linuxaudio.org

FYI, I added the following since

http://nielsmayer.com/envy24control/mudita24-1.0.1.tar.gz

... shall I release a 1.0.2 with the following additions (?):
   * fixed --card and --device to allow valid ALSA names and numbers

        ( https://bugzilla.redhat.com/show_bug.cgi?id=602900 ).

  * Add display of "Delta IEC958 Input Status" under "Hardware Settings."

  * Updated and corrected manual page and README
Before I release, I'd like to know what happens on cards that don't

have this feature, or if it's universally supported, but badly named.

Can those with a Terratec or other card test the following command and

let me know the results of command "amixer -c M66 cget

iface=MIXER,name='Delta IEC958 Input Status'"

e.g.:
>> amixer -c M66 cget iface=MIXER,name='Delta IEC958 Input Status'

quoted text
>> numid=50,iface=MIXER,name='Delta IEC958 Input Status'

>>  ; type=BOOLEAN,access=r-------,values=1

>>  : values=on

.................................................................................................
Also, in case anybody ever wondered what this one, under "Analog

Volume" is for: "Volume Control Rate Register" I added it to the

README:
.........................
Notes on the Envy24's hardware Digital Mixer and hardware Metering,

by Niels Mayer ( http://nielsmayer.com ):

--------------------
The "Monitor Inputs" and "Monitor PCMs" tabs contain multiple scale widgets

grouped into L/R pairs and an associated peak-level meter. Each scale

widget represents the 24 bit attenuation value of each input to the

ice1712-based soundcard's digital mixer. This mixer is typically used for

zero-latency monitoring of "live" inputs, alongside backing sounds and

effects coming from the eight channels of PCM feeding the digital mixer.

When many inputs are "hot" simultaneously these scale-widgets attenuate the

inputs going into the digital mixer to prevent the output from clipping.

For details see http://nielsmayer.com/npm/envy24mixer-architecture.png
(from http://alsa.cybermirror.org/manuals/icensemble/envy24.pdf )
This is what the above manual says about the Envy24's digital mixer:

quoted text
> 4.5.5 Multi-Track Digital Monitoring

>

> The Envy24 integrates a 36-bit resolution digital hardware mixer. The

> width of the data path is strictly to ensure that during processing of

> all the channels, under any condition, no resolution is lost. The

> dynamic range of the end user system will be limited by the range of the

> physical output devices used. In order to maintain identical gain to the

> input stream (i.e. 0dB), the resulting 24-bit is not msb-aligned to the

> 36-bit. The overflow bits correspond to the analog distortion due to

> saturation. The user would need to reduce the overall attenuation of the

> inputs to avoid clipping. Insertion of the digital mixer adds only a

> single sample cycle delay with respect to the original data. This

> extremely low latency all digital mixer provides monitoring

> functionality and can replace a traditional external analog input

> mixer. There are 20 independent audio data streams to mix and control

> the volume.

Adjustment of responsivity vs. "zipper noise" from the 1.5dB steps at

the top-range of

the digital mixer attenuators is achieved by the following control

under "Hardware Settings":
> MT3B: Volume Control Rate Register

quoted text
> ...

> Volume update rate control (sampling rate, PSYNC)

> This register allows gradual change of the digital mixer volume

> setting. The value in MT3B specifies the number of samples to elapse (in

> hex) between each 1.5dB increment/decrement in volume mixer.  This gradual

> volume update continues until the setting programmed into MT38 is

> reached. The appropriate value to program may vary, but 00 or 01h are good

> choices for most cases.

The peak metering data is displayed as 0 to -48dBFS in envy24control's

meters. This data is derived from the envy24's hardware peak metering:
> Peak data derived from the absolute value of 9 msb.  00h min - FFh max

quoted text
> volume. Reading the register resets the meter to 00h.

This resolution of the hardware metering is descibed by Fons Adriaensen in

a mailing list discussion:
http://lists.linuxaudio.org/pipermail/linux-audio-dev/2010-August/029009...

quoted text
> [...] You have 128 steps between 0 and -6dB...

> And even at -24dB the next step is 1.3dB lower. Below that

> it gets worse radipdly. For a meter that is just supposed

> to keep a check on peak levels it's OK.

Note that hardware metering data is also available from the command-line:
> amixer -c M66 cget iface=PCM,name='Multi Track Peak',numid=45

quoted text
> numid=45,iface=PCM,name='Multi Track Peak'

>   ; type=INTEGER,access=r-------,values=22,min=0,max=255,step=0

>   : values=63,62,51,49,56,60,63,62,59,54,0,0,0,0,0,0,0,0,0,0,113,112

....................................................................
Niels

http://nielsmayer.com

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