A New Approach to Components in a Digital World - Something to think about - Page 4

cafink · 01-29-2007, 10:32 AM

Thanks, Robert, for writing such an informative and well-written article. My current "home theater" set-up is quite modest, especially on the video side, and I've been looking to take the HD plunge in the near future. Your suggestions have been most helpful.

I have two simple questions I hope you might address.

First, how can I know that my DVD player (or any video source) is passing an unprocessed signal? You suggested using a DVD player that can output 480i via HDMI, but does that guarantee that the 480i signal being output is exactly the same as the video data stored on the disc? My current DVD player, for example, includes controls for adjusting the brightness and contrast of its output. I have left them on the default settings, but just because the player's video output is in the same format (480i) as a disc's native resolution doesn't mean that there is no video processing taking place, does it? How can I ensure an unprocessed signal?

The same basic question applies, of course, to the display device. Since I want to let my external video processor do all the work, I want to make sure my TV or projector doesn't do anything to the incoming video signal except display it as-is.

Quote:

Originally Posted by RAF

The correct order of connectivity is to pass all the HDMI signals into the receiver or pre/pro first, let that device extract all the pertinent audio information to send to the speakers and then pass the video signal unaltered to the video processor. There is absolutely no need to have a source provide more than one HDMI output since everything goes to the audio processor first. For "legacy" devices (those without HDMI capabilities) you still treat audio and video as before. Audio (via toslink, RCA or analog inputs) goes to the receiver and video goes to the video processor via DVI, component, S-Video or composite as offered/needed. (You can still send the video through your receiver first especially if you want to take advantage of on-screen menu functions but that's up to your specific needs and preferences.)

Second, don't most video processors introduce a slight delay in the video signal between source (DVD player) and destination (display)? If this is indeed the case, then sending the video signal through the processor but not the audio signal, as you suggest, would cause the video and audio to become out-of-sync, correct? Is there a way to compensate for this?

Thanks again.

RAF · 01-29-2007, 03:18 PM

Quote:

Originally Posted by Carl Fink

Thanks, Robert, for writing such an informative and well-written article. My current "home theater" set-up is quite modest, especially on the video side, and I've been looking to take the HD plunge in the near future. Your suggestions have been most helpful.

I have two simple questions I hope you might address.

First, how can I know that my DVD player (or any video source) is passing an unprocessed signal? You suggested using a DVD player that can output 480i via HDMI, but does that guarantee that the 480i signal being output is exactly the same as the video data stored on the disc? My current DVD player, for example, includes controls for adjusting the brightness and contrast of its output. I have left them on the default settings, but just because the player's video output is in the same format (480i) as a disc's native resolution doesn't mean that there is no video processing taking place, does it? How can I ensure an unprocessed signal?

The same basic question applies, of course, to the display device. Since I want to let my external video processor do all the work, I want to make sure my TV or projector doesn't do anything to the incoming video signal except display it as-is.

Second, don't most video processors introduce a slight delay in the video signal between source (DVD player) and destination (display)? If this is indeed the case, then sending the video signal through the processor but not the audio signal, as you suggest, would cause the video and audio to become out-of-sync, correct? Is there a way to compensate for this?

Thanks again.

Some excellent questions, Carl. Let me try to answer each of them in the order asked.

Regarding assuring that the player and the display provide a video path free from any other processing by these devices: This is an area where you really have to do your homework to find out if this is the case. I have come to the conclusion that although most of the major manufacturers offering 480i output over HDMI (and 1080p input to a 1080p display) generally offer a direct link from the DVD and to the display it doesn't hurt to dig a little deeper if it's not clearly spelled out in the specs. In my case (my Denon 2930ci DVD player and my HP MD5880n 1080p DLP display) I actually talked to technicians to find this out. Granted, I'm taking their word for this and I guess the only way to tell for sure would be to examine the circuit diagrams (if available) to see if the path is, in fact, "pure." In any event, in most cases I would think that there is minimal intrusion by the circuitry and where there are adjustment available for the output (like in your case) setting them to the neutral position would take case of most if not all problems. And keep in mind that brightness and contrast adjustments have nothing to do with the pixel structure which is the main focus of video processing. 480i will be 480i regardless of the brightness, etc. Advertising 480i over HDMI should convey the message that this means you have a direct link to the content on an SD DVD but, as you pointed out, it might not be the actual case. At least with "480i out over HDMI" you can be reasonably sure that there is minimal intrusion. The same goes for the display end of the video chain.

As to your second situation involving video processors introducing a slight delay in the video signal: while this is quite possible I haven't found it to be true with my DVDO iScan VP-50 (and the VP-30 that preceded it). Maybe I've just been lucky with my combination of components but maybe it's a function of how good the video processor does its job. However, if there were a noticeable audio/video sync problem (looking like a badly dubbed movie) there are several ways to handle this. For one thing, many of the newer receivers/pre-pros offer audio timing adjustments so you could match the audio to the video if needed. My Denon 3806 has an "Audio Delay" function which can be set from, if I recall, 0 to 200 msec and can have a separate setting for each input if required. Additionally, my VP-50 all has audio delay capability (I think they call it "lip sync") that works in a similar fashion. Of course, if I wanted to use the VP for audio delay it would have to precede the Denon 3806 in the chain. In my case it's just easier to send audio directly to the receiver. One less wire for analog sources. This is totally flexible for a variety of needs.

