diff --git a/plugins/obs-ffmpeg/ffmpeg-mux/ffmpeg-mux.c b/plugins/obs-ffmpeg/ffmpeg-mux/ffmpeg-mux.c
index a2287a66dc533b..d6ba35013871cb 100644
--- a/plugins/obs-ffmpeg/ffmpeg-mux/ffmpeg-mux.c
+++ b/plugins/obs-ffmpeg/ffmpeg-mux/ffmpeg-mux.c
@@ -1051,6 +1051,11 @@ static int ffmpeg_mux_init_context(struct ffmpeg_mux *ffm)
 	ffm->output->oformat->audio_codec = AV_CODEC_ID_NONE;
 #endif
 
+#if LIBAVFORMAT_VERSION_INT < AV_VERSION_INT(60, 0, 100)
+	/* Allow FLAC/OPUS in MP4 */
+	ffm->output->strict_std_compliance = FF_COMPLIANCE_EXPERIMENTAL;
+#endif
+
 	if (!init_streams(ffm)) {
 		free_avformat(ffm);
 		return FFM_ERROR;
diff --git a/plugins/obs-ffmpeg/obs-ffmpeg-mux.c b/plugins/obs-ffmpeg/obs-ffmpeg-mux.c
index b821ada05d8081..1a3ce9cb402c60 100644
--- a/plugins/obs-ffmpeg/obs-ffmpeg-mux.c
+++ b/plugins/obs-ffmpeg/obs-ffmpeg-mux.c
@@ -313,7 +313,9 @@ static void build_command_line(struct ffmpeg_muxer *stream, struct dstr *cmd,
 		add_video_encoder_params(stream, cmd, vencoder);
 
 	if (num_tracks) {
-		dstr_cat(cmd, "aac ");
+		const char *codec = obs_encoder_get_codec(aencoders[0]);
+		dstr_cat(cmd, codec);
+		dstr_cat(cmd, " ");
 
 		for (int i = 0; i < num_tracks; i++) {
 			add_audio_encoder_params(cmd, aencoders[i]);