eARC implementation and SQ question.

[Davesrose]

Sorry for any confusion, I am after two channel sound only, preferably lossless with high bit-rate.
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After having read my Sony TVs manual it states:

HDMI ARC
Two channel linear PCM: 48 kHz 16 bits,

DIGITAL AUDIO OUT (OPTICAL)
Two channel linear PCM: 48 kHz 16 bits, (both are identical in bit depth)


From Internet:
In the context of HDMI ARC, the maximum achievable bit-rate for an uncompressed stereo signal is likely around 768 kbps
In the context of OPTICAL, For a stereo signal, a commonly used bit-rate for optical transmission is 1,536 kbps (96 kHz, 24-bit PCM)

So, from the above it looks very much that Optical for an uncompressed stereo signal is superior. My Sony Manual does not state bit-rate.

Your OP makes no sense. ARC and eARC are bidirectional HDMI for TVs. ARC being the older format where the receiver/TV could output Dolby Digital Plus via HDMI to either component (normally there is one HDMI input on the TV that's ARC/eARC). More recent TVs support eARC HDMI: lossless TrueHD. So really the application is pretty limited as far is if you need to carry Atmos with your TV. I have an OLED as my main TV that's ARC (and my bedroom has a more modern OLED with eARC). I don't utilize either because with my main system, my receiver does all the processing (and has 7.1.4 Atmos) and just sends TV signal to TV. I do have a PS5 attached to another HDMI input on the TV, so it does get send compressed 5.1 to receiver for surround sound. With my bedroom TV that has eARC and could utilize TrueHD Atmos from a UHD disc, it's never used as such. Number one, the audio I use is from a movie centric soundbar system. Also all the content I use is from Apple TV 4K as an input in the soundbar (so it's surround PCM is direct in the soundbar and the TV is monitor).

Don't think of ARC or eARC as some kind of new high end audio connection: think of it as a way to communicate surround for a HDMI connection. For audio quality, optical is perfectly fine for bit perfect stereo music. The only thing I can think about audio music and HDMI is that there are some systems that can stream SACD through it. Originally Sony didn't allow SACD to be output through digital (so it's never been possible with optical/coax). Now that it's pretty much dead, there are some new systems that let you stream SACDs pure digital via HDMI.

 

[uncletim]

I am planning to purchase a headphone/Dac setup to listen to movies via headphones.

I am confused, I didn't know this was audio only.

Regarding your last point on needing an external DAC/Amp, never use (as you know) the internal TV facility as it is mediocre at best.

Plugging in a USb or portable drive like I use works like a treat

you are plugging a USB into the TV and using the HDMI out, so this is passing the audio through the TV, and Kodi is running on the Sony Android 10 OS?

TV is Sony X90L, I'm more concerned with movie playback on this system, I have a separate headphone system for music, and music audio on the Wiim isn't going though the TV, Tidal connect or DLNA - can't get Plex to work yet..

my Wiim Ultra is reporting 24 bit LPCM when playing DTS-HD audio, I plugged a basic SMSL DAC into the USB out and it sounds better than internal DAC but volume is much lower, this is with TV set to PCM.

This is completely different than your setup, I have onn 4k pro box with Plex set to output multichannel, goes in the HDMI 2.1 port on TV set to PCM to the Ultra using eARC. I also need to look at the passthrough settings on Plex app itself, not really sure about the best place to make the conversion from multichannel to PCM, working well just *low* volume.

Dialog is already better with more center image, so I will look for a better DAC.

 

[bigshot]

With audio only, and two channel only, it really doesn’t matter what kind of connection you use. It would be best to go with the simplest and least expensive solution.

eARC has a reputation for being persnickety, so simplicity would be the right choice here.

 

[gregorio]

Why not up the ante.
https://www.ebay.com/itm/353354399159
Lets input the HDMI cable into this unit and let it extract via 1IIS straight into a quality DAC then to Headphone amp.

But that doesn’t “up the ante”, if anything it lowers the ante. However, assuming it has been implemented correctly (which is not guaranteed) then it shouldn’t lower the “ante” audibly.

This product has been taken up by some in Hollywood to mix their soundtracks and is used for testing.

