diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
index 71d3026d40..1a869ab865 100644
--- a/libavcodec/ac3enc.c
+++ b/libavcodec/ac3enc.c
@@ -503,28 +503,6 @@ static void ac3_adjust_frame_size(AC3EncodeContext *s)
     s->samples_written += AC3_BLOCK_SIZE * s->num_blocks;
 }
 
-/*
- * Copy input samples.
- * Channels are reordered from FFmpeg's default order to AC-3 order.
- */
-static void copy_input_samples(AC3EncodeContext *s, uint8_t * const *samples)
-{
-    const unsigned sampletype_size = SAMPLETYPE_SIZE(s);
-
-    /* copy and remap input samples */
-    for (int ch = 0; ch < s->channels; ch++) {
-        /* copy last 256 samples of previous frame to the start of the current frame */
-        memcpy(&s->planar_samples[ch][0],
-               s->planar_samples[ch] + AC3_BLOCK_SIZE * sampletype_size * s->num_blocks,
-               AC3_BLOCK_SIZE * sampletype_size);
-
-        /* copy new samples for current frame */
-        memcpy(s->planar_samples[ch] + AC3_BLOCK_SIZE * sampletype_size,
-               samples[s->channel_map[ch]],
-               sampletype_size * AC3_BLOCK_SIZE * s->num_blocks);
-    }
-}
-
 /**
  * Set the initial coupling strategy parameters prior to coupling analysis.
  *
@@ -2018,9 +1996,7 @@ int ff_ac3_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
     if (s->bit_alloc.sr_code == 1 || s->eac3)
         ac3_adjust_frame_size(s);
 
-    copy_input_samples(s, frame->extended_data);
-
-    s->encode_frame(s);
+    s->encode_frame(s, frame->extended_data);
 
     ac3_apply_rematrixing(s);
 
@@ -2442,8 +2418,7 @@ static av_cold int allocate_buffers(AC3EncodeContext *s)
     const unsigned sampletype_size = SAMPLETYPE_SIZE(s);
 
     for (int ch = 0; ch < s->channels; ch++) {
-        s->planar_samples[ch] = av_mallocz((AC3_FRAME_SIZE + AC3_BLOCK_SIZE) *
-                                                  sampletype_size);
+        s->planar_samples[ch] = av_mallocz(AC3_BLOCK_SIZE * sampletype_size);
         if (!s->planar_samples[ch])
             return AVERROR(ENOMEM);
     }
diff --git a/libavcodec/ac3enc.h b/libavcodec/ac3enc.h
index 4241a908a1..30812617cc 100644
--- a/libavcodec/ac3enc.h
+++ b/libavcodec/ac3enc.h
@@ -253,7 +253,7 @@ typedef struct AC3EncodeContext {
     int ref_bap_set;                                         ///< indicates if ref_bap pointers have been set
 
     /** fixed vs. float function pointers */
-    void (*encode_frame)(struct AC3EncodeContext *s);
+    void (*encode_frame)(struct AC3EncodeContext *s, uint8_t * const *samples);
 
     /* AC-3 vs. E-AC-3 function pointers */
     void (*output_frame_header)(struct AC3EncodeContext *s);
diff --git a/libavcodec/ac3enc_template.c b/libavcodec/ac3enc_template.c
index 698042ae5c..49fc6d7f37 100644
--- a/libavcodec/ac3enc_template.c
+++ b/libavcodec/ac3enc_template.c
@@ -48,25 +48,33 @@
  * This applies the KBD window and normalizes the input to reduce precision
  * loss due to fixed-point calculations.
  */
-static void apply_mdct(AC3EncodeContext *s)
+static void apply_mdct(AC3EncodeContext *s, uint8_t * const *samples)
 {
     int blk, ch;
 
     for (ch = 0; ch < s->channels; ch++) {
+        const SampleType *input_samples0 = (const SampleType*)s->planar_samples[ch];
+        /* Reorder channels from native order to AC-3 order. */
+        const SampleType *input_samples1 = (const SampleType*)samples[s->channel_map[ch]];
+
         for (blk = 0; blk < s->num_blocks; blk++) {
             AC3Block *block = &s->blocks[blk];
-            const SampleType *input_samples = (SampleType*)s->planar_samples[ch] + blk * AC3_BLOCK_SIZE;
             SampleType *windowed_samples = s->RENAME(windowed_samples);
 
-            s->fdsp->vector_fmul(windowed_samples, input_samples,
+            s->fdsp->vector_fmul(windowed_samples, input_samples0,
                                  s->RENAME(mdct_window), AC3_BLOCK_SIZE);
             s->fdsp->vector_fmul_reverse(windowed_samples + AC3_BLOCK_SIZE,
-                                         &input_samples[AC3_BLOCK_SIZE],
+                                         input_samples1,
                                          s->RENAME(mdct_window), AC3_BLOCK_SIZE);
 
             s->tx_fn(s->tx, block->mdct_coef[ch+1],
                      windowed_samples, sizeof(*windowed_samples));
+            input_samples0  = input_samples1;
+            input_samples1 += AC3_BLOCK_SIZE;
         }
+        /* Store last 256 samples of current frame */
+        memcpy(s->planar_samples[ch], input_samples0,
+               AC3_BLOCK_SIZE * sizeof(*input_samples0));
     }
 }
 
@@ -336,9 +344,9 @@ static void compute_rematrixing_strategy(AC3EncodeContext *s)
 }
 
 
-static void encode_frame(AC3EncodeContext *s)
+static void encode_frame(AC3EncodeContext *s, uint8_t * const *samples)
 {
-    apply_mdct(s);
+    apply_mdct(s, samples);
 
     s->cpl_on = s->cpl_enabled;
     ff_ac3_compute_coupling_strategy(s);