diff --git a/audio_splitter/constants.py b/audio_splitter/constants.py
index 941c788..dae9e79 100644
--- a/audio_splitter/constants.py
+++ b/audio_splitter/constants.py
@@ -67,6 +67,9 @@ CODEC_INFO = [
 CODEC_TO_CONTAINER_MAP = {codec['name']: codec['recommended_container'] for codec in CODEC_INFO}
 CODEC_TO_EXTENSION_MAP = {codec['name']: codec['recommended_extension'] for codec in CODEC_INFO}
 
+# Map codec name → FFmpeg encoder name
+CODEC_NAME_TO_FFMPEG = {codec['name']: codec['ffmpeg'] for codec in CODEC_INFO}
+
 # ------------------------------------------------------------------------------
 # Video codec support per container (legacy, will be superseded by compatibility matrix)
 # ------------------------------------------------------------------------------
diff --git a/audio_splitter/core.py b/audio_splitter/core.py
index bfb35ef..76eeb74 100644
--- a/audio_splitter/core.py
+++ b/audio_splitter/core.py
@@ -6,7 +6,11 @@ import subprocess
 import sys
 from typing import List, Dict, Any
 
-from .constants import FORMAT_INFO, CODEC_TO_EXTENSION_MAP
+from .constants import (
+    FORMAT_INFO,
+    CODEC_TO_EXTENSION_MAP,
+    CODEC_NAME_TO_FFMPEG,   # <-- Add this
+)
 from .ffmpeg import (
     get_audio_duration,
     get_stream_info,
@@ -192,6 +196,18 @@ def split_audio(input_file: str, output_directory: str, tracks: List[Dict[str, A
         # ----------------------------------------------------------------------
         # 8d. Build and execute FFmpeg command
         # ----------------------------------------------------------------------
+        # Map codec names to FFmpeg encoder names
+        audio_enc = args.audio_codec
+        if audio_enc != 'copy':
+            audio_enc = CODEC_NAME_TO_FFMPEG.get(audio_enc, audio_enc)  # fallback to itself if not found
+        video_enc = args.video_codec
+        if video_enc != 'copy':
+            video_enc = CODEC_NAME_TO_FFMPEG.get(video_enc, video_enc)
+        subtitle_enc = args.subtitle_codec
+        if subtitle_enc != 'copy':
+            subtitle_enc = CODEC_NAME_TO_FFMPEG.get(subtitle_enc, subtitle_enc)
+        
+        # Then build command with these mapped encoders
         cmd = build_ffmpeg_command(
             input_file=input_file,
             start_seconds=start_seconds,
@@ -199,9 +215,9 @@ def split_audio(input_file: str, output_directory: str, tracks: List[Dict[str, A
             output_path=output_path,
             stream_info=stream_info,
             format_opt=output_container,
-            audio_codec=args.audio_codec,
-            video_codec=args.video_codec,
-            subtitle_codec=args.subtitle_codec,
+            audio_codec=audio_enc,
+            video_codec=video_enc,
+            subtitle_codec=subtitle_enc,
             metadata=metadata,
             cover_image_path=cover_image_path,
             video_quality=getattr(args, 'video_quality', None),