From cba85c169b6f5d8cc2b4b807276ffca5ae98e1c7 Mon Sep 17 00:00:00 2001 From: Trek H Date: Tue, 9 Apr 2019 15:45:28 +0930 Subject: [PATCH] pcm: deleted files in old location --- audio/pcm/pcm.go | 145 ------------------------------------------ audio/pcm/pcm_test.go | 118 ---------------------------------- 2 files changed, 263 deletions(-) delete mode 100644 audio/pcm/pcm.go delete mode 100644 audio/pcm/pcm_test.go diff --git a/audio/pcm/pcm.go b/audio/pcm/pcm.go deleted file mode 100644 index 5ead3143..00000000 --- a/audio/pcm/pcm.go +++ /dev/null @@ -1,145 +0,0 @@ -/* -NAME - pcm.go - -DESCRIPTION - pcm.go contains functions for processing pcm. - -AUTHOR - Trek Hopton - -LICENSE - pcm.go is Copyright (C) 2019 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 pcm - -import ( - "encoding/binary" - "fmt" - - "github.com/yobert/alsa" -) - -// Resample takes an alsa.Buffer (b) and resamples the pcm audio data to 'rate' Hz and returns the resulting pcm. -// If an error occurs, an error will be returned along with the original b's data. -// Notes: -// - Currently only downsampling is implemented and b's rate must be divisible by 'rate' or an error will occur. -// - If the number of bytes in b.Data is not divisible by the decimation factor (ratioFrom), the remaining bytes will -// not be included in the result. Eg. input of length 480002 downsampling 6:1 will result in output length 80000. -func Resample(b alsa.Buffer, rate int) ([]byte, error) { - fromRate := b.Format.Rate - if fromRate == rate { - return b.Data, nil - } else if fromRate < 0 { - return nil, fmt.Errorf("Unable to convert from: %v Hz", fromRate) - } else if rate < 0 { - return nil, fmt.Errorf("Unable to convert to: %v Hz", rate) - } - - // The number of bytes in a sample. - var sampleLen int - switch b.Format.SampleFormat { - case alsa.S32_LE: - sampleLen = 4 * b.Format.Channels - case alsa.S16_LE: - sampleLen = 2 * b.Format.Channels - default: - return nil, fmt.Errorf("Unhandled ALSA format: %v", b.Format.SampleFormat) - } - inPcmLen := len(b.Data) - - // Calculate sample rate ratio ratioFrom:ratioTo. - rateGcd := gcd(rate, fromRate) - ratioFrom := fromRate / rateGcd - ratioTo := rate / rateGcd - - // ratioTo = 1 is the only number that will result in an even sampling. - if ratioTo != 1 { - return nil, fmt.Errorf("unhandled from:to rate ratio %v:%v: 'to' must be 1", ratioFrom, ratioTo) - } - - newLen := inPcmLen / ratioFrom - result := make([]byte, 0, newLen) - - // For each new sample to be generated, loop through the respective 'ratioFrom' samples in 'b.Data' to add them - // up and average them. The result is the new sample. - bAvg := make([]byte, sampleLen) - for i := 0; i < newLen/sampleLen; i++ { - var sum int - for j := 0; j < ratioFrom; j++ { - switch b.Format.SampleFormat { - case alsa.S32_LE: - sum += int(int32(binary.LittleEndian.Uint32(b.Data[(i*ratioFrom*sampleLen)+(j*sampleLen) : (i*ratioFrom*sampleLen)+((j+1)*sampleLen)]))) - case alsa.S16_LE: - sum += int(int16(binary.LittleEndian.Uint16(b.Data[(i*ratioFrom*sampleLen)+(j*sampleLen) : (i*ratioFrom*sampleLen)+((j+1)*sampleLen)]))) - } - } - avg := sum / ratioFrom - switch b.Format.SampleFormat { - case alsa.S32_LE: - binary.LittleEndian.PutUint32(bAvg, uint32(avg)) - case alsa.S16_LE: - binary.LittleEndian.PutUint16(bAvg, uint16(avg)) - } - result = append(result, bAvg...) - } - return result, nil -} - -// StereoToMono returns raw mono audio data generated from only the left channel from -// the given stereo recording (ALSA buffer) -// if an error occurs, an error will be returned along with the