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  1. #1
    Senior Member Philip Meyer's Avatar
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    Ripping and playing multi-channel audio

    I've never really understood why multi-channel ripped audio can't be ripped and played directly through Squeezeboxes.

    More and more products are being released in DTS/DD5.1/DVD-A formats. Why can't the audio be ripped to an ac3 file, and played through a squeezebox player without first wrapping the audio in a container file format?

    I have been using a utilitity that someone posted many years ago now called "spdifconvert.py" to do this. Is this a standard process that other audio players use? Are there any other tools to do this audio conversion?

    I recently got a 4-channel 96/24 LPCM DVD-A album. I can open this in Foobar and other desktop applications, and it plays back fine. I've ripped the music from Foobar to flac, and the flac files report the correct properties:

    Sample Rate: 96000 Hz
    Channels: 4
    Bits Per Sample: 24
    Bitrate 9216 kbps
    Codec: PCM

    I can play this back through PC, and it downmixes to 2 channels and sounds great.

    I don't think that spdifconvert.py can process this audio content, so I can't stream the album from SBS to my surround sound amp.

    (I should point out that 9Mbps would be too much for my Wifi network to stream anyway, but potentially I could stream from a Touch using TinySC to stream the audio from a USB stick?)

  2. #2
    Senior Member Mnyb's Avatar
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    Hmm i don't think there is a lossless multichannel format for one single spdif connection ?

    All DVD players outputs lossy multichannel formats like DTS and Dolby digital.
    Blue ray players does lossless but only over the hdmi not the spdif.

    I sometimes wrap a DTS or Dolby track as a FLAC file, this works but it is not lossless .

    So lossless multichannel over a squeezebox needs 3 or 4 spdif outputs or hdmi output, hint hint for future products .

    My Meridian DVD player uses a proprietary link with 3 parallel spdif's to move the DVD Audio to my processor.
    --------------------------------------------------------------------
    Main hifi: Rasbery PI digi+ MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub.
    Bedroom/Office: Boom
    Loggia: Raspi hifiberry dac + Adams
    Bathroom : Radio (with battery)
    iPad with iPengHD & SqueezePad
    (spares Touch, SB3, reciever ,controller )
    server Intel NUC Esxi VM Linux mint 18 LMS 7.9.2

    http://people.xiph.org/~xiphmont/demo/neil-young.html

  3. #3
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    Quote Originally Posted by Philip Meyer View Post
    I've never really understood why multi-channel ripped audio can't be ripped and played directly through Squeezeboxes.

    More and more products are being released in DTS/DD5.1/DVD-A formats. Why can't the audio be ripped to an ac3 file, and played through a squeezebox player without first wrapping the audio in a container file format?

    I have been using a utilitity that someone posted many years ago now called "spdifconvert.py" to do this. Is this a standard process that other audio players use? Are there any other tools to do this audio conversion?

    I recently got a 4-channel 96/24 LPCM DVD-A album. I can open this in Foobar and other desktop applications, and it plays back fine. I've ripped the music from Foobar to flac, and the flac files report the correct properties:

    Sample Rate: 96000 Hz
    Channels: 4
    Bits Per Sample: 24
    Bitrate 9216 kbps
    Codec: PCM

    I can play this back through PC, and it downmixes to 2 channels and sounds great.

    I don't think that spdifconvert.py can process this audio content, so I can't stream the album from SBS to my surround sound amp.

    (I should point out that 9Mbps would be too much for my Wifi network to stream anyway, but potentially I could stream from a Touch using TinySC to stream the audio from a USB stick?)
    SPDIF has limited bandwidth which won't support multi-channel lossless audio. This is why HDMI come in to become the standard for Blu-ray. High definition audio sure is the next wave. Most likely supported in the next generation of media players.

    However, squeezebox is able to support regular dvd ac3 or dts in 5.1 format. These formats encode multi-channels in pcm stream which will be handled by the player without problem. Output through the SPDIF or coaxial plug could go directly into home receiver and play as 5.1 format. The only trick is that you have to make sure the volume is at 100%.

