[FFmpeg-devel] [PATCH 3/4] eac3dec: fix scaling

Christophe Gisquet christophe.gisquet at gmail.com
Sat Mar 14 12:48:59 CET 2015


This is the remaining error, the output on the SPX samples,
respectively csi_miami_stereo_128_spx.eac3 and
csi_miami_5.1_256_spx.eac3, goes from:
stddev:    8.71 PSNR: 77.52 MAXDIFF:  235
stddev:24270.51 PSNR: 22.17 MAXDIFF:47166
to:
stddev:    0.12 PSNR:114.12 MAXDIFF:    1
stddev:    0.12 PSNR:114.73 MAXDIFF:    1
---
 libavcodec/eac3dec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/eac3dec.c b/libavcodec/eac3dec.c
index cd2eec8d..ef815af 100644
--- a/libavcodec/eac3dec.c
+++ b/libavcodec/eac3dec.c
@@ -143,7 +143,9 @@ static void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
             float nscale = s->spx_noise_blend[ch][bnd] * rms_energy[bnd] * (1.0f / INT32_MIN);
             float sscale = s->spx_signal_blend[ch][bnd];
 #if USE_FIXED
+            // spx_noise_blend and spx_signal_blend are both FP.23
             nscale *= 1.0 / (1<<23);
+            sscale *= 1.0 / (1<<23);
 #endif
             for (i = 0; i < s->spx_band_sizes[bnd]; i++) {
                 float noise  = nscale * (int32_t)av_lfg_get(&s->dith_state);
-- 
1.9.2.msysgit.0



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