mlpdec.c File Reference

MLP decoder. More...

#include <stdint.h>
#include "avcodec.h"
#include "libavutil/internal.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"
#include "config.h"

Go to the source code of this file.

Data Structures
struct	SubStream
struct	MLPDecodeContext

Macros
#define	VLC_BITS   9
	number of bits used for VLC lookup - longest Huffman code is 9 More...
#define	VLC_STATIC_SIZE   512
#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 int	mlp_channel_layout_subset (uint64_t channel_layout, uint64_t mask)
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. More...
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. More...
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. More...
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. More...
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. More...
static int	read_matrix_params (MLPDecodeContext *m, unsigned int substr, GetBitContext *gbp)
	Read parameters for primitive matrices. More...
static int	read_channel_params (MLPDecodeContext *m, unsigned int substr, GetBitContext *gbp, unsigned int ch)
	Read channel parameters. More...
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. More...
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. More...
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). More...
static void	generate_2_noise_channels (MLPDecodeContext *m, unsigned int substr)
	Noise generation functions. More...
static void	fill_noise_buffer (MLPDecodeContext *m, unsigned int substr)
	Generate a block of noise, used when restart sync word == 0x31eb. More...
static int	output_data (MLPDecodeContext *m, unsigned int substr, AVFrame *frame, int *got_frame_ptr)
	Write the audio data into the output buffer. More...
static int	read_access_unit (AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt)
	Read an access unit from the stream. More...

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. More...

Detailed Description

MLP decoder.

Definition in file mlpdec.c.

Macro Definition Documentation

VLC_BITS

#define VLC_BITS   9

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

Definition at line 47 of file mlpdec.c.

Referenced by init_static(), and read_huff_channels().

VLC_STATIC_SIZE

#define VLC_STATIC_SIZE   512

Definition at line 48 of file mlpdec.c.

Referenced by init_static().

PARAM_BLOCKSIZE

#define PARAM_BLOCKSIZE   (1 << 7)

Definition at line 86 of file mlpdec.c.

Referenced by read_decoding_params().

PARAM_MATRIX

#define PARAM_MATRIX   (1 << 6)

Definition at line 87 of file mlpdec.c.

Referenced by read_decoding_params().

PARAM_OUTSHIFT

#define PARAM_OUTSHIFT   (1 << 5)

Definition at line 88 of file mlpdec.c.

Referenced by read_decoding_params().

PARAM_QUANTSTEP

#define PARAM_QUANTSTEP   (1 << 4)

Definition at line 89 of file mlpdec.c.

Referenced by read_decoding_params().

PARAM_FIR

#define PARAM_FIR   (1 << 3)

Definition at line 90 of file mlpdec.c.

Referenced by read_channel_params().

PARAM_IIR

#define PARAM_IIR   (1 << 2)

Definition at line 91 of file mlpdec.c.

Referenced by read_channel_params().

PARAM_HUFFOFFSET

#define PARAM_HUFFOFFSET   (1 << 1)

Definition at line 92 of file mlpdec.c.

Referenced by read_channel_params().

PARAM_PRESENCE

#define PARAM_PRESENCE   (1 << 0)

Definition at line 93 of file mlpdec.c.

Referenced by read_decoding_params().

MSB_MASK

#define MSB_MASK

(

bits

)

(-1u << (bits))

Definition at line 921 of file mlpdec.c.

Referenced by filter_channel(), and output_data().

Function Documentation

mlp_channel_layout_subset()

static int mlp_channel_layout_subset ( uint64_t  channel_layout, uint64_t  mask  )

static

Definition at line 183 of file mlpdec.c.

Referenced by read_restart_header().

thd_channel_layout_extract_channel()

static uint64_t thd_channel_layout_extract_channel ( uint64_t  channel_layout, int  index  )

static

Definition at line 188 of file mlpdec.c.

Referenced by read_restart_header().

init_static()

static av_cold void init_static ( void  )

static

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

Definition at line 206 of file mlpdec.c.

Referenced by mlp_decode_init().

calculate_sign_huff()

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

inlinestatic

Definition at line 223 of file mlpdec.c.

Referenced by read_decoding_params().

read_huff_channels()

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 244 of file mlpdec.c.

Referenced by read_block_data().

mlp_decode_init()

static av_cold int mlp_decode_init ( AVCodecContext *  avctx )

static

Definition at line 280 of file mlpdec.c.

Referenced by read_access_unit().

read_major_sync()

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 299 of file mlpdec.c.

Referenced by read_access_unit().

read_restart_header()

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 473 of file mlpdec.c.

Referenced by read_access_unit().

read_filter_params()

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 643 of file mlpdec.c.

Referenced by read_channel_params().

read_matrix_params()

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

static

Read parameters for primitive matrices.

Definition at line 718 of file mlpdec.c.

Referenced by read_decoding_params().

read_channel_params()

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

static

Read channel parameters.

Definition at line 786 of file mlpdec.c.

Referenced by read_decoding_params().

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 843 of file mlpdec.c.

Referenced by read_access_unit().

filter_channel()

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 926 of file mlpdec.c.

Referenced by read_block_data().

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 953 of file mlpdec.c.

Referenced by read_access_unit().

generate_2_noise_channels()

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 1024 of file mlpdec.c.

Referenced by output_data().

fill_noise_buffer()

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 1044 of file mlpdec.c.

Referenced by output_data().

output_data()

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 1061 of file mlpdec.c.

Referenced by apng_do_inverse_blend(), read_access_unit(), and test_function().

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 1132 of file mlpdec.c.

Variable Documentation

thd_channel_order

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 167 of file mlpdec.c.

Referenced by thd_channel_layout_extract_channel().

huff_vlc

VLC huff_vlc[3]

static

Definition at line 202 of file mlpdec.c.

noise_table

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 995 of file mlpdec.c.

Referenced by fill_noise_buffer(), and main().