  4. #4
    Senior Member Phil Leigh's Avatar
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    A Single spdif connnection can't handle this. You need 2 spdifs for a 4.0 playback.... or alternatively you could encode them as DTS and feed via a single spdif to an AV unit...

    I assume you want to play your DVD-A in stereo via the SB? In which case, you can either rip the native 2-ch hires versions/files from the DVD-A or...if there aren't any (e.g. ELP - Brain Salad Surgery) use the downmix capability of DVDAudio Explorer or Foobar to create them from the 5.1 files and the matrix file.
    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.

  5. #5
    Senior Member Philip Meyer's Avatar
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    Ripping and playing multi-channel audio

    Hmmm, multiple issues rolled up into one post I think has confused the discussion.

    In the past, I have ripped DD5.1 (ac3) and DTS 5.1 from DVDs, and to get these to play through Transporter -> Surround Sound amp, I've had to wrap the .ac3 or .dts audio into a flac file. This plays as static through a stereo amp.

    Why is this wrapping needed - why can't .ac3 or .dts files be detected by the scanner, and passed through the SB player digital out without going out to the stereo outputs?

    i.e. other media players understand .ac3 or .dts and play the files fine, without wrapping.

    ---

    In addition to that, I recently bought the 40th Anniversary Series of King Crimson albums.

    These have:
    MLP Lossless 5.1 Surround (48KHz, 24 bit)
    MLP Lossless 2.0 Stereo (96KHz, 24 bit)
    DTS 5.1 Digital Surround (48KHz, 24 bit)
    LCPM 2.0 Stereo (48KHz, 24 bit)

    I managed to extract the MLP Lossless 5.1 Surround using DVD Audio Extractor, played this in Foobar and saved as flac. The flacs play back fine in Foobar; when I tried to play on Transporter, it mucks the Transporter up - no output at all (either Digital out or Stereo out), and nothing else can be played until after I power cycle the player. I understand that perhaps this was ambitious - the files have a bitrate ~7Mbps.

  6. #6
    Senior Member Mnyb's Avatar
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    Quote Originally Posted by Philip Meyer View Post
    Hmmm, multiple issues rolled up into one post I think has confused the discussion.

    In the past, I have ripped DD5.1 (ac3) and DTS 5.1 from DVDs, and to get these to play through Transporter -> Surround Sound amp, I've had to wrap the .ac3 or .dts audio into a flac file. This plays as static through a stereo amp.

    Why is this wrapping needed - why can't .ac3 or .dts files be detected by the scanner, and passed through the SB player digital out without going out to the stereo outputs?

    i.e. other media players understand .ac3 or .dts and play the files fine, without wrapping.

    ---

    In addition to that, I recently bought the 40th Anniversary Series of King Crimson albums.

    These have:
    MLP Lossless 5.1 Surround (48KHz, 24 bit)
    MLP Lossless 2.0 Stereo (96KHz, 24 bit)
    DTS 5.1 Digital Surround (48KHz, 24 bit)
    LCPM 2.0 Stereo (48KHz, 24 bit)

    I managed to extract the MLP Lossless 5.1 Surround using DVD Audio Extractor, played this in Foobar and saved as flac. The flacs play back fine in Foobar; when I tried to play on Transporter, it mucks the Transporter up - no output at all (either Digital out or Stereo out), and nothing else can be played until after I power cycle the player. I understand that perhaps this was ambitious - the files have a bitrate ~7Mbps.
    .ac3 or .dts that would require an actuall DD and DDTS decoder in the player software if you want it to be downmixed and passed trough the stereo outputs. Of course such a decoder could be built in to squeezeboxserver, maybe a good project for a plugin author .

    For now the pass-trough principle is what works but it do yield static at the analog outs and don't work with replay gain or use of the volume controll .

