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  1. #1
    Senior Member AndrewFG's Avatar
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    Settings | Advanced | File Types & Settings | Player | Audio?

    How does Settings | Advanced | File Types work?
    And does Settings | Player | Audio have any impact on it?

    If I understand it correctly, SqueezeCenter can convert any given input file type on the fly to three or four different other stream formats before sending it to the player concerned ??

    If so, what are the parameters of e.g. client PC, O/S, SqeezeCenter, LAN type, LAN speed, player type etc. that determine which actual stream format is sent?

    All of my music files are in Apple MP4 (file extension .M4A) and 99% of them are are encoded using Apple Lossless. Is this what you call "alac"? The File Types page allows conversion of Apple Lossless to FLAC, MP3 or WAV. I suppose the best stream type for my files is FLAC? Or is it WAV? And are there any circumstances why I would want SqueezeCenter to convert to any other format than the best? Is it safer to disable all but the best formats?

    Presently my players are a Transporter and a Duet. Perhaps, in future -- when the feature finally becomes available -- I may also play music over SoftSqueeze/SqueezePlay or the audio outputs on the Duet controller...

    This leads to my next question: does Settings | Player | Audio have any impact on how Settings | Advanced | File Types works? Do any of the player specific crossfade, clock, bitrate limiting, LAME quality level, volume adjustment, replay gain, settings have any impact on the stream format that SqueezeCenter sends? And what happens when I have two (different type) players synchronized to the same music?

    Finally are there any plans for Transporter and Duet to handle Apple Lossless natively in firmware, and thus eliminate all this trancoding entirely?
    Regards,
    AndrewFG

    Try out Whitebear. The middleware that joins the two worlds of:
    1. UPnP/DLNA media clients and media players, and,
    2. Squeezebox Server and Squeeze Players
    Download it for free here: http://www.whitebear.ch/mediaserver

  2. #2
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    Andrew - that's a mega-question!
    I'll make a start:
    1) Slim can't support Apple natively because Apple is a proprietory format - sorry but AFAIK that will never happen, thanks to Apple.
    2) Your player settings are independent of each other - even when synced.
    3) You should set ALAC to stream as FLAC for minimum impact on your network.
    4) Some features (eg replaygain) don't work if streaming WAV instead of FLAC/MP3
    5) if you specific "no limit" in the limit bitrate box, then it will stream FLAC or WAV - not sure how it chooses which if both are enabled. If you set limiting, it will stream as MP3 instead (unless youhave disabled this option in file settings)

    6) LAME quality level is about degree of compression vs. CPU load not sound quality - leave it set on 9
    7) not sure if crossfade works with WAV? - maybe FLAC/MP3 only
    8) some people need to stream as MP3 for marginal wi-fi setups or for streaming across the net.
    You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...
    Touch(wired/W7)+Teddy Pardo PSU - Audiolense 3.3/2.0+INGUZ DRC - MF M1 DAC - Linn 5103 - full Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Pekin Tuner, Townsend Supertweeters,VdH Toslink,Kimber 8TC Speaker & Chord Signature Plus Interconnect cables
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  3. #3
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    Quote Originally Posted by AndrewFG View Post
    How does Settings | Advanced | File Types work?
    And does Settings | Player | Audio have any impact on it?
    They're related. First comes the File Types settings, which is universal and mostly tells SqueezeCenter what it is permitted to do as far as streaming and transcoding are concerned. Its only practical function, as I see it, is to permit the user to disable streaming in some particular format. Since Flac is normally the default format use, then this in turn means it's only really useful for forcing streaming in WAV.

    If so, what are the parameters of e.g. client PC, O/S, SqeezeCenter, LAN type, LAN speed, player type etc. that determine which actual stream format is sent?
    OS (and the software expected to be installed on that OS) determines which conversions might be found on the File Types page.

    The actual streaming format is determined by that, the player type, and the bitrate limiting setting on the player's Audio setting page.