That depends on who you mean by “some in Hollywood”? Assuming you’re referring to the typical meaning of the main film studios/film industry (rather than just members of the public who happen to live in Hollywood) then no, absolutely no one in Hollywood is using the Smyth Realiser to mix film soundtracks! Not sure where you got that from?

Which Sony TV do you have as you stated you're getting 24/48 out which is damn good.

24/48 isn’t “damn good”, it’s the basic standard. 24/48 has been the standard audio format for digital film and TV sound getting on for a couple of decades and all digital films (DCP) and HDTVs must support it, otherwise the films cannot be screened at digital cinemas or the TV does not actually comply with HDTV specifications.

It seems that you maybe a little confused with digital audio formats and maybe digital audio in general?

G

 

[Cecala]

But that doesn’t “up the ante”, if anything it lowers the ante. However, assuming it has been implemented correctly (which is not guaranteed) then it shouldn’t lower the “ante” audibly.

That depends on who you mean by “some in Hollywood”? Assuming you’re referring to the typical meaning of the main film studios/film industry (rather than just members of the public who happen to live in Hollywood) then no, absolutely no one in Hollywood is using the Smyth Realiser to mix film soundtracks! Not sure where you got that from?

24/48 isn’t “damn good”, it’s the basic standard. 24/48 has been the standard audio format for digital film and TV sound getting on for a couple of decades and all digital films (DCP) and HDTVs must support it, otherwise the films cannot be screened at digital cinemas or the TV does not actually comply with HDTV specifications.

It seems that you maybe a little confused with digital audio formats and maybe digital audio in general?

G

I don't remember were I read it about some people using the device in Hollywood, I never said for mixing, could be on the Smyth site although don't quote me.
I doubt many people could tell the difference going higher than 24/48 in bit-rate in a blind test.
I could be confused a little about "digital audio formats and maybe digital audio in general" but that's OK, I have you to point out my many faults and errors!

 

[bigshot]

I don’t know why any sound house would need to synthesize speakers when every sound mixing and recording room already has monitor speakers.

People can’t discern 16/44.1, so 24/48 should be safe too.

Gregorio is a good resource for learning more about digital audio.

 

[gregorio]

I don't remember were I read it about some people using the device in Hollywood, I never said for mixing …

That is in fact exactly what you said, quote: “This product has been taken up by some in Hollywood to mix their soundtracks …”!

I could be confused a little about "digital audio formats and maybe digital audio in general" but that's OK …

No, if you’re making assertions on that basis in a science discussion forum then it is not OK! Being confused about digital audio is hardly surprising, it is a highly developed technical/scientific area and will be confusing to anyone who hasn’t studied it, so it’s perfectly OK to be confused about it but of course (and especially in a science discussion forum) in that case, the rational and respectful thing to do it to ask questions rather than making assertions.

G

 

[Cecala]

That is in fact exactly what you said, quote: “This product has been taken up by some in Hollywood to mix their soundtracks …”!

No, if you’re making assertions on that basis in a science discussion forum then it is not OK! Being confused about digital audio is hardly surprising, it is a highly developed technical/scientific area and will be confusing to anyone who hasn’t studied it, so it’s perfectly OK to be confused about it but of course (and especially in a science discussion forum) in that case, the rational and respectful thing to do it to ask questions rather than making assertions.

G

“This product has been taken up by some in Hollywood to mix their soundtracks …”!
Typo on my part.


"It seems that you maybe a little confused with digital audio formats and maybe digital audio in general"?
My assertion came from detecting a condescending tone (perhaps) in your above comment. I see that I'm incorrect therefore I humbly retract my comment'

 

[Cecala]

Gregorio is a good resource for learning more about digital audio.

Good to know.

 

[myusernameislove]

My experience is that Arc connection is superior to Optical sound quality wise.