    Note that no Squeezebox can handle an actual multitrack FLAC file that could be your problem. The FLAC file must be 2ch only foobar can play 5.1 ch flac files. You have probably made an 5.1 ch FLAC file .
    You should extract the 2.0 MLP or let the program downmix to 2.0 but I think the actual 2.o mix would be better , these auto remixes is not the same as when a sound engineer is doing it.
    --------------------------------------------------------------------
    Main hifi: Rasbery PI digi+ MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub.
    Bedroom/Office: Boom
    Loggia: Raspi hifiberry dac + Adams
    Bathroom : Radio (with battery)
    iPad with iPengHD & SqueezePad
    (spares Touch, SB3, reciever ,controller )
    server Intel NUC Esxi VM Linux mint 18 LMS 7.9.2

    http://people.xiph.org/~xiphmont/demo/neil-young.html

  7. #7
    Senior Member Phil Leigh's Avatar
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    Phil - if your TP is connected to a stereo replay chain, you want to extract the MLP Lossless 2.0 Stereo (96KHz, 24 bit) track from your KC DVD-A for use with your TP
    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
    Senior Member Philip Meyer's Avatar
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    Ripping and playing multi-channel audio

    >Phil - if your TP is connected to a stereo replay chain, you want to
    >extract the MLP Lossless 2.0 Stereo (96KHz, 24 bit) track from your KC
    >DVD-A for use with your TP


    My TP is connected to a stereo replay chain, and also a surround sound amplifier.

    I extract the lossless 2.0 stereo and this plays fine for stereo playback.

    I have no problem ripping .ac3 files from DVD, and converting into a wrapper file using spdiffconvert.py. This then plays 5.1 audio back fine through the surround sound amp.

    But this process is pretty slow:

    1. Rip using DVD Decrypter to a single .ac3 file, and a chapter information file.
    2. Use spdiffconvert.py to wrap the .ac3 content in a .wav container file.
    3. Convert .wav > .flac using dbPowerAmp
    4. Hand-create a .cue file from the chapter information.
    5. Open .cue in Foobar to convert the .flac file into a .flac per chapter/song.
    6. Use mp3Tag to enter tags.

    I was hoping for something a bit easier/quicker ;-)

    I'm wondering if there's any point - I might as well conceed and go back to inserting DVD discs into DVD player. This also prevents accidental wreckage of my stereo speakers when random play decides to play surround-sound audio on another player.

  9. #9
    Quote Originally Posted by Philip Meyer View Post
    I might as well conceed and go back to inserting DVD discs into DVD player...
    Heresy! I thought it was this sort of challenge that appealed to this community

    I bumped into this issue myself recently - it was quite a surprise actually - I took an SB3 and a couple of powerline adapters round to my dad's house to show him how he could unleash his music collection and, importantly, pipe it into his really nice Arcam surround setup. I wasn't expecting any technical challenges from my Dad, but the very first piece of music thrown at me to rip was a DVD-A by Sting... with resultant white noise when ripped straight to FLAC. Wouldn't you just believe it. Anyhow, the standard CD music brought a smile to his face.

    So your process above sounds intriguing... but as you have indicated, not without some drawbacks. I'll probably do some further experiments based on the dialogue above, once I've got a bit of spare time.

    I just wanted to register the view that, whilst I don't have any technical wizardry I can offer to solve this issue, this conversation is very helpful, and could be of interest to more people than you might assume, including my dad!

    Thanks
    sp.
    10TB N5200Pro/SB Server 7.8.0 > SB3 > Anthem MRX500 > PMC OB1i & Wafers
    SB3 > AudioEngine A5 and 3xSBRs

  10. #10
    Former Squeezebox Guy andyg's Avatar
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    There's no reason we couldn't support .ac3 and .dts files with the scanner and firmware. The only reason FLAC is used is because it is a simple workaround and works without any server or firmware changes. Supporting ac3/dts in the firmware would require adding a 'raw' mode that just passes everything directly to spdif while probably also disabling the analog outputs. It should also disable volume control in this mode.

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