    With lossless file formats, newer (Squeezebox2 and later) players will normally use Flac for streaming. Older players, which aren't capable of decoding Flac in their firmware, will be sent a WAV stream.

    All of my music files are in Apple MP4 (file extension .M4A) and 99% of them are are encoded using Apple Lossless. Is this what you call "alac"?
    Yes and no. Apple Lossless is often referred to as ALAC. But on the File Types page, at least on my Windows system, the file format is shown as "Apple Lossless" and the decoder "alac" refers to the alac.exe program that is used to decode the format.

    The File Types page allows conversion of Apple Lossless to FLAC, MP3 or WAV. I suppose the best stream type for my files is FLAC? Or is it WAV?
    You shouldn't have to worry about it, as the best format will automaticlaly be chosen. But see the next answer, below.

    And are there any circumstances why I would want SqueezeCenter to convert to any other format than the best?
    Two that I can think of. One practical, the other fairly controversial and argued in other threads.

    If you have wireless network issues, you might want to set bitrate limiting just to get wireless streaming to work. This is particular the case for older players that must be streamed WAV over a slower 802.11b network and that have small buffers, making dropouts much more common than with newer players.

    The other reason is debatable, but I'll mention it, and hope the thread doesn't go off on a tangent. Some audiophiles claim that WAV sounds better than Flac (and some claim Flac sounds better than WAV, so it goes both ways). This shouldn't be the case, as Flac is lossless and will decode to exactly the same bits and bytes. Theories on why this might be the case generally speculate that the greater CPU activity needed to decode the Flac stream has a negative audible effect. Conversely, speculation as to why Flac might sound better than WAV is that the CPU and network electronics actually do less work handling the lower network traffic.

    They sound exactly the same to me.

    Is it safer to disable all but the best formats?
    Can't hurt anything, but it's no "safer".

    Disabling, say, Mp3 streaming for ALAC, won't accomplish anything if you don't have bitrate limiting set. I stream from my home SqueezeCenter to my work computer running Squeezeslave, with a library in Flac. The only practical way to do that is to set bitrate limiting and stream in Mp3. But that only affects that one player, and the others are streamed in Flac.

    This leads to my next question: does Settings | Player | Audio have any impact on how Settings | Advanced | File Types works?

    Do any of the player specific crossfade, clock, bitrate limiting, LAME quality level, volume adjustment, replay gain, settings have any impact on the stream format that SqueezeCenter sends?
    Just bitrate limiting. Setting it to anything other than 'No Limit' will mean transcoding to Mp3.

    And what happens when I have two (different type) players synchronized to the same music?
    You won't have to worry about it unless you have a pre-SB2 player synched to a newer one. All the newer players have the same decoding capabilities in their firmware.

  4. #4
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    Quote Originally Posted by Phil Leigh View Post
    6) LAME quality level is about degree of compression vs. CPU load not sound quality - leave it set on 9
    That's incorrect. It isn't a compression level, but a separate quality level. This is a LAME setting, so it's only used when bitrate limiting is set. It would be nice if related options like this in the SC server settings could be grayed out or hidden when another makes it moot.

    According to the LAME documentaion:

    Code:
      Noise shaping & psycho acoustic algorithms:
        -q <arg>        <arg> = 0...9.  Default  -q 5 
                        -q 0:  Highest quality, very slow 
                        -q 9:  Poor quality, but fast 
        -h              Same as -q 2.   Recommended.
        -f              Same as -q 7.   Fast, ok quality
    By default it's set at -q 9 in SC, I suppose, just to be safe, but I see very little difference in CPU usage on the server when set to -q 2. Using -q 0 on my server does show a bit more CPU.

    Anyway... only relevant when bitrate limiting is forcing transcoding to Mp3. Most people only use this for remote streaming to a player off of their home network.

