Tvheadend

I don't like when third-party software touches tvheadend's configuration files. All requests should be handled using the json API or htsp API.

Also, the 'picon://' URLs are generated only when the user configures tvheadend to use this picon scheme in the base config.

Obtaining the list of channels is simple as (hint: "limit" "start" to get only subset of items):

TVH_USER=user TVH_PASS=pass TVH_API_URL='http://localhost:9981/api' tvh-json.py get channel/grid "{\"limit\":1000}" 

But I think that the problem is with the picon scheme, you need to walk through all services/muxes etc., filter them with enabled channels and generate picons:

tvh-json.py get mpegts/mux/grid "{\"limit\":1000}" 
tvh-json.py get mpegts/service/grid "{\"limit\":1000}" 

Use 'uuid' to see which services belongs to a channel.

Sorry, you're already using the http json api, but this is really available only when the correct picon scheme is set in the base config (tvheadend).

serviceref=$(echo $rx_buf |  jq -r '.entries[].icon'  | grep -o '1_0_.*_.*_.*_.*_.*_0_0_0')

It must be set in the base config:

'Prefer picons over channel icons'

It may cause clashes between name based channel icons and picons (service id based icons).

Anyway, you're really looking for a deep info, thus I would really suggest to gather the information using all sources (service/mux/channel database). Another way is to export all used picon paths through the http protocol (something like playlist) - the list would be generated by tvh.