libavcodec/qcelpdec.c File Reference

QCELP decoder. More...

#include <stddef.h>
#include "avcodec.h"
#include "internal.h"
#include "get_bits.h"
#include "qcelpdata.h"
#include "celp_math.h"
#include "celp_filters.h"
#include "acelp_filters.h"
#include "acelp_vectors.h"
#include "lsp.h"
#include <assert.h>

Go to the source code of this file.

Data Structures

struct QCELPContext

Enumerations

enum qcelp_packet_rate {
I_F_Q = -1, SILENCE, RATE_OCTAVE, RATE_QUARTER,
RATE_HALF, RATE_FULL
}

Functions

static av_cold int qcelp_decode_init (AVCodecContext *avctx)

Initialize the speech codec according to the specification.

static int decode_lspf (QCELPContext *q, float *lspf)

Decodes the 10 quantized LSP frequencies from the LSPV/LSP transmission codes of any bitrate and checks for badly received packets.

static void decode_gain_and_index (QCELPContext *q, float *gain)

Converts codebook transmission codes to GAIN and INDEX.

static int codebook_sanity_check_for_rate_quarter (const uint8_t *cbgain)

If the received packet is Rate 1/4 a further sanity check is made of the codebook gain.

static void compute_svector (QCELPContext *q, const float *gain, float *cdn_vector)

Computes the scaled codebook vector Cdn From INDEX and GAIN for all rates.

static void apply_gain_ctrl (float *v_out, const float *v_ref, const float *v_in)

Apply generic gain control.

static const float * do_pitchfilter (float memory[303], const float v_in[160], const float gain[4], const uint8_t *lag, const uint8_t pfrac[4])

Apply filter in pitch-subframe steps.

static void apply_pitch_filters (QCELPContext *q, float *cdn_vector)

Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.

static void lspf2lpc (const float *lspf, float *lpc)

Reconstructs LPC coefficients from the line spectral pair frequencies and performs bandwidth expansion.

static void interpolate_lpc (QCELPContext *q, const float *curr_lspf, float *lpc, const int subframe_num)

Interpolates LSP frequencies and computes LPC coefficients for a given bitrate & pitch subframe.

static qcelp_packet_rate buf_size2bitrate (const int buf_size)

static qcelp_packet_rate determine_bitrate (AVCodecContext *avctx, const int buf_size, const uint8_t **buf)

Determine the bitrate from the frame size and/or the first byte of the frame.

static void warn_insufficient_frame_quality (AVCodecContext *avctx, const char *message)

static void postfilter (QCELPContext *q, float *samples, float *lpc)

static int qcelp_decode_frame (AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)

Variables

AVCodec qcelp_decoder

Detailed Description

QCELP decoder.

Author:: Reynaldo H. Verdejo Pinochet

Remarks:: FFmpeg merging spearheaded by Kenan Gillet
Development mentored by Benjamin Larson

Definition in file qcelpdec.c.

Enumeration Type Documentation

enum qcelp_packet_rate

Enumerator:

I_F_Q	insufficient frame quality
SILENCE
RATE_OCTAVE
RATE_QUARTER
RATE_HALF
RATE_FULL

Definition at line 47 of file qcelpdec.c.

Function Documentation

static void apply_gain_ctrl	(	float *	v_out,
		const float *	v_ref,
		const float *	v_in
	)			`[static]`

Apply generic gain control.

Parameters:

	v_out	output vector
	v_in	gain-controlled vector
	v_ref	vector to control gain of

TIA/EIA/IS-733 2.4.8.3, 2.4.8.6

Definition at line 423 of file qcelpdec.c.

Referenced by apply_pitch_filters().

static void apply_pitch_filters	(	QCELPContext *	q,
		float *	cdn_vector
	)			`[static]`

Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.

TIA/EIA/IS-733 2.4.5.2, 2.4.8.7.2

Parameters:

	q	the context
	cdn_vector	the scaled codebook vector

Definition at line 500 of file qcelpdec.c.

Referenced by qcelp_decode_frame().

static qcelp_packet_rate buf_size2bitrate ( const int buf_size ) [static]

Definition at line 632 of file qcelpdec.c.

