Confirmed: Chromecast audio analog output is 48kHz 16-bit today

I gave a hand to +FrAndroid​​​​​ +Manuel C.​​​​​ to explore the audio capabilities of the Chromecast audio.

Google confirmed what we found in measurements earlier: Chromecast audio resamples everything to 48 KHz 16-bit for both the optical and analog output.

– It is a poor default choice for audio since most material is sampled at 44.1 KHz.
– The resampler itself is not so great, introducing various distortion artifacts.
– The 16-bit output limitation is not welcome, including for 16-bit material since the volume control is software and digital.
– And it prevents playing 96 KHz 24-bit material without loss of quality.

Google say they are working on it, however they didn't adjust their marketing material announcing the support of 96 KHz 24-bit resolution which is rather unfortunate.

I have a lot more measurements and data than the graph +FrAndroid​​​​​ republished, would you like to see them?

#supercurioBlog #audio #measurements #chromecast

Test du Chromecast Audio, le parfait compagnon de vos oreilles – FrAndroid
Après avoir rendu intelligents les écrans les plus basiques avec son Chromecast, Google a souhaité aller plus loin cette année avec le Chromecast Audio, un

Source post on Google+

Published by

François Simond

Mobile engineer & analyst specialized in, display, camera color calibration, audio tuning

33 thoughts on “Confirmed: Chromecast audio analog output is 48kHz 16-bit today”

  1. Can't. Can't configure chromecast to use hotspot. I have only phone and chromecast, not a separate hotspot (which I won't pay for, not for this) When phone is doing hotspot, can't get to other devices that are using it.

    Mind you, I have gotten it to make the tones on the radio. But without internet, the casting icon won't show. I also tried it with my DIR-810L pocket router. Again, no internet connection.

  2. +David Eckard You indeed can't use the phone used as hotspot to also control the Chromecast itself, however last time I tried using my Nexus 5 as a hotspot, both the Chromecast Audio and a tablet being connected to the Nexus 5, I could then control the the CC audio as usual.

    Which phone were you trying with?
    It's possible that some hotspot isolate each device in a virtual private network, or preventing broadcast packets to spread.

  3. Will it be possible to avoid the usage of the internal DAC? I was hoping that using the toslink connection, would allow this, but it looks like Chromecast is always touching the files. Or how could it else control volume?

  4. +David Eckard the DAC inside the Chromecast Audio can do 192kHz/24-bit, but the Chromecast software layer only supports 96kHz/24-bit. And due to the current bug, it resamples everything to 48kHz/16-bit. The toslink connection of Chromecast Audio is limited to 96kHz/24-bit.

  5. Be aware that listening to mastered material at anything more than 16bit 44.1 kHz is effectively pointless – this has been proven many times (lets not argue.. 😉 ) – you won't be getting anything extra except perhaps low level distortions.. Even these resampling distortions if accurate are below -105 dB that is not going to be audible in any kind of real situation unless there are other issues too. Granted they def shouldn't be there but let's not panic, and seems an easy fix to switch output to source rate, even if as a new option.

    In my little tests I recorded some stuff (flacs) out of CCA optical then compared to the actual source file. They didn't null which is prob understandable given the resampling issue and recording process but the takeaway was I could switch between them and barely notice any difference and certainly not pin down if one was 'better'. I'd like to reduce variables and repeat but need to create some lossless files at different bit depth and rates, then upload them to then stream via CCA.

  6. +Ben K is right. A classic to highlight his point:

    However, when it comes to resampling ({up|down}sampling from a format to another, many artifacts might occur depending on the quality of the algo being used.