original stereo data. -func StereoToMono(b alsa.Buffer) ([]byte, error) { - if b.Format.Channels == 1 { - return b.Data, nil - } else if b.Format.Channels != 2 { - return nil, fmt.Errorf("Audio is not stereo or mono, it has %v channels", b.Format.Channels) - } - - var stereoSampleBytes int - switch b.Format.SampleFormat { - case alsa.S32_LE: - stereoSampleBytes = 8 - case alsa.S16_LE: - stereoSampleBytes = 4 - default: - return nil, fmt.Errorf("Unhandled ALSA format %v", b.Format.SampleFormat) - } - - recLength := len(b.Data) - mono := make([]byte, recLength/2) - - // Convert to mono: for each byte in the stereo recording, if it's in the first half of a stereo sample - // (left channel), add it to the new mono audio data. - var inc int - for i := 0; i < recLength; i++ { - if i%stereoSampleBytes < stereoSampleBytes/2 { - mono[inc] = b.Data[i] - inc++ - } - } - - return mono, nil -} - -// gcd is used for calculating the greatest common divisor of two positive integers, a and b. -// assumes given a and b are positive. -func gcd(a, b int) int { - for b != 0 { - a, b = b, a%b - } - return a -} diff --git a/audio/pcm/pcm_test.go b/audio/pcm/pcm_test.go deleted file mode 100644 index 713d01d8..00000000 --- a/audio/pcm/pcm_test.go +++ /dev/null @@ -1,118 +0,0 @@ -/* -NAME - pcm_test.go - -DESCRIPTION - pcm_test.go contains functions for testing the pcm package. - -AUTHOR - Trek Hopton - -LICENSE - pcm_test.go is Copyright (C) 2019 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 pcm - -import ( - "bytes" - "io/ioutil" - "log" - "testing" - - "github.com/yobert/alsa" -) - -// TestResample tests the Resample function using a pcm file that contains audio of a freq. sweep. -// The output of the Resample function is compared with a file containing the expected result. -func TestResample(t *testing.T) { - inPath := "../../../test/test-data/av/input/sweep_400Hz_20000Hz_-3dBFS_5s_48khz.pcm" - expPath := "../../../test/test-data/av/output/sweep_400Hz_20000Hz_resampled_48to8kHz.pcm" - - // Read input pcm. - inPcm, err := ioutil.ReadFile(inPath) - if err != nil { - log.Fatal(err) - } - - format := alsa.BufferFormat{ - Channels: 1, - Rate: 48000, - SampleFormat: alsa.S16_LE, - } - - buf := alsa.Buffer{ - Format: format, - Data: inPcm, - } - - // Resample pcm. - resampled, err := Resample(buf, 8000) - if err != nil { - log.Fatal(err) - } - - // Read expected resampled pcm. - exp, err := ioutil.ReadFile(expPath) - if err != nil { - log.Fatal(err) - } - - // Compare result with expected. - if !bytes.Equal(resampled, exp) { - t.Error("Resampled data does not match expected result.") - } -} - -// TestStereoToMono tests the StereoToMono function using a pcm file that contains stereo audio. -// The output of the StereoToMono function is compared with a file containing the expected mono audio. -func TestStereoToMono(t *testing.T) { - inPath := "../../../test/test-data/av/input/stereo_DTMF_tones.pcm" - expPath := "../../../test/test-data/av/output/mono_DTMF_tones.pcm" - - // Read input pcm. - inPcm, err := ioutil.ReadFile(inPath) - if err != nil { - log.Fatal(err) - } - - format := alsa.BufferFormat{ - Channels: 2, - Rate: 44100, - SampleFormat: alsa.S16_LE, - } - - buf := alsa.Buffer{ - Format: format, - Data: inPcm, - } - - // Convert audio. - mono, err := StereoToMono(buf) - if err != nil { - log.Fatal(err) - } - - // Read expected mono pcm. - exp, err := ioutil.ReadFile(expPath) - if err != nil { - log.Fatal(err) - } - - // Compare result with expected. - if !bytes.Equal(mono, exp) { - t.Error("Converted data does not match expected result.") - } -}