MLP decoder. More...

#include <stdint.h>
#include "avcodec.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/channel_layout.h"
#include "get_bits.h"
#include "internal.h"
#include "libavutil/crc.h"
#include "parser.h"
#include "mlp_parser.h"
#include "mlpdsp.h"
#include "mlp.h"

Data Structures
struct	SubStream

struct	MLPDecodeContext

Macros
#define	VLC_BITS 9
	number of bits used for VLC lookup - longest Huffman code is 9

#define	MSB_MASK(bits) (-1u << bits)


#define	PARAM_BLOCKSIZE (1 << 7)

#define	PARAM_MATRIX (1 << 6)

#define	PARAM_OUTSHIFT (1 << 5)

#define	PARAM_QUANTSTEP (1 << 4)

#define	PARAM_FIR (1 << 3)

#define	PARAM_IIR (1 << 2)

#define	PARAM_HUFFOFFSET (1 << 1)

#define	PARAM_PRESENCE (1 << 0)

Functions
static uint64_t	thd_channel_layout_extract_channel (uint64_t channel_layout, int index)

static av_cold void	init_static (void)
	Initialize static data, constant between all invocations of the codec.

static int32_t	calculate_sign_huff (MLPDecodeContext *m, unsigned int substr, unsigned int ch)

static int	read_huff_channels (MLPDecodeContext m, GetBitContext gbp, unsigned int substr, unsigned int pos)
	Read a sample, consisting of either, both or neither of entropy-coded MSBs and plain LSBs.

static av_cold int	mlp_decode_init (AVCodecContext *avctx)

static int	read_major_sync (MLPDecodeContext m, GetBitContext gb)
	Read a major sync info header - contains high level information about the stream - sample rate, channel arrangement etc.

static int	read_restart_header (MLPDecodeContext m, GetBitContext gbp, const uint8_t *buf, unsigned int substr)
	Read a restart header from a block in a substream.

static int	read_filter_params (MLPDecodeContext m, GetBitContext gbp, unsigned int substr, unsigned int channel, unsigned int filter)
	Read parameters for one of the prediction filters.

static int	read_matrix_params (MLPDecodeContext m, unsigned int substr, GetBitContext gbp)
	Read parameters for primitive matrices.

static int	read_channel_params (MLPDecodeContext m, unsigned int substr, GetBitContext gbp, unsigned int ch)
	Read channel parameters.

static int	read_decoding_params (MLPDecodeContext m, GetBitContext gbp, unsigned int substr)
	Read decoding parameters that change more often than those in the restart header.

static void	filter_channel (MLPDecodeContext *m, unsigned int substr, unsigned int channel)
	Generate PCM samples using the prediction filters and residual values read from the data stream, and update the filter state.

static int	read_block_data (MLPDecodeContext m, GetBitContext gbp, unsigned int substr)
	Read a block of PCM residual data (or actual if no filtering active).

static void	generate_2_noise_channels (MLPDecodeContext *m, unsigned int substr)
	Noise generation functions.

static void	fill_noise_buffer (MLPDecodeContext *m, unsigned int substr)
	Generate a block of noise, used when restart sync word == 0x31eb.

static void	rematrix_channels (MLPDecodeContext *m, unsigned int substr)
	Apply the channel matrices in turn to reconstruct the original audio samples.

static int	output_data (MLPDecodeContext m, unsigned int substr, AVFrame frame, int *got_frame_ptr)
	Write the audio data into the output buffer.

static int	read_access_unit (AVCodecContext avctx, void data, int got_frame_ptr, AVPacket avpkt)
	Read an access unit from the stream.

Variables
static const uint64_t	thd_channel_order []

static VLC	huff_vlc [3]

static const int8_t	noise_table [256]
	Data table used for TrueHD noise generation function.

Detailed Description

MLP decoder.

Definition in file mlpdec.c.

Macro Definition Documentation

#define VLC_BITS 9

number of bits used for VLC lookup - longest Huffman code is 9

Definition at line 41 of file mlpdec.c.

Referenced by init_static(), and read_huff_channels().

#define PARAM_BLOCKSIZE (1 << 7)

Definition at line 76 of file mlpdec.c.

Referenced by read_decoding_params().

#define PARAM_MATRIX (1 << 6)

Definition at line 77 of file mlpdec.c.

Referenced by read_decoding_params().

#define PARAM_OUTSHIFT (1 << 5)

Definition at line 78 of file mlpdec.c.

Referenced by read_decoding_params().

#define PARAM_QUANTSTEP (1 << 4)

Definition at line 79 of file mlpdec.c.

Referenced by read_decoding_params().

#define PARAM_FIR (1 << 3)

Definition at line 80 of file mlpdec.c.

