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Review and Measurements of Chromecast Audio Digital Output

kaka89

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Spotify app likely isn't bit perfect too as it sends audio through the system mixer, definitely so on Windows. CCA optical output to a DAC is your best bet to get best quality Spotify playback short of using more expensive streamers.

Pi provides better quality in similar price :D
 

gvl

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Pi provides better quality in similar price :D

I tried the librespot based Spotify client on Linux and it wasn't all that great when using "connect", my phone would constantly get out of sync with the currently playing track, etc. Perhaps things improved since then.
 

jo_r

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Hi,
Wow, what a great article. I'm searching for a while about some information and didn't find until now.
I have got a few questions.
I have a Denon AVR3313 amp and would like to plug the Chromecast by using a toslink cable.
And I have got an android player hooked up to a projector (hdmi).
I would like to be able to display the image to the projector and stream the audio to my AVR.
I have read that multichannel (5.1) would work but I don't know if 7.1 would.
I don't know if sound and image will be synced.
And I don't know if it would work using Kodi.
I would really appreciate your feeedback.
Thank you and good day.
 

jaynyc

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@kaka89 @gvl regarding 'sound quality' of Spotify via Chromecast, there's a lot of discussion about this. It seems that Spotify's official position is to use 256AAC with Spotify Premium to Chromecast, which is different than 320OggVorbis. Though I'll leave the debate of lossy encoding formats to others.

https://support.spotify.com/us/using_spotify/system_settings/high-quality-streaming/
(expand the Chromecast section)

https://community.spotify.com/t5/Ot...mecast-bitrate-solution-verified/td-p/4661520

https://community.spotify.com/t5/Ot...otify-Premium-on-Chromecast-Audio/m-p/4363193
 

nicv

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I wonder if you could do a similar test of the Apple Airport Express (A1392), please?

After Apple updated its firmware to support Airplay 2 I jumped on it to feed my DAC since Airplay 2 is lossless (ALAC).

However, at some point I noticed audible crackling on certain tracks, e.g., Mia & Sebastian's Theme from the LA LA Land soundtrack.

The crackling isn't present when using the same optical cable directly from my MacBook Pro. Further, since my DAC has USB & Toslink inputs I A/B'd (volume matched) the Airport Express (Toslink) and my MacBook Pro (USB) and the only audible difference was the crackling. I also tried two other Airport Express units I own and they all had the same problem. Finally, to rule out the DAC as the source of problems, I ran the same tests on my Vanatoo Transparent Zero's Toslink input and found the same problems.

I'll soon have a Topping DX3 Pro and will see if the problem persists…
 

Cebolla

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Conclusions
There are a few here:

1. The CAST audio functionality of Google Chrome is horrid. There is no excuse for it to be butchering even simple 16-bit signals as it did. While audibly it is not as dire as it looks, I still would avoid it if you can.

2. Roon's implementation of Chromecast streaming is superb. It is bit accurate up to 24 bits and 48 kHz that I tested. Congratulations to Roon for job well done. I assume they received support from Google to implement it as the protocol otherwise is not open to the public.

3. The Chromecast output has more jitter than an audiophile/instrument grade Toslink output. This is evident when used with low quality DACs like Schiit Modi 2 Uber.

4. Using a well-designed Dac like the Topping D50, there is no difference at all between Toslink from Chromecast or higher fidelity sources. All the jitter is filtered out resulting in the performance of the DAC itself being the limit.

#4 is a great news here. It means that if you have a good DAC and use Roon, you can turn your DAC into a streamer/renderer using the Chromecast Audio. For just $35, that is a superb addition. As such, the combination of Roon and Chromecase audio is highly recommended!

EDIT: bit-perfect playback is also supported in Android apps like Hi-Fi Cast. See: https://audiosciencereview.com/foru...omecast-audio-digital-output.4544/post-102185. So you are not just limited to Roon.
Hi Amir

Just read this excellent review, after being directed to it from another forum.

However, I'm slightly concerned by what appears to come across as the Google Cast protocol not being bit perfect when streaming audio, unless a non-publically available feature is unlocked by some 'special' support from Google.

The actual normal case is that the Google Cast does bit-perfectly stream audio encoded in the formats that it supports (including lossless formats, such as FLAC, with a resolution up to 24-bits/96kHz). This is used by the vast majority of audio applications that support Google Cast, such as Roon and those Android apps you mentioned.

So the special case is actually the dubious quality audio capture, used by Google Cast's Cast Screen/Audio feature, which is very likely what the Google Chrome browser was using when 'casting' while it was playing your test audio file that you had dragged onto its window.


John
 
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captain paranoia

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Hi Amir
So the special case is actually the dubious quality audio capture, used by Google Cast's Cast Screen/Audio feature, which is very likely what the Google Chrome browser was using when 'casting' while it was playing your test audio file that you had dragged onto its window.

I think it's perfectly clear, even from the post you quoted, that it's a problem with casting from the Google Chrome app, not the Google Cast/Chromecast protocol itself. The very next image after the appalling Chrome app casting is of casting from Roon, using the Chromecast protocol, where the performance is described as 'Perfect!'.
 

