Format Conversion / RAAT

that’s exactly the process I used.
Creating 3 from the same song 3 different versions to listen to

They sound different to me and to the people ( 3 ) I asked their feedback
The difference between FLAC 0 and WAV was challenging but FLAC 5 was recognised in seconds

Hmmm :thinking:

What is the playback chain for this? All from Roon or allowing the streamers to process them. I am unsure about the processes used here.

I understand but that was not the direction I was going here.
It is more that what I understood that RAAT is PCM transport.
But if we see on the Linn MP3 then is that metadata or is it indeed MP3. and is that Linn specific or is it how RAAT works ?
I started to connected/ related a question I posted a few years ago about FLAC.

My understanding is that when Roon talks to a Linn box, it uses a different protocol, not RAAT, that Linn and Roon worked out between the two of them. OpenHome?

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Buried in my long post above I pointed out this is an unknown. We only know that the PCM in is the PCM out (this can be / has been tested and verified by others). As to what exactly hits the wire for transport is unknown as its a closed specification.

It is very common for transport protocols to send metadata along with the stream. In the case of a Roon Ready device the device can retrieve artwork and original format. So, what it displays on the screen could be combination of this plus the actual PCM bitstream data. That will be implementation specific so don’t tryst the screen unless you really know what it is they are displaying. I trust the signal path.

I have no idea what the Linn transport protocol supports or what they decide to display or for where. That’s a Linn question.

As others pointed out… your ability to hear differences in various lossless containers can usually be caused by a poor USB implementation on a DAC connected to a PC (caused by the different amount of “work” the PC is doing to get to the PCM bitstream in the file). This variable goes away when using a network streamer and using the better (SPDIF) input of the DAC.

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I believe it uses the same thing that Linn Kazoo uses. Roon supports Linn natively just like they support Sonos natively. I don’t believe its something specific to the Roon / Linn combo. It’s just Roon supporting Kazoo. But I don’t work for either company so this is a guess.

Linn uses OpenHome for its streaming and Kazoo is an openhome server and client app.

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Indeed. Or „Songcast“ in Linn-Lingo. This is why Multizone works only among Linn Streamers in Roon.

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afaik open home is an advanced upnp server client solution where the server transports the unmodified! flac file to the renderer which decompresses it.
at least it worked that way in my old setup. there the used sever was not able to decompress anything and i could play flac files.
the raat protocol definitely transports meta data to the streamer. my dac can show track infos like track titles via rs232 from the streaming bridge that gets the data via raat from the roon server.

btw there is possibly an easy way to verfy this:
install the freeware wireshark and trace the tcp protocol.
if the transferred data is the same with a flac file and a decompressed file then you know what happens :wink: if everything works bit perfect the identical data should be somewhere in the stream.

More generally, Open Home is designed so that the endpoint does all the container and codec decoding. Of course it would be possible for the server to transcode the flie/stream input to whatever container/codec it is programmed to output to endpoints. Certainly that will happen if the server does DSP before sending the material to endpoints. If one reads Roon’s explanation for RAAT, their goal is to have a very uniform protocol that does not depend on what formats/codecs are already implemented on endpoints.

You do realize there is very little difference between FLAC compression levels 0 and 5. Flac level 0 compresses at about 71% while FLAC level 5 compresses at 66%. If there were a difference, it should be challenging to tell the difference between FLAC level 0 and FLAC level 5. FLAC Uncompressed should sound just like a WAV file since both contained the same exact uncompressed PCM data in a slightly different container.

The fact that you said telling the difference between FLAC level 0 and WAV was challenging, tells me this is indeed expectation bias.

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The fact that the compression difference (size) between 5 and 0 is minor I agree with.
That FLAC is bit perfect, yes I agree with that to.
The conclusion that it is therefore non hearable that…I disagree with.
3 other people came to the same conclusion.
My friend with the Linn DAC is able to hear the difference between FLAC 5 and FLAC 0 on his own system.

Strangely enough the response on FLAC compression never changes. We all except that there are sound differences between DAC’s, that a power supply matters, that Jitter is killing etc.
However that how things sound can differ as a result of the decompressing stage is false.
The connection between technology and what we hear is now disconnected

Like I wrote earlier, I have had this discussion around FLAC a few years ago where it very quickly moved from a technical topic into a " placebo " topic.

I don’t think you get my point.