  5. #5
    Senior Member AndrewFG's Avatar
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    Quote Originally Posted by JJZolx View Post
    The other reason is debatable, but I'll mention it, and hope the thread doesn't go off on a tangent. Some audiophiles claim that WAV sounds better than Flac (and some claim Flac sounds better than WAV, so it goes both ways). This shouldn't be the case, as Flac is lossless and will decode to exactly the same bits and bytes. Theories on why this might be the case generally speculate that the greater CPU activity needed to decode the Flac stream has a negative audible effect. Conversely, speculation as to why Flac might sound better than WAV is that the CPU and network electronics actually do less work handling the lower network traffic.

    They sound exactly the same to me.
    I notice that on Settings | Advanced | File Types | Apple Lossless, the dropdown selection box for FLAC offers "alac/flac" whereas the dropdown for WAV offers "alac".

    Does this mean that when Apple Lossless is transcoded to FLAC it goes through first an ALAC processor and then a FLAC processor? Whereas when it is transcoded to WAV it only goes through the ALAC processor?

    If so, then I would naturally assume that the simpler solution (via WAV) would be better. Any comments??

    Also what happens at the player end? Is WAV transcoded to FLAC or vice versa? I may be a bit simple in the head (or I perhaps I am just an audiophile) but I would imagine that whichever end-to-end path has the fewer overall transcoding steps, would ultimately be the one that sounds better??
    Regards,
    AndrewFG

    Try out Whitebear. The middleware that joins the two worlds of:
    1. UPnP/DLNA media clients and media players, and,
    2. Squeezebox Server and Squeeze Players
    Download it for free here: http://www.whitebear.ch/mediaserver

  6. #6
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    Quote Originally Posted by AndrewFG View Post
    I notice that on Settings | Advanced | File Types | Apple Lossless, the dropdown selection box for FLAC offers "alac/flac" whereas the dropdown for WAV offers "alac".

    Does this mean that when Apple Lossless is transcoded to FLAC it goes through first an ALAC processor and then a FLAC processor? Whereas when it is transcoded to WAV it only goes through the ALAC processor?

    If so, then I would naturally assume that the simpler solution (via WAV) would be better. Any comments??

    Also what happens at the player end? Is WAV transcoded to FLAC or vice versa? I may be a bit simple in the head (or I perhaps I am just an audiophile) but I would imagine that whichever end-to-end path has the fewer overall transcoding steps, would ultimately be the one that sounds better??
    From a sound quality point of view, lossless is lossless and it doesn't matter how long the code path length is, the sound remains the same...
    You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...
    Touch(wired/W7)+Teddy Pardo PSU - Audiolense 3.3/2.0+INGUZ DRC - MF M1 DAC - Linn 5103 - full Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Pekin Tuner, Townsend Supertweeters,VdH Toslink,Kimber 8TC Speaker & Chord Signature Plus Interconnect cables
    Stax4070+SRM7/II phones
    Kitchen Boom, Outdoors: SB Radio, Harmony One remote for everything.

  7. #7
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    Quote Originally Posted by JJZolx View Post
    That's incorrect. It isn't a compression level, but a separate quality level. This is a LAME setting, so it's only used when bitrate limiting is set. It would be nice if related options like this in the SC server settings could be grayed out or hidden when another makes it moot.

    According to the LAME documentaion:

    Code:
      Noise shaping & psycho acoustic algorithms:
        -q <arg>        <arg> = 0...9.  Default  -q 5 
                        -q 0:  Highest quality, very slow 
                        -q 9:  Poor quality, but fast 
        -h              Same as -q 2.   Recommended.
        -f              Same as -q 7.   Fast, ok quality
    By default it's set at -q 9 in SC, I suppose, just to be safe, but I see very little difference in CPU usage on the server when set to -q 2. Using -q 0 on my server does show a bit more CPU.

    Anyway... only relevant when bitrate limiting is forcing transcoding to Mp3. Most people only use this for remote streaming to a player off of their home network.

