Streaming and Audio degradation.

[abdo123]

I have been noticing that streaming 16/44.1khz FLACs over Airplay is changing the sound a bit. Airplay works by decoding whatever audio that comes through and encoding it to 16/44.1KHz ALAC.

While the process should theoritically be lossless but i still hear differences in sound, I cannot tell whether it’s a good difference or a bad difference because I didn’t produce any of these tracks.

now using mconnect to stream to a DLNA renderer (LPCM not MP3) should also be lossless in theory, I didn’t do a double blind test yet but it’s a clear (albeit subjective for now) difference from Airplay. I think the sound stage is altered and/or volume level. But i’m not sure I haven’t tested it out.

Recently i purchased Roon because of its blackfriday deal and i have to say it sounds really good. Perhaps better than the two lossless methods above.

What does science has to say about this. Is re-encoding (even to a lossless format) inherently lossy?

 

[tw99]

FLAC to ALAC at the same bit depth and rate is totally transparent.

 

[abdo123]

FLAC to ALAC at the same bit depth and rate is totally transparent.

Do you mean a CD rip or converting FLAC to ALAC and vise versa? There is a big difference.

 

[tw99]

Do you mean a CD rip or converting FLAC to ALAC and vise versa? There is a big difference.

I meant exactly what I wrote.

It's also true if the FLAC or ALAC file contains a CD ripped at 44.1/16, you can convert them backwards and forwards as many times as you like with no effect at all.

 

[sigbergaudio]

FLAC/ALAC is basically like zip, lossless compression and everything can be restored when decompressing. So there should be no loss when converting back and forth.

 

[abdo123]

FLAC/ALAC is basically like zip, lossless compression and everything can be restored when decompressing. So there should be no loss when converting back and forth.

This is not about ALAC, i did a double blind test and i could tell everytime when Airplay was used. It does has an influence i’m sure.

 

[sigbergaudio]

This is not about ALAC, i did a double blind test and i could tell everytime when Airplay was used. It does has an influence i’m sure.

OK, so it's not clear from your first post (apologies if I'm missing anything) what you are comparing to. FLAC over Airplay sounds different than what?

 

[abdo123]

OK, so it's not clear from your first post (apologies if I'm missing anything) what you are comparing to. FLAC over Airplay sounds different than what?

Playing the track directly (on the streamer).

 

[tuga]

Playing the track directly (on the streamer).

Could it be that the processing (FLAC to ALAC conversion) is causing audible "artefacts"?

Have you tried streaming ALAC and thus bypass the FLAC to ALAC conversion?
If so, how does that compare to streaming FLAC?

 

[abdo123]

Could it be that the processing (FLAC to ALAC conversion) is causing audible "artefacts"?

Have you tried streaming ALAC and thus bypass the FLAC to ALAC conversion?
If so, how does that compare to streaming FLAC?

i have a few CD rips to ALAC, but for those I don’t have the FLAC version so i’m not sure if it’s a faithful comparison. I can use Tidal for FLAC over Airplay but i cannot eliminate stuff like different masters and stuff.

I remember there was a website that you can download the same tracks in different formats. Maybe i can try that?

 

[tuga]

i have a few CD rips to ALAC, but for those I don’t have the FLAC version so i’m not sure if it’s a faithful comparison. I can use Tidal for FLAC over Airplay but i cannot eliminate stuff like different masters and stuff.

I remember there was a website that you can download the same tracks in different formats. Maybe i can try that?

You can download a Qobuz purchased track in AIFF, ALAC, FLAC and WAVE.

 

[abdo123]

You can download a Qobuz purchased track in AIFF, ALAC, FLAC and WAVE.

So i need a 16/44.1 Khz track. Any recommendations?

 

[ElNino]

What does science has to say about this. Is re-encoding (even to a lossless format) inherently lossy?

Airplay is not inherently lossy for 16/44.1kHz media, BUT the protocol does not actually sync the sending and receiving clocks, so the protocol does have to perform receiver-side resampling to handle clock drift, in cases where there is substantial clock drift. This can be a source of differences in sound between different Airplay implementations.

You can confirm this by looking at Apple's actual reference source code for the protocol, which has been leaked and you can find on various sketchy websites if you hunt around.

 

[Vini darko]

http://www.2l.no/hires/
This is the site with the colection of free music in most hires formats. However i dont see alac there.

 

[abdo123]

Airplay is not inherently lossy for 16/44.1kHz media, BUT the protocol does not actually sync the sending and receiving clocks, so the protocol does have to perform receiver-side resampling to handle clock drift, in cases where there is substantial clock drift. This can be a source of differences in sound between different Airplay implementations.

You can confirm this by looking at Apple's actual reference source code for the protocol, which has been leaked and you can find on various sketchy websites if you hunt around.

Thank you for the detailed response.

how is it in comparison to DLNA? Or Roon transport?

 

[ElNino]

Thank you for the detailed response.

how is it in comparison to DLNA? Or Roon transport?

DLNA and Roon transport are pull-based protocols. The receiver pulls as much as it needs to buffer and play, on its own time, so there's no need to synchronize clocks or resample.

 

[abdo123]

DLNA and Roon transport are pull-based protocols. The receiver pulls as much as it needs, on its own time, so there's no need to resample.

is there a reason (other than the impressive feature pack that Roon has) for Roon transport to be better than DLNA or is it just my bias?

 

[ElNino]

is there a reason (other than the impressive feature pack that Roon has) for Roon transport to be better than DLNA or is it just my bias?

Roon has more features, like multi-room support.

 

[Soniclife]

how is it in comparison to DLNA? Or Roon transport?

Roon have information about how they handle it at the following link.
https://help.roonlabs.com/portal/en/kb/articles/airplay-setup

There are issues* with airplay that may cause audible issues, it also may work great, given the price of things like a Pi there is no reason to use it with Roon, or many other players as your main way of playing music, it's a nice option to have in a system though.

 

[tuga]

So i need a 16/44.1 Khz track. Any recommendations?

A track you know well, perhaps something with a wide dynamic and frequency range.