Make Your Own High Definition Digital Video Recorder-HD DVR 2

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Make Your Own High Definition Digital Video Recorder-HD DVR
Record ATSC Broadcasts in HD

It usually isn’t necessary to pay cable or satellite companies to receive HDTV broadcasts. The new digital transmissions are not plagued with ghosts and multiple images like analog TV is. That doesn’t mean everyone will be able to receive HDTV broadcasts. If you’re located down in hole or surrounded by high rises, the signal may not get through. But for the vast majority of locations, broadcast HDTV is available, free and yours for the taking. If broadcast reception is not
possible or desired, connect to a cable system.

Virtually all HDTV is broadcast on UHF frequencies, so we use a UHF antenna. Since UHF is primarily a line-of-sight transmission, the higher the antenna, the better the performance. I bought a small outdoor UHF antenna from Radio Shack for $25 (no. 15-2160) and it works great. This antenna is small enough, that it could be easily mounted in an attic space. VERY IMPORTANT! If the antenna is mounted outside, always install a surge block on the lead-in cable and properly ground it to a cold water pipe. Don’t expose your expensive electronics to static surges from electrical storms. Once the cable is routed to the TV, split it into two feeds with a passive splitter, one for the TV and one for the HD DVR. If you live in a rural location with weak signals, it may be necessary to use an amplified splitter.

Now that the signal is at the TV we can get down to business. The heart of the HD DVR is an Apple Mac mini computer. This turned out to be the easiest, lowest cost way to go. To process live HD video in real time, the Mac mini with the dual core processor is necessary. One Meg of RAM is a good idea. The original Mac mini that used the Power PC chip can’t do the job. I’m using the base model ($599). If burning DVD’s is desired, then get the $799 model or an external DVD burner. I’m waiting for an external HD DVD read/writer. The computer must have access to the Internet which is easy to do with a wireless router or an Ethernet cable can be used.

The hard drive has 40 gigabytes free for video storage. HD video requires 8 gigabytes per hour, so a full 5 hours of HD recording is available. If more storage is desired, larger internal hard drives are available or a big external hard drive can be added. The external drives provide much more storage per dollar than the internal ones. Use a firewire drive and save your USB ports for other peripherals. Firewire drives can be daisy chained together to further increase storage capacity.

The video output of the Mac is a DVI (digital video interface) port. Don’t use a computer with a VGA port. This is critical for proper operation. My TV set also has a VGA input port and I found that the video quality using that port was much lower when used with the Mac and its VGA adapter. It’s DVI or nothing. Whatever TV you buy, make sure it has at least two HDMI inputs for other uses. The difference between a DVI signal and a HDMI signal is that the HDMI signal has digital audio combined with the video. A DVI signal only has digital video. On my TV set, one of the HDMI inputs has a corresponding analog audio input so the TV can be driven from a DVI source. Use a DVI to HDMI cable to connect the computer to the TV. Then a simple analog audio cable is used to pipe the sound into the audio input.

With the direct DVI connection, the computer recognized that it is connected to a TV and automatically set its video output to 1920 X 1080I at 60 frames per second. Because of its extremely small size, low cost, resident software, and the fact that the Mac mini can directly feed an HD video signal into a television with no intervening hardware, it became my choice as the centerpiece for my HD DVR.

This is also very important. It is essential that the TV set can have its display set to FULL PIXEL. What happens is that TV sets are made to slightly over-scan the video image. Connect a computer and the menu bar at the top of the screen is blown off and there is no way to control it. The full pixel setting eliminates the over-scan.

Now for the main component required to complete our HD DVR. It is an HD tuner that receives either ATSC broadcast and includes the software required to create a HD DVR with a Mac called a Elgato EyeTV. It is USB powered and can be purchased for $149. It outputs unaltered MPEG-2 HD video to the computer’s hard drive. Since the video is not altered or compressed, the quality of the playback is lossless. Now we’re talking, a true DVR. The software that comes with it is excellent.

Recording is a snap. Just click on a show from a schedule (provided by TitanTV) and that’s it. The schedule contains a description of what the show is to help the user decide if it’s worth recording. Put the computer to sleep and it will wake up, make the recording and then go back to sleep.

Once the video is stored on the hard drive it can be exported into virtually any video format available. It can be down-sampled and converted for use by hand held video players, converted to DVD, digital video for editing, or just about anything else.

Since the video is stored on a hard drive, the issue of media compatibility becomes moot. There are no disks or tapes to inventory. If formats ever change, that’s just a matter of a software update.

The computer is still a computer and can be utilized to do anything that computers do. Since it is connected to the Internet, any content (video or otherwise) that can be down-loaded from the web can be displayed on the TV. Get a wireless mouse and keyboard and put that coffee table to work.

When all of the features and benefits are added up, it becomes apparent that using a computer as the heart of a HD DVR is the most flexible and economical way to enjoy that new flat screen HDTV. The crucial features the TV must have to implement this project are that it accepts a DVI signal through an HDMI port, and its display can be set
to full pixel mode. I’m very pleased that I can record shows to watch later at full HD quality, with no monthly fees.

NOTE: Please direct any questions concerning the installation and use of the equipment mentioned in this article to their manufacturers and retailers.


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