    In case of recording, a higher samplerate and resolution is often welcome (noise floor & stuff like that) but I strongly doubt the Chromecast Audio main use-case (not even sure it's possible to record with it) is about recording, which again leaves us with the link just above 😉

  7. +Ben K​​​​ remember that this explanation of anything beyond 44.1kHz being useless has been written by a specialist of lossy codecs and is used as a plain dogma for the most part, while most of what he describes doesn't apply to anything beyond absolutely ideal conditions, ideal hardware, ideal software implementation – including bit perfect output (required for the dithering to produce the desired effect and not just adding noise or distortions)

    In reality, things are very much different, and in this case absolutely none applies to the Chromecast discussion.

  8. I didn't reference any one author or article so maybe you have confused me with another poster, I thought it relevant to those considering streaming their collections at 24 96 etc because it is 'better' that the really its a waste of time. I don't wish to point to the resources as they are abundant, and what is relevant to chromecast is that the quality for listening to services like Gmusic is perfectly good and Better than many other costlier solutions even with the issue of material being resampled.

  9. +Ben K​ I disagree with the statement that 24 96 streaming is a "waste of time"
    Instead, aiming at higher quality targets pushes a whole ecosystem forward in terms of quality, sometimes directly, sometimes indirectly, sometimes even through ripples of unintended side effects.

  10. +François Simond​ sure, it probably does no harm so if people want to, great. I suppose i aim remarks at those less experienced or casual hifiers to just keep in mind that no microphones (commonly used) respond beyond 20k, no speakers produce beyond 20k and no human ears respond to beyond 20k, so having mastered finished material going up to 48khz as they do with 96khz sample rates is at least a bit unnecessary. Anyways don't want to get sucked into a whirlpool of death conversation, let's hope they sort the CCA out so we are all happy as its a cool device 👍😊

  11. I will say that very very little content makes real use of 16 bit sampling. It has a dynamic range north of 90 db. Nearly nothing uses more than oh, 10 or 20 percent of that. Most not even 10 percent. Just looked that up, 6 db per bit or 96 db with 24 bit at 144. No DAC can do more than 125db which is plenty IMHO

    24 bits can better do the quiet flute to the full orchestra better. That range in a real orchestra can be nearly 100 db. And yes, they wear earplugs.

  12. +Ben K "no speaker beyond 20k?"

    In terms of headphones, the ones I'm using for a few years now are rated for 10-39500 Hz:

    I'm past 30 and according to some I should not be able to hear much high frequencies anymore, yet one of my usual test sample is a sine oscillating between 18 and 19 KHz.

    I observe that starting from broad statements and generalizations establishing that a lot of things can't be reproduced heard or perceived altogether leads to such "it's useless" conclusions quickly, but I respectfully disagree and happily challenge most 😉

    And yeah I'll continue measuring the Chromecast audio to figure out exactly what they changed and how!

  13. There is also harmonics. Even if you can't hear the original, sometimes harmonics color the sound.

    Me, hearing loss so in college, learned that I could not hear beyond about 12,500 Hz or so. Unless it is loud. I could hear the 15750 oscillator that old style TV could do as it often passed 90 db in the set. (30 fps * 525 lines, many kids are shocked that old style TV had that many, they think its 640 by 480 and you have to explain that it is analog)

  14. Well Sure.. and you can get supersonic mics to listen to bats but most people don't own them or use them to record instruments.. 😊
    People just do not hear beyond 20k. At my age it's lower.. Also the musical value of anything in that region is very little, it brings nothing to the party. I've recorded and mixed a great deal for 20+ yrs and anything north of 16 is often rolled off. Old classic records had little above 12k. Believe me I arrived at statements after much analysis.
    If It's not captured and its not delivered and it isn't sensed, any sensible observer would conclude its a waste, even if only one the 3 is true.
    +David Eckard​​​ don't worry you are only missing out on some sizzle squire, plus IF (and this is very unlikely and applies to literally none of the best music ever made) an instrument were recorded with a high freq range mic and delivered to you pristine via high range transducers, it would sound exactly the same as if it was down sampled to CD quality with a modern resampling algo. Anyway said I wouldn't go there but have a great day all!

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