25% lower error rate
Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
libavradio/sdrdemux.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/libavradio/sdrdemux.c b/libavradio/sdrdemux.c
index bbd756f1d6..c0ca420c84 100644
--- a/libavradio/sdrdemux.c
+++ b/libavradio/sdrdemux.c
@@ -1031,6 +1031,19 @@ static int demodulate_fm(SDRContext *sdr, Station
*station, AVStream *st, AVPack
memcpy(sdr->fm_block + i, sdr->fm_block + 3*carrier19_i,
sizeof(AVComplexFloat)*len2_4_i);
memcpy(sdr->fm_block + i + 2*sdr->fm_block_size_p2 - len2_4_i,
sdr->fm_block + 3*carrier19_i - len2_4_i, sizeof(AVComplexFloat)*len2_4_i);
+
+ //This improves the decoder performace from an error rate per packet
of 0.539578 to 0.410425
+ for (int j= 0; j<len2_4_i; j++) {
+ float J = j / (float)len2_4_i;
+ float W = 1 - J*J;
+ sdr->fm_block[i+j].re *= W;
+ sdr->fm_block[i+j].im *= W;
+ if (j) {
+ sdr->fm_block[i + 2*sdr->fm_block_size_p2 - j].re *= W;
+ sdr->fm_block[i + 2*sdr->fm_block_size_p2 - j].im *= W;
+ }
+ }
+
sdr->fm_ifft_p2(sdr->fm_ifft_p2_ctx, sdr->fm_iside , sdr->fm_block +
i, sizeof(AVComplexFloat));
synchronous_am_demodulationN(sdr->fm_iside, sdr->fm_icarrier,
sdr->fm_window_p2, 2*sdr->fm_block_size_p2, 3);
ff_sdr_decode_rds(sdr, station, sdr->fm_iside);
--
2.31.1
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