MPEG-4 ALS decoder. More...

#include "avcodec.h"
#include "get_bits.h"
#include "unary.h"
#include "mpeg4audio.h"
#include "bytestream.h"
#include "bgmc.h"
#include "dsputil.h"
#include "internal.h"
#include "libavutil/samplefmt.h"
#include "libavutil/crc.h"
#include <stdint.h>

Data Structures
struct	ALSSpecificConfig

struct	ALSChannelData

struct	ALSDecContext

struct	ALSBlockData

Macros
#define	MISSING_ERR(cond, str, errval)

#define	INTERLEAVE_OUTPUT(bps)

Enumerations
enum	RA_Flag { RA_FLAG_NONE, RA_FLAG_FRAMES, RA_FLAG_HEADER }

Functions
static av_cold void	dprint_specific_config (ALSDecContext *ctx)

static av_cold int	read_specific_config (ALSDecContext *ctx)
	Read an ALSSpecificConfig from a buffer into the output struct.

static int	check_specific_config (ALSDecContext *ctx)
	Check the ALSSpecificConfig for unsupported features.

static void	parse_bs_info (const uint32_t bs_info, unsigned int n, unsigned int div, unsigned int *div_blocks, unsigned int num_blocks)
	Parse the bs_info field to extract the block partitioning used in block switching mode, refer to ISO/IEC 14496-3, section 11.6.2.

static int32_t	decode_rice (GetBitContext *gb, unsigned int k)
	Read and decode a Rice codeword.

static void	parcor_to_lpc (unsigned int k, const int32_t par, int32_t cof)
	Convert PARCOR coefficient k to direct filter coefficient.

static void	get_block_sizes (ALSDecContext ctx, unsigned int div_blocks, uint32_t *bs_info)
	Read block switching field if necessary and set actual block sizes.

static int	read_const_block_data (ALSDecContext ctx, ALSBlockData bd)
	Read the block data for a constant block.

static void	decode_const_block_data (ALSDecContext ctx, ALSBlockData bd)
	Decode the block data for a constant block.

static int	read_var_block_data (ALSDecContext ctx, ALSBlockData bd)
	Read the block data for a non-constant block.

static int	decode_var_block_data (ALSDecContext ctx, ALSBlockData bd)
	Decode the block data for a non-constant block.

static int	read_block (ALSDecContext ctx, ALSBlockData bd)
	Read the block data.

static int	decode_block (ALSDecContext ctx, ALSBlockData bd)
	Decode the block data.

static int	read_decode_block (ALSDecContext ctx, ALSBlockData bd)
	Read and decode block data successively.

static void	zero_remaining (unsigned int b, unsigned int b_max, const unsigned int div_blocks, int32_t buf)
	Compute the number of samples left to decode for the current frame and sets these samples to zero.

static int	decode_blocks_ind (ALSDecContext ctx, unsigned int ra_frame, unsigned int c, const unsigned int div_blocks, unsigned int *js_blocks)
	Decode blocks independently.

static int	decode_blocks (ALSDecContext ctx, unsigned int ra_frame, unsigned int c, const unsigned int div_blocks, unsigned int *js_blocks)
	Decode blocks dependently.

static int	read_channel_data (ALSDecContext ctx, ALSChannelData cd, int c)
	Read the channel data.

static int	revert_channel_correlation (ALSDecContext ctx, ALSBlockData bd, ALSChannelData *cd, int reverted, unsigned int offset, int c)
	Recursively reverts the inter-channel correlation for a block.

static int	read_frame_data (ALSDecContext *ctx, unsigned int ra_frame)
	Read the frame data.

static int	decode_frame (AVCodecContext avctx, void data, int got_frame_ptr, AVPacket avpkt)
	Decode an ALS frame.

static av_cold int	decode_end (AVCodecContext *avctx)
	Uninitialize the ALS decoder.

static av_cold int	decode_init (AVCodecContext *avctx)
	Initialize the ALS decoder.

static av_cold void	flush (AVCodecContext *avctx)
	Flush (reset) the frame ID after seeking.

