aacenc_ltp: disable LTP with high lambda values

Makes no sense to enable for high bitrates, the coder does well enough.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

libavcodec/aacenc_ltp.c

@@ -173,7 +173,7 @@ void ff_aac_search_for_ltp(AACEncContext *s, SingleChannelElement *sce,
         return;
     }
 
-    if (!sce->ics.ltp.lag)
+    if (!sce->ics.ltp.lag || s->lambda > 120.0f)
         return;
 
     for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {

tests/fate/aac.mak

@@ -209,7 +209,7 @@ fate-aac-ltp-encode: CMD = enc_dec_pcm adts wav s16le $(TARGET_SAMPLES)/audio-re
 fate-aac-ltp-encode: CMP = stddev
 fate-aac-ltp-encode: REF = $(SAMPLES)/audio-reference/luckynight_2ch_44kHz_s16.wav
 fate-aac-ltp-encode: CMP_SHIFT = -4096
-fate-aac-ltp-encode: CMP_TARGET = 1273
+fate-aac-ltp-encode: CMP_TARGET = 1270
 fate-aac-ltp-encode: SIZE_TOLERANCE = 3560
 fate-aac-ltp-encode: FUZZ = 17