From 943a61f359f28e9d5203edf02834f72cbf8dc895 Mon Sep 17 00:00:00 2001
From: Trek H <trek.hopton@gmail.com>
Date: Thu, 10 Mar 2022 16:18:26 +1030
Subject: [PATCH] spectrogram: add golang spectrogram generator

---
 exp/spectrogram/main.go | 126 ++++++++++++++++++++++++++++++++++++++++
 go.mod                  |   2 +
 go.sum                  |   4 ++
 3 files changed, 132 insertions(+)
 create mode 100644 exp/spectrogram/main.go

diff --git a/exp/spectrogram/main.go b/exp/spectrogram/main.go
new file mode 100644
index 00000000..5a6d2d8e
--- /dev/null
+++ b/exp/spectrogram/main.go
@@ -0,0 +1,126 @@
+/*
+DESCRIPTION
+
+
+AUTHORS
+  Trek Hopton <trek@ausocean.org>
+
+LICENSE
+  Copyright (C) 2020 the Australian Ocean Lab (AusOcean)
+
+  It is free software: you can redistribute it and/or modify them
+  under the terms of the GNU General Public License as published by the
+  Free Software Foundation, either version 3 of the License, or (at your
+  option) any later version.
+
+  It is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+  for more details.
+
+  You should have received a copy of the GNU General Public License
+  in gpl.txt.  If not, see http://www.gnu.org/licenses.
+*/
+
+// Package spectrogram is a program that generates a spectrogram given an audio file.
+// package main
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"image"
+	"image/draw"
+	"log"
+	"os"
+
+	"github.com/trekhopton/spectrogram"
+	"github.com/xigh/go-wavreader"
+)
+
+func main() {
+	flag.Parse()
+
+	if flag.NArg() == 0 {
+		fmt.Printf("usage: fft [options] file.wav\n")
+		return
+	}
+
+	name := flag.Arg(0)
+
+	r, err := os.Open(name)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer r.Close()
+
+	wr, err := wavreader.New(r)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("%s: %dHz, %d channels, %d samples, %v\n",
+		name, wr.Rate(), wr.Chans(), wr.Len(), wr.Duration())
+
+	start := *spectrogram.OFFSET
+	if start > wr.Len() {
+		log.Fatalf("offset bigger than file")
+	}
+
+	length := *spectrogram.LENGTH
+	if start+length > wr.Len() {
+		log.Printf("length too long\n")
+		length = wr.Len() - start
+	}
+
+	length = wr.Len()
+	samples := make([]float64, length)
+	for i := uint64(0); i < length; i++ {
+		s, err := wr.At(0, start+i)
+		if err != nil {
+			log.Fatal(err)
+		}
+		samples[i] = float64(s)
+	}
+
+	if *spectrogram.PREEMP > 0 {
+		for i := len(samples) - 1; i > 0; i-- {
+			samples[i] = samples[i] - *spectrogram.PREEMP*samples[i-1]
+		}
+	}
+
+	W := int(*spectrogram.WIDTH)
+	H := int(*spectrogram.HEIGHT)
+	B := int(*spectrogram.BINS)
+
+	bounds := image.Rect(-20, -20, W+20, H+40+B)
+	img := spectrogram.NewImage128(bounds)
+
+	bg0 := spectrogram.ParseColor(*spectrogram.BG0)
+	fmt.Printf("bg0: %.8x\n", bg0)
+	draw.Draw(img, img.Bounds(), image.NewUniform(bg0), image.ZP, draw.Src)
+
+	fmt.Println("drawwav:")
+	i0 := img.Sub(image.Rect(0, 0, W, H))
+	spectrogram.Drawwav(i0, samples)
+
+	fmt.Println("drawfft:")
+	i1 := img.Sub(image.Rect(0, H+20, W, H+20+B))
+	spectrogram.Drawfft(i1, samples, wr.Rate(), uint32(B))
+
+	a0, s0 := img.Stats()
+	fmt.Printf("img stats: %d reads, %d writes\n", a0, s0)
+
+	fmt.Printf("saving %q\n", *spectrogram.OUT)
+
+	err = spectrogram.SavePng(img, *spectrogram.OUT)
+	if err != nil {
+		log.Fatalf("savePng failed: %v", err)
+	}
+
+	fmt.Printf("saved %q\n", *spectrogram.OUT)
+
+	a1, s1 := img.Stats()
+	fmt.Printf("img stats: %d reads, %d writes\n", a1, s1)
+}
diff --git a/go.mod b/go.mod
index 16f5c3c3..4443787b 100644
--- a/go.mod
+++ b/go.mod
@@ -12,6 +12,8 @@ require (
 	github.com/kidoman/embd v0.0.0-20170508013040-d3d8c0c5c68d
 	github.com/mewkiz/flac v1.0.5
 	github.com/pkg/errors v0.9.1
+	github.com/trekhopton/spectrogram v1.0.0
+	github.com/xigh/go-wavreader v0.0.0-20210516212152-f49019aa7352
 	github.com/yobert/alsa v0.0.0-20180630182551-d38d89fa843e
 	gocv.io/x/gocv v0.29.0
 	gonum.org/v1/gonum v0.9.3
diff --git a/go.sum b/go.sum
index 7c028dfa..c5e8ab22 100644
--- a/go.sum
+++ b/go.sum
@@ -83,6 +83,10 @@ github.com/stretchr/testify v1.2.1/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/trekhopton/spectrogram v1.0.0 h1:Y1+G+oTDtNCrnuEjgm91s8Uyi0dF6vjwB+VTLECPoKw=
+github.com/trekhopton/spectrogram v1.0.0/go.mod h1:ea0tlSV7WC0Rqq9PcY2DGN88Lw13lAhCOPFUK8U/2zk=
+github.com/xigh/go-wavreader v0.0.0-20210516212152-f49019aa7352 h1:iK7SnIgPre4wrUN7HpIhZpfP7884mcc7CQS3FeyGTes=
+github.com/xigh/go-wavreader v0.0.0-20210516212152-f49019aa7352/go.mod h1:SiPEYpvfimzIRkLfaOYXVNGbQGVmgQZ6BQHcKyj/iic=
 github.com/yobert/alsa v0.0.0-20180630182551-d38d89fa843e h1:3NIzz7weXhh3NToPgbtlQtKiVgerEaG4/nY2skGoGG0=
 github.com/yobert/alsa v0.0.0-20180630182551-d38d89fa843e/go.mod h1:CaowXBWOiSGWEpBBV8LoVnQTVPV4ycyviC9IBLj8dRw=
 github.com/yryz/ds18b20 v0.0.0-20180211073435-3cf383a40624/go.mod h1:MqFju5qeLDFh+S9PqxYT7TEla8xeW7bgGr/69q3oki0=