[baliset]

Apple have dropped S-Video output on the new MacBook Pro, which is a huge disappointment.

Another forum made a very brief mention of the existance of a "$19 adaptor that will restore this output via the DVI socket". There are several adaptors from Apple I can see that come close.


This is the "MiniDVI to Video adaptor". It's rated for the Intel based iMac and 12" Powerbooks. I can't see how it would help with a MacBook because MacBooks come with a full-sized DVI socket, not a mini-DVI socket.

Well, how about this:

This is the "Apple DVI to Video Adaptor" and has the right socket on both ends. It's got a full-size DVI plug on one end and combo S-Video and composite video out on the other.

The problem? Apple's website only rates it for use on "Mac Minis or PowerMac G5's". No word on if this will restore S-Video or composite video out on MacBooks.

This is a question I desperately need answered because it's the key thing standing in the way of me ordering a MacBook straight away. Can anyone shed some light on if this adaptor will categorically work on a MacBook? Presumably Apple state that the DVI to Video adaptor will only work on certain models for a reason... something to do with the circuitry of the DVI socket being able to support this adaptor to push out S-Video/Composite, perhaps?

I hope someone can help. Thanks.

[swichd]

The only thing I can think of is a scan converter like this. http://www.comparemaster.com/ssprodu...pf_id=10475369. A DVI to VGA adapter might be needed, but I think the MacBook comes with one. Hope it helps

[jamil5454]

I would bet money that the Apple DVI to video adapter (for PowerMacs and Mac Minis) works on the new MBP. DVI is a standard; it's either implemented or it's not. I would imagine that the signals coming out of the DVI port from the MBP would be indistinguishable from the ones coming from a PowerMac or Mac Mini.

[analogika]

The DVI to Video adapter will work fine.

And no, it's not a "HUGE" disappointment, nor a major issue.

It's a very small, lightweight, and cheap adapter needed for that fraction of Apple notebook owners who already carry around an S-Video cable, anyway.

[Drakino]

Originally Posted by jamil5454

DVI is a standard; it's either implemented or it's not. I would imagine that the signals coming out of the DVI port from the MBP would be indistinguishable from the ones coming from a PowerMac or Mac Mini.

The DVI standard has nothing in it for sending SVideo, Composite, or Component signals over it. These adaptors are specific to video cards that go beyond the standard and output these signals. Generally they ground a few pins to signal the card to output SVideo, or ground some different pins to do Component. Though no Mac video card supports Component out via the adapter ATI ships. I'm hoping it might be different on these newer cards.

[baliset]

Aha. This is what I suspected. There is no consensus about whether the DVi standard is "generic" and that any device with DVI out has the native ability to push out an S-Video or composite video signal with the appropriate adaptor cable, or, that the ability of this adaptor to push it out is specific to those models, and special features of their DVI sockets.

This is precisely why some clarification from Apple is needed about the DVI sockets on their MacBooks. Let's keep looking.

[Troll]

I read somewhere that there will be a DVI to S-Video converter included in the box.

[mrgaskell]

Nope. From Apple:

"In the Box

• MacBook Pro
• Power Adapter with MagSafe Connector, AC wall plug and power cord
• Lithium-polymer battery
• Apple Remote
• DVI to VGA adapter
• Install/restore DVDs
• Printed and electronic documentation"

Methinks that you will be able to buy a DVI to S-Video Adapter for $19. And a USB dial-up modem, DVI-ADC, etc....

[jamil5454]

Originally Posted by Drakino

The DVI standard has nothing in it for sending SVideo, Composite, or Component signals over it. These adaptors are specific to video cards that go beyond the standard and output these signals. Generally they ground a few pins to signal the card to output SVideo, or ground some different pins to do Component. Though no Mac video card supports Component out via the adapter ATI ships. I'm hoping it might be different on these newer cards.

Ahhh. Of course. So the adapter just alters the wiring, not the signal coming out of the DVI port, correct?

[ibook_steve]

OK, for everybody, the final word on this since I helped design the original mini-VGA to video out on the iBooks and mini-DVI to video out for the 12" Powerbooks: The DVI-I connector used on the 15" and 17" and now on the MacBook Pro has RGB pins for VGA out (analog video out). That's why you can use an adaptor with DVI to connect to CRTs or older LCDs. Graphics chips from both ATI and Nvidia output the analog video from a DAC (digital to analog converter). The DAC used in the Powerbooks can switch between outputting RGB for analog VGA and composite/s-video. They're all analog signals, so they can be sent on the same wires from the chip to the same pins on the connector. Composite video (typically yellow plug) is one wire and s-video is two wires (chrominance and luminance). So it's a simple matter to switch between the two analog output types depending what is attached to the connector. So yes, the DVI to video dongle (the second one pictured in the original post) will work fine with the MacBook Pro.

Steve

[mduell]

Originally Posted by jamil5454

Ahhh. Of course. So the adapter just alters the wiring, not the signal coming out of the DVI port, correct?

No. The adapter signals to the video card to send a different signal.
Changing the signal requires a scan converter, and those are expensive.

[Simon]

Steve, thanks for that information. I'm glad the MBP does it the way we hoped.

Since you actually know how this is technically implemented, could you explain how the adapter communicates to the DAC? I mean, how does the adapter let the DAC know that it has to do d/a conversion according to S-Vid or Composite instead of VGA? I didn't know there was the possibility of communication from the peripheral *to* the graphics circuitry on analog video ports.

[ibook_steve]

When you hook up a monitor to your Powerbook, the computer "talks" to the monitor through a two-wire bus called DDC. These extra 2 wires are included in the VGA specification. It's basically talking to a small ROM that holds all the information about what the capabilities and resolutions of the monitor are. If you could program your own DDC ROM and attach it to the Powerbook, you could "trick" the machine into thinking that a monitor was attached even though you just have a ROM. That's what the TV dongle does. It has a small DDC ROM in it that contains all the settings for NTSC and PAL video formats. This tells the graphics chip to output video instead of VGA on the same pins. Since it can't know what kind of TV you'll be plugging in to the other side of the dongle (TVs don't typically have their own DDC and can't relay that information over standard analog composite or s-video connections), you still have to pick the resolution and format from the menu, but that's it. Hope that explains it.

Steve

[Simon]

Hey Steve, thanks! Interesting. Didn't know about DDC. I'll go read a bit more about it.

http://en.wikipedia.org/wiki/Display_Data_Channel