[vlc-devel] [RFC] DTS-HD and audio_format_t

[Thomas Guillem]

Hello,

In order to play DTS-HD samples via HDMI I need a way to differentiate
DTS from DTS-HD. Theoretically, they should use the same fourcc, since
DTS-HD is just an extension of the DTS codec (we can play a DTS-HD
sample as DTS if we skip the substream, and use only the core).

But some aout like wasapi or audiotrack need to know if the format is
DTS or DTS-HD. For example, in wasapi, if the
KSDATAFORMAT_SUBTYPE_IEC61937_DTS_HD format initialization fails, we can
fallback to KSDATAFORMAT_SUBTYPE_IEC61937_DTS and modify to
audio_format_t to tell the spdif converter that we only want to send the
DTS CORE.

So my question is: how to differentiate DTS from DTS-HD in
audio_format_t.

 - Add a DTSHD fourcc: VLC_FOURCC('d','t','s','h'). This is kind of
 wrong since this should be the same codec but then we don't need to
 modify audio_format_t.

 - Add a new int i_profile in audio_format_t ? This is the correct way
 but this will be used only for this codec.

Best regards,
Thomas Guillem