TV downmixes surround source track (DTS or Dolby) to PCM stereo and it sounds better via ARC then via Optical in my case. Not sure why. In my opinion these downmixed stereo tracks should have the same bitrate and bit depth, probably 16bit 44.1KHz upto 1411Kbps in both cases, yet the sound I hear when I switch Bravia 8 TV outputs (I unplugged optical) while using the same source track in Sony Pictures Core (DTS tracks sound so much better than Atmos, btw) or in Disney+ (where I lack the option to select which track is used, and I only guess Atmos track is selected by the app) is just so much better via ARC than via Optical. These differences are present with lowbitrate AAC stereo tracks in General TV broadcasts too.

With ARC: Bass is stronger. Notes are denser. Atmosphere in space is much better. Sound is less narrow. Not bright at all.
With Optical: Narrow, less heavy, less dense, less immersive. Less natural. Bright.

So if the difference is not tied to the output track's bitrate or to cable quality (which is above average in both cases), than it is either tied to the quality of implementaion of these inputs in DAC itself, or to the way how TV downmixes source surround tracks to stereo if ARC is targeted vs if Optical is used.

In any case: I will keep my cheap SMSL DO100 Pro dac with ARC input even if I was using it for this input only. I may buy 2nd dac for better sound over other inputs (USB), and I will switch both dacs with my amp's remote control's input selection button on my Aune S17 Pro Evo amp. SMSL can be connected via RCA and "better dac" via XLR.

But the point is there is hearable difference, at least in my current setup.
After I buy new DAC (LAIV uDAC?) maybe optical connection will start to sound superior to SMSL's ARC, who knows. But till then, ARC sounds superior.

edit:
In Sony Pictures Core DTS track downmixed by TV sounds much better then Dolby Atmos track downmixed by TV. Downmixed Atmos track sounds kinda richer in information than downmixed 5.1 Dolby track. Source stereo track, which may have been created by Sony from DTS is one step below TV's downmixed DTS track in terms of spatial presentation, but it keeps the sound aspects of TV's DTS downmix, and I kinda preferred it to TV's downmixes of Dolby tracks.

 

[bigshot]

You're not running a 5.1 system? Perhaps the optical is just the left and right mains without the sub channel folded in.

 

[myusernameislove]

You're not running a 5.1 system? Perhaps the optical is just the left and right mains without the sub channel folded in.

Of course I do not. My whole system is stereo - headphones and speakers. I am describing how ARC sounds better than Optical in stereo use from High quality (DTS HD MA 7.1 or Atmos) surround tracks.

Maybe you do not understand why I do not use stereo tracks. Because downmixes to stereo made inside TV from DTS or Atmos tracks have superior space presentation to stereo tracks that were created quite conservatively, usually for speakers by companies that make those downmixes. Headphones benefit from good surround downmix, and this is Headfi forum, so I thought it is obvious that I share my findings about ARC and Optical outputs in headphones.

TV is the brain that knows how to decode DTS HD MA or Atmos, so I simply say that to really benefit from it you need to use DAC with ARC port.

Manufacturers say they do not want to mix their product lines (Hifi vs AV), but if you ask me, I say it is either because of some licence fees (for PCM stereo? maybe no licence fee is hidden there) or just because they do not understand, that ARC is superior sounding to Optical output with TV, that can decode those High quality audio formats from Dolby and DTS. Maybe they do not want their consumers to use one product for everything. Especially if it is stereo, because they promote surround speakers so much. More speakers - more stuff needed to be sold. But it does not have to be - clearly. TV does the downmix. DAC with ARC port grabs it and your ears benefit from it without miriades of speakers because one or two manufacturers decided to implement port, that behaves better, based on my findings, than Optical.

 

[gregorio]

Headphones benefit from good surround downmix, and this is Headfi forum, so I thought it is obvious that I share my findings about ARC and Optical outputs in headphones.

Ah but this is the Sound Science part of Head-Fi, so it should be “obvious that you share your findings” only if they are factually accurate/supported by facts.

TV is the brain that knows how to decode DTS HD MA or Atmos, so I simply say that to really benefit from it you need to use DAC with ARC port.

