Crate firewire_tascam_protocols

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Expand description

The library crate includes implementation of protocols for models of TASCAM FireWire series, designed to audio and music unit in IEEE 1394 bus.

TASCAM FireWire series

As of 2022, TASCAM is an subsidiary of TEAC Corporation. FW-1884 was launched in 2003 as the first TASCAM product for audio and music unit in IEEE 1394 bus. At the same time, FE-8 was launched as expander unit for FW-1884. FW-1082 was launched in 2005 as console model smaller than FW-1884. FW-1804 was launched in 2006 as rack model. The above models were provided by the joint project between TASCAM and Frontier Design Group.

The models transmit state of hardware by subsequence of quadlet messages, while the way of transmission is different between models. The most of models transmit the message in isochronous packet multiplexed with PCM frame. FE-8 is an exception to transmits the message by asynchronous transaction to registered address.

ALSA firewire-tascam driver

Linux sound subsystem, a.k.a ALSA, provides loadable kernel module (snd-firewire-tascam) as driver for the units except for FE-8. The driver maintains isochronous packet stream for audio frames and the state messages as well as MIDI transmission by asynchronous transaction.

The driver allows user space application to retrieve the cached state and read notification for the state change by executing system call. hitaki library has SndTascam GObject class for the purpose. The class implements TascamProtocol GObject interface, which is also implemented by asynch::TascamExpander structure so that FE-8 can be supported as well.

Anyway, the crate is supplemental implementation for runtime program to configure digital signal processing functions and console surfaces which are not implemented in the driver.

Dependency

This is the list of dependent crates.

The glib and hinawa crates require some underlying system libraries

The functions of Linux FireWire and Sound subsystem is called via hinawa and hitaki crates and libraries to communicate with node in IEEE 1394 bus, thus the crate is not portable.

Supported models

This is the list of models currently supported.

  • Tascam FW-1884
  • Tascam FW-1082
  • Tascam FW-1804
  • Tascam FE-8

Status of the crate

The crate is developed and maintained by ALSA GObject Introspection team for snd-firewire-ctl-services project, and not stable yet. The included Rust elements are likely changed without backward compatibility.

License

The crate is released under GNU Lesser General Public License v3.0 or later with respect to clause for reverse engineering.

Support

If finding issue, please file it in https://github.com/alsa-project/snd-firewire-ctl-services/.

Disclaimer

The implementation of protocol is developed by the way of reverse engineering; sniffing IEEE 1394 bus to which target device is connected, and analysis of the communication between the device and driver provided by hardware vendor. It’s natural not to work with your device since developer worked with blackbox.

Utilities

Some programs are available under ‘src/bin’ directory.

tascam-config-rom-parser.rs

This program parses content of Configuration ROM specialized by TASCAM, then print the information.

Without any command line argument, it prints help message and exit.

$ cargo run --bin tascam-config-rom-parser
Usage:
  tascam-config-rom-parser CDEV

  where:
    CDEV:       The path to special file of firewire character device, typically '/dev/fw1'.

Please run with an argument for firewire character device:

$ cargo run --bin tascam-config-rom-parser /dev/fw1
...

tascam-hardware-info.rs

This program retrieves information from node of target device by protocol defined by TASCAM, then print the information.

Without any command line argument, it prints help message and exit.

$ cargo run --bin tascam-hardware-info
Usage:
  tascam-hardware-info CDEV

  where:
    CDEV:       The path to special file of firewire character device, typically '/dev/fw1'.

Please run with an argument for firewire character device:

$ cargo run --bin tascam-hardware-info /dev/fw1
...

Process events for control surface

Tascam FW-1884, FW-1082, and FE-8 have control surface, in which the hardware make no superficial change to the surface according to user operation. Instead, the surface notifies the operation to system.

In FE-8, the image consists of 32 quadlets. Asynchronous notification is simply sent for one of quadlet to which user operation effects.

In FW-1884 and FW-1082, the state of surface is expressed as an image which consists of 64 quadlets. One of the quadlets is multiplexed to data block in isochronous packet as well as PCM frame in order.

FW-1884 and FW-1082 has shift button to divert some buttons. Furthermore, FW-1082 has some rotaries and buttons which change their role according to encoder mode. The module includes two stuffs to abstract the above design; surface state and machine state. The former is used used to parse surface imageg and detect event and operate LED. The latter is used to monitor current state of each surface item by handling the event, and generate normalized events. It’s task of runtime implementation to prepare converter between the machine event and application specific message such as ALSA Sequencer and Open Sound Control.

The relationship between the constrol surface, surface state, machine state, and message converter is illustrated in below diagram:

                      ++====================================================++
                      ||                  Service runtime                   ||
                      ||                                                    ||
++==========++  surface image    +---------+   machine event   +---------+  ||
||          || ----------------> |         | ----------------> |         |  ||
|| surface  ||        ||         | surface |                   | machine |  ||
|| hardware ||  LED operation    |  state  |   machine event   |  state  |  ||
||          || <---------------- |         | <---------------- |         |  ||
++==========++        ||         +---------+                   +---------+  ||
                      ||                                         ^    |     ||
                      ||                                      machine event ||
                      ||                                         |    v     ||
                      ||                                       +---------+  ||
                      ||                                       |         |  ||
                      ||                                       | message |  ||
                      ||                                       |converter|  ||
                      ||                                       |         |  ||
                      ||                                       +---------+  ||
                      ||                                         ^    |     ||
                      ||                                   specific message ||
                      ||                                         |    |     ||
                      ++=========================================|====|=====++
                                                                 |    |
                                    Inter process communication  |    |
                                    (ALSA Sequencer, OSC, etc.)  |    v
                                                            ++=============++
                                                            || application ||
                                                            ++=============++

Modules

  • asynch
    Protocols defined for Tascam for FireWire series only with asynchronous communication.
  • config_rom
    Parser of configuration ROM for Tascam FireWire series.
  • isoch
    Protocols defined for Tascam for FireWire series with isochronous communication.

Structs

Enums

Traits