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[79.124.17.100]) by mx.google.com with ESMTP id f26-20020a056402151a00b00521777afc15si2889919edw.288.2023.07.16.17.27.45; Sun, 16 Jul 2023 17:27:45 -0700 (PDT) Received-SPF: pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) client-ip=79.124.17.100; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) smtp.mailfrom=ffmpeg-devel-bounces@ffmpeg.org Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 3F1DD68C642; Mon, 17 Jul 2023 03:27:18 +0300 (EEST) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from relay6-d.mail.gandi.net (relay6-d.mail.gandi.net [217.70.183.198]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 9DF9768C36A for ; Mon, 17 Jul 2023 03:27:09 +0300 (EEST) Received: by mail.gandi.net (Postfix) with ESMTPSA id 0C2CAC0004 for ; Mon, 17 Jul 2023 00:27:08 +0000 (UTC) From: Michael Niedermayer To: FFmpeg development discussions and patches Date: Mon, 17 Jul 2023 02:27:01 +0200 Message-Id: <20230717002704.3092192-4-michael@niedermayer.cc> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230717002704.3092192-1-michael@niedermayer.cc> References: <20230717002704.3092192-1-michael@niedermayer.cc> MIME-Version: 1.0 X-GND-Sasl: michael@niedermayer.cc Subject: [FFmpeg-devel] [PATCH 4/7] avradio/sdrdemux: Use a local noise floor in FM Probing X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" X-TUID: 7J0SnZlZNill The global one caused problems when the spectrum is not flat Signed-off-by: Michael Niedermayer --- 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; ilen2block[i]; tri += i*sdr->len2block[i]; @@ -883,12 +886,19 @@ static int probe_fm(SDRContext *sdr) mean += i*sdr->len2block[i]; } + for (i=0; ilen2block[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);