I hope that this answers most of your questions. Let me know if you need further clarification.

Take care.

cafink · 01-31-2007, 03:00 PM

That's exactly the sort of explanation I was looking for.

Thanks again, Robert!

RAF · 01-31-2007, 07:12 PM

Glad to help, Carl.

RAF · 03-04-2007, 01:06 PM

Note: The following arrived in my PM mailbox this morning and I felt that it was something of wider interest than just PM so I'm reposting it here.

Quote:

Originally Posted by Ryan Peddle

Hi Robert,

I read your article and found it very interesting and insightful. A component set up has always been the way I have intended to go when I have the money to build a dedicated theater room.

But I do have one question as it pertains to HDMI, the new audio formats for HD discs, and prepros/vid pros.

How will it all work. The HDMI would come out of the HDDVD/Blu-ray player and need to go to two different areas. Would it go the the PrePro and then to the Vid Pro? Would you need some sort of splitter?

Look forward to your response,
Ryan Peddle

Good question, Ryan (and one that should probably be discussed in the main forum thread instead of PM since it will reach a wider audience.)

Yes, the HDMI a/v output of your players needs to go "two places" but a splitter is not required (nor advised because of HDMI handshaking issues). Here's how I do it.

First I route the HDMI output from the devices that provide both HDMI video and audio to my HDMI capable receiver (or pre-pro). The AVR extracts the pertinent audio information and sends it to the speakers. At the same time the AVR has an HDMI output which then sends the video to my Video Processor. My AVR (Denon 3806 used as a pre-pro) does not alter the video signal as it passes into and out of the HDMI jacks so, in a manner of speaking it is functioning in the role of a HDMI "splitter" without any of the handshake issues that are possible if a poorly designed splitter were added to the HDMI path.

It is also possible to reverse the process (put the HDMI signal from the players into your video processor first and then send the audio out to your receiver/pre-pro) but you have to make sure that your VP supports audio throughput. The "AVR first" pathway is usually the favored method.

As a bonus, if your AVR or pre-pro supports audio delay you can compensate for any audio/video lip sync issues that might occur. I've never encountered such lip sync problems myself with my Denon 3806/DVDO VP50 combo, but maybe I've been lucky with choice of components or content. (Lip sync issues can usually also be corrected in the "VP first" method as long as that feature is available in the VP as well as audio output of course.)

For sources that don't need to use the HDMI output for audio I still use the "old" method of connecting the video output directly to my Video Processor and the audio directly to my AVR (usually via toslink, etc.). However, to use the lossless HD audio codecs you either need to go the HDMI route or get into using analog 5.1 (soon 7.1) inputs which gets a little more complicated. The uncompressed audio isn't sent over S/PDIF (optical and coaxial) for copy protection reasons so that's not an option with the newer players.

Hope this helps. I'm going to take the liberty of posting this in the pertinent thread if you don't mind.

Take care.

Ryan Peddle · 03-04-2007, 08:31 PM

Thanks Robert. I absolutely agree that there are still needs in the world of home audio video for Composite/SVid 2 channel anolog.

But an evolution has to take place at some point. As a point of interest I have a before and after picture of my receiver.

Before, just as it is right now...and the only think I have connected to it is one optical and one coax for digital audio, and obviously speakers (which the outboard amp would manage)....that's it.

And this is what I would want to have (with HDMI connections as well)...just an audio processor, and the HDMI out(s) would go to the VP where the component connection would be found. The audio processor would have 3 or 4 Coax dig, 3 or 4 optical dig, 3 or 4 HDMI and 2 out, a 5.1 to 7.1 analog in, and a 5.1 to 7.1 preout section.

Look at the real estate that is taken up with connections I will probably never use again. This is something that I think should be seriously thought about. I know that the enthusiast community would provide a martek place for this type of device.

RAF · 03-05-2007, 07:16 PM

An excellent visual, Ryan!

Joe S. · 03-13-2007, 01:28 PM

I have a small problem and a question to the VP owners. I recently purchased a VP30 and have been running pretty much everything through it (D*TV, DVD, Xbox 360, Wii, VCR, ???) with great success. This unit also came equipped with the deinterlacing card (102).

The problem is that for some 480i sources, especially the Directivo box, the image 'skips' or is 'jumpy' when decoding a 480i source and the scene pans or scans. When the Directivo box is outputing 720p on an HDTV station this never happens, only on SD channels at 480i. More unusual still is that this doesn't happen all the time, but it is frequent.

Any ideas on what could be causing this issue? Ways to correct it? Sometimes if I reset the VP30 by powering down it will correct, sometimes it does not. A little frustrating as otherwise I love the picture it provides, but the jumping is annoying (and paying $1K+ to be annoyed wasn't part of the plan

)

Thanks for any thoughts...

RAF · 03-13-2007, 01:45 PM

Quote:

Originally Posted by Joe S.

I have a small problem and a question to the VP owners. I recently purchased a VP30 and have been running pretty much everything through it (D*TV, DVD, Xbox 360, Wii, VCR, ???) with great success. This unit also came equipped with the deinterlacing card (102).

The problem is that for some 480i sources, especially the Directivo box, the image 'skips' or is 'jumpy' when decoding a 480i source and the scene pans or scans. When the Directivo box is outputing 720p on an HDTV station this never happens, only on SD channels at 480i. More unusual still is that this doesn't happen all the time, but it is frequent.

Any