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Thread: 48KHz playback?

  1. #1
    Auricle
    Guest

    48KHz playback?

    From a discussion back in April, I learned that the SB will support
    48KHz playback. I have extracted the audio from a DVD (a series of DJ
    mixes) to AC3. These files were converted to raw PCM and then
    compressed with FLAC.

    If I play these FLAC files on my SB, the audio sounds like it is being
    played back too slowly.

    I've confirmed that

    flac -dsc --force-raw-format --endian=big --sign=signed filename.flac |
    esdcat -r 48000

    sounds correct (on the computer speakers). If I don't specify the
    sample rate to esdcat I get the same "slow pitch" playback I hear from
    the SB. The default rate for esdcat is 44.1KHz, so it *seems* like
    SlimServer is making the same assumption on the sample rate.

    I'm using the optical digital out of the SB and my external DAC says
    the signal received is 44.1KHz.

    Am I misunderstanding what is going on here? Is there something else I
    need to do to get the correct sample rate?

    This is using today's (5.30) nightly build of the server on MacOS X
    10.3.4 and firmware V23 on the SB.

    --jeff

    --
    auricle (AT) io (DOT) com

  2. #2
    Gadfly, Former Founder Slim Devices dean's Avatar
    Join Date
    Apr 2005
    Location
    San Francisco, CA
    Posts
    4,427

    48KHz playback?

    Hi Auricle,

    Indeed, SlimServer is assuming that the sample rate for uncompressed
    (and converted) format is at 44.1k. This is a known bug and we'll be
    addressing it.

    Thanks,

    dean

    On May 30, 2004, at 9:03 PM, Auricle wrote:

    > >From a discussion back in April, I learned that the SB will support

    > 48KHz playback. I have extracted the audio from a DVD (a series of DJ
    > mixes) to AC3. These files were converted to raw PCM and then
    > compressed with FLAC.
    >
    > If I play these FLAC files on my SB, the audio sounds like it is being
    > played back too slowly.
    >
    > I've confirmed that
    >
    > flac -dsc --force-raw-format --endian=big --sign=signed filename.flac
    > | esdcat -r 48000
    >
    > sounds correct (on the computer speakers). If I don't specify the
    > sample rate to esdcat I get the same "slow pitch" playback I hear from
    > the SB. The default rate for esdcat is 44.1KHz, so it *seems* like
    > SlimServer is making the same assumption on the sample rate.
    >
    > I'm using the optical digital out of the SB and my external DAC says
    > the signal received is 44.1KHz.
    >
    > Am I misunderstanding what is going on here? Is there something else
    > I need to do to get the correct sample rate?
    >
    > This is using today's (5.30) nightly build of the server on MacOS X
    > 10.3.4 and firmware V23 on the SB.
    >
    > --jeff
    >
    > --
    > auricle (AT) io (DOT) com

  3. #3
    Junior Member
    Join Date
    Feb 2006
    Posts
    24

    48KHz files playing slowly

    I am having problems playing back flac files encoded at 48KHz. Is this still a known issue? Is there a solution?

  4. #4
    Senior Member
    Join Date
    Apr 2005
    Location
    Montreal, Canada
    Posts
    147
    I did something similar and I converted the ac3 to wav, converted 48KHz to 44.1KHz using ssrc_hp.exe and then used lame to convert it to mp3. I find the result quite acceptable.

    You might use this (ssrc_hp.exe) as a temporary measure until the bug in slimserver/squeezebox) is fixed.

    Daniel

  5. #5
    Senior Member crooner's Avatar
    Join Date
    Jan 2006
    Location
    San Diego, CA
    Posts
    461
    I've experimenting with higher sampling rates encoding a few DADs (classic records 96/24 recordings) into FLAC files.

    My laptop was able to play the 96 kHz 24 and 16 bit FLAC files.

    However, the SB3 would play them at slow speed.

    The higher I can go is 48 kHz and 16 bits resolution. 24 bits would cause the files to cut off. Presumably because of bandwidth problems. I am using a wireless connection.

    pkcrawford: are you using 24 bits and 48 kHz by any chance?
    "Audio Preservationist"
    Specialized in Marantz Vacuum Tube Electronics


  6. #6
    Senior Member
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    UK
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    I have noticed similar issues - 48 kHz flac plays back at 44.1 kHz, and 24 bit flac skips. This is on a 100 Mbit ethernet connection.

  7. #7
    Junior Member
    Join Date
    Feb 2006
    Posts
    24
    crooner,
    My 48KHz files are at 16 bit.
    Does this problem only happen with FLAC, or does it happen with all formats?

  8. #8
    Junior Member
    Join Date
    Apr 2005
    Posts
    24
    Quote Originally Posted by pkcrawford
    Indeed, SlimServer is assuming that the sample rate for uncompressed
    (and converted) format is at 44.1k. This is a known bug and we'll be
    addressing it.
    I have some 16bit 48khz files that seem to play fine on the sb2 over a wireless connection (i've not noticed any slow down or skipping). However I have noticed one problem and that is they don't play back gapless - I have a bug logged for this (#2990). I'm not sure if this is the same/related to/or nothing to do with the bug mentioned earlier in this thread - if it is related could this possibly be looked in to at the same time?

    Thanks

    Chris

  9. #9

    This much I know on flac from music dvds

    I've just had 'fun' extracting tracks from various concert DVDs.

    I use DVD Decrypter in IFO mode (in the Options - IFO mode tab) set the file splitting to By Chapter. Back on the main interface, in IFO mode, tick the Stream processing options and only tick the PCM stream. Click on the pcm stream and select the demux option.

    When you decrypt you get one wav per chapter on the dvd.

    Then use flac with plenty of -t options to flac them with the right meta data. I wrote a .bat file that I can post a sample of if you need it.

    I also have bought Tag And Rename to fix any resulting mess.

    Good guides here:
    http://forum.digital-digest.com/show...?postid=267286
    http://www.doom9.org/index.html?/dvddec.htm


    I find my sb2 plays 48khz flac at the right speed but my sb1 doesn't.

    cheers

  10. #10
    Junior Member
    Join Date
    Apr 2005
    Posts
    24
    Quote Originally Posted by gvh
    I find my sb2 plays 48khz flac at the right speed but my sb1 doesn't.
    cheers
    gvh - do you find that the resulting files playback gapless or not on the sb2?

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