Improve Audio Description handling

[prl]

Current default settings in MENU>Setup>TV>Auto language (Prefer audio track stored by service enabled, Prefer AC3 track enabled, Audio language selection options all set to None) mean that if a service scan is done by users with those settings, on most channels that carry Audio Description (AD), the Audio Described channel will be preferred because it’s encoded in AAC-HE, and it’s a cumbersome process to change this to the user’s preference.

This can be avoided if the default for Audio language selection 1 is changed from None to English.

However, that means that there would be no way that someone who wanted AD could have it preferred on all channels, because SBS ONE and ABC TV have both the AD soundtrack and the non-AD soundtrack encoded in MPEG, and the default choice is the non-AD soundtrack.

The AD soundtracks are distinguished on the ABC and SBS by having their language descriptor set to the non-ISO 639 language name “aus”. The choice list for the Audio language selection options already includes an entry for the non-ISO 639 language name “NAR”.

User preference for an AD soundtrack can be enabled by changing the ("NAR", _("Visual impaired commentary")) entry in the Audio language selection list in Components/UsageConfig.py to ("NAR aus", _("Audio Description")) so that both “NAR” and “aus” can be set to be the preferred “language” for users who prefer an AD soundtrack, and so that the local preferred name is used for the option.

The AudioSelection popup can also be made more informative about the AD soundtracks by adding:

    LanguageCodes["NAR"] = (_("Audio Description"), )
    LanguageCodes["aus"] = (_("Audio Description"), )

to Tools/ISO639.py.

[Peter Urbanec]

This should now be resolved. New implementation will not use the audio PID cache as default, thus respecting the user preferences for language priorities. By default English is pre-selected as the default language. Audio Description is also added as an option and it maps to "aus"