[Sivar]

I use XBMC on my FireTV. Because of one of Android's limitations, FireTV does not support high-def audio.
Almost all of my movies have a 5.1 or 7.1 track in FLAC/16-bit/48KHz, but FireTV cannot handle these so I have to make XBMC encode then to Dolby Digital 5.1

I am familiar with numerous studies that indicate people cannot reliably discern lossy from lossless audio, but most of these studies used AAC or lossy DTS audio of a reasonable bit rate.
My understanding is that Dolby Digital is discernible from lossless in certain cases below about 640Kb/sec.

Thus, what bitrate does XBMC encode Dolby Digital to?

[loekf]

I use XBMC on my FireTV. Because of one of Android's limitations, FireTV does not support high-def audio.
Almost all of my movies have a 5.1 or 7.1 track in FLAC/16-bit/48KHz, but FireTV cannot handle these so I have to make XBMC encode then to Dolby Digital 5.1

I am familiar with numerous studies that indicate people cannot reliably discern lossy from lossless audio, but most of these studies used AAC or lossy DTS audio of a reasonable bit rate.
My understanding is that Dolby Digital is discernible from lossless in certain cases below about 640Kb/sec.

Thus, what bitrate does XBMC encode Dolby Digital to?

AFAIK, XBMC doesn't transcode video or audio into another format before sending out the video over HDMI/VGA/DV/DP and audio over analog/HDMI/optical.

I'm a bit puzzled why you would encode audio from (ripped ?) DVDs or BD sources to multi-channel FLAC. Multi-channel FLAC is non-standard. Though DTS-MA and
TrueHD are in principle lossless, they lossless compress (via MLP or linear prediction, guess FLAC is doing something similar) the delta between the lossy core stream (= DD or DTS) and the original raw audio. So to my opinion it's not 100% lossless.

So why not keeping the original DTS-MA or TrueHD audio ?

[popcornmix]

A quick search through the code suggests it it 640kbit/s
https://github.com/xbmc/xbmc/blob/master...eg.cpp#L21

[Sivar]

AFAIK, XBMC doesn't transcode video or audio into another format before sending out the video over HDMI/VGA/DV/DP and audio over analog/HDMI/optical.

It does, but only to Dolby Digital and only under certain circumstances (strangely, I need to tell XBMC that my system is 2.1 in order to make it output 5.1!)

I'm a bit puzzled why you would encode audio from (ripped ?) DVDs or BD sources to multi-channel FLAC. Multi-channel FLAC is non-standard. Though DTS-MA and
TrueHD are in principle lossless, they lossless compress (via MLP or linear prediction, guess FLAC is doing something similar) the delta between the lossy core stream (= DD or DTS) and the original raw audio. So to my opinion it's not 100% lossless.

So why not keeping the original DTS-MA or TrueHD audio ?

DTS-MA or TrueHD are true lossless in that the end resulting waveform is identical to the original, but I use FLAC because it is a more intelligently designed format. The resulting files, still lossless, are smaller, so I save a significant amount of disk space.

I could save more by encoding with a lossy format such that the difference is inaudible to humans, but sound formats advance and change. Using an open, well-designed format, I guarantee perfect recordings while also allowing myself the freedom of transcoding to some future lossy format should I need to save space.