Willem

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The problem is precisely this: the Chrome browser is terrible with the CCA but casting from your tablet or smartphone is perfect.
 

Willem

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So it is not the CCA app on your phone. If you are using the app on your phone or tablet it only serves to establish a connection. Streaming is done between the CCA and your router. You can even turn off your phone.
When you are using the Chrome browser the music is cast from your computer and not directly from the router. So turn off your computer and the music is gone.
 

Cebolla

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I think it's perfectly clear, even from the post you quoted, that it's a problem with casting from the Google Chrome app, not the Google Cast/Chromecast protocol itself. The very next image after the appalling Chrome app casting is of casting from Roon, using the Chromecast protocol, where the performance is described as 'Perfect!'.
The point I was making was that the article seemed to imply that Roon's bit perfect use of Google Cast protocol, with assumed 'special' support from Google to implement, was not otherwise available publicly:
Congratulations to Roon for job well done. I assume they received support from Google to implement it as the protocol otherwise is not open to the public.


The reality is that the vast majority of applications available to the public that support Google Cast, get the Chromecast devices to stream bit perfectly.
 
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Cebolla

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So it is not the CCA app on your phone. If you are using the app on your phone or tablet it only serves to establish a connection. Streaming is done between the CCA and your router. You can even turn off your phone.
When you are using the Chrome browser the music is cast from your computer and not directly from the router. So turn off your computer and the music is gone.
You still have to careful not to say all Chromecast supporting apps do as you say - though the majority do.

For example, the Hi-Fi Cast Android app, as mentioned in the Edit at the end of the OP/article, has a gapless function option for Chromecast devices that can only be implemented by the Hi-Fi Cast app actually itself decoding and (gaplessly) playing the audio files in the playlist, so its player's resulting continuous audio output is what is being bit perfectly streamed by the Chromecast device from the Android phone/tablet (so not the individual audio file tracks provided by another device on the network) - switch the phone/tablet off and streaming stops in that specific case!
 
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M00ndancer

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The problem is precisely this: the Chrome browser is terrible with the CCA but casting from your tablet or smartphone is perfect.
Can confirm, playing audio from Chrome Browser (Google Music/YouTube Music) works fine using a USB DAC. But casting from the the browser does not. Casting from apps on the phone works fine as expected.
 

tranq

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@amirm

Good evening, I think alot of us would really appreciate you testing out how Chromecast Audio casting functions in certain apps. Tidal, Spotify, Qobuz, IheartRadio, Deezer. All have casting functionality.
 

dweekie

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For those that do cast from the desktop browser, try this Chrome flag:

--disable-audio-output-resampler

I haven't tested it on Chromecast, but I use this flag because I subscribe to Google Play Music, which doesn't have a standalone app. When I originally compared the sound quality of Google Chrome in regular playback to the Spotify App, identical songs sounded different to my ears. I kept thinking it may be the encoding quality differences, but that didn't make sense given both high quality bitrates. Then I ran across this resampling flag that people needed to output ac3/dts. When comparing them again with the resampling disabled, I couldn't tell a difference. I'm wondering if the reduced quality is due to Chrome resampling audio before outputting it (to the Chromecast in this instance).

I'll leave that with the usual measurement/bias caveats. I still can't imagine a resampler to be that bad, but I guess I'll re-explore the issue if others contradict my ears.
 

M00ndancer

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I have found (subjectively!) that playing Google Play Music, Youtube Music and casting from Chrome, it seems to do some weird things to the audio.
However, just playing thru my USB amp/DAC there is no issues, and no issues using a CA as a transport (toslink into DAC) casting it from a phone.
Same happens when I plug in my headset directly into the CA using it as a headphone amp.
Casting thru Chrome = bad
Similar to what @amirm experienced.
I suspect that when casting thru Chrome, it works the same way casting directly from your phone (not using an app).
But I do not have the knowledge or equipment to measure and prove it.
 

dkinric

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Bumping this thread.
As I look at the myriad of high dollar streamers in the market, I keep coming back to my Chromecast Audio and wondering if this simple device is all I need for good 24/96 performance?
Simply using the Tidal or Qobuz iOS app as a remote and the CCA streaming to my DAC, how does this compare to these high $ streamers/transports on the market?

Amir @amirm , you verified that it was bit perfect using it as a Roon Endpoint and explained this by supposing the Roon software team was able to make it work well, does this logic also follow to the Tidal and Qobuz apps?

I would very much appreciate a follow up test for Chromecast Audio with additional testing outside of Roon. It seems that is the main goal of this site is to cut through the Audio Industry BS and show that even inexpensive products can tout good performance. Considering the cost and the number of CCA owners out there, this would interest and affect many more readers than some of the products being reviewed lately.

Would anyone else like to echo this request? Thanks for considering.
 

Sueekhy

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I echo that. Roon subscription is more expensive than CCA, hope Tidal or Qobuz app are on par with it.
 
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