On 3/22/2025 2:49 PM, Massimo Eynard wrote:
This patch adds support for decoding the fourth MLP substream
which contains the 16-channel presentation used for Atmos
audio objects.

By default only the first three substreams are decoded
unless the new extract_objects flag is enabled as the resulting
presentation contains audio object feeds instead of classic
loudspeaker feeds.

As this introduces interpolation of primitive matrices, precision
has been increased to 2.18 fixed point. Therefore this requires
DSP code upgrade which has been done for C and x86 implementations
but not the ARM implementation.

Adds two FATE tests using existing atmos.thd sample to reflect
changes.

Signed-off-by: Massimo Eynard <eynard.mass...@gmail.com>
---
  libavcodec/arm/mlpdsp_armv5te.S  |   2 +-
  libavcodec/arm/mlpdsp_init_arm.c |   3 +-
  libavcodec/mlp.h                 |  10 +-
  libavcodec/mlp_parse.c           |  31 ++-
  libavcodec/mlp_parse.h           |   1 +
  libavcodec/mlp_parser.c          |  11 +-
  libavcodec/mlpdec.c              | 389 +++++++++++++++++++++++++++----
  libavcodec/mlpdsp.c              |  50 +++-
  libavcodec/mlpdsp.h              |  25 ++
  libavcodec/x86/mlpdsp.asm        |  19 +-
  tests/fate/truehd.mak            |  10 +
  11 files changed, 476 insertions(+), 75 deletions(-)

With atmos.thd i get:

[aist#0:0/truehd @ 00000209caf3ee00] Guessed Channel Layout: 7.1.4
Input #0, truehd, from '../samples/truehd/atmos.thd':
  Duration: N/A, start: 0.000000, bitrate: N/A
  Stream #0:0: Audio: truehd (Dolby TrueHD + Dolby Atmos), 48000 Hz, 7.1.4, s32 
(24 bit)

Which is unlikely to be correct. The file has 11 (or 12) objects, which is exported as 12 channels in an unspecified layout, and automatically assumed to be a 7.1.4 fixed layout.

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