Referenced by read_channel_params().

#define PARAM_IIR (1 << 2)

Definition at line 81 of file mlpdec.c.

Referenced by read_channel_params().

#define PARAM_HUFFOFFSET (1 << 1)

Definition at line 82 of file mlpdec.c.

Referenced by read_channel_params().

#define PARAM_PRESENCE (1 << 0)

Definition at line 83 of file mlpdec.c.

Referenced by read_decoding_params().

#define MSB_MASK ( bits ) (-1u << bits)

Definition at line 818 of file mlpdec.c.

Referenced by filter_channel(), and rematrix_channels().

Function Documentation

static uint64_t thd_channel_layout_extract_channel	(	uint64_t	channel_layout,
		int	index
	)

static

Definition at line 170 of file mlpdec.c.

Referenced by read_restart_header().

static av_cold void init_static ( void )

static

Initialize static data, constant between all invocations of the codec.

Definition at line 188 of file mlpdec.c.

Referenced by mlp_decode_init().

static int32_t calculate_sign_huff	(	MLPDecodeContext *	m,
		unsigned int	substr,
		unsigned int	ch
	)

inlinestatic

Definition at line 205 of file mlpdec.c.

Referenced by read_channel_params(), and read_decoding_params().

static int read_huff_channels	(	MLPDecodeContext *	m,
		GetBitContext *	gbp,
		unsigned int	substr,
		unsigned int	pos
	)

inlinestatic

Read a sample, consisting of either, both or neither of entropy-coded MSBs and plain LSBs.

Definition at line 226 of file mlpdec.c.

Referenced by read_block_data().

static av_cold int mlp_decode_init ( AVCodecContext * avctx )

static

Definition at line 262 of file mlpdec.c.

static int read_major_sync	(	MLPDecodeContext *	m,
		GetBitContext *	gb
	)

static

Read a major sync info header - contains high level information about the stream - sample rate, channel arrangement etc.

Most of this information is not actually necessary for decoding, only for playback.

Definition at line 281 of file mlpdec.c.

Referenced by read_access_unit().

static int read_restart_header	(	MLPDecodeContext *	m,
		GetBitContext *	gbp,
		const uint8_t *	buf,
		unsigned int	substr
	)

static

Read a restart header from a block in a substream.

This contains parameters required to decode the audio that do not change very often. Generally (always) present only in blocks following a major sync.

Definition at line 395 of file mlpdec.c.

Referenced by read_access_unit().

static int read_filter_params	(	MLPDecodeContext *	m,
		GetBitContext *	gbp,
		unsigned int	substr,
		unsigned int	channel,
		unsigned int	filter
	)

static

Read parameters for one of the prediction filters.

Definition at line 572 of file mlpdec.c.

Referenced by read_channel_params().

static int read_matrix_params	(	MLPDecodeContext *	m,
		unsigned int	substr,
		GetBitContext *	gbp
	)

static

Read parameters for primitive matrices.

Definition at line 647 of file mlpdec.c.

Referenced by read_decoding_params().

static int read_channel_params	(	MLPDecodeContext *	m,
		unsigned int	substr,
		GetBitContext *	gbp,
		unsigned int	ch
	)

static

Read channel parameters.

Definition at line 710 of file mlpdec.c.

Referenced by read_decoding_params().

static int read_decoding_params	(	MLPDecodeContext *	m,
		GetBitContext *	gbp,
		unsigned int	substr
	)

static

Read decoding parameters that change more often than those in the restart header.

Definition at line 769 of file mlpdec.c.

Referenced by read_access_unit().

static void filter_channel	(	MLPDecodeContext *	m,
		unsigned int	substr,
		unsigned int	channel
	)

static

Generate PCM samples using the prediction filters and residual values read from the data stream, and update the filter state.

Definition at line 823 of file mlpdec.c.

Referenced by read_block_data().

static int read_block_data	(	MLPDecodeContext *	m,
		GetBitContext *	gbp,
		unsigned int	substr
	)

static

Read a block of PCM residual data (or actual if no filtering active).

Definition at line 850 of file mlpdec.c.

Referenced by read_access_unit().

static void generate_2_noise_channels	(	MLPDecodeContext *	m,
		unsigned int	substr
	)

static

Noise generation functions.

I'm not sure what these are for - they seem to be some kind of pseudorandom sequence generators, used to generate noise data which is used when the channels are rematrixed. I'm not sure if they provide a practical benefit to compression, or just obfuscate the decoder. Are they for some kind of dithering? Generate two channels of noise, used in the matrix when restart sync word == 0x31ea.

Definition at line 921 of file mlpdec.c.

