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stl.go
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stl.go
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package astisub
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"math"
"strconv"
"strings"
"time"
"github.com/asticode/go-astitools/byte"
"github.com/asticode/go-astitools/map"
"github.com/asticode/go-astitools/ptr"
"github.com/pkg/errors"
"golang.org/x/text/unicode/norm"
)
// https://tech.ebu.ch/docs/tech/tech3264.pdf
// https://github.com/yanncoupin/stl2srt/blob/master/to_srt.py
// STL block sizes
const (
stlBlockSizeGSI = 1024
stlBlockSizeTTI = 128
)
// STL character code table number
const (
stlCharacterCodeTableNumberLatin uint16 = 12336
stlCharacterCodeTableNumberLatinCyrillic = 12337
stlCharacterCodeTableNumberLatinArabic = 12338
stlCharacterCodeTableNumberLatinGreek = 12339
stlCharacterCodeTableNumberLatinHebrew = 12340
)
// STL character code tables
// TODO Add missing tables
var (
stlCharacterCodeTables = map[uint16]*astimap.Map{
stlCharacterCodeTableNumberLatin: astimap.NewMap(0x0, "").
Set(0x20, " ").Set(0x21, "!").Set(0x22, "\"").Set(0x23, "#").
Set(0x24, "¤").Set(0x25, "%").Set(0x26, "&").Set(0x27, "'").
Set(0x28, "(").Set(0x29, ")").Set(0x2a, "*").Set(0x2b, "+").
Set(0x2c, ",").Set(0x2d, "-").Set(0x2e, ".").Set(0x2f, "/").
Set(0x30, "0").Set(0x31, "1").Set(0x32, "2").Set(0x33, "3").
Set(0x34, "4").Set(0x35, "5").Set(0x36, "6").Set(0x37, "7").
Set(0x38, "8").Set(0x39, "9").Set(0x3a, ":").Set(0x3b, ";").
Set(0x3c, "<").Set(0x3d, "=").Set(0x3e, ">").Set(0x3f, "?").
Set(0x40, "@").Set(0x41, "A").Set(0x42, "B").Set(0x43, "C").
Set(0x44, "D").Set(0x45, "E").Set(0x46, "F").Set(0x47, "G").
Set(0x48, "H").Set(0x49, "I").Set(0x4a, "J").Set(0x4b, "K").
Set(0x4c, "L").Set(0x4d, "M").Set(0x4e, "N").Set(0x4f, "O").
Set(0x50, "P").Set(0x51, "Q").Set(0x52, "R").Set(0x53, "S").
Set(0x54, "T").Set(0x55, "U").Set(0x56, "V").Set(0x57, "W").
Set(0x58, "X").Set(0x59, "Y").Set(0x5a, "Z").Set(0x5b, "[").
Set(0x5c, "\\").Set(0x5d, "]").Set(0x5e, "^").Set(0x5f, "_").
Set(0x60, "`").Set(0x61, "a").Set(0x62, "b").Set(0x63, "c").
Set(0x64, "d").Set(0x65, "e").Set(0x66, "f").Set(0x67, "g").
Set(0x68, "h").Set(0x69, "i").Set(0x6a, "j").Set(0x6b, "k").
Set(0x6c, "l").Set(0x6d, "m").Set(0x6e, "n").Set(0x6f, "o").
Set(0x70, "p").Set(0x71, "q").Set(0x72, "r").Set(0x73, "s").
Set(0x74, "t").Set(0x75, "u").Set(0x76, "v").Set(0x77, "w").
Set(0x78, "x").Set(0x79, "y").Set(0x7a, "z").Set(0x7b, "{").
Set(0x7c, "|").Set(0x7d, "}").Set(0x7e, "~").
Set(0xa0, string([]byte{0xC2, 0xA0})).Set(0xa1, "¡").Set(0xa2, "¢").
Set(0xa3, "£").Set(0xa4, "$").Set(0xa5, "¥").Set(0xa7, "§").
Set(0xa9, "‘").Set(0xaa, "“").Set(0xab, "«").Set(0xac, "←").
Set(0xad, "↑").Set(0xae, "→").Set(0xaf, "↓").
Set(0xb0, "°").Set(0xb1, "±").Set(0xb2, "²").Set(0xb3, "³").
Set(0xb4, "×").Set(0xb5, "µ").Set(0xb6, "¶").Set(0xb7, "·").
Set(0xb8, "÷").Set(0xb9, "’").Set(0xba, "”").Set(0xbb, "»").
Set(0xbc, "¼").Set(0xbd, "½").Set(0xbe, "¾").Set(0xbf, "¿").