Referenced by determine_bitrate().

static int codebook_sanity_check_for_rate_quarter ( const uint8_t * cbgain ) [static]

If the received packet is Rate 1/4 a further sanity check is made of the codebook gain.

Parameters:

cbgain

the unpacked cbgain array

Returns:: -1 if the sanity check fails, 0 otherwise

TIA/EIA/IS-733 2.4.8.7.3

Definition at line 295 of file qcelpdec.c.

Referenced by qcelp_decode_frame().

static void compute_svector	(	QCELPContext *	q,
		const float *	gain,
		float *	cdn_vector
	)			`[static]`

Computes the scaled codebook vector Cdn From INDEX and GAIN for all rates.

The specification lacks some information here.

TIA/EIA/IS-733 has an omission on the codebook index determination formula for RATE_FULL and RATE_HALF frames at section 2.4.8.1.1. It says you have to subtract the decoded index parameter from the given scaled codebook vector index 'n' to get the desired circular codebook index, but it does not mention that you have to clamp 'n' to [0-9] in order to get RI-compliant results.

The reason for this mistake seems to be the fact they forgot to mention you have to do these calculations per codebook subframe and adjust given equation values accordingly.

Parameters:

	q	the context
	gain	array holding the 4 pitch subframe gain values
	cdn_vector	array for the generated scaled codebook vector

Definition at line 332 of file qcelpdec.c.

Referenced by qcelp_decode_frame().

static void decode_gain_and_index	(	QCELPContext *	q,
		float *	gain
	)			`[static]`

Converts codebook transmission codes to GAIN and INDEX.

Parameters:

	q	the context
	gain	array holding the decoded gain

TIA/EIA/IS-733 2.4.6.2

Definition at line 207 of file qcelpdec.c.

Referenced by qcelp_decode_frame().

static int decode_lspf	(	QCELPContext *	q,
		float *	lspf
	)			`[static]`

Decodes the 10 quantized LSP frequencies from the LSPV/LSP transmission codes of any bitrate and checks for badly received packets.

Parameters:

	q	the context
	lspf	line spectral pair frequencies

Returns:: 0 on success, -1 if the packet is badly received

TIA/EIA/IS-733 2.4.3.2.6.2-2, 2.4.8.7.3

Definition at line 114 of file qcelpdec.c.

Referenced by qcelp_decode_frame().

static qcelp_packet_rate determine_bitrate	(	AVCodecContext *	avctx,
		const int	buf_size,
		const uint8_t **	buf
	)			`[static]`

Determine the bitrate from the frame size and/or the first byte of the frame.

Parameters:

	avctx	the AV codec context
	buf_size	length of the buffer
	buf	the bufffer

Returns:: the bitrate on success, I_F_Q if the bitrate cannot be satisfactorily determined

TIA/EIA/IS-733 2.4.8.7.1

Definition at line 658 of file qcelpdec.c.

Referenced by qcelp_decode_frame().

static const float* do_pitchfilter	(	float	memory[303],
		const float	v_in[160],
		const float	gain[4],
		const uint8_t *	lag,
		const uint8_t	pfrac[4]
	)			`[static]`

Apply filter in pitch-subframe steps.

Parameters:

	memory	buffer for the previous state of the filter must be able to contain 303 elements the 143 first elements are from the previous state the next 160 are for output
	v_in	input filter vector
	gain	per-subframe gain array, each element is between 0.0 and 2.0
	lag	per-subframe lag array, each element is between 16 and 143 if its corresponding pfrac is 0, between 16 and 139 otherwise
	pfrac	per-subframe boolean array, 1 if the lag is fractional, 0 otherwise

Returns:: filter output vector

Definition at line 452 of file qcelpdec.c.

Referenced by apply_pitch_filters().

static void interpolate_lpc	(	QCELPContext *	q,
		const float *	curr_lspf,
		float *	lpc,
		const int	subframe_num
	)			`[static]`

Interpolates LSP frequencies and computes LPC coefficients for a given bitrate & pitch subframe.

TIA/EIA/IS-733 2.4.3.3.4, 2.4.8.7.2

Parameters:

	q	the context
	curr_lspf	LSP frequencies vector of the current frame
	lpc	float vector for the resulting LPC
	subframe_num	frame number in decoded stream

Definition at line 607 of file qcelpdec.c.

