How to check if something is bit perfect?

[Keith_W]

Situation: I want to use my Android tablet to stream music to my PC. The reason I want to do this is because I want to use Idagio (classical music streaming) and this is the only way to have some kind of remote control.

I came across Soundwire and Airdroid, which both cast audio from the tablet to PC via wired USB, Bluetooth, or Wi-Fi. A companion app needs to be installed on both tablet and PC. As I understand it, the tablet receives the stream and then it sends it to the PC. Obviously Bluetooth is out, since it is lossy. But I do not know if the wired USB options or Wi-Fi is bit perfect. I checked their forums and did a Google search but came up with nothing.

Is there a way to check if the audio received on the PC is bit perfect compared to the original stream?

 

[wwenze]

Try Googling the DTS test. Emphasize on try because it seems the articles about it have already disappeared since it is so old.

The idea: DTS is just a PCM .WAV file containing digital data (that sounds like noise) but when fed to a DTS decoder the decoder knows it is DTS and produces music. If the PCM was sent without alteration the DTS player will play music, if the PCM was altered then it plays noise.

And just some short comments:

1) The implementation matters more than the physical layer connection. With many YouTube streamer/"caster" e.g. The phone tells the TV to play this YouTube video or Spotify audio, the TV actually grabs the video or audio from YouTube or Spotify itself. In which case the result is identical for both phone and TV i.e. the TV will stream lossless from Spotify if able to. For screen mirroring / audio output device emulation, it is pretty much guaranteed to be not bit-perfect because of timing restrictions unless the interface is specifically designed to be bit-perfect.

2) I'm not really bothered. I even found my Musiland USD don't do bitperfect outside of bitstreaming mode (or is it unable to bitstream period, can't remember) but I don't care.

 

[TonioRoffo]

The above method is indeed the perfect way to measure bitperfect playback, I used this in the past.

There is a second way - if you have a HDCD capable receiver, you can rip a HDCD CD to WAV or FLAC and play that back through your receiver, check for the HDCD indicator to come on & stay on. Be sure to have maximum volume on the source or it will alter the bits for sure.

Here is a list:

...of HDCD CD's