Chromecast Audio into nDac

Odd...
nDAC will indicate hi-res audio feed on any connection type. Hi-res means 48 kHz and above.

Quite ofthen there is a problem with a source actually sending the hi-res file. Some sources simply restrict data output on digital connections forcing the source to down-sample the material.
So in your case if FLAC is working, so should WAV. Are you sure your WAV file is actually a high-res one?

Yes, WAV files certainly hi-res. I think it must be to do with Plex, as I believe Chromecast Audio is able to "cast" both FLAC and WAV, it's only limitation being a maximum rate of 24/96, i.e. not able to deal with 24/192. I guess it transcodes these down to 24/96, but not absolutely sure.

What app are you using on the iPad, and how are you configuring the cast?

It's entirely possible that the app on the iPad is informing Plex that it can't handle the bitrate of 24/96 LPCM so Plex is transcoding to 16/44.1 for it.

Unfortunately my technical understanding of the topic is limited! Chromecast Audio is streaming the content, and I know that it allows playback up to 24/96 in both FLAC and WAV. I am not sure about Plex Media Server though. It certainly allows playback through the nDac, and with hi-res FLAC, I assume is recognising the higher bit rate, as both the sync and hd lights on the dac are illuminated. But as I said earlier for WAV files, which I know to be hi-res, only the sync light is on. ???   

I assume you are using the Plex app on the iPad, and Plex Media server on a PC...  Is this so?

Happy to read that the Sound Quality is well. I would trust your nDac and assume that there is indeed some transcoding done to e.g. Mp3. Have had that problem on Synology.

Chromecast Audio can handle FLAC and WAVE (LPCM) to 24/96 directly without transcoding, provided the WiFi connection is good enough.

Yes Huge, I'm using Plex App on IPad and Plex Media Server on PC. Also in response to Ardgeg10y's post, it is my understanding that Chromecast can handle FLAC and WAV up to 24/96 as you indicate. Assumption therefore that Plex must not like WAV? I am assuming of course that the facia lighting on the nDac will always accurately indicates the hd quality? 

Further to my above post, I've just read on the Plex site that Plex does support FLAC and WAV (together with some others) and that others will be transcoded. So, still not sure why nDac nd light not lit. Could it be the Plex app itself or the nDac??

It may be the quality of your WiFi connection.  Transmitting an LPCM stream from a WAVE file requires twice the bandwidth (and 1/2 the latency) that's needed for the compressed data from a FLAC file.

If Plex detects a lower quality of connection, it may decide to downsample the LPCM stream to get reliability.

Thanks Huge, that sounds plausible. I'll play safe and convert/play my files in FLAC. Just listening to Wayne Shorter - Speak no Evil on 24/96 FLAC and sounding excellent!

A Chromecast with the optical connection is way better than it has any right to be for £20!

I've found that I can even stream FLAC at 24/192 IF the WiFi connection is stable enough (which it often isn't!).

Huge posted:

It may be the quality of your WiFi connection.  Transmitting an LPCM stream from a WAVE file requires twice the bandwidth (and 1/2 the latency) that's needed for the compressed data from a FLAC file.

Sorry Huge, where do you get this from? FLAC will in many real world scenarios be about 75% of PCM for the same bit depth and sample rate - and of course if your file is white noise - it will be pretty much the same as PCM. Also not sure of the latency issue per se - latency for a given throughput will depend on the negoitated TCP window sizes of the send and receive hosts.

I think the real consideration of Wifi verses regular layer 2 Ethernet is that Wifi has a huge overhead and so only about  30% to 40% of the bandwidth is typically used for the payload (with the Naim wifi protocols) in typical good wifi conditions. In wired Ethernet with a MTU of 1500 bytes the typical overheads using TCP are only 20 bytes with 14 bytes for Ethernet frame header

S

I agree Huge. I paid £35 for chromecast audio and the digital cable. It is genuinely better than it has any right to be. Your point about 24/192 is interesting, as Google indicate it can play up to 24/96. 

