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Vincent Herbst
1191609d38
A DTS:X stream in the standard presentation is DTS-HD Master Audio with a 7.1 bed and an extension at the end of every XLL frame, behind the syncword the decoder already recognises (DCA_SYNCWORD_XLL_X). The extension is a 22-byte header followed by a regular XLL channel set: four channels, every one coded in full (no residual against the core), no speaker mask, its own NAVI table with the frame's segment geometry, then a two-byte trailer. Its channels are the front and rear height pairs, and the encoder folds each of them into the bed speaker below it (L, R, Lsr, Rsr) at -3 dB, gain code 23170/32768, so the 7.1 bed plays them on players that ignore the extension. The decoder now parses that channel set with the existing channel set code, outputs 7.1.4 (TFL, TFR, TBL, TBR), and removes the fold from the bed at output resolution. A "downmix" request for 7.1 keeps the bed as coded, heights folded in, which is what the decoder output before; the requests for 5.1 and stereo skip the extension as well, so their output is unchanged. Streams without the extension are not affected. A frame whose extension does not decode keeps the 7.1.4 layout with silent heights and the bed as coded, and the frame still ends where it did before. The alternate presentations, which carry objects behind DCA_SYNCWORD_XLL_X_IMAX, are not touched. The format facts (header size, channel order, the fold) come from the public analysis in harletty-bridge's dca crate and kristofferR's SpatialAudioBridge; this is an implementation on FFmpeg's own XLL code, not a translation. Signed-off-by: Vincent Herbst <superuser404@tuta.com>
46 lines
1.6 KiB
C
46 lines
1.6 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_VERSION_H
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#define AVCODEC_VERSION_H
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/**
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* @file
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* @ingroup libavc
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* Libavcodec version macros.
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*/
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#include "libavutil/version.h"
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#include "version_major.h"
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#define LIBAVCODEC_VERSION_MINOR 25
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#define LIBAVCODEC_VERSION_MICRO 101
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#define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
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LIBAVCODEC_VERSION_MINOR, \
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LIBAVCODEC_VERSION_MICRO)
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#define LIBAVCODEC_VERSION AV_VERSION(LIBAVCODEC_VERSION_MAJOR, \
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LIBAVCODEC_VERSION_MINOR, \
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LIBAVCODEC_VERSION_MICRO)
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#define LIBAVCODEC_BUILD LIBAVCODEC_VERSION_INT
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#define LIBAVCODEC_IDENT "Lavc" AV_STRINGIFY(LIBAVCODEC_VERSION)
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#endif /* AVCODEC_VERSION_H */
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