4.0 over HDMI - Why it is problematic and ways to fix it

QuadraphonicQuad

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Krobar

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Mar 19, 2007
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What is this thread for:
To help you get your 4.0 / multichannel files playing properly
To help understand why they are problematic
To aid future purchase and software decisions

Typical problem:
"5.1 PCM/Flac/Wav/Wavpack works on my setup but 4.0 just plays as stereo"
The likely cause is your source device is outputting FL+FR+SBL+SBR but you receiver only supports FL+FR+SL+SR.

The Multichannel PCM problem:
Multichannel PCM did not originally have any way of defining which channels are present, it just defined how many channels so had no way of defining if a 4 channel file was 4.0 or 3.1 for example. An optional header called waveformatextensible_channel_mask allows Flac and many other PCM based formats to define the actual channel map.

How the channel mapping header is used:
Many players and playback software ignore this header entirely. For the applications and players that support this header they will try to output the given channel map if they can. If the header is not present or the player/software does not support the header then a default channel mapping is used. Particularly with Windows but also with many disc players the default is often the badly supported FL+FR+SBL+SBR channel map.

The receiver compatibility thread:
This thread was a good start but because the issues are caused by a combination of file headers, player and the receiver it became quite conflicted.

The Windows Uneven Channel Count Issue:
(Note: Unsure if this is only Intel HDMI which is affected by this)
Windows WASAPI using Intel HDMI seem to never support uneven channel counts (eg. 3.0, 4.1 or 5.0). Under Linux this is not an issue. For many layouts affected by this problem adding a silent LFE channel is an ideal solution (4.1 is an exception).

The HDMI Problem:
The HDMI EDID only supports reporting which channels are present on the receiver, it has no way of reporting which channel layouts are supported. This means most of the channel layouts presented by your Graphics card HDMI driver are a guess and nothing to do with what your receiver supports.

Player / Player Software:
Key: Name : Channel Mapping Support: Default Channel Mapping
Kodi (Windows/WASAPI) : NO* : FL+FR+SBL+SBR
JRiver Media Center (Windows): NO : FL+FR+SBL+SBR
Foobar 2000 V1.66 + WASAPI Plugin** : YES : FL+FR+SBL+SBR
Sony BDP-S760 : NO : FL+FR+SBL+SBR

Receiver Support:
Key: Name : FL+FR+SL+SR : FL+FR+SBL+SBR : FL+FR+C+LFE
Arcam HDA (2020) : Yes : No : Yes

Ways to fix or workaround the issue

Add extra channels to make it standard 5.1:
@HomeJau's excellent MediaHelper makes this quite easy to do:
Pros:
Excellent Compatibility
Cons:
Upmixing (eg. Doby Surround or Neural X) will result in silent channels. If you are adding only an LFE channel this is a non-issue.

Add or change the channel mapping header:
Pros:
Upmixes Properly
If your device chain supports both quad formats channel map can always be correct
Cons:
Need source and receiver to support the channel layout being used

Use Bitstream:
DTS HD MA do not tend to suffer from these channel mapping issues
Consider using MKA (Especially if the source was originally a lossless bitstream)
Pros:
Upmixes Properly
Support will work for anything that can bitstream DTS HD MA
Cons:
Limited player support
MKAs can be more difficult to work with
Encoder software not so common
I believe FL+FR+SBL+SBR might be unsupported (Unsure)

A Windows setup which supports channel mapping headers:
Download and install Foobar 2000 1.66: foobar2000: Downloading
Download and install the Foobar WASAPI plugin: https://www.foobar2000.org/getcomponent/160564374cf1fd0fdf039dd20d09cf46/WASAPI.fb2k-component
Within Foobar -> File -> Preferences -> Playback -> Output - Pick a WASAPI entry for your HDMI output -> OK

How to add headers to a Flac file:
You need metaflac which is included with the official Flac download:
Add FL+FR+SL+SR header:
metaflac.exe --remove-tag=WAVEFORMATEXTENSIBLE_CHANNEL_MASK --set-tag=WAVEFORMATEXTENSIBLE_CHANNEL_MASK=0x0603 file.flac
Add FL+FR+SBL+SBR header:
metaflac.exe --remove-tag=WAVEFORMATEXTENSIBLE_CHANNEL_MASK --set-tag=WAVEFORMATEXTENSIBLE_CHANNEL_MASK=0x0033 file.flac
Add FL+FR+C+LFE header:
metaflac.exe --remove-tag=WAVEFORMATEXTENSIBLE_CHANNEL_MASK --set-tag=WAVEFORMATEXTENSIBLE_CHANNEL_MASK=0x000F file.flac

FL+FR+SBL+SBR vs FL+FR+SL+SR:
If you have a 5,1 setup then there is effectively no difference between the two. If you have a 7.1 setup then which is correct for a given recording varies as does which people prefer. In many 7.1 setups SBL+SBR is closer to the setup suggested for quad LP.

*Foobar V1.67 Beta with integrated WASAPI does not work
** Kodi support for channel mapping at least within video files is being worked on. No news on the audio player side yet though.

There are likely bits I got wrong here or could be improved so all feedback welcome. Any reports on receiver compatibility with the three different channel mapping or ATI / AMD HDMI outputs also appreciated.
 
Last edited:

ar surround

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A lot of fixes here, thanks. This is another reason I have trepidations about upgrading my current set up…Having to mess with rips of quads that only have four channels. Right now, they play just fine from my Oppo 205 analog outputs and into my processor‘s analog inputs.
 

drh3b

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I understand this is old, but how I "fixed" things in Jriver is to force 7.1 playback, no upmixing or downmixing in the DSP and output options, which fixes both the multi channel tracks that want to force to stereo, and the quad(mainly Chicago Quadio) flac files that don't play all the channels. It's annoying, I'd much rather use "source number of channels. I guess this is probably technically wrong, as the back Quad channels play from the side, but it still sounds good, and ignorance is bliss, I guess.
Of course, if you want to experience Chicago with fewer instruments, just use the source number of channels.
 
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Krobar

Member
Joined
Mar 19, 2007
Messages
14
I understand this is old, but how I "fixed" things in Jriver is to force 7.1 playback, no upmixing or downmixing in the DSP and output options, which fixes both the multi channel tracks that want to force to stereo, and the quad(mainly Chicago Quadio) flac files that don't play all the channels. It's annoying, I'd much rather use "source number of channels. I guess this is probably technically wrong, as the back Quad channels play from the side, but it still sounds good, and ignorance is bliss, I guess.
Of course, if you want to experience Chicago with fewer instruments, just use the source number of channels.

Thats another way of doing it which is similar to the re-encoding in a higher channel count method.

I upgraded my Arcam AV40 to the new HDMI 2.1 card and since then it supports FL+FR+SBL+SBR so everything works nicely including upmixing. The same happened with some Denon models once upgraded to HDMI 2.1 (eg. AVC-X8500HA). Nothing to do with the HDMI 2.1 having better support but I suspect after many manufacturers dropped support with the HDMI 2.0 gen products they got some complaints and reinstated FL+FR+SBL+SBR support with HDMI 2.1 gen.
 
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