[mythtv-users] Difficulty conceptualizing the relationship of Zap2it data and scanning for channels.

Kevin Kuphal kuphal at dls.net
Thu May 25 18:54:51 UTC 2006


H P Ladds wrote:
> I am currently capturing HDTV OTA, and am having difficulty 
> conceptualizing the relationship between "scanning for channels" and 
> importing channel info. using Zap2it.
>
> My assumptions:
>
> 1. mythtv-setup>Input connections>"scan for channels" uses the capture 
> card to scan the airwaves for signals. When it finds a signal, Myth 
> records the information in a .conf file. After the information is 
> obtained, Myth references this .conf file and predisposes the capture 
> card to tune-in a specific channel(s) -- rather than scanning for 
> channels every time a user wishes to watch or record video content.
No, all channel information is in the database in the channel table.
>
> 2. The "mythfillmydatabase" command downloads a listing of when and on 
> what channel television programming will occur.
True
>
> 3. Somehow MythTV cross references the info. obtain from Zap2it 
> "mythfillmydatabase" and From "scan for channels" to facilitate 
> recording.
Yes.  An xmltvid is inserted for each channel in the database which 
corresponds to the listings information from zap2it.
>
> Put another way, the information obtained from "scan for channels" is 
> a list of hardware settings that tune in OTA stations. The information 
> obtained from Zap2it is a list of channel information. These separate 
> databases are indexed together to faciltate viewing and recording.
>
> 4. However, when using a cablebox one should not use mythtv-setup's 
> "scan for channels"  feature. Zap2It's information is used to populate 
> both (all?) databases.
Because from a cablebox or standard cable/antenna source, the channel 
frequency information is a standard and populated from tables in the 
source code.   OTA HDTV and other sources do not have this standard 
mapping and so the frequency information must be scanned for or imported.

Kevin




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