/* NAME resample.go DESCRIPTION resample.go is a program for resampling a pcm file. AUTHOR Trek Hopton <trek@ausocean.org> LICENSE resample.go is Copyright (C) 2018 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 [GNU licenses](http://www.gnu.org/licenses). */ package main import ( "flag" "fmt" "io/ioutil" "log" "bitbucket.org/ausocean/av/audio/pcm" "github.com/yobert/alsa" ) // This program accepts an input pcm file and outputs a resampled pcm file. // Input and output file names, to and from sample rates, channels and sample format can be specified as arguments. func main() { var inPath = *flag.String("in", "data.pcm", "file path of input data") var outPath = *flag.String("out", "resampled.pcm", "file path of output") var from = *flag.Int("from", 48000, "sample rate of input file") var to = *flag.Int("to", 8000, "sample rate of output file") var channels = *flag.Int("ch", 1, "number of channels in input file") var sf = *flag.String("sf", "S16_LE", "sample format of input audio, eg. S16_LE") flag.Parse() // Read pcm. inPcm, err := ioutil.ReadFile(inPath) if err != nil { log.Fatal(err) } fmt.Println("Read", len(inPcm), "bytes from file", inPath) var sampleFormat alsa.FormatType switch sf { case "S32_LE": sampleFormat = alsa.S32_LE case "S16_LE": sampleFormat = alsa.S16_LE default: log.Fatalf("Unhandled ALSA format: %v", sf) } format := alsa.BufferFormat{ Channels: channels, Rate: from, SampleFormat: sampleFormat, } buf := alsa.Buffer{ Format: format, Data: inPcm, } // Resample audio. resampled, err := pcm.Resample(buf, to) if err != nil { log.Fatal(err) } // Save resampled to file. err = ioutil.WriteFile(outPath, resampled, 0644) if err != nil { log.Fatal(err) } fmt.Println("Encoded and wrote", len(resampled), "bytes to file", outPath) }