Discussion in 'Audio Hardware' started by stereoptic, Jun 2, 2017.
I've successfully used FLAC for DoP. Decodes as pure DSD.
Huh? So you converted DSF to FLAC, and then played it back successfully as DSD?
Putting aside that doesn't sound at all possible, how and why did you find yourself in this situation?
It's a way of playing back DSD files using a system that handles PCM - I think I used a Pi running Volumio. FLAC is just compressed PCM, which in this case is actually a DSD file in a PCM wrapper (that is what DoP is). Since FLAC is lossless it is fine for this purpose.
I know what DoP - what you're describing isn't DoP. DoP begins with DSD, and uses a PCM wrapper as you say to pass the DSD information to a compatible DAC to decode. But you're saying you're using the FLAC format, which means you've converted the DSD to FLAC, which means you converted the DSD to PCM, and are playing PCM - NOT playing DSD over DoP.
No, it plays DSD as confirmed by the DSD light on my DAC. It's not really PCM in the FLAC, it's DSD over PCM. Not sure why this is so hard to grasp!
How to use the Squeezebox Touch to play DSD files on a DoP compatible DAC
From what I understand, that is the whole purpose of the codec. The fact that his DSD light is coming should be an indication that it is working.
As best I can tell by that Squeezebox article, there was a time when you had to "trick" a DAC (or some early implementations) into performing DoP by making it think its seeing a FLAC file?
This certainly isn't required anymore, assuming it ever was. The DAC itself is supposed to do all the work - Actually encapsulating DSD files inside PCM is nonsense, and makes them incompatible with any device that does native DSD. It's certainly possible to use an unadulterated DSD file with DoP.
That's just it - referring to DoP as a codec and a file format as that linked doc does is nonsensical. As I said, there might have been a very brief window of time when that was necessary for some hardware, but at this point its misinformation. I don't want people to stumble on this thread and determine they have to doctor their DSD files somehow to "make them into DoP". DoP just refers to the mechanism some (most) DSD capable DACs use in processing native DSD files.
Pic - I changed the title tag in the FLAC properties to make sure I had the right one!
Maybe this hack is still needed with the Squeezebox if DSF/DFF support was never added to it?
With any good modern software player DSF, DFF, Wavpack compressed DSD will all work with DoP and like Rolltide says it is the DAC that is doing the "unpacking".
The whole reason that I am doing this is so that my Raspberry pi running Squeezelite to pass the DSD signal to my receiver (through HDMI). Squeezelite will not play .dsf files. However my Squeezebox Touch does play .dsf files with the EDO plugin through coaxial output. However, the DSD light does not illuminate. I have to prepare a matrix of which equipment works with which file types, etc.
There is a plugin now, but not when I first did this. Still, I didn't want to suggest that this is the *best* approach, but it does work and can be handy; you get exactly the same result as playing a DSF or DFF.
I think it's a pretty neat hack to send DSD as 24/176, and I wouldn't have known about it if you didn't mention it. What I would love to see is FLAC adding support for DSD compression, just don't mention it on the Hydrogen Audio forums !
Interesting band aid. I didn't know people were doing this. Off topic for a quick question, is the bottleneck from the SBT or does Pi have an issue as well?
I've toyed with the idea of swapping Jriver for a Pi to remove a laptop from the equipment rack but if the Pi can't handle DSD then I'll skip it for a few years until they catch up.
As also mentioned by others, it's probably a good idea to include a tag and file naming convention to note that these aren't normal flacs. Could be problematic, like having an unlabeled pair of reverse polarity XLRs laying around.
Like I said earlier, there's what the Pi hardware can do, and then there's what the software can do. The MPD based players (Volumio, Runeaudio) can handle DSD just fine. The issue the OP is having seems to all relate to using the Squeezebox/Squeezelite.
What I badly want to catch up is gear that supports DSD over SPDIF. This is possible, just very rare, I've only seen a handful of DACs that support it. It seems doing away with the need for USB and/or HDMI eliminates a lot of nonsense.
The Fiio X3 can do DoP and output by its SPDIF, what I haven't tried yet is if it also outputs multichannel DSD 'though I don't think so, not because the Fiio X3 is a stereo player by its phones and analog line outputs but for the lack of bandwith of SPDIF to cope with such a high bandwith of multichannel DSD.
For anyone searching the web for info on DoP, this is incorrect.
Out of curiosity, what specifically is incorrect?
Fair question. The FLAC is lost, DSD has to be ISO, DSF or DFF...basically anything that says what comes out the other end of the DoP wrapper isn’t DSD.
Agree, but that's not what he was saying. He was saying once you convert a DSD file to a FLAC it's no longer DSD, it's PCM. He's not describing the process by which DOP sort of "cheats" by using a PCM wrapper.
Note too that this thread is describing a very specific and very unusual situation involving DSD as it relates to old squeezebox hardware. People were talking about how it was necessary to manually "convert" DSD to DOP in advance of playback, something that doesn't even make sense to anybody not in that particular niche.
Sorry, I was getting ready to board a plane and made a typo. You are correct. I meant to write “DSD is lost” is incorrect, not FLAC is lost. It remains DSD throughout. There is no FLAC to be lost per se. It’s never FLAC. It’s just a wrapper.
I’m familiar with the whole DoP/Squeezebox thing. Been using that method for quite some time. But it’s not exclusive to Squeezebox use and the poster posted generically. DoP is just one method of transporting DSD. It just so happens it’s the only way (AFAIK) with a Squeezebox.
The reason I ran across this thread is I was trying to find what current receivers/processors might handle DoP for multichannel since I have everything set up for this method and my current pre/pro is getting a little long in the tooth.
I am not aware of any.
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