FOREWORD: This is pretty dry post on my journey as I discover how audio is played on my home theatre system.
Setting up an audio system is easy.
BUT, if you want the audio to be played at it’s best quality, then it gets complicated.
Even as tech geek, I am confused on how I can play a music at it’s best quality.
My home system setup is as such:
- Apple TV - For my Macs and iPhones to airplay to it
- AV Receiver - A budget Yamaha RX-V377 to receive input from Apple TV via HDI, and output to the 5.1 speaks and TV projector
- iMac 2014
- Macbook 2015
Many of my audio and video are played from the mac via airplay to Apple TV.
What is best quality music?
Many of us know music as MP3.
But do you know MP3 is not music in it’s best form?
MP3 is actually a compressed format, and very popular, because it compresses a lot of data, sacrificing some quality along the way, yet still sounds great.
It loses quality during compression.
FLAC and ALAC Lossless format
A lossless format is FLAC. It’s don’t loss any quality. It’s like zip.
For some reason, Apple has it’s own version of FLAC, known as ALAC. Not surprisingly, Apple products such as iTunes don’t support FLAC. Of course it supports ALAC.
Therefore, if you have FLAC, you need to cover to ALAC. Fortunately, X Lossless Decoder (XLD) is a free Mac app to convert easily.
FLAC (or ALAC) is what you first need for best quality audio.
Conclusion: When you airplay, use only ALAC (not MP3).
High Definition Audio (aka HD/HIFI)
Next, you would want the music to have high bit rate, and high sample rate.
You usually see 12 bit, 16 bit or 24 bit. And sampling rate at 44.1kHz, 96kHz, 192 kHz etc.
These are what define the quality of a audio.
Let’s assume our definition of a high definition audio is at least 24 bit, 96 kHz.
Conceptually how it should work..
Assume now we have a audio in ALAC (converted from FLAC) which is 24bit/96kHz.
When we play the ALAC file on Mac, it opens in iTunes, then stream via Airplay to Apple TV, which connects via HDMI to the AV receiver, and we hear the audio on the 5.1 speakers.
Yup, that is how the music flow through the system.
BUT, it doesn’t output 24bit/96kHz audio.
Why?
Because there is a technique used by system known as downsampling.
When your Mac airplay to Apple TV, it down sample all audio to 16 bit/44.1k.
So while the original audio file is at a higher quality of 24 bit/96k, it got down sampled. It got degraded.
Note: You can check this on your Mac. Open Audio MIDI Setup app > Select Airplay > Output format. The good news is that Airplay is already streaming in lossless ALAC.
Conclusion: Airplay is fine if your audio source is no more than 16 bit/44.1k.
How to play higher than 16 bit/44.1k
We now know Airplay is the culprit - any audio streamed via Airplay is at best 16 bit/44.1k. That is good, but not great.
We can’t change airplay.
A few solutions bypassing airplay:
- Connect Mac to receiver directly via Thunderbolt (Mini DisplayPort) to HDMI adaptor - support up to 24bit/192kHz
- Connect Mac to receiver directly via optical audio cable (iMac is able to connect optical audio via it’s 3.5mm headphone jack)Having a Mini Display to HDMI adaptor would be good as it can play both video and audio to the AV receiver.
You can buy on Apple Store - Moshi Mini DisplayPort to HDMI Adapter (4K) at $49 SGD - or from Amazon at $10 :)