[mythtv-users] Mapping OTA channels to HDHomerun tuners

Nick Morrott knowledgejunkie at gmail.com
Fri Feb 22 00:03:04 UTC 2013


On 21 February 2013 21:50, Mike Perkins <mikep at randomtraveller.org.uk> wrote:
> On 21/02/13 18:16, Michael T. Dean wrote:
>>

>> Multiple Video Sources can specify the same XMLTV grabber/configuration,
>> however, MythTV does nothing to "cache" the results for XMLTV*, so it may,
>> effectively, just hit the site twice (unless the grabber, itself, or some
>> other
>> XMLTV thing does the caching).  If that's the case for your grabber, the
>> best
>> approach is to configure an external script that does the caching for you.
>>
>> Someone who knows XMLTV better than I may be able to give you more
>> information.
>> As a matter of fact, I wouldn't be surprised if there's some "standard"
>> XMLTV
>> caching script or capability.
>>
>> Mike
>>
>> *TTBOMK, MythTV only caches Schedules Direct listings data so that it can
>> be
>> reused by multiple Video Sources without fetching, again, and does not do
>> the
>> same for XMLTV data.  However, we would be happy to have a patch to enable
>> XMLTV
>> data caching (as a matter of fact, if I get my way--and switch MythTV to
>> use
>> XMLTV for Schedules Direct users, too--we'll need it so we don't "lose"
>> capability).
>>
> As far as I am aware, in the UK at least, xmltv *does* cache data as part of
> the process. What it caches and how I don't know but there is a cache
> directory you need to specify when you set up an xmltv source, which ends up
> full of hashed files.

The following XMLTV grabbers - uk_rt included - transparently cache
listings data (via the HTTP::Cache::Transparent module) in order to
speed up subsequent runs and avoid retrieval of unchanged data:

$ ack-grep -l --perl "HTTP::Cache::Transparent" grab/ |sort
grab/ee/tv_grab_ee
grab/eu_egon/tv_grab_eu_egon
grab/fr/tv_grab_fr
grab/hr/tv_grab_hr
grab/no_gfeed/tv_grab_no_gfeed
grab/se_swedb/tv_grab_se_swedb
grab/se_tvzon/tv_grab_se_tvzon
grab/uk_rt/tv_grab_uk_rt


Historically, XMLTV supported (and still does) the '--cached' runtime
option, but those grabbers listed above cache data transparently as
part of their regular operation without requiring additional options.

In the specific case of tv_grab_uk_rt, upstream listings are generated
once per day and cached upon successful retrieval by the grabber. The
grabber will only check for updated upstream listings after one hour
has elapsed since the last successful retrieval - otherwise the cache
will supply repeat requests for any data already retrieved. After an
hour has elapsed since retrieval, the grabber will check for updated
upstream data but the cache will still supply the listings data if no
updates are available.

Cheers,
Nick


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