All 5.1 DTS-HDMA gets passed-through as 7.1

So this has been an issue since day one basically and only happens to DTS-HDMA files (Dolby TrueHD, DD+, DD, and normal DTS get passed trough correctly).

Videos that have a DTS-HDMA track with 5.1 channel audio, will show up as 7.1 during playback (when the seek bar with info is displayed at the bottom it’ll show the 7.1 icon on the default Kodi skin instead of an 5.1 icon).

This is further confirmed by using the CodecInfo-overlay, it’ll show:
with RAW listed 8 times instead of the expected 6 times.

Unfortunately my receiver can’t show me how many channels it actually receives, so maybe that is just a weird display bug (…but in 2 different places?!).

This really happens to ALL 5.1 DTS-HDMA files.
The library will list them correctly as 5.1 though, so Kodi does scan them correctly.

I’ve uploaded a small sample file:
15mb Sample File
(I can reupload somewhere else if needed)

ID                                       : 2
Format                                   : DTS
Format/Info                              : Digital Theater Systems
Format profile                           : MA / Core
Codec ID                                 : A_DTS
Duration                                 : 14 s 59 ms
Bit rate mode                            : Variable / Constant
Bit rate                                 : 3 323 kb/s / 1 509 kb/s
Channel(s)                               : 6 channels
Channel positions                        : Front: L C R, Side: L R, LFE
Sampling rate                            : 48.0 kHz
Frame rate                               : 93.750 FPS (512 SPF)
Bit depth                                : 24 bits
Compression mode                         : Lossless / Lossy
Delay relative to video                  : 1 ms
Stream size                              : 5.57 MiB (36%)
Default                                  : No
Forced                                   : No

From the Debug Log:

04:26:10.300 T:3000427264    INFO: CAEStreamParser::SyncDTS - dtsHD MA stream detected (8 channels, 48000Hz, 16bit BE, period: 8192, syncword: 0x41a29547, target rate: 0x18, framesize 4460)
04:26:10.301 T:3000427264  NOTICE: Creating audio stream (codec id: 86020, channels: 8, sample rate: 48000, pass-through)

This is absolutely normal behaviour as kodi only shows RAW 8 times for DTS-HD MA passthrough… This doesn’t mean that 8 channels are sent, it just means that DTS-HD MA is passed through (it’s kind of a placeholder). The information may be confusing, but the receiver will receive the untouched channel layout of your audio stream - which would have 5.1 channels in your case.


I see. It just got further confusing because the debug-log basically says “dtsHD-MA stream detected with 8 channels” when parsing the files. And I guess the player OSD saying it’s playing 7.1 is just a visual bug as well?
It just seemed weird it was showing up as 7.1/8 channels in three different places, most of all the player OSD…

Now I see… That’s a bug we’re aware of, but it doesn’t have any effect on what’s actually passed through to the AVR via HDMI. It’s just a bug which let’s skins think a DTS-HD MA 5.1 track has 7.1 channels.

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I wouldn’t call this a bug, but I suppose it’s a niggle. What’s happening is that for hi-res audio, all 8 ‘channels’ (4 sub-packets each carrying the equivalent of stereo PCM) in the HDMI stream are used. So the audio processor is reporting 8xRAW meaning 8 non-PCM streams. Since kodi is passing the audio through, it doesn’t know which speakers are being targeted, hence RAW,RAW…

If your AVR reported the actual channels decoded (surprised it doesn’t) it would tell you 5.1. The info label in Kodi will tell you 5.1. You will hear 5.1 channels and if you actually have 7.1 speakers your AVR will probably upmix the rears to the sides, depending on how it’s set.

It was that last bit - the upmixing - which didn’t happen before we fixed it about a year ago.

I figured something like that could be the explanation. However, Dolby TrueHD 5.1 does display correctly as 5.1 in the player OSD and with only 6 RAWs in CodecInfo. Shouldn’t it, in this case, also use all 8 channels?

I was hoping you wouldn’t notice that :wink:

FWIW I have a 6.1 DTS-MA clip which is shown as 5.1 on both OSMC and in Windoze Kodi. Maybe it will be improved in Leia.

I reported this a few months back, like you I noticed that the Kodi skin can mis-report the number of channels with DTS files, although my receiver indicates that the correct channel layout is being received, which is the main thing. Have not yet had chance to see if this is fixed in Kodi 18.

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