AVS Forum banner
Status
Not open for further replies.
1 - 8 of 8 Posts

·
Registered
Joined
·
1,545 Posts
Discussion Starter · #1 ·
I've been trying to use the advertised 480i output of the MyHD. I've now had the opportunity to put the output on an oscilloscope, and I've determined that the output is wrong.


The most glaring error is that the VSYNC is a different length on the even and odd fields (3 lines vs. 4 lines). This may explain why, after feeding this signal through the AD723, the s-video/composite signal contains no field ID information, and why the color modulation appears on the sync itself, causing color corruption in the image.


Also, 16:9 progressive streams are scaled wrong in letterbox mode. Only the top half of the image is visible. I'm also pretty sure the image isn't being scaled down enough horizontally, even in the 16:9 modes that work.


Is there any way Cliff Watson or someone can hook me up with a fix for this? I'd even be willing to make the modifications myself (22+ years of programming experience; 15+ years of digital video experience), signing appropriate NDA's as necessary.


I bought the MyHD based on the advertised output of 480i. I even posted to their support board and was assured the 480i output would provide the output I needed. I think it's reasonable for this device to deliver on its promise, and I'd be willing to work with MIT (who don't seem to respond to e-mails or their own support board any more) to get this worked out.


Xesdeeni
 

·
Registered
Joined
·
231 Posts
Xesdeeni:


Thanks for keeping at it. I don't have any expertise to offer, other than also having hardware to test a fix on. But I, too, would like to use the advertised 480i output capability on my trusty old Sony.


How about it, Cliff? Would you at least add it to the buglist next time you submit one to MITS? Maybe it's a (slap forehead) "Doh!" kind of a thing. A one-line driver fix. Give 'em a chance to make it right.
 

·
Registered
Joined
·
1,545 Posts
Discussion Starter · #4 ·
I haven't been able to determine whether Teralogic/Oak/Zoran provided the TL880 settings to MIT, or if they created their own. In either case, I'll do whatever I can to help fix these problems. This includes signing an NDA so I can get register information, tweaking the registers, and writing the code.


Xesdeeni
 

·
Registered
Joined
·
1,545 Posts
Discussion Starter · #5 ·
I'm still not seeing any activity from MIT on their support board. Is there any chance Cliff Watson can help us out here?


Xesdeeni
 

·
Registered
Joined
·
582 Posts
I have had a 720p incompatibility with my Sony Professional HD Monitor. The problem occurs with both my MyHD MDP-100 and my Nvidia Geforce4 MX420 but not my DCT5100 STB. An engineer at Sony gave me the following response:
Quote:
Not all video sources conform to the SMPTE standards for the HDTV signals. They may be using the EBU or VISA standards, which will work well with computer and consumer displays, but will have problems with professional and broadcast displays.
Sounds like SMPTE is more picky than some other HD standards. I wonder if MyHD and my video card might conform to EBU and/or VISA but not completely to SMPTE (at least for 720p). Also, perhaps the AD723 eval board expects SMPTE...
 

·
Registered
Joined
·
1,545 Posts
Discussion Starter · #7 ·
I can see where there might be several standards for the other (non-480i) modes. SMPTE entered the picture when the DTV standards were set. And before that, VESA ruled on the PC. But since 480i was SMPTE for NTSC and is still SMPTE for DTV, I'd think they would be the same. But I may have to look up SMPTE for the analog version of DTV and see how it compares to NTSC. Thanks for the info.


Xesdeeni
 

·
Registered
Joined
·
1,545 Posts
Discussion Starter · #8 ·
According to the info I've been able to find, the SMPTE standards for DTV utilize a tri-level sync and do not have the multiple line syncs associated with NTSC. However, the output of the MyHD has only a bi-level sync and utilizes multi-line syncs (see above). This still comes back to a non-standard output.


What do I have to do to get this fixed?


Xesdeeni
 
1 - 8 of 8 Posts
Status
Not open for further replies.
Top