Simon-in-Suffolk posted:

Huge posted:

It may be the quality of your WiFi connection.  Transmitting an LPCM stream from a WAVE file requires twice the bandwidth (and 1/2 the latency) that's needed for the compressed data from a FLAC file.

Sorry Huge, where do you get this from? FLAC will in many real world scenarios be about 75% of PCM for the same bit depth and sample rate - and of course if your file is white noise - it will be pretty much the same as PCM. Also not sure of the latency issue per se - latency for a given throughput will depend on the negoitated TCP window sizes of the send and receive hosts.

I think the real consideration of Wifi verses regular layer 2 Ethernet is that Wifi has a huge overhead and so only about  30% to 40% of the bandwidth is typically used for the payload (with the Naim wifi protocols) in typical good wifi conditions

S

 

Simon, I've found that in practice FLAC(5) gives file sizes 50%-60% of WAVE, and about 75%-80 percent when using FLAC(0).  The usual estimate for FLAC(5) is normally quoted as 50%.  The latency issue is complicated and I didn't want to go into details that confuse people, but as you rightly say, in reality it's highly dependant on the negotiated configuration (details of which most people are completely unaware as they don't need to know the minutiae!)

I wasn't comparing Wired to WiFi as the Chromecast Audio can't use regular layer 2 wired Ethernet!

HardBop posted:

I agree Huge. I paid £35 for chromecast audio and the digital cable. It is genuinely better than it has any right to be. Your point about 24/192 is interesting, as Google indicate it can play up to 24/96. 

Google only quote 24/96 as that's the limit of reliability under all but the MOST favourable conditions.  The DAC and processing chips are however 24/192 capable, it's just that in reality WiFi isn't really capable of this with sufficient reliability to claim it as viable!

Huge posted:

Simon, I've found that in practice FLAC(5) gives file sizes 50%-60% of WAVE, and about 75%-80 percent when using FLAC(0).  The usual estimate for FLAC(5) is normally quoted as 50%.  The latency issue is complicated and I didn't want to go into details that confuse people, but as you rightly say, in reality it's highly dependant on the negotiated configuration (details of which most people are completely unaware as they don't need to know the minutiae!)

I wasn't comparing Wired to WiFi as the Chromecast Audio can't use regular layer 2 wired Ethernet!

Wow - you are lucky - I use FLAC 8 and over a typical album I see 75 % and occasionally if I am lucky 60% - you are very luck with your music - do you listen to a lot of sine wave tones 

When I look at my network - I typically see the FLAC data moving between .8Mbps and 1.1Mbps - and PCM is a steady 1.411Mbps plus a tiny overahead. Clearly at points of silence - which there is a surprising amount of in music - the rate drops right down - but not to zero.

That really surprises me;      I have no way to explain the differences we find (but I can definitely see why you though my figures were odd!).

I think you might be looking at file length ?? I am looking at the  non silence  throughput at a point in time as FLAC is vbr such as I see on an network taking the extremes out... silence at the end and start and pauses compresses right down in FLAC but not in PCM of course.. that is the only thing I can think that would explain it..

I'm looking at file length but only where silence is less than 1% of time (i.e. max 2% error at 50% file length!).  I'm aware of the typical behaviour of compression algorithms, and aware that FLAC uses RLE for constant, predictable signals.  Your method will give better information as the bandwidth requirement has to be for peak, not mean bandwidth.

Point taken:  Best to rely of an estimate of 75% bandwidth requirement when comparing FLAC to LPCM.

Can you you do a moving average data rate as you go through your file? - it might be i am ignoring the tails more and you are including them - the wifi issue throughput issue will be determined by the VBR at a point in time of course.. edit just seen your update.. funny old game 

I think you crossed over with my edit!

Huge posted:

 

I wasn't comparing Wired to WiFi as the Chromecast Audio can't use regular layer 2 wired Ethernet!

There is actually an utp / power adapter available for the ChromeCast Audio.

Stick in the utp cable in the adapter and the CCA is hardwired.

I have it and it does lower the latency times drastically. Also dropouts are reduced much more.