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package thumbnailgen
import (
"bytes"
"fmt"
"os/exec"
"regexp"
"slices"
"strconv"
"strings"
"time"
)
type TimeFilter struct {
Start float64
End float64
}
func GetThumbnail(path string, intervalSeconds int, maxThumbnails int, enableFilter bool) ([][]byte, int, error) {
var filters []TimeFilter
if enableFilter {
f, err := GetFilter(path)
if err != nil {
return nil, 0, err
}
filters = f
}
fps, err := GetFramerate(path)
if err != nil {
return nil, 0, err
}
length, err := GetVideoLength(path)
if err != nil {
return nil, 0, err
}
buf := bytes.NewBuffer(nil)
currFrame := 0
framesExtracted := 0
var out [][]byte
if maxThumbnails > 0 {
out = make([][]byte, maxThumbnails)
} else {
out = make([][]byte, 0)
}
for {
time := float64(currFrame) / fps
if (maxThumbnails > 0 && framesExtracted >= maxThumbnails) || time >= length {
break
}
currFrame += int(fps) * intervalSeconds
if enableFilter && FrameLiesWithinFilter(time, filters) {
continue
}
err := GetImage(buf, path, int(time), "png")
if err != nil {
return nil, 0, err
}
b := bytes.Clone(buf.Bytes())[0:buf.Len()]
if maxThumbnails > 0 {
out[framesExtracted] = b
} else {
out = append(out, b)
}
framesExtracted += 1
buf.Reset()
}
return out, framesExtracted, nil
}
func FrameLiesWithinFilter(time float64, filters []TimeFilter) bool {
for _, filter := range filters {
if time >= filter.Start && time <= filter.End {
return true
}
}
return false
}
func GetImage(buf *bytes.Buffer, path string, timestamp int, format string) error {
var t time.Time
t = t.Add(time.Duration(timestamp) * time.Second)
cmd := exec.Command("ffmpeg", "-ss", t.Format("15:04:05"), "-i", path, "-vframes", "1", "-c:v", format, "-f", "image2pipe", "-")
cmd.Stdout = buf
err := cmd.Run()
return err
}
func GetVideoLength(path string) (float64, error) {
cmd := exec.Command("ffprobe", "-v", "quiet", "-select_streams", "v:0", "-show_entries", "stream=duration", "-of", "default=noprint_wrappers=1:nokey=1", path)
buf := bytes.NewBuffer(nil)
cmd.Stdout = buf
err := cmd.Run()
if err != nil {
return 0, err
}
return strconv.ParseFloat(strings.ReplaceAll(buf.String(), "\n", ""), 64)
}
func GetFilter(path string) ([]TimeFilter, error) {
buf := bytes.NewBuffer(nil)
cmd := exec.Command("ffprobe", "-f", "lavfi", "-i", fmt.Sprintf("movie=%s,blackdetect[out0]", path), "-show_entries", "tags=lavfi.black_start,lavfi.black_end", "-of", "default=nw=1", "-v", "quiet")
cmd.Stdout = buf
err := cmd.Run()
// TODO: Replace with strings.Builder
filterStr := buf.String()
filters := strings.Split(filterStr, "\n")
filters = slices.Compact(filters)
i := 0
reg := regexp.MustCompile(`([0-9]*\.?[0-9]+)`)
blackFilters := make([]TimeFilter, len(filters)/2)
for {
if i >= len(filters) {
break
}
start := reg.FindString(filters[i])
var end string
if i+1 >= len(filters) || filters[i+1] == "" {
end = start
} else {
end = reg.FindString(filters[i+1])
}
if start == "" || end == "" {
break
}
// fmt.Printf("Start: %s, End: %s\n", start, end)
s, err := strconv.ParseFloat(start, 64)
if err != nil {
return nil, err
}
e, err := strconv.ParseFloat(end, 64)
if err != nil {
return nil, err
}
blackFilters[i/2] = TimeFilter{
Start: s,
End: e,
}
i += 2
}
return blackFilters, err
}
func GetFramerate(path string) (float64, error) {
cmd := exec.Command("ffprobe", "-v", "0", "-of", "csv=p=0", "-select_streams", "v:0", "-show_entries", "stream=r_frame_rate", path)
buf := bytes.NewBuffer(nil)
cmd.Stdout = buf
err := cmd.Run()
if err != nil {
return 0, err
}
s := buf.String()
s = strings.ReplaceAll(s, "\n", "")
s = strings.TrimSpace(s)
ss := strings.Split(s, "/")
f1, err := strconv.Atoi(ss[0])
if err != nil {
return 0, err
}
f2, err := strconv.Atoi(ss[1])
if err != nil {
return 0, err
}
return float64(f1) / float64(f2), nil
}
|
