Interface structure

The process block interface concept is based on columns. A column consists of an array of process blocks, and the number of blocks a column can contain is unre-stricted. The Gestalt laws of grouping (see the section 2.3 “Concepts of interaction and usability”) have been used as significant design tools in the development of the interface concept; in fact, the process block structure is essentially based on carefully defined groupings.

Elements related to a single function, e.g. a destination selector and a level control for a signal send, are fused into entities, and these entities, the process blocks, are further combined into columns. The block column is the most central part of a channel²⁰, i.e. an entity consisting of one or more related signal paths. The number of channels can be changed without restrictions. The basic structure of the block-based mixing interface is illustrated in Figure 13.

20 See 2.1 “Terminology”.

The basic concept of the process block is described in the subsection 4.2.1 “Process block-based mixing”. The subsection 4.2.2 “Signal flow” presents the fundamental approach to signal flow specific to the block interface.

4.2.1 Process block-based mixing

The wireframe interface structure illustrated in Figure 13 does not portray any signal flow elements; to initiate the signal flow, process blocks need to be added to the boxes. A bare minimum setup to allow signals to travel through the system would consist of source blocks and output blocks. New channels could also be in-itialised with, for example, a source block, a metering block, and an output block.

Thus far, the basic principle is quite similar to existing console-based interfac-es, but the main difference between the console structure and the column-based block structure becomes evident when assessing specific channel elements. The

Channel Channel Channel Channel Channel Channel Channel Channel Figure 13: The fundamental process block interface structure consisting of vertical chains of blocks. The number of channels and the number of blocks contained in each column can be changed without restrictions.

common processing and routing elements available in current digital audio work-station channels offer many possibilities for processing the audio. However, the categorisation of these elements restricts the versatility of the mixing environ-ment: for example, channel effects are typically pre-sends, and the user cannot change this behaviour. The mixing view structure presented here changes the fo-cus from the specific processing and routing elements to generalised processes, which can be placed in virtually any order. Figure 14 illustrates the core element functions abstracted from a schematised traditional channel strip representation.

The abstract channel elements provide the basis for the process blocks; all routing, processing, and monitoring chains are handled in this concept with the process blocks. The blocks are categorised into four categories according to their tionality. However, the categorisation merely describes the primary element func-tions, and does not restrict the signal chain positions of the elements. The core of the interface consists of:

1. Routing blocks (a source block, a send block, and an output block);

2. Gain blocks (a level block and a panning²¹ block);

3. Meter blocks (different types of meters);

4. Effect blocks (insert-like signal processors).

The mixing environment structure is not limited to just the blocks mentioned above, however. The process block-based structure is highly flexible, and from the user interface standpoint, new specialised blocks can be added with ease.

Different process blocks still benefit from different renditions. The purpose of some traditional channel elements, namely the group designator and the automa-tion mode selector, is essentially to offer a means to select a value for a property (and to display the value). Although the aim in the process block structure is to allow the user to build the mixer structure from individual, detached building blocks, offering separate blocks for such functions would result in unnecessary clutter and complicated access to these properties. Moreover, these functions are in essence channel settings, not elements that are placed on the signal path.

21 Panning is considered here a gain operation for the simplicity of categorisation; the basis for this categorisation is that panning can be thought as a simplified control for simultaneous adjust-ment of multiple channel levels.

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Figure 14: The conversion of the essential channel strip elements into abstract stereotypes.

Supplementary properties such as the group selectors and the automation con-trols are grouped in the process block interface into settings elements, which are separated from the main block columns. Although this may seem to contradict the generalised block-based concept, this approach in fact allows the block col-umns to retain their unambiguous signal flow. The block interface is illustrated in Figure 15 with the separate settings elements.

Selecting a source or an output for a channel is comparable to assigning a group or selecting an automation mode from the standpoint of the user interface. However, the channel source and the channel output relate very directly to the signal path, and hence these functions are implemented as individual process blocks in the block interface.

4.2.2 Signal flow

The signal flow within a channel is very simple in the process block interface: the signal flows vertically, starting from the topmost block. Whereas in traditional channel strips certain elements, e.g. input and output selectors, commonly have fixed positions that do not necessarily correspond to the actual signal chain, the flow in the process block interface is user-definable and unambiguous: there is a one-to-one relation between the order of the blocks and the channel’s signal chain.

group automation

blocks

labels settings Channel

group

Channel Channel Channel

group group group

read read read read

Figure 15: The process block interface with the settings elements. Channel settings are sepa-rated from the main block area: the channel labels act as dividers between the block columns and the settings.