Variables
static const int8_t	parcor_rice_table [3][20][2]
	Rice parameters and corresponding index offsets for decoding the indices of scaled PARCOR values.

static const int16_t	parcor_scaled_values []
	Scaled PARCOR values used for the first two PARCOR coefficients.

static const uint8_t	ltp_gain_values [4][4]
	Gain values of p(0) for long-term prediction.

static const int16_t	mcc_weightings []
	Inter-channel weighting factors for multi-channel correlation.

static const uint8_t	tail_code [16][6]
	Tail codes used in arithmetic coding using block Gilbert-Moore codes.

AVCodec	ff_als_decoder

Detailed Description

MPEG-4 ALS decoder.

Author: Thilo Borgmann <thilo.borgmann at googlemail.com>

Definition in file alsdec.c.

Macro Definition Documentation

#define MISSING_ERR	(	cond,
		str,
		errval
	)

Value:

{                                                   \
        if (cond) {                                     \
            av_log_missing_feature(ctx->avctx, str, 0); \
            error = errval;                             \
        }                                               \
    }

Referenced by check_specific_config().

#define INTERLEAVE_OUTPUT ( bps )

Value:

{                                                                                \
        int##bps##_t *dest = (int##bps##_t*)frame->data[0];                          \
        shift = bps - ctx->avctx->bits_per_raw_sample;                               \
        if (!ctx->cs_switch) {                                                       \
            for (sample = 0; sample < ctx->cur_frame_length; sample++)               \
                for (c = 0; c < avctx->channels; c++)                                \
                    *dest++ = ctx->raw_samples[c][sample] << shift;                  \
        } else {                                                                     \
            for (sample = 0; sample < ctx->cur_frame_length; sample++)               \
                for (c = 0; c < avctx->channels; c++)                                \
                    *dest++ = ctx->raw_samples[sconf->chan_pos[c]][sample] << shift; \
        }                                                                            \
    }

Referenced by decode_frame().

Enumeration Type Documentation

enum RA_Flag

Enumerator:

RA_FLAG_NONE
RA_FLAG_FRAMES
RA_FLAG_HEADER

Definition at line 150 of file alsdec.c.

Function Documentation

static av_cold void dprint_specific_config ( ALSDecContext * ctx )

static

Definition at line 252 of file alsdec.c.

Referenced by read_specific_config().

static av_cold int read_specific_config ( ALSDecContext * ctx )

static

Read an ALSSpecificConfig from a buffer into the output struct.

Definition at line 282 of file alsdec.c.

Referenced by decode_init().

static int check_specific_config ( ALSDecContext * ctx )

static

Check the ALSSpecificConfig for unsupported features.

Definition at line 427 of file alsdec.c.

Referenced by decode_init().

static void parse_bs_info	(	const uint32_t	bs_info,
		unsigned int	n,
		unsigned int	div,
		unsigned int **	div_blocks,
		unsigned int *	num_blocks
	)

static

Parse the bs_info field to extract the block partitioning used in block switching mode, refer to ISO/IEC 14496-3, section 11.6.2.

Definition at line 451 of file alsdec.c.

Referenced by get_block_sizes().

static int32_t decode_rice	(	GetBitContext *	gb,
		unsigned int	k
	)

static

Read and decode a Rice codeword.

Definition at line 474 of file alsdec.c.

Referenced by read_channel_data(), and read_var_block_data().

static void parcor_to_lpc	(	unsigned int	k,
		const int32_t *	par,
		int32_t *	cof
	)

static

Convert PARCOR coefficient k to direct filter coefficient.

Definition at line 492 of file alsdec.c.

Referenced by decode_var_block_data().

static void get_block_sizes	(	ALSDecContext *	ctx,
		unsigned int *	div_blocks,
		uint32_t *	bs_info
	)

static

Read block switching field if necessary and set actual block sizes.

Also assure that the block sizes of the last frame correspond to the actual number of samples.

Definition at line 512 of file alsdec.c.

Referenced by read_frame_data().

static int read_const_block_data	(	ALSDecContext *	ctx,
		ALSBlockData *	bd
	)

static

Read the block data for a constant block.

Definition at line 565 of file alsdec.c.

