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package main
// The spotify backend is based on the librespot-golang code released under MIT
// license.
// Authors of the librespot-golang code are:
// Copyright (c) 2015 Paul Lietar
// Copyright (c) 2015 badfortrains
// Copyright (c) 2018 Guillaume "xplodwild" Lesniak
import (
"errors"
"log"
"fmt"
"os"
"strings"
"sync"
"unsafe"
"github.com/librespot-org/librespot-golang/Spotify"
"github.com/librespot-org/librespot-golang/librespot"
"github.com/librespot-org/librespot-golang/librespot/core"
"github.com/librespot-org/librespot-golang/librespot/utils"
"github.com/xlab/portaudio-go/portaudio"
"github.com/xlab/vorbis-go/decoder"
)
const (
deviceName = "wrms"
// The number of samples per channel in the decoded audio
samplesPerChannel = 2048
// The samples bit depth
bitDepth = 16
// The samples format
sampleFormat = portaudio.PaFloat32
)
type SpotifyBackend struct {
session *core.Session
}
func NewSpotify() (*SpotifyBackend, error) {
spotify := SpotifyBackend{}
if err := portaudio.Initialize(); paError(err) {
return nil, errors.New(paErrorText(err))
}
var err error
username := os.Getenv("WRMS_SPOTIFY_USER")
password := os.Getenv("WRMS_SPOTIFY_PASSWORD")
if username == "" || password == "" {
return nil, errors.New("User and password for spotify must be provided")
}
spotify.session, err = librespot.Login(username, password, deviceName)
if err != nil {
return nil, err
}
return &spotify, nil
}
func (spotify *SpotifyBackend) Play(song *Song) {
trackID := song.Uri
session := spotify.session
fmt.Println("Loading track for play: ", trackID)
// Get the track metadata: it holds information about which files and encodings are available
track, err := session.Mercury().GetTrack(utils.Base62ToHex(trackID))
if err != nil {
fmt.Println("Error loading track: ", err)
return
}
fmt.Println("Track:", track.GetName())
// As a demo, select the OGG 160kbps variant of the track. The "high quality" setting in the official Spotify
// app is the OGG 320kbps variant.
var selectedFile *Spotify.AudioFile
for _, file := range track.GetFile() {
if file.GetFormat() == Spotify.AudioFile_OGG_VORBIS_160 {
selectedFile = file
}
}
// Synchronously load the track
audioFile, err := session.Player().LoadTrack(selectedFile, track.GetGid())
// TODO: channel to be notified of chunks downloaded (or reader?)
if err != nil {
fmt.Printf("Error while loading track: %s\n", err)
} else {
// We have the track audio, let's play it! Initialize the OGG decoder, and start a PortAudio stream.
// Note that we skip the first 167 bytes as it is a Spotify-specific header. You can decode it by
// using this: https://sourceforge.net/p/despotify/code/HEAD/tree/java/trunk/src/main/java/se/despotify/client/player/SpotifyOggHeader.java
fmt.Println("Setting up OGG decoder...")
dec, err := decoder.New(audioFile, samplesPerChannel)
if err != nil {
log.Fatalln(err)
}
info := dec.Info()
go func() {
dec.Decode()
dec.Close()
}()
fmt.Println("Setting up PortAudio stream...")
fmt.Printf("PortAudio channels: %d / SampleRate: %f\n", info.Channels, info.SampleRate)
var wg sync.WaitGroup
var stream *portaudio.Stream
callback := paCallback(&wg, int(info.Channels), dec.SamplesOut())
if err := portaudio.OpenDefaultStream(&stream, 0, info.Channels, sampleFormat, info.SampleRate,
samplesPerChannel, callback, nil); paError(err) {
log.Fatalln(paErrorText(err))
}
fmt.Println("Starting playback...")
if err := portaudio.StartStream(stream); paError(err) {
log.Fatalln(paErrorText(err))
}
wg.Wait()
}
}
func (spotify *SpotifyBackend) Pause() {
}
func (spotify *SpotifyBackend) Search(keyword string) []Song {
session := spotify.session
resp, err := session.Mercury().Search(keyword, 12, session.Country(), session.Username())
if err != nil {
fmt.Println("Failed to search:", err)
return []Song{}
}
res := resp.Results
fmt.Println("Search results for ", keyword)
fmt.Println("=============================")
if res.Error != nil {
fmt.Println("Search result error:", res.Error)
}
fmt.Printf("\nTracks: %d (total %d)\n", len(res.Tracks.Hits), res.Tracks.Total)
results := []Song{}
for _, track := range res.Tracks.Hits {
uriParts := strings.Split(track.Uri, ":")
results = append(results, NewSong(track.Name, track.Artists[0].Name, "spotify", uriParts[len(uriParts) - 1]))
// fmt.Printf(" => %v (%s)\n", track, track.Uri)
}
return results
}
// PortAudio helpers
func paError(err portaudio.Error) bool {
return portaudio.ErrorCode(err) != portaudio.PaNoError
}
func paErrorText(err portaudio.Error) string {
return "PortAudio error: " + portaudio.GetErrorText(err)
}
func paCallback(wg *sync.WaitGroup, channels int, samples <-chan [][]float32) portaudio.StreamCallback {
wg.Add(1)
return func(_ unsafe.Pointer, output unsafe.Pointer, sampleCount uint,
_ *portaudio.StreamCallbackTimeInfo, _ portaudio.StreamCallbackFlags, _ unsafe.Pointer) int32 {
const (
statusContinue = int32(portaudio.PaContinue)
statusComplete = int32(portaudio.PaComplete)
)
frame, ok := <-samples
if !ok {
wg.Done()
return statusComplete
}
if len(frame) > int(sampleCount) {
frame = frame[:sampleCount]
}
var idx int
out := (*(*[1 << 32]float32)(unsafe.Pointer(output)))[:int(sampleCount)*channels]
for _, sample := range frame {
if len(sample) > channels {
sample = sample[:channels]
}
for i := range sample {
out[idx] = sample[i]
idx++
}
}
return statusContinue
}
}
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