Avoid copying imdct output

Use the output buffer directly for imdct output, avoiding use of an
intermediary buffer and copying from it. This works because the output
buffer is offset to always be continous with the overlap buffer in the
decoder. Adjust encoder resynth code to have the same buffer layout.

Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>

1 files changed, 13 insertions, 38 deletions

diff --git a/celt/celt.c b/celt/celt.c
index 26695fae..576ccb92 100644
--- a/celt/celt.c
+++ b/celt/celt.c
@@ -193,7 +193,8 @@ struct OpusCustomEncoder {
    int intensity;
 
 #ifdef RESYNTH
-   celt_sig syn_mem[2][2*MAX_PERIOD];
+   /* +MAX_PERIOD/2 to make space for overlap */
+   celt_sig syn_mem[2][2*MAX_PERIOD+MAX_PERIOD/2];
 #endif
 
    celt_sig in_mem[1]; /* Size = channels*mode->overlap */
@@ -201,9 +202,6 @@ struct OpusCustomEncoder {
    /* opus_val16 oldBandE[],     Size = channels*mode->nbEBands */
    /* opus_val16 oldLogE[],      Size = channels*mode->nbEBands */
    /* opus_val16 oldLogE2[],     Size = channels*mode->nbEBands */
-#ifdef RESYNTH
-   /* opus_val16 overlap_mem[],  Size = channels*overlap */
-#endif
 };
 
 int celt_encoder_get_size(int channels)
@@ -220,9 +218,6 @@ OPUS_CUSTOM_NOSTATIC int opus_custom_encoder_get_size(const CELTMode *mode, int
          + 3*channels*mode->nbEBands*sizeof(opus_val16);  /* opus_val16 oldBandE[channels*mode->nbEBands]; */
                                                           /* opus_val16 oldLogE[channels*mode->nbEBands]; */
                                                           /* opus_val16 oldLogE2[channels*mode->nbEBands]; */
-#ifdef RESYNTH
-   size += channels*mode->overlap*sizeof(celt_sig);       /* celt_sig overlap_mem[channels*mode->nbEBands]; */
-#endif
    return size;
 }
 
@@ -478,18 +473,14 @@ static void compute_mdcts(const CELTMode *mode, int shortBlocks, celt_sig * OPUS
 /** Compute the IMDCT and apply window for all sub-frames and
     all channels in a frame */
 static void compute_inv_mdcts(const CELTMode *mode, int shortBlocks, celt_sig *X,
-      celt_sig * OPUS_RESTRICT out_mem[],
-      celt_sig * OPUS_RESTRICT overlap_mem[], int C, int LM)
+      celt_sig * OPUS_RESTRICT out_mem[], int C, int LM)
 {
    int c;
    const int N = mode->shortMdctSize<<LM;
    const int overlap = OVERLAP(mode);
-   VARDECL(opus_val32, x);
    SAVE_STACK;
 
-   ALLOC(x, N+overlap, opus_val32);
    c=0; do {
-      int j;
       int b;
       int N2 = N;
       int B = 1;
@@ -499,21 +490,14 @@ static void compute_inv_mdcts(const CELTMode *mode, int shortBlocks, celt_sig *X
          N2 = mode->shortMdctSize;
          B = shortBlocks;
       }
-      /* Prevents problems from the imdct doing the overlap-add */
-      OPUS_CLEAR(x, overlap);
+      /* The imdct does the overlap-add */
+      OPUS_COPY(out_mem[c], out_mem[c]+N, overlap);
 
       for (b=0;b<B;b++)
       {
          /* IMDCT on the interleaved the sub-frames */
-         clt_mdct_backward(&mode->mdct, &X[b+c*N2*B], x+N2*b, mode->window, overlap, shortBlocks ? mode->maxLM : mode->maxLM-LM, B);
+         clt_mdct_backward(&mode->mdct, &X[b+c*N2*B], out_mem[c]+N2*b, mode->window, overlap, shortBlocks ? mode->maxLM : mode->maxLM-LM, B);
       }
-
-      for (j=0;j<overlap;j++)
-         out_mem[c][j] = x[j] + overlap_mem[c][j];
-      for (;j<N;j++)
-         out_mem[c][j] = x[j];
-      for (j=0;j<overlap;j++)
-         overlap_mem[c][j] = x[N+j];
    } while (++c<C);
    RESTORE_STACK;
 }
@@ -1988,7 +1972,6 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_val16 * pcm,
    /* Re-synthesis of the coded audio if required */
    {
       celt_sig *out_mem[2];
-      celt_sig *overlap_mem[2];
 
       log2Amp(mode, st->start, st->end, bandE, oldBandE, C);
       if (silence)
@@ -2009,9 +1992,9 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_val16 * pcm,
       /* Synthesis */
       denormalise_bands(mode, X, freq, bandE, effEnd, C, M);
 
