shithub: opus

Download patch

ref: 4600e77583fc29738fd5c2aa6cb5ceb30596cc7d
parent: 9fdc489c359b8723902a8e440d6efa89ba929862
author: Jean-Marc Valin <jmvalin@amazon.com>
date: Tue Jul 11 15:03:13 EDT 2023 

Implement allocation of the DRED bits

Should work for both CBR and VBR. In the CBR case, we can make
CELT VBR and use DRED to fill the rest.


--- a/src/opus_encoder.c
+++ b/src/opus_encoder.c
@@ -1958,7 +1958,6 @@
     if (st->mode != MODE_SILK_ONLY)
     {
         opus_val32 celt_pred=2;
-        celt_encoder_ctl(celt_enc, OPUS_SET_VBR(0));
         /* We may still decide to disable prediction later */
         if (st->silk_mode.reducedDependency)
            celt_pred = 0;
@@ -2056,8 +2055,21 @@
         ec_enc_done(&enc);
         nb_compr_bytes = ret;
     } else {
-       nb_compr_bytes = (max_data_bytes-1)-redundancy_bytes;
-       ec_enc_shrink(&enc, nb_compr_bytes);
+        nb_compr_bytes = (max_data_bytes-1)-redundancy_bytes;
+#ifdef ENABLE_NEURAL_FEC
+        if (st->dred_duration > 0)
+        {
+            int max_celt_bytes;
+            opus_int32 dred_bytes = dred_bitrate_bps/(frame_rate*8);
+            /* Allow CELT to steal up to 25% of the remaining bits. */
+            max_celt_bytes = nb_compr_bytes - dred_bytes*3/4;
+            /* But try to give CELT at least 4 bytes */
+            max_celt_bytes = IMAX(ec_tell(&enc)/8 + 4, max_celt_bytes);
+            /* Subject to the original max. */
+            nb_compr_bytes = IMIN(nb_compr_bytes, max_celt_bytes);
+        }
+#endif
+        ec_enc_shrink(&enc, nb_compr_bytes);
     }
 
 #ifndef DISABLE_FLOAT_API
@@ -2092,6 +2104,7 @@
 
     if (st->mode != MODE_SILK_ONLY)
     {
+        celt_encoder_ctl(celt_enc, OPUS_SET_VBR(st->use_vbr));
         if (st->mode == MODE_HYBRID)
         {
             if( st->use_vbr ) {
@@ -2106,6 +2119,19 @@
                 celt_encoder_ctl(celt_enc, OPUS_SET_BITRATE(st->bitrate_bps));
             }
         }
+#ifdef ENABLE_NEURAL_FEC
+        /* When Using DRED CBR, we can actually make the CELT part VBR and have DRED pick up the slack. */
+        if (!st->use_vbr && st->dred_duration > 0)
+        {
+            opus_int32 celt_bitrate = st->bitrate_bps;
+            celt_encoder_ctl(celt_enc, OPUS_SET_VBR(1));
+            celt_encoder_ctl(celt_enc, OPUS_SET_VBR_CONSTRAINT(0));
+            if (st->mode == MODE_HYBRID) {
+                celt_bitrate -= st->silk_mode.bitRate;
+            }
+            celt_encoder_ctl(celt_enc, OPUS_SET_BITRATE(celt_bitrate));
+        }
+#endif
         if (st->mode != st->prev_mode && st->prev_mode > 0)
         {
            unsigned char dummy[2];
@@ -2118,7 +2144,6 @@
         /* If false, we already busted the budget and we'll end up with a "PLC frame" */
         if (ec_tell(&enc) <= 8*nb_compr_bytes)
         {
-           celt_encoder_ctl(celt_enc, OPUS_SET_VBR(st->use_vbr));
            ret = celt_encode_with_ec(celt_enc, pcm_buf, frame_size, NULL, nb_compr_bytes, &enc);
            if (ret < 0)
            {
-- 
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