Limitless Audio Format

All values are little endian.

9 bytes "LIMITLESS" marker
Custom headers Custom headers with their own markers. The "TAGS" marker is reserved for tags in a later specification.
4 bytes "HEAD" marker
1 byte Quality:
  • 0 - 8-bit little-endian integer
  • 1 - 16-bit little-endian integer
  • 2 - 32-bit IEEE floating point
  • 3 - 24-bit little-endian integer
1 byte Mode:
  • 0 - Channel mode: individual spatial channels are exported with no object movement.
  • 1 - Object mode: individual objects are exported with movement data embedded in the PCM blocks.
4 bytes Channel/object count.
9 bytes for each channel/object
  • Rotation on X axis (32-bit floating point)
  • Rotation on Y axis (32-bit floating point)
  • Low frequency (1 byte boolean, 0 if false)
4 bytes Sample rate.
8 bytes Total samples.
The rest PCM blocks for each second.

PCM blocks

A PCM block is created for each second of audio. Each block begins with channels/objects / 8 (rounded up) bytes: each bit in this byte array shows if a channel has samples or not in the current block. Bits are high-ordered and right-aligned, while bytes are low-ordered (for 12 channels: 8-7-6-5-4-3-2-1, ----12-11-10-9). After these, the samples follow for each channel which was declared active in the previous byte array, channel by channel for each sample (interlaced, the same way as it's done for RIFF WAVE), in ascending channel order, but only for active channels.


Channel mode

In Channel mode, no checks are required: all channel positions are valid if the transport is valid, and no additional tracks are inserted, everything can be played back.

Object mode

For object-based exports, extra PCM tracks are used for object movement data. These tracks are marked with the X axis rotation set to NaN. The Y rotation in this case is reserved and shall be 0. One object position track contains movement data for exactly 16 channels. If there are more channels, more object position tracks are added, but if there are less channels left for the last track, it will fill the remaining channels with skipped data, but the alignment must match with a 16-channel position track. The positions follow each other by their index, and the order of the dimensions is width, height, depth.

Position tracks contain the values dimension by dimension, object by object (object 1 X, object 1 Y, object 1 Z, object 2 X...). LAF is using a right-handed Cartesian coordinate system. The bit depth of the content sets the precision of object positions, these values are encoded the exact same way PCM samples are: from -1 to 1 (these limits are the walls of the virtual room), multiplied by the positive integer limit in integer mode. In floating point mode, placing objects over the room's walls is permitted.