[SCM] libav/experimental: aacenc: Fix the conditions under which 3GPP pre-echo control is run.

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit eafadadaf502560d1d3c2a1cb8e8cb9991221e14
Author: Nathan Caldwell <saintdev at gmail.com>
Date:   Wed Oct 27 05:54:41 2010 +0000

    aacenc: Fix the conditions under which 3GPP pre-echo control is run.
    
    According to the 3GPP spec:
    "Thus the pre-echo control is inactive for the first short window (but
    not all short windows in a short frame) after a start block and for
    all frames with a stop window sequence."
    
    Currently, pre-echo control is only run when the current frame is not
    a short frame, and the previous frame is not a short frame.
    
    patch by Nathan Caldwell saintdev (at) gmail
    
    Originally committed as revision 25587 to svn://svn.ffmpeg.org/ffmpeg/trunk

diff --git a/libavcodec/aacpsy.c b/libavcodec/aacpsy.c
index d5b51f8..5b637b8 100644
--- a/libavcodec/aacpsy.c
+++ b/libavcodec/aacpsy.c
@@ -420,7 +420,7 @@ static void psy_3gpp_analyze(FFPsyContext *ctx, int channel,
             band[g].thr = FFMAX(band[g].thr, band[g+1].thr * coeffs->spread_hi [g]);
         for (g = 0; g < num_bands; g++) {
             band[g].thr_quiet = FFMAX(band[g].thr, coeffs->ath[g]);
-            if (wi->num_windows != 8 && wi->window_type[1] != EIGHT_SHORT_SEQUENCE)
+            if (!(wi->window_type[0] == LONG_STOP_SEQUENCE || (wi->window_type[1] == LONG_START_SEQUENCE && !w)))
                 band[g].thr_quiet = FFMAX(PSY_3GPP_RPEMIN*band[g].thr_quiet,
                                           FFMIN(band[g].thr_quiet,
                                           PSY_3GPP_RPELEV*pch->prev_band[w+g].thr_quiet));

-- 
Libav/FFmpeg packaging