Referenced by qcelp_decode_frame().

static void lspf2lpc	(	const float *	lspf,
		float *	lpc
	)			`[static]`

Reconstructs LPC coefficients from the line spectral pair frequencies and performs bandwidth expansion.

Parameters:

	lspf	line spectral pair frequencies
	lpc	linear predictive coding coefficients

Note:: : bandwidth_expansion_coeff could be precalculated into a table but it seems to be slower on x86

TIA/EIA/IS-733 2.4.3.3.5

Definition at line 578 of file qcelpdec.c.

Referenced by interpolate_lpc().

static void postfilter	(	QCELPContext *	q,
		float *	samples,
		float *	lpc
	)			`[static]`

Definition at line 704 of file qcelpdec.c.

static int qcelp_decode_frame	(	AVCodecContext *	avctx,
		void *	data,
		int *	data_size,
		AVPacket *	avpkt
	)			`[static]`

Definition at line 734 of file qcelpdec.c.

static av_cold int qcelp_decode_init ( AVCodecContext * avctx ) [static]

Initialize the speech codec according to the specification.

TIA/EIA/IS-733 2.4.9

Definition at line 90 of file qcelpdec.c.

static void warn_insufficient_frame_quality	(	AVCodecContext *	avctx,
		const char *	message
	)			`[static]`

Definition at line 697 of file qcelpdec.c.

Referenced by qcelp_decode_frame().

Variable Documentation

AVCodec qcelp_decoder

Initial value:

{
    .name   = "qcelp",
    .type   = AVMEDIA_TYPE_AUDIO,
    .id     = CODEC_ID_QCELP,
    .init   = qcelp_decode_init,
    .decode = qcelp_decode_frame,
    .priv_data_size = sizeof(QCELPContext),
    .long_name = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),
}

Definition at line 845 of file qcelpdec.c.


Data Structures
struct	QCELPContext
Enumerations
enum	qcelp_packet_rate { I_F_Q = -1, SILENCE, RATE_OCTAVE, RATE_QUARTER, RATE_HALF, RATE_FULL }
Functions
static av_cold int	qcelp_decode_init (AVCodecContext *avctx)
	Initialize the speech codec according to the specification.
static int	decode_lspf (QCELPContext q, float lspf)
	Decodes the 10 quantized LSP frequencies from the LSPV/LSP transmission codes of any bitrate and checks for badly received packets.
static void	decode_gain_and_index (QCELPContext q, float gain)
	Converts codebook transmission codes to GAIN and INDEX.
static int	codebook_sanity_check_for_rate_quarter (const uint8_t *cbgain)
	If the received packet is Rate 1/4 a further sanity check is made of the codebook gain.
static void	compute_svector (QCELPContext q, const float gain, float *cdn_vector)
	Computes the scaled codebook vector Cdn From INDEX and GAIN for all rates.
static void	apply_gain_ctrl (float v_out, const float v_ref, const float *v_in)
	Apply generic gain control.
static const float *	do_pitchfilter (float memory[303], const float v_in[160], const float gain[4], const uint8_t *lag, const uint8_t pfrac[4])
	Apply filter in pitch-subframe steps.
static void	apply_pitch_filters (QCELPContext q, float cdn_vector)
	Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.
static void	lspf2lpc (const float lspf, float lpc)
	Reconstructs LPC coefficients from the line spectral pair frequencies and performs bandwidth expansion.
static void	interpolate_lpc (QCELPContext q, const float curr_lspf, float *lpc, const int subframe_num)
	Interpolates LSP frequencies and computes LPC coefficients for a given bitrate & pitch subframe.
static qcelp_packet_rate	buf_size2bitrate (const int buf_size)
static qcelp_packet_rate	determine_bitrate (AVCodecContext avctx, const int buf_size, const uint8_t *buf)
	Determine the bitrate from the frame size and/or the first byte of the frame.
static void	warn_insufficient_frame_quality (AVCodecContext avctx, const char message)
static void	postfilter (QCELPContext q, float samples, float *lpc)
static int	qcelp_decode_frame (AVCodecContext avctx, void data, int data_size, AVPacket avpkt)
Variables
AVCodec	qcelp_decoder