diff --git a/libavcodec/acelp_pitch_delay.c b/libavcodec/acelp_pitch_delay.c
index a070d1b25d..1eca97ec69 100644
--- a/libavcodec/acelp_pitch_delay.c
+++ b/libavcodec/acelp_pitch_delay.c
@@ -29,47 +29,6 @@
 #include "celp_math.h"
 #include "audiodsp.h"
 
-int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
-{
-    ac_index += 58;
-    if(ac_index > 254)
-        ac_index = 3 * ac_index - 510;
-    return ac_index;
-}
-
-int ff_acelp_decode_4bit_to_2nd_delay3(
-        int ac_index,
-        int pitch_delay_min)
-{
-    if(ac_index < 4)
-        return 3 * (ac_index + pitch_delay_min);
-    else if(ac_index < 12)
-        return 3 * pitch_delay_min + ac_index + 6;
-    else
-        return 3 * (ac_index + pitch_delay_min) - 18;
-}
-
-int ff_acelp_decode_5_6_bit_to_2nd_delay3(
-        int ac_index,
-        int pitch_delay_min)
-{
-        return 3 * pitch_delay_min + ac_index - 2;
-}
-
-int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
-{
-    if(ac_index < 463)
-        return ac_index + 105;
-    else
-        return 6 * (ac_index - 368);
-}
-int ff_acelp_decode_6bit_to_2nd_delay6(
-        int ac_index,
-        int pitch_delay_min)
-{
-    return 6 * pitch_delay_min + ac_index - 3;
-}
-
 void ff_acelp_update_past_gain(
     int16_t* quant_energy,
     int gain_corr_factor,
diff --git a/libavcodec/acelp_pitch_delay.h b/libavcodec/acelp_pitch_delay.h
index 2aade2f226..73fa3c331a 100644
--- a/libavcodec/acelp_pitch_delay.h
+++ b/libavcodec/acelp_pitch_delay.h
@@ -41,7 +41,13 @@
  *    with 1/3 resolution, 19  < pitch_delay <  85
  *    integers only,       85 <= pitch_delay <= 143
  */
-int ff_acelp_decode_8bit_to_1st_delay3(int ac_index);
+static inline int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
+{
+    ac_index += 58;
+    if (ac_index > 254)
+        ac_index = 3 * ac_index - 510;
+    return ac_index;
+}
 
 /**
  * @brief Decode pitch delay of the second subframe encoded by 5 or 6 bits
@@ -58,9 +64,11 @@ int ff_acelp_decode_8bit_to_1st_delay3(int ac_index);
  * @remark The routine is used in G.729 @@8k, AMR @@10.2k, AMR @@7.95k,
  *         AMR @@7.4k for the second subframe.
  */
-int ff_acelp_decode_5_6_bit_to_2nd_delay3(
-        int ac_index,
-        int pitch_delay_min);
+static inline int ff_acelp_decode_5_6_bit_to_2nd_delay3(int ac_index,
+                                                        int pitch_delay_min)
+{
+        return 3 * pitch_delay_min + ac_index - 2;
+}
 
 /**
  * @brief Decode pitch delay with 1/3 precision.
@@ -78,9 +86,16 @@ int ff_acelp_decode_5_6_bit_to_2nd_delay3(
  * @remark The routine is used in G.729 @@6.4k, AMR @@6.7k, AMR @@5.9k,
  *         AMR @@5.15k, AMR @@4.75k for the second subframe.
  */
-int ff_acelp_decode_4bit_to_2nd_delay3(
-        int ac_index,
-        int pitch_delay_min);
+static inline int ff_acelp_decode_4bit_to_2nd_delay3(int ac_index,
+                                                     int pitch_delay_min)
+{
+    if (ac_index < 4)
+        return 3 * (ac_index + pitch_delay_min);
+    else if (ac_index < 12)
+        return 3 * pitch_delay_min + ac_index + 6;
+    else
+        return 3 * (ac_index + pitch_delay_min) - 18;
+}
 
 /**
  * @brief Decode pitch delay of the first subframe encoded by 9 bits
@@ -95,7 +110,13 @@ int ff_acelp_decode_4bit_to_2nd_delay3(
  *
  * @remark The routine is used in AMR @@12.2k for the first and third subframes.
  */
-int ff_acelp_decode_9bit_to_1st_delay6(int ac_index);
+static inline int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
+{
+    if (ac_index < 463)
+        return ac_index + 105;
+    else
+        return 6 * (ac_index - 368);
+}
 
 /**
  * @brief Decode pitch delay of the second subframe encoded by 6 bits
@@ -111,9 +132,11 @@ int ff_acelp_decode_9bit_to_1st_delay6(int ac_index);
  *
  * @remark The routine is used in AMR @@12.2k for the second and fourth subframes.
  */
-int ff_acelp_decode_6bit_to_2nd_delay6(
-        int ac_index,
-        int pitch_delay_min);
+static inline int ff_acelp_decode_6bit_to_2nd_delay6(int ac_index,
+                                                     int pitch_delay_min)
+{
+    return 6 * pitch_delay_min + ac_index - 3;
+}
 
 /**
  * @brief Update past quantized energies