Referenced by rematrix_channels().

static void fill_noise_buffer	(	MLPDecodeContext *	m,
		unsigned int	substr
	)

static

Generate a block of noise, used when restart sync word == 0x31eb.

Definition at line 941 of file mlpdec.c.

Referenced by rematrix_channels().

static void rematrix_channels	(	MLPDecodeContext *	m,
		unsigned int	substr
	)

static

Apply the channel matrices in turn to reconstruct the original audio samples.

Definition at line 960 of file mlpdec.c.

Referenced by read_access_unit().

static int output_data	(	MLPDecodeContext *	m,
		unsigned int	substr,
		AVFrame *	frame,
		int *	got_frame_ptr
	)

static

Write the audio data into the output buffer.

Definition at line 1005 of file mlpdec.c.

Referenced by read_access_unit().

static int read_access_unit	(	AVCodecContext *	avctx,
		void *	data,
		int *	got_frame_ptr,
		AVPacket *	avpkt
	)

static

Read an access unit from the stream.

Returns: negative on error, 0 if not enough data is present in the input stream, otherwise the number of bytes consumed.

Definition at line 1053 of file mlpdec.c.

Variable Documentation

const uint64_t thd_channel_order[]

static

Initial value:

= {
    AV_CH_FRONT_LEFT, AV_CH_FRONT_RIGHT,                     
    AV_CH_FRONT_CENTER,                                      
    AV_CH_LOW_FREQUENCY,                                     
    AV_CH_SIDE_LEFT, AV_CH_SIDE_RIGHT,                       
    AV_CH_TOP_FRONT_LEFT, AV_CH_TOP_FRONT_RIGHT,             
    AV_CH_FRONT_LEFT_OF_CENTER, AV_CH_FRONT_RIGHT_OF_CENTER, 
    AV_CH_BACK_LEFT, AV_CH_BACK_RIGHT,                       
    AV_CH_BACK_CENTER,                                       
    AV_CH_TOP_CENTER,                                        
    AV_CH_SURROUND_DIRECT_LEFT, AV_CH_SURROUND_DIRECT_RIGHT, 
    AV_CH_WIDE_LEFT, AV_CH_WIDE_RIGHT,                       
    AV_CH_TOP_FRONT_CENTER,                                  
    AV_CH_LOW_FREQUENCY_2,                                   
}

Definition at line 154 of file mlpdec.c.

Referenced by thd_channel_layout_extract_channel().

VLC huff_vlc[3]

static

Definition at line 184 of file mlpdec.c.

const int8_t noise_table[256]

static

Initial value:

= {
     30,  51,  22,  54,   3,   7,  -4,  38,  14,  55,  46,  81,  22,  58,  -3,   2,
     52,  31,  -7,  51,  15,  44,  74,  30,  85, -17,  10,  33,  18,  80,  28,  62,
     10,  32,  23,  69,  72,  26,  35,  17,  73,  60,   8,  56,   2,   6,  -2,  -5,
     51,   4,  11,  50,  66,  76,  21,  44,  33,  47,   1,  26,  64,  48,  57,  40,
     38,  16, -10, -28,  92,  22, -18,  29, -10,   5, -13,  49,  19,  24,  70,  34,
     61,  48,  30,  14,  -6,  25,  58,  33,  42,  60,  67,  17,  54,  17,  22,  30,
     67,  44,  -9,  50, -11,  43,  40,  32,  59,  82,  13,  49, -14,  55,  60,  36,
     48,  49,  31,  47,  15,  12,   4,  65,   1,  23,  29,  39,  45,  -2,  84,  69,
      0,  72,  37,  57,  27,  41, -15, -16,  35,  31,  14,  61,  24,   0,  27,  24,
     16,  41,  55,  34,  53,   9,  56,  12,  25,  29,  53,   5,  20, -20,  -8,  20,
     13,  28,  -3,  78,  38,  16,  11,  62,  46,  29,  21,  24,  46,  65,  43, -23,
     89,  18,  74,  21,  38, -12,  19,  12, -19,   8,  15,  33,   4,  57,   9,  -8,
     36,  35,  26,  28,   7,  83,  63,  79,  75,  11,   3,  87,  37,  47,  34,  40,
     39,  19,  20,  42,  27,  34,  39,  77,  13,  42,  59,  64,  45,  -1,  32,  37,
     45,  -5,  53,  -6,   7,  36,  50,  23,   6,  32,   9, -21,  18,  71,  27,  52,
    -25,  31,  35,  42,  -1,  68,  63,  52,  26,  43,  66,  37,  41,  25,  40,  70,
}

Data table used for TrueHD noise generation function.

Definition at line 892 of file mlpdec.c.

Referenced by fill_noise_buffer(), and main().

Data Structures

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

Function Documentation

Variable Documentation