From 570c2a9516ba95de9510586f38bd6d67bc15ca6e Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jeanmarcv@google.com>
Date: Mon, 16 Dec 2024 15:02:48 -0500
Subject: [PATCH] Allow for more than 1275 bytes for qext packets

---
 celt/bands.c            |  2 +-
 celt/celt_encoder.c     | 11 ++++++++---
 celt/modes.h            |  1 +
 celt/opus_custom_demo.c |  5 +++++
 4 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/celt/bands.c b/celt/bands.c
index 5e33bf117..0a4221b8d 100644
--- a/celt/bands.c
+++ b/celt/bands.c
@@ -1835,7 +1835,7 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
                ec_ctx ext_ec_save, ext_ec_save2;
                unsigned char *ext_bytes_buf;
                int ext_nstart_bytes, ext_nend_bytes, ext_save_bytes;
-               unsigned char ext_bytes_save[1275];
+               unsigned char ext_bytes_save[QEXT_PACKET_SIZE_CAP];
 #endif
                opus_val16 w[2];
                compute_channel_weights(bandE[i], bandE[i+m->nbEBands], w);
diff --git a/celt/celt_encoder.c b/celt/celt_encoder.c
index b7f7108e1..41b3c3568 100644
--- a/celt/celt_encoder.c
+++ b/celt/celt_encoder.c
@@ -1714,6 +1714,7 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_res * pcm, in
    opus_val32 toneishness=0;
    VARDECL(celt_glog, surround_dynalloc);
    int qext_bytes=0;
+   int packet_size_cap = 1275;
 #ifdef ENABLE_QEXT
    int qext_scale;
    int qext_end=0;
@@ -1763,6 +1764,7 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_res * pcm, in
 
 #ifdef ENABLE_QEXT
    qext_scale = st->qext_scale;
+   if (st->enable_qext) packet_size_cap = QEXT_PACKET_SIZE_CAP;
 #endif
 
    prefilter_mem = st->in_mem+CC*(overlap);
@@ -1810,7 +1812,7 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_res * pcm, in
 #endif
 
    /* Can't produce more than 1275 output bytes */
-   nbCompressedBytes = IMIN(nbCompressedBytes,1275);
+   nbCompressedBytes = IMIN(nbCompressedBytes,packet_size_cap);
 
    if (st->vbr && st->bitrate!=OPUS_BITRATE_MAX)
    {
@@ -1910,6 +1912,9 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_res * pcm, in
       /* Pretend we've filled all the remaining bits with zeros
             (that's what the initialiser did anyway) */
       tell = nbCompressedBytes*8;
+#ifdef ENABLE_QEXT
+      if (st->enable_qext) nbCompressedBytes = IMIN(nbCompressedBytes, 1275);
+#endif
       enc->nbits_total+=tell-ec_tell(enc);
    }
    c=0; do {
@@ -2347,7 +2352,7 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_res * pcm, in
 
      /* Don't attempt to use more than 510 kb/s, even for frames smaller than 20 ms.
         The CELT allocator will just not be able to use more than that anyway. */
-     nbCompressedBytes = IMIN(nbCompressedBytes,1275>>(3-LM));
+     nbCompressedBytes = IMIN(nbCompressedBytes,packet_size_cap>>(3-LM));
      if (!hybrid)
      {
         base_target = vbr_rate - ((40*C+20)<<BITRES);
@@ -2441,7 +2446,7 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_res * pcm, in
       int new_compressedBytes;
       /* Don't give any bits for the first 80 kb/s per channel. Then 80% of the excess. */
       opus_int32 offset = C*80000*frame_size/mode->Fs/8;
-      qext_bytes = IMAX(0, (nbCompressedBytes-offset)*4/5);
+      qext_bytes = IMAX(nbCompressedBytes-1275, IMAX(0, (nbCompressedBytes-offset)*4/5));
       padding_len_bytes = (qext_bytes+253)/254;
       qext_bytes = IMIN(qext_bytes, nbCompressedBytes-min_allowed-padding_len_bytes-1);
       padding_len_bytes = (qext_bytes+253)/254;
diff --git a/celt/modes.h b/celt/modes.h
index f37dbdd83..a45333f61 100644
--- a/celt/modes.h
+++ b/celt/modes.h
@@ -81,6 +81,7 @@ struct OpusCustomMode {
 };
 
 #ifdef ENABLE_QEXT
+#define QEXT_PACKET_SIZE_CAP 3825
 #define NB_QEXT_BANDS 14
 void compute_qext_mode(CELTMode *qext, const CELTMode *m);
 #endif
diff --git a/celt/opus_custom_demo.c b/celt/opus_custom_demo.c
index 1b1650ba7..2cb30d387 100644
--- a/celt/opus_custom_demo.c
+++ b/celt/opus_custom_demo.c
@@ -32,12 +32,17 @@
 
 #include "opus_custom.h"
 #include "arch.h"
+#include "modes.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <math.h>
 #include <string.h>
 
+#ifdef ENABLE_QEXT
+#define MAX_PACKET QEXT_PACKET_SIZE_CAP
+#else
 #define MAX_PACKET 1275
+#endif
 
 static void print_usage(char **argv) {
    fprintf (stderr, "Usage: %s [-e | -d] <rate> <channels> <frame size> "