Real Audio 1.0 (14.4K) encoder. More...

#include <float.h>
#include "avcodec.h"
#include "audio_frame_queue.h"
#include "celp_filters.h"
#include "internal.h"
#include "mathops.h"
#include "put_bits.h"
#include "ra144.h"

Functions
static av_cold int	ra144_encode_close (AVCodecContext *avctx)

static av_cold int	ra144_encode_init (AVCodecContext *avctx)

static int	quantize (int value, const int16_t *table, unsigned int size)
	Quantize a value by searching a sorted table for the element with the nearest value. More...

static void	orthogonalize (float v, const float u)
	Orthogonalize a vector to another vector. More...

static void	get_match_score (float work, const float coefs, float vect, const float ortho1, const float ortho2, const float data, float score, float gain)
	Calculate match score and gain of an LPC-filtered vector with respect to input data, possibly orthogonalizing it to up to two other vectors. More...

static void	create_adapt_vect (float vect, const int16_t cb, int lag)
	Create a vector from the adaptive codebook at a given lag value. More...

static int	adaptive_cb_search (const int16_t adapt_cb, float work, const float coefs, float data)
	Search the adaptive codebook for the best entry and gain and remove its contribution from input data. More...

static void	find_best_vect (float work, const float coefs, const int8_t cb[][BLOCKSIZE], const float ortho1, const float ortho2, float data, int idx, float *gain)
	Find the best vector of a fixed codebook by applying an LPC filter to codebook entries, possibly orthogonalizing them to up to two other vectors and matching the results with input data. More...

static void	fixed_cb_search (float work, const float coefs, float data, int cba_idx, int cb1_idx, int *cb2_idx)
	Search the two fixed codebooks for the best entry and gain. More...

static void	ra144_encode_subblock (RA144Context ractx, const int16_t sblock_data, const int16_t lpc_coefs, unsigned int rms, PutBitContext pb)
	Encode a subblock of the current frame. More...

static int	ra144_encode_frame (AVCodecContext avctx, AVPacket avpkt, const AVFrame frame, int got_packet_ptr)

Variables
AVCodec	ff_ra_144_encoder

Detailed Description

Real Audio 1.0 (14.4K) encoder.

Author: Francesco Lavra franc.nosp@m.esco.nosp@m.lavra.nosp@m.@int.nosp@m.erfre.nosp@m.e.it

Definition in file ra144enc.c.

Function Documentation

◆ ra144_encode_close()

static av_cold int ra144_encode_close ( AVCodecContext * avctx )

static

Definition at line 38 of file ra144enc.c.

Referenced by ra144_encode_init().

◆ ra144_encode_init()

static av_cold int ra144_encode_init ( AVCodecContext * avctx )

static

Definition at line 47 of file ra144enc.c.

◆ quantize()

static int quantize	(	int	value,
		const int16_t *	table,
		unsigned int	size
	)

static

Quantize a value by searching a sorted table for the element with the nearest value.

Parameters

value	value to quantize
table	array containing the quantization table
size	size of the quantization table

Returns: index of the quantization table corresponding to the element with the nearest value

Definition at line 89 of file ra144enc.c.

Referenced by ra144_encode_frame().

◆ orthogonalize()

static void orthogonalize	(	float *	v,
		const float *	u
	)

static

Orthogonalize a vector to another vector.

Parameters

v	vector to orthogonalize
u	vector against which orthogonalization is performed

Definition at line 114 of file ra144enc.c.

Referenced by fixed_cb_search(), and get_match_score().

◆ get_match_score()

static void get_match_score	(	float *	work,
		const float *	coefs,
		float *	vect,
		const float *	ortho1,
		const float *	ortho2,
		const float *	data,
		float *	score,
		float *	gain
	)

static

Calculate match score and gain of an LPC-filtered vector with respect to input data, possibly orthogonalizing it to up to two other vectors.

Parameters

work	array used to calculate the filtered vector
coefs	coefficients of the LPC filter
vect	original vector
ortho1	first vector against which orthogonalization is performed
ortho2	second vector against which orthogonalization is performed
data	input data
score	pointer to variable where match score is returned
gain	pointer to variable where gain is returned

Definition at line 142 of file ra144enc.c.

Referenced by adaptive_cb_search(), and find_best_vect().

◆ create_adapt_vect()

static void create_adapt_vect	(	float *	vect,
		const int16_t *	cb,
		int	lag
	)

static

Create a vector from the adaptive codebook at a given lag value.

Parameters

vect	array where vector is stored
cb	adaptive codebook
lag	lag value

Definition at line 175 of file ra144enc.c.

Referenced by adaptive_cb_search().

◆ adaptive_cb_search()

static int adaptive_cb_search	(	const int16_t *	adapt_cb,
		float *	work,
		const float *	coefs,
		float *	data
	)

static

Search the adaptive codebook for the best entry and gain and remove its contribution from input data.