You claim to hear a clear difference between FLAC level 0 and FLAC level 5. You claim it is “challenging” to hear the difference between FLAC level 0 and WAV. The problem with that is that FLAC level 0 and FLAC level 5 are only a 5% different in compression and MUCH more similar to each other than than FLAC level 0 and WAV. FLAC level 0 and WAV are 29% different as WAV has no compression at all.

So, do you see the issue here? I think you went in to this thinking that FLAC level 0 was much closer to WAV and that is what you think you heard. In reality, both FLAC levels are MUCH to each other than they are to the WAV files.

If you use a Roon endpoint (and a non-Linn DAC) this is all moot anyway as the end point receives the same PCM data regardless of file format or compression level. The endpoint buffers the data and send it to the DAC so timing isn’t an issues.

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Hi Speed_Racer, Perhaps I’m wrong but you still conclude that it’s impossible that it can lead to a difference in sound. and there we think different

You address it from a technical side and as there’s no technical clarification it’s false ( btw I agree with the technical analysis)
That said, I’m hearing a difference, and so do a few people I’ve asked to agree or disagree with me.
Now another person confirms he’s hearing it on his own system.

Because multiple people confirm that there’s a difference in sound it raised the question why is that ? Like I said, technical I agree it doesn’t make any sense.

I starting with streaming music 10 years ago, and coming out of IT packets were packets.
I have come a long way over the years. Some steps were easier to take then others :slight_smile:
I’m now to the level that I’m accepting, jitter, power supply noise, galvanic isolation, reflections, etc.
10 years ago I would group all of the above as " placebo"
I have learned that the best reference for qualifying music are my ears, not the technology and protocols

Let’s assume for a moment that compression levels or lack thereof do make a difference in sound quality. More compression sounds worse and less compression sounds better, right?

How do you explain your findings in that WAV and FLAC level 0 are “challenging” to tell apart while FLAC level 0 and FLAC level 5 are relatively easy to tell apart? After all, there is really very little difference between FLAC level 0 and FLAC level 5 while there is a rather large difference between WAV and FLAC level 0. By any measure, the FLAC compression levels should be harder to differentiate than a WAV and a FLAC compression level.

Or, are you going to tell me that I cannot apply logic to this phenomenon and just must accept that it is what it is?

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I’m not sure even that is a safe assumption, at least in part because ‘better’ is an individual subjective judgement. What anyone ‘prefers’ doesn’t necessarily correlate with ‘technically better’ and, if the processing required to unpack flac affects the analogue output, so might any other processing required, perhaps including the display of artwork and metadata.

Sometimes I’m surprised any of this works at all…

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@AndyR

Let’s look at the facts:

WAV, which has no compression, sounds best to @Hans_Bogaert. Second best is FLAC Level 0 with some compression and last is FLAC level 5 with the most compression. @Hans_Bogaert said that WAV and FLAC level 0 were “challenging” to tell apart while WAV and FLAC level 5 were not.

So, you are going to tell me that the although there is correlation between the sound quality and compression levels here, I should not assume causation? What then? Is it possible that FLAC level 1 might sound better than WAV? Or that FLAC level 8 might sound better than FLAC level 5?

Both FLAC level 0 and FLAC level 5 require processing to unpack the PCM data where that is not required by WAV. The difference in processing required is almost non-existent. So, if it is not unpacking the compression, what is it that causes WAV to sound better than FLAC to @Hans_Bogaert?

Correct. You should not assume causation. And yes, it’s quite possible that any particular level of flac compression might be preferred. After all, in some tests people prefer mp3. I’d guess that’s because it’s what they are used to, much like a preference for mild tape saturation…

How do you infer that it’s ‘not unpacking the compression’ from the assertion that the ‘difference in processing is almost non existent’?

To be clear, I’m not arguing the facts, more that some of the inferences are a bit iffy. Similarly, I’m sure @Hans_Bogaert heard differences, but is conflating ‘preference’ with ‘better’. And it’s very system dependent…

Edit - it might also be helpful to know how @Hans_Bogaert is feeding the three DACs listed; and also how the test files were prepared.

You can’t have it both ways. Either unpacking the compression is what matters here or unpacking the compression is not what matters. If compression makes a difference, the amount of compression must matter too. Or, do you want to tell me all that matters is that they are not the same and how they are different isn’t what matters, only that they are different.