HDMI/DMI versus Component Cables

[TimB]

I have a Sony HDTV, and I use Monster THX component cables for my connection from my cable box. Would I see any improve in picture quality by changing to a HDMI to DMI connection and if so would if be enough to justify the cost to change over? Would a HDMI to DMI support the audio portion of the transmission or only the video?

 

[BMXTRIX]

1. Only the video
2. It may look better, it may not. Some people say it looks worse over DVI/HDMI than over component. From what I have heard, it is 100% impossible to tell.
3. It is worth it to try it as long as you can return cables and get your money back.

 

[mkossler]

Boy this sure sounds a lot like a question a friend of mine, also called Tim, recently asked me... You sure that Sony ain't a Toshiba?

 

[soundsfine]

1. Only the video
2. It may look better, it may not. Some people say it looks worse over DVI/HDMI than over component. From what I have heard, it is 100% impossible to tell.
3. It is worth it to try it as long as you can return cables and get your money back.

I thought HDMI included the audio, whereas DVI does not.

 

[BMXTRIX]

That is correct and I didn't answer that.

HDMI includes audio information. DVI is a video only format. The video portion only is what will be carried if a HDMI/DVI cable is used or an adapter is used.

 

[warhummer]

The HDMI does carry an audio signal but DVI does not. So in cases like mine (Motorola DCT 6200 HD cable box), I run a DVI to HDMI connector and a separate digital coax connector to my receiver for sound.

 

[warhummer]

and BMXTRIX beats me to the punch....

 

[Waveform]

HDMI vs DVI

The video signal is not the same as per Secrets DVD Benchmark review of the Panasonic DVD S77. Money quote
"There is a common misconception in the electronics world that DVI and HDMI are identical except for HDMI’s ability to carry multi-channel audio signals on top of video. This is not true. DVI outputs 8 bit RGB signals only and cannot carry 10 bit video like HDMI can. In fact, HDMI is actually capable of 12 bit transmission as well. What does this buy you? Well if you are lucky enough to have a display with an HDMI input, you can significantly reduce the contouring artifacts that are commonly associated with digital displays. A lot of this may depend on the internal processing of your display though too. This is one of the gripes I’ve had with DLP based projectors and displays. Most are DVI- based and only incorporate 8 bit processing internally. So contouring in gray ramps is quite evident. You’ll also usually see it in skies and underwater scenes. If you are lucky enough to have a display with an HDMI input, and with high bit processing, this is pretty much eliminated."

 

[Waveform]

Component vs HDMI

I am feeding a Panasonic AE 700 with HDMI from a Toshiba SD-5980. On a really well rendered DVD (e.g. I, Robot) I can easily tell the difference between component 480p or 480i versus HDMI at any resolution. In my eyes the colors seem to be rendered with better contrast with HDMI. Of course my observations are only applicable to the above-mentioned components; however, there is great satisfaction in the possibility that there is zero D/A conversion in the whole data stream from the DVD or digital cable to a digital projection device such as an LCD or DLP display.

 

[BMXTRIX]

The follow up to that quote that isn't mentioned is that it seems that most source material is actually 24 bit (8 bits per color) so that even though HDMI is 36 compatible, most sources are still only 24 bit and only at DVI levels. I did NOT know about the 36 bit thing though, so that is some useful info, thanks.

I have seen a HDMI connection to the AE-700 as well and saw the huge quality jump from 480i to 720p or 1080i over HDMI. I'm not sure if this is indicative of the HDMI connection or the conversion process that is going on inside upconverting DVD players. I mean, are you comparing 480p component to 480p HDMI or are you comparing 480p component to 1080i or 720p HDMI? If the later (which I think is what you said) then you aren't comparing the same source really and the conversion may be what is giving you the much higher quality image, not the cable itself. As I said, when I saw a AE-700 hooked up via HDMI, I put the DVD player into 1080i mode, then into 480i mode and the quality jump was significant. It makes me wonder how good the video processors are inside the AE-700 considering that there should have been a very minimal improvement in image quality. The cable remained the same throughout.

Any insight from others?

 

[soundsfine]

I actually asked this question of Oppo. I wanted to know if they were planning an HDMI version of their DVD player and thought that the HDMI would give better resolution. This was their reply:


At this time, there is no plans for incorporating 10 bit through HDMI
due to the nature of DVD. DVD, as a standard, is only 8 bit. Therefore,
switching to a 10 or 12 bit signal will not yeild a greater visual
response.

Best Regards,

Customer Service
Oppo Digital, Inc.
2269 Old Middlefield Way
Mountain View CA 94043
Tel: 650-961-1118

 

[Waveform]

I actually asked this question of Oppo. I wanted to know if they were planning an HDMI version of their DVD player and thought that the HDMI would give better resolution. This was their reply:


At this time, there is no plans for incorporating 10 bit through HDMI
due to the nature of DVD. DVD, as a standard, is only 8 bit. Therefore,
switching to a 10 or 12 bit signal will not yeild a greater visual
response.

I think the point that the review of the Panasonic S77 was making was that the the quality afforded by 10 bit video processing (if carried out by DVD player) would be preserved by an HDMI cable and that there would be a loss of quality by converting to DVI. This does not contradict the Oppo statement if the DVD player only uses 8 bit video processing, i.e., this situation is only true for DVD players that carry out processing using more than 8 bits and also output HDMI. I realize that there may be a difference of opinion about whether this makes a difference if the source material is only 8 bits.

 

[soundsfine]

I think the point that the review of the Panasonic S77 was making was that the the quality afforded by 10 bit video processing (if carried out by DVD player) would be preserved by an HDMI cable and that there would be a loss of quality by converting to DVI. This does not contradict the Oppo statement if the DVD player only uses 8 bit video processing, i.e., this situation is only true for DVD players that carry out processing using more than 8 bits and also output HDMI. I realize that there may be a difference of opinion about whether this makes a difference if the source material is only 8 bits.

I think that 10-bit (or 12-bit) processing could actually be helpful with 8-bit source material when upscaling. Do we know if any players actually make use of the extra? Does the S77? For that matter, do displays with HDMI actually use the bits, or do they assume an 8-bit source?

 

[Waveform]

I think that 10-bit (or 12-bit) processing could actually be helpful with 8-bit source material when upscaling. Do we know if any players actually make use of the extra? Does the S77?

Yes

For that matter, do displays with HDMI actually use the bits, or do they assume an 8-bit source?

This is the blurb from the Pioneer 5040HD plasma:
"ACE II (Advanced Continuous Emission II) uses 10-bit processing to produce 1, 024 gradation steps for each cell - creating a palette of over 1.07 billion colors and delivering reproduction accuracy up to 16 times greater than competitors panels."

and another one
"The new HP-R5052 Samsung Plasma TV uses advanced 12-bit color processing, yielding over 68 billion colors for a more lifelike picture than ever before."

However I think it is unlikely that every (or even perhaps most) displays with HDMI inputs do this.