1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
package tts
import (
"context"
"fmt"
"os"
"os/exec"
"path/filepath"
"strconv"
"strings"
"google.golang.org/genai"
"codeberg.org/snonux/comicforge/internal/provider"
)
const (
// DefaultModel is the Gemini TTS model used for narration.
DefaultModel = "gemini-2.5-flash-preview-tts"
)
// GeminiConfig configures the Gemini TTS provider.
type GeminiConfig struct {
APIKey string
Model string
Voice string
}
// GeminiProvider generates MP3 audio with Gemini TTS.
type GeminiProvider struct {
client *genai.Client
model string
voice string
err error
}
var _ provider.TTSProvider = (*GeminiProvider)(nil)
// NewGeminiProvider creates a Gemini TTS provider.
func NewGeminiProvider(cfg *GeminiConfig) *GeminiProvider {
g := &GeminiProvider{model: DefaultModel}
if cfg == nil {
g.err = fmt.Errorf("tts config is required")
return g
}
g.model = defaultOr(cfg.Model, DefaultModel)
g.voice = cfg.Voice
if strings.TrimSpace(cfg.APIKey) == "" {
g.err = fmt.Errorf("google API key is required for TTS")
return g
}
client, err := genai.NewClient(context.Background(), &genai.ClientConfig{
APIKey: cfg.APIKey,
Backend: genai.BackendGeminiAPI,
})
if err != nil {
g.err = fmt.Errorf("create Gemini client: %w", err)
return g
}
g.client = client
return g
}
// Name returns the provider name.
func (g *GeminiProvider) Name() string { return "gemini" }
// IsAvailable reports whether the provider was initialized successfully.
func (g *GeminiProvider) IsAvailable() error {
if g == nil {
return fmt.Errorf("tts provider is nil")
}
return g.err
}
// GenerateAudio writes MP3 audio for the provided text to outputFile.
func (g *GeminiProvider) GenerateAudio(ctx context.Context, text, outputFile string) error {
if g == nil {
return fmt.Errorf("tts provider is nil")
}
if ctx == nil {
ctx = context.Background()
}
if g.err != nil {
return g.err
}
if strings.TrimSpace(text) == "" {
return fmt.Errorf("text is required")
}
if strings.TrimSpace(outputFile) == "" {
return fmt.Errorf("output file is required")
}
voiceName := g.voice
if strings.TrimSpace(voiceName) == "" {
voiceName = "Aoede"
}
speechCfg := &genai.SpeechConfig{
VoiceConfig: &genai.VoiceConfig{
PrebuiltVoiceConfig: &genai.PrebuiltVoiceConfig{VoiceName: voiceName},
},
LanguageCode: "bg-BG",
}
resp, err := g.client.Models.GenerateContent(ctx, g.model, genai.Text(text), &genai.GenerateContentConfig{
ResponseModalities: []string{"AUDIO"},
SpeechConfig: speechCfg,
})
if err != nil {
return fmt.Errorf("generate audio: %w", err)
}
data, mimeType, err := extractAudio(resp)
if err != nil {
return err
}
if err := writeAudioFile(data, mimeType, outputFile); err != nil {
return err
}
return nil
}
func extractAudio(resp *genai.GenerateContentResponse) ([]byte, string, error) {
if resp == nil || len(resp.Candidates) == 0 || resp.Candidates[0] == nil || resp.Candidates[0].Content == nil {
return nil, "", fmt.Errorf("no audio returned")
}
for _, part := range resp.Candidates[0].Content.Parts {
if part != nil && part.InlineData != nil && len(part.InlineData.Data) > 0 {
return part.InlineData.Data, part.InlineData.MIMEType, nil
}
}
return nil, "", fmt.Errorf("audio payload missing")
}
func writeAudioFile(data []byte, mimeType, outputFile string) error {
if strings.TrimSpace(outputFile) == "" {
return fmt.Errorf("output file is required")
}
lowerMime := strings.ToLower(strings.TrimSpace(mimeType))
switch {
case strings.HasPrefix(lowerMime, "audio/mpeg"), strings.HasPrefix(lowerMime, "audio/mp3"):
if err := os.WriteFile(outputFile, data, 0o644); err != nil {
return fmt.Errorf("write audio: %w", err)
}
return nil
case strings.Contains(lowerMime, "audio/l16"), strings.Contains(lowerMime, "codec=pcm"), lowerMime == "":
return encodePCMToMP3(data, lowerMime, outputFile)
default:
return fmt.Errorf("unsupported audio mime type %q", mimeType)
}
}
func encodePCMToMP3(data []byte, mimeType, outputFile string) error {
ffmpegPath, err := exec.LookPath("ffmpeg")
if err != nil {
return fmt.Errorf("ffmpeg not found for audio conversion: %w", err)
}
rate := 24000
if idx := strings.Index(mimeType, "rate="); idx >= 0 {
value := mimeType[idx+len("rate="):]
for i, r := range value {
if r < '0' || r > '9' {
value = value[:i]
break
}
}
if parsed, parseErr := strconv.Atoi(value); parseErr == nil && parsed > 0 {
rate = parsed
}
}
tmpDir := filepath.Dir(outputFile)
rawFile, err := os.CreateTemp(tmpDir, "comicforge-tts-*.pcm")
if err != nil {
return fmt.Errorf("create temporary audio file: %w", err)
}
rawPath := rawFile.Name()
if _, err := rawFile.Write(data); err != nil {
_ = rawFile.Close()
_ = os.Remove(rawPath)
return fmt.Errorf("write temporary audio file: %w", err)
}
if err := rawFile.Close(); err != nil {
_ = os.Remove(rawPath)
return fmt.Errorf("close temporary audio file: %w", err)
}
defer func() {
_ = os.Remove(rawPath)
}()
cmd := exec.Command(ffmpegPath,
"-nostdin", "-hide_banner", "-loglevel", "error", "-y",
"-f", "s16le",
"-ar", fmt.Sprintf("%d", rate),
"-ac", "1",
"-i", rawPath,
"-codec:a", "libmp3lame",
"-q:a", "2",
outputFile,
)
out, err := cmd.CombinedOutput()
if err != nil {
return fmt.Errorf("convert PCM audio to mp3: %w\n%s", err, strings.TrimSpace(string(out)))
}
return nil
}
func defaultOr(value, fallback string) string {
if strings.TrimSpace(value) != "" {
return value
}
return fallback
}
|
