diff --git a/trunk/auto/depends.sh b/trunk/auto/depends.sh
index c29c908c0..edcba041a 100755
--- a/trunk/auto/depends.sh
+++ b/trunk/auto/depends.sh
@@ -709,6 +709,10 @@ if [[ $SRS_FFMPEG_FIT == YES ]]; then
         if [[ $SRS_CROSS_BUILD_CPU != "" ]]; then FFMPEG_OPTIONS="$FFMPEG_OPTIONS --cpu=$SRS_CROSS_BUILD_CPU"; fi
         FFMPEG_OPTIONS="$FFMPEG_OPTIONS --cross-prefix=$SRS_CROSS_BUILD_PREFIX"
         FFMPEG_OPTIONS="$FFMPEG_OPTIONS --cc=${SRS_TOOL_CC} --cxx=${SRS_TOOL_CXX} --ar=${SRS_TOOL_AR} --ld=${SRS_TOOL_LD}"
+    fi
+    # For cross-build.
+    if [[ $SRS_CROSS_BUILD == YES ]]; then
+        # Note that the audio might be corrupted, if use FFmpeg native opus.
         FFMPEG_OPTIONS="$FFMPEG_OPTIONS --enable-decoder=opus --enable-encoder=opus"
     else
         FFMPEG_OPTIONS="$FFMPEG_OPTIONS --enable-decoder=libopus --enable-encoder=libopus --enable-libopus"
diff --git a/trunk/src/app/srs_app_rtc_codec.cpp b/trunk/src/app/srs_app_rtc_codec.cpp
index 2b504fc2a..9a8b2575c 100644
--- a/trunk/src/app/srs_app_rtc_codec.cpp
+++ b/trunk/src/app/srs_app_rtc_codec.cpp
@@ -17,6 +17,7 @@ static const AVCodec* srs_find_decoder_by_id(SrsAudioCodecId id)
     } else if (id == SrsAudioCodecIdOpus) {
         const AVCodec* codec = avcodec_find_decoder_by_name("libopus");
         if (!codec) {
+            // TODO: FIXME: Note that the audio might be corrupted, if use FFmpeg native opus.
             codec = avcodec_find_decoder_by_name("opus");
         }
         return codec;
@@ -31,6 +32,7 @@ static const AVCodec* srs_find_encoder_by_id(SrsAudioCodecId id)
     } else if (id == SrsAudioCodecIdOpus) {
         const AVCodec* codec = avcodec_find_encoder_by_name("libopus");
         if (!codec) {
+            // TODO: FIXME: Note that the audio might be corrupted, if use FFmpeg native opus.
             codec = avcodec_find_encoder_by_name("opus");
         }
         return codec;