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Frame erasure support for LSF decoding

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This commit is contained in:
Vladimir Voroshilov 2009-06-11 12:30:46 +07:00 committed by Michael Niedermayer
parent a5e0c4ddb5
commit 388f225561
2 changed files with 36 additions and 4 deletions
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5
libavcodec/g729data.h
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@ -268,6 +268,11 @@ static const int16_t cb_ma_predictor_sum[2][10] = { /* (0.15) */
{14585, 18333, 19772, 17344, 16426, 16459, 15155, 15220, 16043, 15708}
};
static const int16_t cb_ma_predictor_sum_inv[2][10] = { /* (3.12) */
{17210, 15888, 16357, 16183, 16516, 15833, 15888, 15421, 14840, 15597},
{ 9202, 7320, 6788, 7738, 8170, 8154, 8856, 8818, 8366, 8544}
};
/**
* initial LSP coefficients belongs to virtual frame preceding the
* first frame of the stream

35
libavcodec/g729dec.c
View File

@ -90,6 +90,8 @@ typedef struct {
int16_t lsfq[10]; ///< (2.13) quantized LSF coefficients from previous frame
int16_t lsp_buf[2][10]; ///< (0.15) LSP coefficients (previous and current frames) (3.2.5)
int16_t *lsp[2]; ///< pointers to lsp_buf
int ma_predictor_prev; ///< switched MA predictor of LSP quantizer from last good frame
} G729Context;
static const G729FormatDescription format_g729_8k = {
@ -157,13 +159,26 @@ static void lsf_decode(int16_t* lsfq, int16_t* past_quantizer_outputs[MA_NP + 1]
lsfq[i] = sum >> 15;
}
/* Rotate past_quantizer_outputs. */
memmove(past_quantizer_outputs + 1, past_quantizer_outputs, MA_NP * sizeof(int16_t*));
past_quantizer_outputs[0] = quantizer_output;
ff_acelp_reorder_lsf(lsfq, LSFQ_DIFF_MIN, LSFQ_MIN, LSFQ_MAX, 10);
}
static void lsf_restore_from_previous(int16_t* lsfq,
int16_t* past_quantizer_outputs[MA_NP + 1],
int ma_predictor_prev)
{
int16_t* quantizer_output = past_quantizer_outputs[MA_NP];
int i,k;
for (i = 0; i < 10; i++) {
int tmp = lsfq[i] << 15;
for (k = 0; k < MA_NP; k++)
tmp -= past_quantizer_outputs[k][i] * cb_ma_predictor[ma_predictor_prev][k][i];
quantizer_output[i] = ((tmp >> 15) * cb_ma_predictor_sum_inv[ma_predictor_prev][i]) >> 12;
}
}
static av_cold int decoder_init(AVCodecContext * avctx)
{
G729Context* ctx = avctx->priv_data;
@ -201,6 +216,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
int frame_erasure = 0; ///< frame erasure detected during decoding
int bad_pitch = 0; ///< parity check failed
int i;
int16_t *tmp;
G729Context *ctx = avctx->priv_data;
int16_t lp[2][11]; // (3.12)
uint8_t ma_predictor; ///< switched MA predictor of LSP quantizer
@ -238,9 +254,20 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
quantizer_2nd_lo = get_bits(&gb, VQ_2ND_BITS);
quantizer_2nd_hi = get_bits(&gb, VQ_2ND_BITS);
if(frame_erasure)
lsf_restore_from_previous(ctx->lsfq, ctx->past_quantizer_outputs,
ctx->ma_predictor_prev);
else {
lsf_decode(ctx->lsfq, ctx->past_quantizer_outputs,
ma_predictor,
quantizer_1st, quantizer_2nd_lo, quantizer_2nd_hi);
ctx->ma_predictor_prev = ma_predictor;
}
tmp = ctx->past_quantizer_outputs[MA_NP];
memmove(ctx->past_quantizer_outputs + 1, ctx->past_quantizer_outputs,
MA_NP * sizeof(int16_t*));
ctx->past_quantizer_outputs[0] = tmp;
ff_acelp_lsf2lsp(ctx->lsp[1], ctx->lsfq, 10);