That is not the case. An AVR might be “the brain that knows how to decode DTS or Atmos” and in either case it would actually be the licensed Dolby or DTS software/chips that are the “brain”. There are various ways to get the audio data to a DAC and AFAIK, ARC is not necessarily better than other ways, in fact it could be worse in some cases, although eARC should have solved those cases. If you have some facts, science or objective data which demonstrates that ARC is in fact superior, this is indeed the place to post that but if you’re just sharing some subjective impressions, that may only apply to the way you have your system setup or that may not even exist at all and only be due to some perceptual biases, then you’re posting in the wrong place, unless you’re asking questions rather than making assertions.

G

 

[Davesrose]

That is not the case. An AVR might be “the brain that knows how to decode DTS or Atmos” and in either case it would actually be the licensed Dolby or DTS software/chips that are the “brain”. There are various ways to get the audio data to a DAC and AFAIK, ARC is not necessarily better than other ways, in fact it could be worse in some cases, although eARC should have solved those cases. If you have some facts, science or objective data which demonstrates that ARC is in fact superior, this is indeed the place to post that but if you’re just sharing some subjective impressions, that may only apply to the way you have your system setup or that may not even exist at all and only be due to some perceptual biases, then you’re posting in the wrong place, unless you’re asking questions rather than making assertions.

G

I don't know what myusernameislove's whole setup is, but he says he has a Sony Bravia 8 OLED TV. Higher end TVs have had Dolby licensing to be able to decode Atmos. The specs for the TV says its EARC and can passthrough TrueHD, DTS-MA, DD+ Atmos, DTS-MA DTS:X....with optical it passes through Dolby Digital and DTS. Through HDMI, the TV might send the original signal if it sees a device that supports the formats. Otherwise it could be downmixing a TrueHD/DTS-MA/DD+ to stereo over HDMI, and it may be taking a Dolby Digital/DTS track for optical. Who knows what the actual sources are, though. He claims DTS sounds better than Atmos with Disney+. Most Disney are only in DD+ (Atmos stream included in it with a movie that has Atmos). Apparently there are a few Marvel movies that have IMAX Enhanced DTS:X. IMAX uses DTS and HDR10+ because they're 3D audio/HDR video that doesn't require licensing. You also need a reciever that supports IMAX in order to get its metadata (otherwise it's a DTS, DTS:X track). My receiver supports IMAX Enhanced-out of all the movies I collect, I just have 2 UHD discs that have it. If he is selecting between Atmos and DTS:X with streaming, then he's probably switching between two different tracks (apparently there are Sony devices that support IMAX Enhanced DTS:X). It might be possible that they sound different because you're comparing apples to oranges (two separate mixes). So you can't generalize one audio format sounding the best, when the sound quality of a movie title depends on the audio's mastering (not audio codec). I'm also not sure about CZ, but broadcast TV in the US uses Dolby AC-3 (not AAC).

 

[myusernameislove]

Exactly. Tv is the brain, in my opinion too, Gregorio, because it provides the decoding. There is no need for AVR when you downstream downmixed PCM audio. I am simply pointing out, that downmixes executed in the brain (TV) sound better then source stereo track and that through ARC they sound better in my system then via Optical and I also tried to explain why it might be so.

AAC codec is mentioned in signal information of TV, Davesrose. Perplexity says it is quite common in digital broadcasting to use AAC codec for audio.

One thing I may have exaggerated is the DTS HD MA 7.1 thing. It says English DTS and English Atmos in Pictures Core audio track selection settings. DTS sounded better to my ears.

I do not own UHD player so I can not comment on the point if TV would receive DTS HD MA 5.1 or 7.1 track from UHD player and downmix it the same way to stereo PCM as it does with streaming services and what the result would sound like in comparison to source stereo or downmixed 5.1 track.

On Windows there is an option to use DTS or Dolby virtualizer which I may try once I obtain some UHD disk with those tracks and play it locally from harddrive. But I think these virtualizers can not use these tracks because they do not act as decoders, so I will probably have to passthrough audio via HDMI to Bravia 8, that will hopefully be able to decode it. If not, I will have to puchase UHD player and pass these tracks to TV from it.

Rest of chain was already described (stereo PCM downmix created in TV, ARC connection to stereo DAC, stereo headphone amp and its PRE OUTs connected to stereo power amplifier and speakers).

No AVR and stereo lives! And provides highest quality possible. Hurray!