from Sony M25 into an LHe card.
If anybody in this area has this device, or if CD is demoing it anywhere close, I'd appreciate being allowed to take a look at it for myself.
Re: Anybody around Baltimore-DC have one? by Michael Palmer on Aug 22, 2007 at 3:11:47 am
I use this same M25 to CD-MI to Kona LHe and it is amazing.
I believe CD will allow a trial for 14 days. Give John or Mike a call.
I totally recommend the Convergent Design product line.
