Signaling immersive stereo content

For every presentation in the ac4_toc signaling immersive stereo content, an additional regular stereo-compatible presentation must be included in the ac4_dsi_v1.

Dolby AC-4 bitstreams signal immersive stereo content by setting the following fields:
  • presentation_version is set to 2.
  • b_presentation_id is set to 1.
  • presentation_id is any nonnegative number.
  • channel_mode is set to 0b1111001 (signaling Dolby Atmos content in IMS) or 0b1111000 (any content in IMS), with ch_mode set to 1.
  • b_pre_virtualized is set to 0.

To signal immersive stereo in the ISO base media file format, the ac4_dsi_v1 must include two ac4_presentation_v1_dsi instances for each immersive stereo presentation.

  1. One instance uses presentation version 2 and signals the immersive stereo content. The corresponding field settings are as follows:
    • presentation_version is set to 2.
    • b_presentation_id is set to 1.
    • presentation_id is set to the same number as in the corresponding ac4_presentation_info of the Dolby AC-4 bitstream.
    • dsi_presentation_ch_mode is set to 1.
    • b_pre_virtualized is set to 1.
    • If channel_mode for the Dolby AC-4 bitstreams is set to 0b1111001, dolby_atmos_indicator is set to 1; otherwise, dolby_atmos_indicator is set to 0.
  2. A second instance uses presentation version 1 and signals a regular stereo-compatible presentation of the immersive stereo content. This ac4_presentation_v1_dsi instance must come after the instance that signals the immersive stereo content. The corresponding field settings are as follows:
    • presentation_version is set to 1.
    • b_presentation_id is set to 1.
    • presentation_id is set to the same number as in the corresponding ac4_presentation_info of the Dolby AC-4 bitstream.
    • dsi_presentation_ch_mode is set to 1.
    • b_pre_virtualized is set to 0.
    • dolby_atmos_indicator is set to 0.
library_booksNote: Signaling in the MPD file is based on the first instance only.