byjp.me
An art project of mine; showing 30 second video clips of calm places & moments I've enjoyed being in.
stream.place/byjp.me
video
streaming
art
Ensure audio, and validate output
This prevents the audio lag I was seeing on stream place
+54
-3
main.go
+54
-3
main.go
···
32
33
func check(err error) {
34
if err != nil {
35
-
panic(err)
36
log.Fatal(err)
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}
38
}
···
51
start := (videoLength - length) / 2
52
53
outPath, err := multiEncode(in, start, created)
54
-
check(err)
55
56
fmt.Println("Encoded", outPath)
57
}
···
94
name := strings.TrimSuffix(base, ext)
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lenMinus3 := len(name) - 3
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noAudio := name[lenMinus3:] == ".na"
97
-
audioFilter := "[0:a]adelay=1000|1000,afade=in:st=1:d=1,afade=out:st=30:d=1,apad=whole_dur=32,asetpts=PTS-STARTPTS[outa]"
98
if noAudio {
99
name = name[0:lenMinus3]
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audioFilter = "anullsrc=r=44100:cl=stereo:d=32,asetpts=PTS-STARTPTS[outa]"
···
138
return "", fmt.Errorf("ffmpeg error %s: %w", strings.Join(cmd.Args, " "), cmdErr)
139
}
140
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movePath := filepath.Join(filepath.Dir(path), "done", filepath.Base(path))
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_ = os.Rename(path, movePath)
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return outPath, nil
145
}
146
147
func listVideos() (videos []string, err error) {
···
32
33
func check(err error) {
34
if err != nil {
35
log.Fatal(err)
36
}
37
}
···
50
start := (videoLength - length) / 2
51
52
outPath, err := multiEncode(in, start, created)
53
+
if err != nil {
54
+
log.Println(err)
55
+
continue
56
+
}
57
58
fmt.Println("Encoded", outPath)
59
}
···
96
name := strings.TrimSuffix(base, ext)
97
lenMinus3 := len(name) - 3
98
noAudio := name[lenMinus3:] == ".na"
99
+
audioFilter := "anullsrc=r=44100:cl=stereo:d=32[silence];[0:a]adelay=1000|1000,afade=in:st=1:d=1,afade=out:st=30:d=1,apad=whole_dur=32[delayed];[silence][delayed]amix=inputs=2:duration=first:normalize=0,asetpts=PTS-STARTPTS[outa]"
100
if noAudio {
101
name = name[0:lenMinus3]
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audioFilter = "anullsrc=r=44100:cl=stereo:d=32,asetpts=PTS-STARTPTS[outa]"
···
140
return "", fmt.Errorf("ffmpeg error %s: %w", strings.Join(cmd.Args, " "), cmdErr)
141
}
142
143
+
// Validate output before moving source to done
144
+
if err := validateOutput(outPath); err != nil {
145
+
_ = os.Remove(outPath)
146
+
return "", fmt.Errorf("validation failed for %s: %w", path, err)
147
+
}
148
+
149
movePath := filepath.Join(filepath.Dir(path), "done", filepath.Base(path))
150
_ = os.Rename(path, movePath)
151
152
return outPath, nil
153
+
}
154
+
155
+
const (
156
+
expectedVideoFrames = 800
157
+
expectedAACFrames = 1380 // 44100 Hz × 32 seconds ÷ 1024 samples/frame ≈ 1378, rounded up
158
+
)
159
+
160
+
func validateOutput(path string) error {
161
+
// Count video frames
162
+
videoCmd := exec.Command("/opt/homebrew/bin/ffprobe",
163
+
"-v", "error", "-select_streams", "v:0", "-count_frames",
164
+
"-show_entries", "stream=nb_read_frames", "-of", "csv=p=0", path)
165
+
videoOut, err := videoCmd.Output()
166
+
if err != nil {
167
+
return fmt.Errorf("failed to count video frames: %w", err)
168
+
}
169
+
videoFrames, err := strconv.Atoi(strings.Split(strings.TrimSpace(string(videoOut)), "\n")[0])
170
+
if err != nil {
171
+
return fmt.Errorf("failed to parse video frame count: %w", err)
172
+
}
173
+
174
+
// Count AAC frames
175
+
audioCmd := exec.Command("/opt/homebrew/bin/ffprobe",
176
+
"-v", "error", "-select_streams", "a:0", "-count_frames",
177
+
"-show_entries", "stream=nb_read_frames", "-of", "csv=p=0", path)
178
+
audioOut, err := audioCmd.Output()
179
+
if err != nil {
180
+
return fmt.Errorf("failed to count audio frames: %w", err)
181
+
}
182
+
aacFrames, err := strconv.Atoi(strings.Split(strings.TrimSpace(string(audioOut)), "\n")[0])
183
+
if err != nil {
184
+
return fmt.Errorf("failed to parse audio frame count: %w", err)
185
+
}
186
+
187
+
// Validate
188
+
if videoFrames != expectedVideoFrames {
189
+
return fmt.Errorf("invalid video frame count: got %d, expected %d", videoFrames, expectedVideoFrames)
190
+
}
191
+
if aacFrames < expectedAACFrames-5 || aacFrames > expectedAACFrames+5 {
192
+
return fmt.Errorf("invalid audio frame count: got %d, expected ~%d", aacFrames, expectedAACFrames)
193
+
}
194
+
195
+
return nil
196
}
197
198
func listVideos() (videos []string, err error) {