I have a large amount of analog audio I need to digitize and
naturaly want to ensure best transfer quality. So I need to set
the analog level at the input to the adc as high as possible
without clipping. Ideally, I'll get the workstation hardware
set to certin defaults, then adjust the incomming audio as
required.
This leads to a couple of questions:
Are there (typicaly) any variable gain stages in the analog input
path in the computer. Mixerctl -av (full output below) shows a
node called 'record.adc'. It seems reasonable that this might
opperate on the analog input to the adc. However there is also
'record.volume', though I would assume this operates on the mixed
digital signals at the end of the chain.
Also: a lot of the gain stages have defaults of 120.120. Would
it be reasonable to assume that this is the 0 gain setting?
Any thoughts appreciated.
paulm
molly:/home/paul >mixerctl -a
record.adc_mute=off
record.adc=248,248
record.adc2_mute=off
record.adc2=120,120
inputs.mix_source=mic,mic2,line-in,hp,line
inputs.mix_mic=120,120
inputs.mix_mic2=120,120
inputs.mix_line-in=248,248
inputs.mix_hp=120,120
inputs.mix_line=120,120
outputs.mix2=120,120
inputs.mix2_source=dac,mix
outputs.mix3=120,120
inputs.mix3_source=dac2,mix
outputs.mix4=120,120
inputs.mix4_source=dac3,mix
outputs.mix5=120,120
inputs.mix5_source=dac4,mix
outputs.line_source=mix2
outputs.line_mute=off
inputs.line=85,85
outputs.line_dir=output
outputs.line_boost=off
outputs.line_eapd=on
outputs.mic_source=mix3
outputs.mic_mute=off
inputs.mic=85,85
outputs.mic_dir=input-vr80
outputs.mic_boost=off
outputs.mic2_source=mix8
outputs.mic2_mute=off
inputs.mic2=85,85
outputs.mic2_dir=input-vr80
outputs.mic2_boost=off
outputs.line-in_source=mix4
outputs.line-in_mute=off
inputs.line-in=85,85
outputs.line-in_dir=input
outputs.line-in_boost=off
outputs.hp_source=mix5
outputs.hp_mute=off
inputs.hp=85,85
outputs.hp_dir=output
outputs.hp_boost=off
outputs.SPDIF_source=dig-dac
record.adc2_source=mic,mic2,line-in,hp,line,mix
record.adc_source=mic,mic2,line-in,hp,line,mix
outputs.mix8=120,120
inputs.mix8_source=dac5,mix
outputs.line_sense=plugged
outputs.mic_sense=plugged
outputs.mic2_sense=unplugged
outputs.line-in_sense=unplugged
outputs.hp_sense=unplugged
outputs.master=120,120
outputs.master.mute=off
outputs.master.slaves=mix2,line
record.volume=120,120
record.volume.mute=off
record.volume.slaves=adc,adc2
outputs.mode=analog
molly:/home/paul >dmesg
OpenBSD 4.6 (GENERIC.MP.RAID) #0: Mon Mar 29 11:47:19 NZDT 2010
r...@molly.no-tek.local:/molly0/src/sys/arch/i386/compile/
GENERIC.MP.RAID
cpu0: Pentium(R) Dual-Core CPU E5400 @ 2.70GHz ("GenuineIntel"
686-class) 2.73 GHz
cpu0:
FPU,V86,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,
CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-
CPL,VMX,EST,TM2,CX16,xTPR
real mem = 1037135872 (989MB)
avail mem = 993542144 (947MB)
mainbus0 at root
bios0 at mainbus0: AT/286+ BIOS, date 09/21/09, BIOS32 rev. 0 @
0xf0010, SMBIOS rev. 2.5 @ 0xf06c0 (50 entries)
bios0: vendor American Megatrends Inc. version "0317" date 09/21/2009
bios0: ASUSTeK Computer INC. P5QPL-AM
acpi0 at bios0: rev 0
acpi0: tables DSDT FACP APIC MCFG OEMB HPET GSCI SSDT
acpi0: wakeup devices P0P2(S4) P0P3(S4) P0P1(S4) UAR1(S4) PS2K(S4)
PS2M(S4) USB0(S4) USB1(S4) USB2(S4) USB3(S4) EUSB(S4) MC97(S4) P0P4(S4)
P0P5(S4) P0P6(S4) P0P7(S4) P0P8(S4) P0P9(S4) SLPB(S4)
acpitimer0 at acpi0: 3579545 Hz, 24 bits
acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: apic clock running at 201MHz
cpu1 at mainbus0: apid 1 (application processor)
cpu1: Pentium(R) Dual-Core CPU E5400 @ 2.70GHz ("GenuineIntel"
686-class) 2.73 GHz
cpu1:
FPU,V86,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,
CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-
CPL,VMX,EST,TM2,CX16,xTPR
ioapic0 at mainbus0: apid 2 pa 0xfec00000, version 20, 24 pins
acpihpet0 at acpi0: 14318179 Hz
acpiprt0 at acpi0: bus 0 (PCI0)
acpiprt1 at acpi0: bus -1 (P0P2)
acpiprt2 at acpi0: bus -1 (P0P3)
acpiprt3 at acpi0: bus 3 (P0P1)
acpiprt4 at acpi0: bus 2 (P0P4)
acpiprt5 at acpi0: bus 1 (P0P5)
acpicpu0 at acpi0: PSS
acpicpu1 at acpi0: PSS
acpibtn0 at acpi0: SLPB
acpibtn1 at acpi0: PWRB
