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bonzuccio
2009-05-19, 15:19
Hi all,
I have some question for you about my duet.
The first question is about the "file types" page in the settings form of squeezecenter.How does it work exactly? For example I have all my files in flac format, in the file types page I have
Flac --> Flac --> Native
Flac --> Mp3 --> Disabled
Flac --> WAV --> flac
I immagine it's about the way the audio file is or not decoded and then sent to the duet receiver from squeezecenter but I hope someone will help me to understand the way it can be done.
The second question is about the way an audio file is sent to the duet receiver: a flac file is sent to the receiver as it is (the flac format) or is it decoded in the squeezecenter in WAV or PCM format instead?
The third question is about jitter: assuming that the audio file can be sent as is in its encoded form to the duet, is the ethernet protocol used able to verify that all bits sent are equal to the source file?
I hope that my English is quite understandable to have some answers :)
Ciao!

dsdreamer
2009-05-19, 22:36
Flac --> Flac --> Native
Flac --> Mp3 --> Disabled
Flac --> WAV --> flac


Means if the source is FLAC, and the stream type supported by the player is FLAC, then native (no transcoding) will be used.

You have disabled transcoding from Flac to MP3

Flac to WAV transcoding would be done if your streaming device was not capable of playing native FLAC. But, in fact, all modern squeezebox variants can decode FLAC streams natively.

Since the duet receiver is receiving a native FLAC stream, use *could* be made of the frame footer CRC-16 checksums for error detection and possible retransmission or frame blanking. However, I don't know much about how the streaming protocol works, so someone else should answer that part of your question.

Best regards,

bonzuccio
2009-05-19, 23:30
Ok thanks for your answers, so if in the third row of the flac type settings I disable Flac to WAV decoding I can be sure that no decode process is performed by the squeezecenter server.
In the same way, if the goal was to not to do any decoding at the receiver while playng a flac file could this decoding to PCM be done by the squeezecenter changing the settings to:
Flac --> Flac --> Disabled
Flac --> Mp3 --> Disabled
Flac --> WAV --> flac..(or disabled?)
Or is it possible only playng a wav file in this way?
WAV --> Flac --> Disabled
WAV --> Mp3 --> Disabled
WAV --> WAV --> native ??
It could go well if you wanted to bypass the problem of the lack of native support for file 24/96, assuming that the network interface supports the amount of data in transit that would be bigger.. and that the Wolfson DAC supports the convertion from 24/96 PCM

SuperQ
2009-05-20, 08:25
The 3 different selections are taken in order, the other ones are ignored. mp3 is commonly used if you enable bitrate limiting. If you have a duet, it will always be something like:

FLAC -> FLAC (native is best)
flac -> mp3 (ignored, FLAC is supported by your squeezebox)
flac -> wav (ignored, FLAC is supported by your squeezebox)

WAV -> FLAC (flac is best)
wav -> mp3 (ignored, as above)
...

dsdreamer
2009-05-20, 13:46
The 3 different selections are taken in order, the other ones are ignored. mp3 is commonly used if you enable bitrate limiting. If you have a duet, it will always be something like:

FLAC -> FLAC (native is best)
flac -> mp3 (ignored, FLAC is supported by your squeezebox)
flac -> wav (ignored, FLAC is supported by your squeezebox)

WAV -> FLAC (flac is best)
wav -> mp3 (ignored, as above)
...

In my opinion, his first proposal of:


Flac --> Flac --> Disabled
Flac --> Mp3 --> Disabled
Flac --> WAV --> flac

Would force the decoding from Flac to WAV to be done in the SC using the Flac executable. However, I don't think that any trick along these lines is going to help him stream a file at 24/96, which is simply not supported by the hardware.