Parameters

adapt_cb	array from which the adaptive codebook is extracted
work	array used to calculate LPC-filtered vectors
coefs	coefficients of the LPC filter
data	input data

Returns: index of the best entry of the adaptive codebook

Re-calculate the filtered vector from the vector with maximum match score and remove its contribution from input data.

Definition at line 198 of file ra144enc.c.

Referenced by ra144_encode_subblock().

◆ find_best_vect()

static void find_best_vect	(	float *	work,
		const float *	coefs,
		const int8_t	cb[][BLOCKSIZE],
		const float *	ortho1,
		const float *	ortho2,
		float *	data,
		int *	idx,
		float *	gain
	)

static

Find the best vector of a fixed codebook by applying an LPC filter to codebook entries, possibly orthogonalizing them to up to two other vectors and matching the results with input data.

Parameters

work	array used to calculate the filtered vectors
coefs	coefficients of the LPC filter
cb	fixed codebook
ortho1	first vector against which orthogonalization is performed
ortho2	second vector against which orthogonalization is performed
data	input data
idx	pointer to variable where the index of the best codebook entry is returned
gain	pointer to variable where the gain of the best codebook entry is returned

Definition at line 246 of file ra144enc.c.

Referenced by fixed_cb_search().

◆ fixed_cb_search()

static void fixed_cb_search	(	float *	work,
		const float *	coefs,
		float *	data,
		int	cba_idx,
		int *	cb1_idx,
		int *	cb2_idx
	)

static

Search the two fixed codebooks for the best entry and gain.

Parameters

work	array used to calculate LPC-filtered vectors
coefs	coefficients of the LPC filter
data	input data
cba_idx	index of the best entry of the adaptive codebook
cb1_idx	pointer to variable where the index of the best entry of the first fixed codebook is returned
cb2_idx	pointer to variable where the index of the best entry of the second fixed codebook is returned

The filtered vector from the adaptive codebook can be retrieved from work, because this function is called just after adaptive_cb_search().

Re-calculate the filtered vector from the vector with maximum match score and remove its contribution from input data.

Definition at line 281 of file ra144enc.c.

Referenced by ra144_encode_subblock().

◆ ra144_encode_subblock()

static void ra144_encode_subblock	(	RA144Context *	ractx,
		const int16_t *	sblock_data,
		const int16_t *	lpc_coefs,
		unsigned int	rms,
		PutBitContext *	pb
	)

static

Encode a subblock of the current frame.

Parameters

ractx	encoder context
sblock_data	input data of the subblock
lpc_coefs	coefficients of the LPC filter
rms	RMS of the reflection coefficients
pb	pointer to PutBitContext of the current frame

Calculate the zero-input response of the LPC filter and subtract it from input data.

Codebook search is performed without taking into account the contribution of the previous subblock, since it has been just subtracted from input data.

The filtered vector from the adaptive codebook can be retrieved from work, see implementation of adaptive_cb_search().

Definition at line 330 of file ra144enc.c.

Referenced by ra144_encode_frame().

◆ ra144_encode_frame()

static int ra144_encode_frame	(	AVCodecContext *	avctx,
		AVPacket *	avpkt,
		const AVFrame *	frame,
		int *	got_packet_ptr
	)

static

< reflection coefficients of the frame

< RMS of the reflection coefficients

Since the LPC coefficients are calculated on a frame centered over the fourth subframe, to encode a given frame, data from the next frame is needed. In each call to this function, the previous frame (whose data are saved in the encoder context) is encoded, and data from the current frame are saved in the encoder context to be used in the next function call.

TODO: apply perceptual weighting of the input speech through bandwidth expansion of the LPC filter.

The filter is unstable: use the coefficients of the previous frame.

Definition at line 430 of file ra144enc.c.

Variable Documentation

◆ ff_ra_144_encoder

AVCodec ff_ra_144_encoder

Initial value:

= {
    .name           = "real_144",
    .long_name      = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = AV_CODEC_ID_RA_144,
    .priv_data_size = sizeof(RA144Context),
    .init           = ra144_encode_init,
    .encode2        = ra144_encode_frame,
    .close          = ra144_encode_close,
    .capabilities   = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_SMALL_LAST_FRAME,
    .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
                                                     AV_SAMPLE_FMT_NONE },
    .supported_samplerates = (const int[]){ 8000, 0 },
    .channel_layouts = (const uint64_t[]) { AV_CH_LAYOUT_MONO, 0 },
}

Definition at line 545 of file ra144enc.c.

Functions

Variables

Detailed Description

Function Documentation

◆ ra144_encode_close()

◆ ra144_encode_init()

◆ quantize()

◆ orthogonalize()

◆ get_match_score()

◆ create_adapt_vect()

◆ adaptive_cb_search()

◆ find_best_vect()

◆ fixed_cb_search()

◆ ra144_encode_subblock()

◆ ra144_encode_frame()

Variable Documentation

◆ ff_ra_144_encoder