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
32
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33
func check(err error) {
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if err != nil {
35
-
panic(err)
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log.Fatal(err)
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}
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}
···
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start := (videoLength - length) / 2
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51
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outPath, err := multiEncode(in, start, created)
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-
check(err)
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+
if err != nil {
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+
log.Println(err)
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+
continue
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+
}
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fmt.Println("Encoded", outPath)
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}
···
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name := strings.TrimSuffix(base, ext)
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lenMinus3 := len(name) - 3
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noAudio := name[lenMinus3:] == ".na"
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-
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]"
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+
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]"
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if noAudio {
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name = name[0:lenMinus3]
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audioFilter = "anullsrc=r=44100:cl=stereo:d=32,asetpts=PTS-STARTPTS[outa]"
···
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return "", fmt.Errorf("ffmpeg error %s: %w", strings.Join(cmd.Args, " "), cmdErr)
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}
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+
// Validate output before moving source to done
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+
if err := validateOutput(outPath); err != nil {
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+
_ = os.Remove(outPath)
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+
return "", fmt.Errorf("validation failed for %s: %w", path, err)
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+
}
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+
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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
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+
}
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+
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+
const (
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+
expectedVideoFrames = 800
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+
expectedAACFrames = 1380 // 44100 Hz × 32 seconds ÷ 1024 samples/frame ≈ 1378, rounded up
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+
)
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+
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+
func validateOutput(path string) error {
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+
// Count video frames
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+
videoCmd := exec.Command("/opt/homebrew/bin/ffprobe",
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+
"-v", "error", "-select_streams", "v:0", "-count_frames",
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+
"-show_entries", "stream=nb_read_frames", "-of", "csv=p=0", path)
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+
videoOut, err := videoCmd.Output()
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+
if err != nil {
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+
return fmt.Errorf("failed to count video frames: %w", err)
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+
}
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+
videoFrames, err := strconv.Atoi(strings.Split(strings.TrimSpace(string(videoOut)), "\n")[0])
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+
if err != nil {
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+
return fmt.Errorf("failed to parse video frame count: %w", err)
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+
}
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+
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+
// Count AAC frames
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+
audioCmd := exec.Command("/opt/homebrew/bin/ffprobe",
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+
"-v", "error", "-select_streams", "a:0", "-count_frames",
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+
"-show_entries", "stream=nb_read_frames", "-of", "csv=p=0", path)
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+
audioOut, err := audioCmd.Output()
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+
if err != nil {
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+
return fmt.Errorf("failed to count audio frames: %w", err)
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+
}
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+
aacFrames, err := strconv.Atoi(strings.Split(strings.TrimSpace(string(audioOut)), "\n")[0])
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+
if err != nil {
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+
return fmt.Errorf("failed to parse audio frame count: %w", err)
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+
}
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+
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+
// Validate
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+
if videoFrames != expectedVideoFrames {
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+
return fmt.Errorf("invalid video frame count: got %d, expected %d", videoFrames, expectedVideoFrames)
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+
}
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+
if aacFrames < expectedAACFrames-5 || aacFrames > expectedAACFrames+5 {
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+
return fmt.Errorf("invalid audio frame count: got %d, expected ~%d", aacFrames, expectedAACFrames)
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+
}
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+
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+
return nil
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196
}
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func listVideos() (videos []string, err error) {