I don't have any squeezebox hardware, but thanks to Triode's excellent
squeezelite and BBC iplayer plugins I've been using LMS on my
multimedia PC which is connected to a DAC either via its optical SPDIF
or USB input.
Everything has worked fine without any special configuration and I only
had to pick the Audio Output Device in the local player plugin
settings. My music library consists exclusively of 16/44 flac audio
files. And I've had no problem with any of the Internet radio station I
listen to. But my attempts to play some hirez 24/192 audio has raised
some issues and question about squeezelite and LMS.
I'm running Logitech Media Server Version: 7.7.2 - r33893 on a 64bit
aptosid linux install. I can either route audio output via my DAC's
adaptive USB connection which, like the Rega DAC, is only up to 16/48,
or I can use the PC's on-board SPDIF which supposedly supports up to
24/192. As the DAC's receiver is limited to 24/96, which is probably
the practical limit of the toslink cable, hirez 24/192 audio files need
to be down sampled.
My questions are:
(1) If I play a 24/192 flac file via my DAC's USB input, mplayer, for
example, chooses a bit depth and rate that matches the hardware's
capabilites. e.g
Code:
--------------------
mplayer -ao alsa:device=hw=2.0 7041888513520_01_13_192kHz.flac
..
Selected audio codec: FLAC (Free Lossless Audio Codec) [libavcodec]
AUDIO: 192000 Hz, 2 ch, s32le, 0.0 kbit/0.00% (ratio: 0->1536000)
[AO_ALSA] Format s32le is not supported by hardware, trying default.
AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
.
--------------------
Am I correct in thinking squeezelite does not work like this? So server
side transcoding is needed to play 24/192 audio flac files on hardware
which is only 16/48 capable.
(2) Is there any particular benefit in specifying the rate and format
via the -a and -r switches when using squeezelite? I can play 16/44
audio files on hardware which has a native S32_LE format with out
specifying any ALSA parameters (I think it defaults to 40:4:?:1) and
squezelite appears to workout the audio devices MaxSampleRate.
(3) I've seen various values of Alsa Buffer Size and Alsa Buffer Count
used. If possible, how do you determine the optimum values to use?
(4) When I turn squeezelite logging on I'm getting entries like this:
Code:
--------------------
[17:56:14.921613] alsa_open:270 opened device iec958:CARD=SB,DEV=0 using
format: S32_LE sample rate: 44100 mmap: 1
[17:56:14.921791] alsa_open:335 buffer: 40 period: 4 -> buffer size: 1792
period size: 448
[17:56:14.922066] ALSA snd_pcm_hw_start:588 SNDRV_PCM_IOCTL_START failed (-32)
--------------------
Even if I use -a :::0, mmap still seems to be set to 1
Do I need to change my squeezelite config?
(5) If I want to transcode 24/196 to 24/96, or 16/48, for example in my
setup, I believe I need to create a custom-convert.conf for the server
side. As this is a 64bit install I think I need to copy my /usr/bin/sox
to /usr/share/squeezeboxserver/Bin/i386-linux/ or smylink it. Also, how
do I tell if squeezelite is receiving flac or PCM from LMS?
------------------------------------------------------------------------
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