mudita24 - Control tool for Envy24 (ice1712) based soundcards Based on envy24control found in ALSA.
Needs: ALSA-1.0.0 or later, GTK+-2.20 or later, an Envy24-based soundcard
To build:
cmake . (That's cmake 'dot')
To change the default installation location (/usr/local) add:
-DCMAKE_INSTALL_PREFIX=install_location
To change the default build type (none, CMAKE_C_FLAGS used) add:
-DCMAKE_BUILD_TYPE=
make
su -c 'make install'or sudo make install
The program 'alsactl' is automatically found and used for storing settings. Environment variable ALSACTL_PROG overrides its location.
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:
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 ... 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:
MT3F: Peak Meter Data Register [...] Peak data derived from the absolute value of 9 msb. 00h min - FFh max 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.html
[...] 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 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