Referenced by read_block().

static void decode_const_block_data	(	ALSDecContext *	ctx,
		ALSBlockData *	bd
	)

static

Decode the block data for a constant block.

Definition at line 595 of file alsdec.c.

Referenced by decode_block().

static int read_var_block_data	(	ALSDecContext *	ctx,
		ALSBlockData *	bd
	)

static

Read the block data for a non-constant block.

Definition at line 609 of file alsdec.c.

Referenced by read_block().

static int decode_var_block_data	(	ALSDecContext *	ctx,
		ALSBlockData *	bd
	)

static

Decode the block data for a non-constant block.

Definition at line 870 of file alsdec.c.

Referenced by decode_block().

static int read_block	(	ALSDecContext *	ctx,
		ALSBlockData *	bd
	)

static

Read the block data.

Definition at line 979 of file alsdec.c.

Referenced by read_decode_block(), and read_frame_data().

static int decode_block	(	ALSDecContext *	ctx,
		ALSBlockData *	bd
	)

static

Decode the block data.

Definition at line 1000 of file alsdec.c.

Referenced by read_decode_block(), and read_frame_data().

static int read_decode_block	(	ALSDecContext *	ctx,
		ALSBlockData *	bd
	)

static

Read and decode block data successively.

Definition at line 1022 of file alsdec.c.

Referenced by decode_blocks(), and decode_blocks_ind().

static void zero_remaining	(	unsigned int	b,
		unsigned int	b_max,
		const unsigned int *	div_blocks,
		int32_t *	buf
	)

static

Compute the number of samples left to decode for the current frame and sets these samples to zero.

Definition at line 1040 of file alsdec.c.

Referenced by decode_blocks(), and decode_blocks_ind().

static int decode_blocks_ind	(	ALSDecContext *	ctx,
		unsigned int	ra_frame,
		unsigned int	c,
		const unsigned int *	div_blocks,
		unsigned int *	js_blocks
	)

static

Decode blocks independently.

Definition at line 1055 of file alsdec.c.

Referenced by read_frame_data().

static int decode_blocks	(	ALSDecContext *	ctx,
		unsigned int	ra_frame,
		unsigned int	c,
		const unsigned int *	div_blocks,
		unsigned int *	js_blocks
	)

static

Decode blocks dependently.

Definition at line 1094 of file alsdec.c.

Referenced by read_frame_data().

static int read_channel_data	(	ALSDecContext *	ctx,
		ALSChannelData *	cd,
		int	c
	)

static

Read the channel data.

Definition at line 1178 of file alsdec.c.

Referenced by read_frame_data().

static int revert_channel_correlation	(	ALSDecContext *	ctx,
		ALSBlockData *	bd,
		ALSChannelData **	cd,
		int *	reverted,
		unsigned int	offset,
		int	c
	)

static

Recursively reverts the inter-channel correlation for a block.

Definition at line 1225 of file alsdec.c.

Referenced by read_frame_data().

static int read_frame_data	(	ALSDecContext *	ctx,
		unsigned int	ra_frame
	)

static

Read the frame data.

< block sizes.

Definition at line 1310 of file alsdec.c.

Referenced by decode_frame().

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

static

Decode an ALS frame.

Definition at line 1448 of file alsdec.c.

static av_cold int decode_end ( AVCodecContext * avctx )

static

Uninitialize the ALS decoder.

Definition at line 1576 of file alsdec.c.

Referenced by decode_init().

static av_cold int decode_init ( AVCodecContext * avctx )

static

Initialize the ALS decoder.

Definition at line 1611 of file alsdec.c.

static av_cold void flush ( AVCodecContext * avctx )

static

Flush (reset) the frame ID after seeking.

Definition at line 1768 of file alsdec.c.