    I stand corrected! - I can't hear any obvious differences between the settings on a casual check.
    You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...
    Touch(wired/W7)+Teddy Pardo PSU - Audiolense 3.3/2.0+INGUZ DRC - MF M1 DAC - Linn 5103 - full Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Pekin Tuner, Townsend Supertweeters,VdH Toslink,Kimber 8TC Speaker & Chord Signature Plus Interconnect cables
    Stax4070+SRM7/II phones
    Kitchen Boom, Outdoors: SB Radio, Harmony One remote for everything.

  8. #8
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    Quote Originally Posted by AndrewFG View Post
    I notice that on Settings | Advanced | File Types | Apple Lossless, the dropdown selection box for FLAC offers "alac/flac" whereas the dropdown for WAV offers "alac".

    Does this mean that when Apple Lossless is transcoded to FLAC it goes through first an ALAC processor and then a FLAC processor? Whereas when it is transcoded to WAV it only goes through the ALAC processor?
    Yes.

    If so, then I would naturally assume that the simpler solution (via WAV) would be better. Any comments??
    Better how? If you get no interruptions in playback then one is as good as the other. If you had a really really really slow server, then _maybe_ only decoding to WAV would be better.

    Also what happens at the player end? Is WAV transcoded to FLAC or vice versa? I may be a bit simple in the head (or I perhaps I am just an audiophile) but I would imagine that whichever end-to-end path has the fewer overall transcoding steps, would ultimately be the one that sounds better??
    At the player end Flac is decoded to WAV/PCM.

    The trancoding doesn't alter the bits at all - nothing is lost. In any case, it can't hurt to try it streamed as WAV instead of Flac. If you connect using wired ethernet it will make very little difference in reliability due to bandwidth issues. If you use wireless and get dropouts, go back to streaming in Flac.

  9. #9
    Senior Member AndrewFG's Avatar
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    Quote Originally Posted by Phil Leigh View Post
    From a sound quality point of view, lossless is lossless and it doesn't matter how long the code path length is, the sound remains the same...
    Indeed lossless is lossless. No dispute on this truism.

    But on the other hand if you ask the sound processing to jump through hoops on the journey from A to B then the more hoops you add, the higher the chances that something WILL get lost.

    { I hope you guys are not designers for nuclear power stations. Personally I prefer the main coolant feed to the reactor to be as short as possible, rather than making a detour round my back yard. }
    Regards,
    AndrewFG

    Try out Whitebear. The middleware that joins the two worlds of:
    1. UPnP/DLNA media clients and media players, and,
    2. Squeezebox Server and Squeeze Players
    Download it for free here: http://www.whitebear.ch/mediaserver

  10. #10
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    Quote Originally Posted by AndrewFG View Post
    Indeed lossless is lossless. No dispute on this truism.

    But on the other hand if you ask the sound processing to jump through hoops on the journey from A to B then the more hoops you add, the higher the chances that something WILL get lost.

    { I hope you guys are not designers for nuclear power stations. Personally I prefer the main coolant feed to the reactor to be as short as possible, rather than making a detour round my back yard. }

    I am a designer of VERY large scale computer systems, and I'm more than happy to state that lossless audio computer software doesn't behave like analogue electronics! ). There is no direct equivalent of transfer loss or generation loss.

    There is no "sound processing", just lossless audio data processing. This has been definitely proven many, many times. If you compare the bits from the CD to what comes out - no matter what lossless chain is in the way - the bits are the same.

    Given an accurate rip and lossless data transmission to the DAC, the audiophile paranoia really starts at the DAC and everything beyond. everything upstream of the Squeezebox is irrelevant to sound quality, given the above caveats.
    You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...
    Touch(wired/W7)+Teddy Pardo PSU - Audiolense 3.3/2.0+INGUZ DRC - MF M1 DAC - Linn 5103 - full Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Pekin Tuner, Townsend Supertweeters,VdH Toslink,Kimber 8TC Speaker & Chord Signature Plus Interconnect cables
    Stax4070+SRM7/II phones
    Kitchen Boom, Outdoors: SB Radio, Harmony One remote for everything.

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