Difference between revisions of "Digital Television"
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== Digital vs. HDTV ==
== Digital vs. HDTV ==
Revision as of 19:10, 8 February 2009
Starting February 17th, 2009, through June 12th, the United States will change from analog broadcast television to digital broadcast television. This change has some implications for MythTV users and this page will try to answer some of the most common questions and misconceptions. This table generalizes the situation
|Type of service||Need to change|
|Analog antenna/broadcast|| |
|Cable television|| |
|Satellite television|| |
Because the cutover has been changed by Congress from a single date to a time period, different stations may change to digital on different dates, and because the digital switch over may involve channel changes you may be forced to update your lineups quite a number of times during the period, depending on where you live. How well scheduling providers will keep up with this is unknown. [If you don't have cable TV, why not? :-) --Baylink]
Digital vs. HDTV
One common point of confusion is the use of digital television and HD television interchangeably. Digital television is simply the digital broadcast of TV signals compared to analog broadcast. Digital does not require a signal to be HD. HD is defined by the resolution of the content. Digital broadcasts can be in both SD (standard definition) and HD (high definition) formats.
Analog antenna/broadcast users
If you currently receive television using a standard antenna, you need to change equipment to continue to receive digital broadcasts. You have two basic options without changing to another type of service: a digital converter, or a digital broadcast capture card.
These are set top boxes which convert the digital broadcast signal back to analog so your existing equipment does not have to change. They tend to cost about $40-50, are of varying quality, and you can get a coupon for up to 2 of them from the government -- though both the coupons and the boxes may be in short supply at this late date. These should work fine with MythTV, but might require use of an IR blaster to change channels and will also require one converter per tuner in your system.
Lirc Config Files for Converter Boxes
Working Config for the RCA DTA800b:
begin remote name RCA_DTA800b bits 24 flags SPACE_ENC eps 30 aeps 250 header 3750 4206 one 252 2240 zero 252 1245 ptrail 275 gap 8292 toggle_bit_mask 0x0 begin codes 1 0x7318CE 2 0x7328CD 3 0x7338CC 4 0x7348CB 5 0x7358CA 6 0x7368C9 7 0x7378C8 8 0x7388C7 9 0x7398C6 0 0x7308CF - 0x76189E menu 0x7088F7 info 0x73C8C3 ok 0x7F480B up 0x7598A6 down 0x7588A7 left 0x7568A9 right 0x7578A8 ch+ 0x72D8D2 ch- 0x72C8D3 end codes end remote
Digital broadcast cards
These cards are commonly sold as HDTV capture cards. They will have various features such as ATSC support, QAM support, or 8VSB support. They may also advertise if they support OTA signals. For digital broadcast capture, OTA support is required. This is synonymous with 8VSB and should be what you look for when purchasing a card. This tuner is analogous to a typical analog capture card like a PVR-150 and would take the place of that card in a digital setup.
A good example of this card in a PCI format is the AverMedia A180 with additional information here. There are other cards available, but you must choose one which is compatible with Linux and hence Myth.
The digital converter coupons cannot be used for computer capture cards.
Changing to digital capture will require changes to your lineup/video sources. This page may provide some guidance on how to proceed in scanning for digital channels and configuring the mapping of them to programming guides.
Cable TV users
That being said, many cable companies are taking advantage of the change to force users to change to digital services and require the use of a STB, set top box, in order to receive programming.
If your cable provider requires the use of a STB to receive all stations, then this change will affect your MythTV configuration. You should refer to the Recording Digital Cable page for additional information. Effectively, you will require one STB per tuner.