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Raspberry Pi as headless streamer

Discussion in 'd.i.y.' started by RichardH, Jan 16, 2013.

  1. S-Man

    S-Man Kinkless Tetrode Admirer

    Where can the fifo option be found and what does it do?

    Are you using hardware or software volume control?
     
  2. tomek

    tomek pfm Member

    Fifo option is under configuration - system - mpd scheduler policy

    fifo - "real-time fixed-priority First-In First-Out scheduling policy"

    i am using software volume control which is very well implemented in mpd - 32 bits with dithering.

    Thinking about making one rc passive pre with TKD pot.
     
  3. S-Man

    S-Man Kinkless Tetrode Admirer

    Thanks Tomek, I had not noticed that before.
    Looks like mine is set to TS (standard). I will give FIFO a try next time I get the chance for a decent blast (when everyone is out).
    I tried the software volume control, along with 32/384 - to bypass the internal digital filters in the PCM5122 - but reverted back to "no upsampling" and hardware volume control.
     
  4. tomek

    tomek pfm Member

    Hardware volume control ! I didn't noticed it. This is the reason, why there is so high pcu load when playing dsd files. Probably with software volume control mpd is convertind dsd into pcm and than making volume control and dithering.

    I will test hardware volume control now :)
     
  5. tomek

    tomek pfm Member

    It sounds better with hardware volume control :)
     
  6. tomek

    tomek pfm Member

    I did some tests with volume software and hardware control. One has to login with ssh on Pi and start the "top" programm and check the CPU load caused by mpd process. The tests where done using dsf and wav files, not flacs, to avoid additional flac-wav decompression load and without sox oversampling.

    File Type------CPU Load SW control------CPU Load HW Control

    DSD-----------~30%-----------------------~30%

    24192---------~7%------------------------~4%

    2496-----------~4%------------------------~2%

    1644-----------~1,5%----------------------~0,7%

    One can see, that with pcm files cpu load of mpd process is 50% smaller when using hardware volume control. Only when playing dsd files, the load is the same . Why ? Dac + pro is using TI 5121 dac chip and this chip is only accepting pcm data (max. 32/384), not dsd, so mpd has to change dsd on the fly into pcm format.
    Lower cpu load with hardware volume control is probably the reason for better sound (lower latency?).

    You can set the type of the volume control in moode player this way:

    configure - audio - open mpd config - volume control

    :)
     
  7. Julf

    Julf Evil brother of Mark V Shaney

    Not sure a difference between 4% and 2% cpu load is significant (considering the 30% load with DSD doesn't seem to cause any problems).
     
  8. S-Man

    S-Man Kinkless Tetrode Admirer

    Glad you found the same as me.

    I'm not sure it's about CPU load.
    In general it seems to me that software manipulation results in poorer sound, whether this is up/oversampling or attenuation.

    Initial impression is that the FIFO setting improved the sound. I wish I knew what this actually does (obvioulsy I know what FIFO stands for).
     
  9. tomek

    tomek pfm Member

    Hmm, but yesterday i did more tests. Differences are very smal. but finally i settled with software volume control and hq oversampling 24/354 from 16/44 ...
    Maybe today my ears will hear different :)

    I would like to upsample 44/88/176 files to 352,8 and 48/96/192 to 384. Any hint ?
     
  10. tomek

    tomek pfm Member

    It looks, that IMHO the best sounding pi player (Moode) will slowly dissappear because of some crazy GPL violation.
    It is no more possible to download complete ready image, first you have to install raspbian, and then go through FOURTEEN !!! pages with unix configuration like this:
    ...
    sudo mkdir /mnt/tmp
    sudo mkdir /mnt/tmp1
    sudo mount /dev/sda1 /mnt/tmp
    sudo mount -v -o offset=4194304 -t vfat /mnt/tmp/2017-09-07-raspbian-stretch-lite.img /mnt/tmp1
    sudo touch /mnt/tmp1/ssh
    sudo sed -i "s/init=.*//" /mnt/tmp1/cmdline.txt
    sudo sed -i "s/quiet.*//" /mnt/tmp1/cmdline.txt
    sudo sed -i "s/^/net.ifnames=0 /" /mnt/tmp1/cmdline.txt
    sudo umount /mnt/tmp1
    sudo mount -v -o offset=48234496 -t ext4 /mnt/tmp/2017-09-07-raspbian-stretch-lite.img /mnt/tmp1
    sudo rm /mnt/tmp1/etc/init.d/resize2fs_once
    ...

    it was only one part of the first page from fourteen...

    Finally you will have Moode player without special LL and RT kernels which where already present in the 3.8 version. Lucky, I have the last "normal" 4.0 beta 5 version and hope to use it for some time ...

    I just can't understand. :(
     
  11. Julf

    Julf Evil brother of Mark V Shaney

    Which player would that be, and what's crazy about the GPL violation?
     
  12. tomek

    tomek pfm Member

    Moode !!! ;)
     
  13. Julf

    Julf Evil brother of Mark V Shaney

    And the GPL violation is that Moode doesn't provide source code to some of the swf binaries?
     
  14. Man in a van

    Man in a van pfm Member

    Well it is a bit longwinded, but nearly all copy and paste, and remember that one is compliing on the raspberry pi.

    I think that aout 90 minutes will get a working player, without the "squash" stuff and the extras like "squeezelite, and upnp thingy".

    So one could spread it over a couple of days.

    Yesterday I did "beta6" on an rpi3b, I did faff about quite a bit as I had to get my head around some simple stuff it would not grasp ("bear of little brain", that I am).

    The main problem as I see it at the moment, is that today there is already "beta7".

    As I don't use Moode much, hardly at all actually, it's just an exercise for me ;).

    The good old Squeezebox is more my Lapsang souchong
     

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