/
srttools.go
240 lines (225 loc) · 4.65 KB
/
srttools.go
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package srttools
import (
"bufio"
"fmt"
"os"
"regexp"
"strconv"
)
var (
regexpID = regexp.MustCompile("^[0-9]+$")
regexpTime = regexp.MustCompile("^([0-9]+):([0-9]+):([0-9]+).*")
)
const (
timeFormat string = "HH:MM:SS,MIL"
timeSep string = " --> "
timePreffMin string = "HH:"
timePreffSec string = "HH:MM:"
timePreffMil string = "HH:MM:SS,"
)
type srtTime struct {
start int
end int
extra string
}
func (t *srtTime) String() string {
return timeMilli2Str(t.start) + timeSep + timeMilli2Str(t.end) + t.extra
}
func (t *srtTime) Offset(offset int) {
t.start += offset
t.end += offset
}
func Concat(output string, files ...string) error {
// Create file
file, err := os.Create(output)
defer func() {
file.Sync()
file.Close()
}()
if err != nil {
return err
}
// Create writter
w := bufio.NewWriter(file)
defer w.Flush()
// At least 2 files are needed
if len(files) < 2 {
return nil
}
// Set offsets
timeOff := 0
idOff := 0
// Parse each file
for index, file := range files {
if index == 0 {
// First file, written as it is
copySRTLines(w, file)
continue
}
// Second file and beyond...
t, id, err := getSRTlimits(files[index-1])
if err != nil {
return err
}
// Increment offset
timeOff += t
idOff += id
// Apply offset
addSRToffset(w, file, timeOff, idOff)
}
return nil
}
func copySRTLines(w *bufio.Writer, path string) error {
// Open SRT file
file, err := os.Open(path)
defer file.Close()
if err != nil {
return err
}
// Create a reader
r := bufio.NewReader(file)
for {
// Read new line
line, _, err := r.ReadLine()
// Write to file
if _, err := w.WriteString(string(line) + "\n"); err != nil {
return err
}
// Check errors
if err != nil {
break
}
}
return nil
}
func getSRTlimits(srt string) (int, int, error) {
// Last readed time
lasTime := srtTime{}
var lastID int
// Open SRT file
file, err := os.Open(srt)
defer file.Close()
if err != nil {
return 0, 0, err
}
// Create a reader
reader := bufio.NewReader(file)
for {
// Read new line
line, _, err := reader.ReadLine()
if regexpID.MatchString(string(line)) {
// Parse ID
lastID, _ = parseID(string(line))
}
// Match time lines
if regexpTime.MatchString(string(line)) {
// Parse Time line
lasTime = parseTime(string(line))
}
// Check errors
if err != nil {
break
}
}
return lasTime.end, lastID, nil
}
func addSRToffset(w *bufio.Writer, srt string, timeOff, idOff int) error {
// Open SRT file
file, err := os.Open(srt)
defer file.Close()
if err != nil {
return err
}
// Create a reader
reader := bufio.NewReader(file)
for {
// Read new line
line, _, err := reader.ReadLine()
if err != nil {
break
}
switch {
case regexpID.MatchString(string(line)):
// Parse ID
id, _ := parseID(string(line))
line = []uint8(fmt.Sprintf("%d", id+idOff))
case regexpTime.MatchString(string(line)):
// Parse Times
time := parseTime(string(line))
time.Offset(timeOff)
line = []uint8(time.String())
default:
// Do nothing
}
// Write to file
if _, err := w.WriteString(string(line) + "\n"); err != nil {
return err
}
}
return nil
}
func parseID(line string) (int, error) {
return strconv.Atoi(line)
}
func parseTime(line string) srtTime {
// Trim times
init := line[:len(timeFormat)]
finish := line[len(timeFormat)+len(timeSep):][:len(timeFormat)]
// Convert to milliseconds
return srtTime{
start: timeStr2Milli(init),
end: timeStr2Milli(finish),
extra: line[2*len(timeFormat)+len(timeSep):],
}
}
func timeStr2Milli(time string) int {
millis := 0
// Convert hours
if hours, err := strconv.Atoi(time[:2]); err != nil {
panic(err)
} else {
millis += hours * 60 * 60 * 1000
}
// Convert minutes
if minutes, err := strconv.Atoi(time[len(timePreffMin):][:2]); err != nil {
panic(err)
} else {
millis += minutes * 60 * 1000
}
// Convert seconds
if seconds, err := strconv.Atoi(time[len(timePreffSec):][:2]); err != nil {
panic(err)
} else {
millis += seconds * 1000
}
// Convert seconds
if milli, err := strconv.Atoi(time[len(timePreffMil):]); err != nil {
panic(err)
} else {
millis += milli
}
return millis
}
func timeMilli2Str(millis int) string {
sec := uint(millis / 1000)
min := uint(sec / 60)
sec = sec % 60
hrs := uint(min / 60)
min = min % 60
return fmt.Sprintf("%s:%s:%s,%s", time2Str(hrs), time2Str(min), time2Str(sec), millis2Str(millis%1000))
}
func time2Str(t uint) string {
if t < 10 {
return fmt.Sprintf("0%d", t)
}
return fmt.Sprintf("%d", t)
}
func millis2Str(t int) string {
if t < 10 {
return fmt.Sprintf("00%d", t)
}
if t < 100 {
return fmt.Sprintf("0%d", t)
}
return fmt.Sprintf("%d", t)
}