The global one caused problems when the spectrum is not flat
Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
libavradio/sdrdemux.c | 33 +++++++++++++++++++++++++--------
1 file changed, 25 insertions(+), 8 deletions(-)
diff --git a/libavradio/sdrdemux.c b/libavradio/sdrdemux.c
index 5a3af23a74..a4c590acf2 100644
--- a/libavradio/sdrdemux.c
+++ b/libavradio/sdrdemux.c
@@ -861,17 +861,20 @@ static int probe_fm(SDRContext *sdr)
int i;
int bandwidth_f = sdr->fm_bandwidth;
int half_bw_i = bandwidth_f * (int64_t)sdr->block_size /
sdr->sdr_sample_rate;
+ int floor_bw_i = 10*1000 * (int64_t)sdr->block_size / sdr->sdr_sample_rate;
float last_score[3] = {FLT_MAX, FLT_MAX, FLT_MAX};
int border_i = (sdr->sdr_sample_rate - FFMIN(sdr->bandwidth,
sdr->sdr_sample_rate*7/8)) * sdr->block_size / sdr->sdr_sample_rate;
- double noise_floor = FLT_MAX;
if (2*half_bw_i > 2*sdr->block_size)
return 0;
- for (int pass = 0; pass < 2; pass ++) {
+ {
double avg[2] = {0}, tri = 0;
+ double floor[2] = {0};
double mean = 0;
double center = 0;
+ float floor_compensation = half_bw_i * half_bw_i / (float)floor_bw_i;
+
for (i = 0; i<half_bw_i; i++) {
avg[0] += sdr->len2block[i];
tri += i*sdr->len2block[i];
@@ -883,12 +886,19 @@ static int probe_fm(SDRContext *sdr)
mean += i*sdr->len2block[i];
}
+ for (i=0; i<floor_bw_i; i++)
+ floor[0] += sdr->len2block[i];
+ for (i=2*half_bw_i - floor_bw_i; i<2*half_bw_i; i++)
+ floor[1] += sdr->len2block[i];
+
for(i = half_bw_i; i<2*sdr->block_size - half_bw_i; i++) {
double b = avg[0] + sdr->len2block[i];
avg[0] += sdr->len2block[i] - sdr->len2block[i - half_bw_i];
avg[1] -= sdr->len2block[i] - sdr->len2block[i + half_bw_i];
b += avg[1];
tri += avg[1] - avg[0];
+ floor[0] += sdr->len2block[i - half_bw_i + floor_bw_i] -
sdr->len2block[i - half_bw_i];
+ floor[1] -= sdr->len2block[i + half_bw_i - floor_bw_i] -
sdr->len2block[i + half_bw_i];
mean += (i+half_bw_i)*sdr->len2block[i+half_bw_i];
center = mean / b;
@@ -897,17 +907,24 @@ static int probe_fm(SDRContext *sdr)
if (i < border_i || i > 2*sdr->block_size - border_i)
continue;
- if (pass == 0) {
- noise_floor = FFMIN(noise_floor, tri);
- } else {
+ {
+ float noise_floor;
+ if (i - half_bw_i < border_i) {
+ noise_floor = floor[1];
+ } else if (i + half_bw_i >= 2*sdr->block_size - border_i) {
+ noise_floor = floor[0];
+ } else
+ noise_floor = (floor[0] + floor[1])/2;
+ noise_floor *= floor_compensation;
+
last_score[2] = last_score[1];
last_score[1] = last_score[0];
- last_score[0] = tri / (noise_floor);
+ last_score[0] = tri;
if (last_score[1] >= last_score[0] &&
last_score[1] > last_score[2] &&
- last_score[1] > sdr->fm_threshold) {
- double score = last_score[1];
+ last_score[1] / noise_floor > sdr->fm_threshold) {
+ double score = last_score[1] / noise_floor;
float rmax = max_in_range(sdr, i-half_bw_i/4,
i+half_bw_i/4);
int lowcount = countbelow(sdr, i-half_bw_i/4,
i+half_bw_i/4, rmax / 100);
--
2.31.1
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