Variable Documentation

const int8_t parcor_rice_table[3][20][2]

static

Initial value:

= {
    { {-52, 4}, {-29, 5}, {-31, 4}, { 19, 4}, {-16, 4},
      { 12, 3}, { -7, 3}, {  9, 3}, { -5, 3}, {  6, 3},
      { -4, 3}, {  3, 3}, { -3, 2}, {  3, 2}, { -2, 2},
      {  3, 2}, { -1, 2}, {  2, 2}, { -1, 2}, {  2, 2} },
    { {-58, 3}, {-42, 4}, {-46, 4}, { 37, 5}, {-36, 4},
      { 29, 4}, {-29, 4}, { 25, 4}, {-23, 4}, { 20, 4},
      {-17, 4}, { 16, 4}, {-12, 4}, { 12, 3}, {-10, 4},
      {  7, 3}, { -4, 4}, {  3, 3}, { -1, 3}, {  1, 3} },
    { {-59, 3}, {-45, 5}, {-50, 4}, { 38, 4}, {-39, 4},
      { 32, 4}, {-30, 4}, { 25, 3}, {-23, 3}, { 20, 3},
      {-20, 3}, { 16, 3}, {-13, 3}, { 10, 3}, { -7, 3},
      {  3, 3}, {  0, 3}, { -1, 3}, {  2, 3}, { -1, 2} }
}

Rice parameters and corresponding index offsets for decoding the indices of scaled PARCOR values.

The table chosen is set globally by the encoder and stored in ALSSpecificConfig.

Definition at line 49 of file alsdec.c.

Referenced by read_var_block_data().

const int16_t parcor_scaled_values[]

static

Scaled PARCOR values used for the first two PARCOR coefficients.

To be indexed by the Rice coded indices. Generated by: parcor_scaled_values[i] = 32 + ((i * (i+1)) << 7) - (1 << 20) Actual values are divided by 32 in order to be stored in 16 bits.

Definition at line 70 of file alsdec.c.

Referenced by read_var_block_data().

const uint8_t ltp_gain_values[4][4]

static

Initial value:

= {
    { 0,  8, 16,  24},
    {32, 40, 48,  56},
    {64, 70, 76,  82},
    {88, 92, 96, 100}
}

Gain values of p(0) for long-term prediction.

To be indexed by the Rice coded indices.

Definition at line 109 of file alsdec.c.

Referenced by read_var_block_data().

const int16_t mcc_weightings[]

static

Initial value:

= {
    204,  192,  179,  166,  153,  140,  128,  115,
    102,   89,   76,   64,   51,   38,   25,   12,
      0,  -12,  -25,  -38,  -51,  -64,  -76,  -89,
   -102, -115, -128, -140, -153, -166, -179, -192
}

Inter-channel weighting factors for multi-channel correlation.

To be indexed by the Rice coded indices.

Definition at line 120 of file alsdec.c.

Referenced by read_channel_data().

const uint8_t tail_code[16][6]

static

Initial value:

= {
    { 74, 44, 25, 13,  7, 3},
    { 68, 42, 24, 13,  7, 3},
    { 58, 39, 23, 13,  7, 3},
    {126, 70, 37, 19, 10, 5},
    {132, 70, 37, 20, 10, 5},
    {124, 70, 38, 20, 10, 5},
    {120, 69, 37, 20, 11, 5},
    {116, 67, 37, 20, 11, 5},
    {108, 66, 36, 20, 10, 5},
    {102, 62, 36, 20, 10, 5},
    { 88, 58, 34, 19, 10, 5},
    {162, 89, 49, 25, 13, 7},
    {156, 87, 49, 26, 14, 7},
    {150, 86, 47, 26, 14, 7},
    {142, 84, 47, 26, 14, 7},
    {131, 79, 46, 26, 14, 7}
}

Tail codes used in arithmetic coding using block Gilbert-Moore codes.

Definition at line 130 of file alsdec.c.

Referenced by read_var_block_data().

AVCodec ff_als_decoder

Initial value:

= {
    .name           = "als",
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = AV_CODEC_ID_MP4ALS,
    .priv_data_size = sizeof(ALSDecContext),
    .init           = decode_init,
    .close          = decode_end,
    .decode         = decode_frame,
    .flush          = flush,
    .capabilities   = CODEC_CAP_SUBFRAMES | CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("MPEG-4 Audio Lossless Coding (ALS)"),
}

Definition at line 1776 of file alsdec.c.

Data Structures

Macros

Enumerations

Functions

Variables

Detailed Description

Macro Definition Documentation

Enumeration Type Documentation

Function Documentation

Variable Documentation