-      OPUS_MOVE(st->syn_mem[0], st->syn_mem[0]+N, MAX_PERIOD);
+      OPUS_MOVE(st->syn_mem[0], st->syn_mem[0]+N, 2*MAX_PERIOD-N);
       if (CC==2)
-         OPUS_MOVE(st->syn_mem[1], st->syn_mem[1]+N, MAX_PERIOD);
+         OPUS_MOVE(st->syn_mem[1], st->syn_mem[1]+N, 2*MAX_PERIOD-N);
 
       c=0; do
          for (i=0;i<M*eBands[st->start];i++)
@@ -2028,15 +2011,11 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_val16 * pcm,
             freq[N+i] = freq[i];
       }
 
-      out_mem[0] = st->syn_mem[0]+MAX_PERIOD;
-      if (CC==2)
-         out_mem[1] = st->syn_mem[1]+MAX_PERIOD;
-
-      overlap_mem[0] = (celt_sig*)(oldLogE2 + CC*nbEBands);
+      out_mem[0] = st->syn_mem[0]+2*MAX_PERIOD-N;
       if (CC==2)
-         overlap_mem[1] = overlap_mem[0] + st->overlap;
+         out_mem[1] = st->syn_mem[1]+2*MAX_PERIOD-N;
 
-      compute_inv_mdcts(mode, shortBlocks, freq, out_mem, overlap_mem, CC, LM);
+      compute_inv_mdcts(mode, shortBlocks, freq, out_mem, CC, LM);
 
       c=0; do {
          st->prefilter_period=IMAX(st->prefilter_period, COMBFILTER_MINPERIOD);
@@ -2486,7 +2465,6 @@ static void celt_decode_lost(CELTDecoder * OPUS_RESTRICT st, opus_val16 * OPUS_R
    int offset;
    celt_sig *out_mem[2];
    celt_sig *decode_mem[2];
-   celt_sig *overlap_mem[2];
    opus_val16 *lpc;
    opus_val32 *out_syn[2];
    opus_val16 *oldBandE, *oldLogE, *oldLogE2, *backgroundLogE;
@@ -2505,7 +2483,6 @@ static void celt_decode_lost(CELTDecoder * OPUS_RESTRICT st, opus_val16 * OPUS_R
    c=0; do {
       decode_mem[c] = st->_decode_mem + c*(DECODE_BUFFER_SIZE+st->overlap);
       out_mem[c] = decode_mem[c]+DECODE_BUFFER_SIZE-MAX_PERIOD;
-      overlap_mem[c] = decode_mem[c]+DECODE_BUFFER_SIZE;
    } while (++c<C);
    lpc = (opus_val16*)(st->_decode_mem+(DECODE_BUFFER_SIZE+st->overlap)*C);
    oldBandE = lpc+C*LPC_ORDER;
@@ -2585,7 +2562,7 @@ static void celt_decode_lost(CELTDecoder * OPUS_RESTRICT st, opus_val16 * OPUS_R
          for (i=bound;i<N;i++)
             freq[c*N+i] = 0;
       } while (++c<C);
-      compute_inv_mdcts(mode, 0, freq, out_syn, overlap_mem, C, LM);
+      compute_inv_mdcts(mode, 0, freq, out_syn, C, LM);
    } else {
       /* Pitch-based PLC */
       VARDECL(opus_val32, e);
@@ -2765,7 +2742,6 @@ int celt_decode_with_ec(CELTDecoder * OPUS_RESTRICT st, const unsigned char *dat
    VARDECL(unsigned char, collapse_masks);
    celt_sig *out_mem[2];
    celt_sig *decode_mem[2];
-   celt_sig *overlap_mem[2];
    celt_sig *out_syn[2];
    opus_val16 *lpc;
    opus_val16 *oldBandE, *oldLogE, *oldLogE2, *backgroundLogE;
@@ -2806,7 +2782,6 @@ int celt_decode_with_ec(CELTDecoder * OPUS_RESTRICT st, const unsigned char *dat
    c=0; do {
       decode_mem[c] = st->_decode_mem + c*(DECODE_BUFFER_SIZE+overlap);
       out_mem[c] = decode_mem[c]+DECODE_BUFFER_SIZE-MAX_PERIOD;
-      overlap_mem[c] = decode_mem[c]+DECODE_BUFFER_SIZE;
    } while (++c<CC);
    lpc = (opus_val16*)(st->_decode_mem+(DECODE_BUFFER_SIZE+overlap)*CC);
    oldBandE = lpc+CC*LPC_ORDER;
@@ -3063,7 +3038,7 @@ int celt_decode_with_ec(CELTDecoder * OPUS_RESTRICT st, const unsigned char *dat
    }
 
    /* Compute inverse MDCTs */
-   compute_inv_mdcts(mode, shortBlocks, freq, out_syn, overlap_mem, CC, LM);
+   compute_inv_mdcts(mode, shortBlocks, freq, out_syn, CC, LM);
 
    c=0; do {
       st->postfilter_period=IMAX(st->postfilter_period, COMBFILTER_MINPERIOD);