diff --git a/libavcodec/qcelpdec.c b/libavcodec/qcelpdec.c
new file mode 100644
index 0000000000..1b52d3f5cd
--- /dev/null
+++ b/libavcodec/qcelpdec.c
@@ -0,0 +1,96 @@
+/*
+ * QCELP decoder
+ * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+/**
+ * @file qcelpdec.c
+ * QCELP decoder
+ * @author Reynaldo H. Verdejo Pinochet
+ */
+
+#include <stddef.h>
+
+#include "avcodec.h"
+#include "bitstream.h"
+
+#include "qcelp.h"
+#include "qcelpdata.h"
+
+#include "celp_math.h"
+#include "celp_filters.h"
+
+#undef NDEBUG
+#include <assert.h>
+
+/**
+ * Apply filter in pitch-subframe steps.
+ *
+ * @param memory buffer for the previous state of the filter
+ *        - must be able to contain 303 elements
+ *        - the 143 first elements are from the previous state
+ *        - the next 160 are for output
+ * @param v_in input filter vector
+ * @param gain per-subframe gain array, each element is between 0.0 and 2.0
+ * @param lag per-subframe lag array, each element is
+ *        - between 16 and 143 if its corresponding pfrac is 0,
+ *        - between 16 and 139 otherwise
+ * @param pfrac per-subframe boolean array, 1 if the lag is fractional, 0 otherwise
+ *
+ * @return filter output vector
+ */
+static const float *do_pitchfilter(float memory[303],
+                                   const float v_in[160],
+                                   const float gain[4],
+                                   const uint8_t *lag,
+                                   const uint8_t pfrac[4]) {
+    int         i, j;
+    float       *v_lag, *v_out;
+    const float *v_len;
+
+    v_out = memory + 143; // Output vector starts at memory[143].
+
+    for (i = 0; i < 4; i++)
+        if (gain[i]) {
+            v_lag = memory + 143 + 40 * i - lag[i];
+            for (v_len = v_in + 40; v_in < v_len; v_in++) {
+                if (pfrac[i]) { // If it is a fractional lag...
+                    for (j = 0, *v_out = 0.; j < 4; j++)
+                        *v_out += qcelp_hammsinc_table[j] * (v_lag[j-4] + v_lag[3-j]);
+                } else
+                    *v_out = *v_lag;
+
+                *v_out = *v_in + gain[i] * *v_out;
+
+                v_lag++;
+                v_out++;
+            }
+        } else {
+            memcpy(v_out, v_in, 40 * sizeof(float));
+            v_in  += 40;
+            v_out += 40;
+        }
+
+    memmove(memory, memory + 160, 143 * sizeof(float));
+    return memory + 143;
+}
+
+static void warn_insufficient_frame_quality(AVCodecContext *avctx,
+                                            const char *message) {
+    av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n", avctx->frame_number, message);
+}