bios0: ROM list: 0xc0000/0xc600! 0xcc800/0x5800
cpu0: Enhanced SpeedStep 2723 MHz: speeds: 2700, 2003, 1603, 1203 MHz
pci0 at mainbus0 bus 0: configuration mode 1 (bios)
pchb0 at pci0 dev 0 function 0 "Intel G41 Host" rev 0x03
vga1 at pci0 dev 2 function 0 "Intel G41 Video" rev 0x03
wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation)
wsdisplay0: screen 1-5 added (80x25, vt100 emulation)
intagp at vga1 not configured
azalia0 at pci0 dev 27 function 0 "Intel 82801GB HD Audio" rev 0x01:
apic 2 int 21 (irq 5)
azalia0: codecs: Realtek/0x0887
audio0 at azalia0
ppb0 at pci0 dev 28 function 0 "Intel 82801GB PCIE" rev 0x01: apic 2
int 16 (irq 11)
pci1 at ppb0 bus 2
ppb1 at pci0 dev 28 function 1 "Intel 82801GB PCIE" rev 0x01: apic 2
int 17 (irq 10)
pci2 at ppb1 bus 1
ale0 at pci2 dev 0 function 0 "Attansic Technology L1E" rev 0xb0: apic
2 int 17 (irq 10), address e0:cb:4e:d3:62:18
atphy0 at ale0 phy 0: F1 10/100/1000 PHY, rev. 9
uhci0 at pci0 dev 29 function 0 "Intel 82801GB USB" rev 0x01: apic 2
int 23 (irq 3)
uhci1 at pci0 dev 29 function 1 "Intel 82801GB USB" rev 0x01: apic 2
int 19 (irq 10)
uhci2 at pci0 dev 29 function 2 "Intel 82801GB USB" rev 0x01: apic 2
int 18 (irq 6)
uhci3 at pci0 dev 29 function 3 "Intel 82801GB USB" rev 0x01: apic 2
int 16 (irq 11)
ehci0 at pci0 dev 29 function 7 "Intel 82801GB USB" rev 0x01: apic 2
int 23 (irq 3)
usb0 at ehci0: USB revision 2.0
uhub0 at usb0 "Intel EHCI root hub" rev 2.00/1.00 addr 1
ppb2 at pci0 dev 30 function 0 "Intel 82801BA Hub-to-PCI" rev 0xe1
pci3 at ppb2 bus 3
ahc0 at pci3 dev 0 function 0 "Adaptec AHA-2940UWPro" rev 0x01: apic 2
int 19 (irq 10)
scsibus0 at ahc0: 16 targets, initiator 7
sd0 at scsibus0 targ 2 lun 0: <SEAGATE, ST39175LW, 0001> SCSI2 0/direct
fixed
sd0: 8683MB, 512 bytes/sec, 17783240 sec total
ichpcib0 at pci0 dev 31 function 0 "Intel 82801GB LPC" rev 0x01: PM
disabled
pciide0 at pci0 dev 31 function 1 "Intel 82801GB IDE" rev 0x01: DMA,
channel 0 configured to compatibility, channel 1 configured to
compatibility
pciide0: channel 0 disabled (no drives)
pciide0: channel 1 disabled (no drives)
pciide1 at pci0 dev 31 function 2 "Intel 82801GB SATA" rev 0x01: DMA,
channel 0 configured to native-PCI, channel 1 configured to native-PCI
pciide1: using apic 2 int 22 (irq 11) for native-PCI interrupt
wd0 at pciide1 channel 0 drive 0: <ST3250310AS>
wd0: 16-sector PIO, LBA48, 238475MB, 488397168 sectors
wd1 at pciide1 channel 0 drive 1: <ST3250318AS>
wd1: 16-sector PIO, LBA48, 238475MB, 488397168 sectors
wd0(pciide1:0:0): using PIO mode 4, Ultra-DMA mode 5
wd1(pciide1:0:1): using PIO mode 4, Ultra-DMA mode 5
atapiscsi0 at pciide1 channel 1 drive 1
scsibus1 at atapiscsi0: 2 targets
cd0 at scsibus1 targ 0 lun 0: <HL-DT-ST, DVDRAM GH20NS10, EL00> ATAPI
5/cdrom removable
cd0(pciide1:1:1): using PIO mode 4, Ultra-DMA mode 5
usb1 at uhci0: USB revision 1.0
uhub1 at usb1 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb2 at uhci1: USB revision 1.0
uhub2 at usb2 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb3 at uhci2: USB revision 1.0
uhub3 at usb3 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb4 at uhci3: USB revision 1.0
uhub4 at usb4 "Intel UHCI root hub" rev 1.00/1.00 addr 1
isa0 at ichpcib0
isadma0 at isa0
com0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo
pckbc0 at isa0 port 0x60/5
pckbd0 at pckbc0 (kbd slot)
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
pcppi0 at isa0 port 0x61
midi0 at pcppi0: <PC speaker>
spkr0 at pcppi0
lpt0 at isa0 port 0x378/4 irq 7
lm0 at isa0 port 0x290/8: W83627DHG
npx0 at isa0 port 0xf0/16: reported by CPUID; using exception 16
mtrr: Pentium Pro MTRR support
Kernelized RAIDframe activated
softraid0 at root
ahc0: target 2 using 16bit transfers
ahc0: target 2 synchronous at 20.0MHz, offset = 0x8
root on sd0a swap on sd0b dump on sd0b
raid0: Component /dev/wd0a being configured at row: 0 col: 0
Row: 0 Column: 0 Num Rows: 1 Num Columns: 2
Version: 2 Serial Number: 8110400 Mod Counter: 1622
Clean: Yes Status: 0
raid0: Component /dev/wd1a being configured at row: 0 col: 1
Row: 0 Column: 1 Num Rows: 1 Num Columns: 2
Version: 2 Serial Number: 8110400 Mod Counter: 1622
Clean: Yes Status: 0
