how-to get HDMI/SPDIF audio passthrough via libVLC?

safari2 · Postby **safari2** » 24 Oct 2018 00:48

Hi.
I'm trying to get pure DTS-HD MA/Dolby TrueHD/ATMOS bitstreaming from HDMI (Win7, NVidia gtx970) to my AV-Reciever.
With libVLC I can get only PCM 7.1, but native VLC media player do that via "HDMI/SPDIF audio passthrough enabled" in preferences without any problem.

How-to switch to HDMI/SPDIF audio passthrough via libVLC?

I'm using Delphi/Lazarus, but C/C++ example code will be also good.

Postby **mfkl** » 24 Oct 2018 04:26

Which libvlc version are you using?

Can you share some logs?

I don't think that's something you can enable/disable through the libvlc API, but I'm not sure.

safari2 · Postby **safari2** » 24 Oct 2018 11:34

3.0.4
how to collect the logs?

safari2 · Postby **safari2** » 24 Oct 2018 12:04

Do you mean to open in GUI preferences/logger enable "log to file" and "verbosity" to "debug"?
This will make to do logs from libVLC?

safari2 · Postby **safari2** » 25 Oct 2018 00:42

there are logs:
https://www.dropbox.com/s/4escl0x37wmqwwp/log.txt?dl=0
https://www.dropbox.com/s/cgi14n8i8cl06w8/log2.txt?dl=0

Postby **mfkl** » 25 Oct 2018 04:10

Don't think there is anything interesting in these logs.

You need to get acquainted with

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libvlc_audio_output_device_types_t
libvlc_AudioOutputDevice_SPDIF

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libvlc_audio_output_list_get

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libvlc_audio_output_device_list_get

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libvlc_audio_output_device_get

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libvlc_audio_output_device_set

safari2 · Postby **safari2** » 25 Oct 2018 15:25

as for these functions:

Code: Select all

libvlc_audio_output_list_get
libvlc_audio_output_device_list_get
libvlc_audio_output_device_get
libvlc_audio_output_device_set

I use it and it works good. I can change audio output from HDMI to analog speakers or headphones.

as for these types:

Code: Select all

libvlc_audio_output_device_types_t
libvlc_AudioOutputDevice_SPDIF

they are associated only with these functions:

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libvlc_audio_output_get_device_type
libvlc_audio_output_set_device_type

I have already tried this function libvlc_audio_output_set_device_type. Unfortunately, there is no result. As was the output in PCM Multi Ch, and remained.

I tried to learn VLC Player sources.That's what i found in \lib\audio.c:

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int libvlc_audio_output_get_device_type( libvlc_media_player_t *mp )
{
    (void) mp;
    return libvlc_AudioOutputDevice_Error;
}

void libvlc_audio_output_set_device_type( libvlc_media_player_t *mp,
                                          int device_type )
{
    (void) mp; (void) device_type;
}

How it works if anyway it returns Error? I'm sorry, I know C++ very superficially.