Set(0xc1, string([]byte{0xCC, 0x80})).Set(0xc2, string([]byte{0xCC, 0x81})).
Set(0xc3, string([]byte{0xCC, 0x82})).Set(0xc4, string([]byte{0xCC, 0x83})).
Set(0xc5, string([]byte{0xCC, 0x84})).Set(0xc6, string([]byte{0xCC, 0x86})).
Set(0xc7, string([]byte{0xCC, 0x87})).Set(0xc8, string([]byte{0xCC, 0x88})).
Set(0xca, string([]byte{0xCC, 0x8A})).Set(0xcb, string([]byte{0xCC, 0xA7})).
Set(0xcd, string([]byte{0xCC, 0x8B})).Set(0xce, string([]byte{0xCC, 0xA8})).
Set(0xcf, string([]byte{0xCC, 0x8C})).
Set(0xd0, "―").Set(0xd1, "¹").Set(0xd2, "®").Set(0xd3, "©").
Set(0xd4, "™").Set(0xd5, "♪").Set(0xd6, "¬").Set(0xd7, "¦").
Set(0xdc, "⅛").Set(0xdd, "⅜").Set(0xde, "⅝").Set(0xdf, "⅞").
Set(0xe0, "Ω").Set(0xe1, "Æ").Set(0xe2, "Đ").Set(0xe3, "ª").
Set(0xe4, "Ħ").Set(0xe6, "IJ").Set(0xe7, "Ŀ").Set(0xe8, "Ł").
Set(0xe9, "Ø").Set(0xea, "Œ").Set(0xeb, "º").Set(0xec, "Þ").
Set(0xed, "Ŧ").Set(0xee, "Ŋ").Set(0xef, "ʼn").
Set(0xf0, "ĸ").Set(0xf1, "æ").Set(0xf2, "đ").Set(0xf3, "ð").
Set(0xf4, "ħ").Set(0xf5, "ı").Set(0xf6, "ij").Set(0xf7, "ŀ").
Set(0xf8, "ł").Set(0xf9, "ø").Set(0xfa, "œ").Set(0xfb, "ß").
Set(0xfc, "þ").Set(0xfd, "ŧ").Set(0xfe, "ŋ").Set(0xff, string([]byte{0xC2, 0xAD})),
}
)
// STL code page numbers
const (
stlCodePageNumberCanadaFrench uint32 = 3683891
stlCodePageNumberMultilingual = 3683632
stlCodePageNumberNordic = 3683893
stlCodePageNumberPortugal = 3683888
stlCodePageNumberUnitedStates = 3420983
)
// STL comment flag
const (
stlCommentFlagTextContainsSubtitleData = '\x00'
stlCommentFlagTextContainsCommentsNotIntendedForTransmission = '\x01'
)
// STL country codes
const (
stlCountryCodeFrance = "FRA"
)
// STL cumulative status
const (
stlCumulativeStatusFirstSubtitleOfACumulativeSet = '\x01'
stlCumulativeStatusIntermediateSubtitleOfACumulativeSet = '\x02'
stlCumulativeStatusLastSubtitleOfACumulativeSet = '\x03'
stlCumulativeStatusSubtitleNotPartOfACumulativeSet = '\x00'
)
// STL display standard code
const (
stlDisplayStandardCodeOpenSubtitling = "0"
stlDisplayStandardCodeLevel1Teletext = "1"
stlDisplayStandardCodeLevel2Teletext = "2"
)
// STL framerate mapping
var stlFramerateMapping = astimap.NewMap("STL25.01", 25).
Set("STL25.01", 25).
Set("STL30.01", 30)
// STL justification code
const (
stlJustificationCodeCentredText = '\x02'
stlJustificationCodeLeftJustifiedText = '\x01'
stlJustificationCodeRightJustifiedText = '\x03'
stlJustificationCodeUnchangedPresentation = '\x00'
)
// STL language codes
const (
stlLanguageCodeEnglish = "09"
stlLanguageCodeFrench = "0F"
)
// STL language mapping
var stlLanguageMapping = astimap.NewMap(stlLanguageCodeEnglish, LanguageEnglish).
Set(stlLanguageCodeFrench, LanguageFrench)
// STL timecode status
const (
stlTimecodeStatusNotIntendedForUse = "0"
stlTimecodeStatusIntendedForUse = "1"
)
// TTI Special Extension Block Number
const extensionBlockNumberReservedUserData = 0xfe
// ReadFromSTL parses an .stl content
func ReadFromSTL(i io.Reader) (o *Subtitles, err error) {
// Init
o = NewSubtitles()
// Read GSI block
var b []byte
if b, err = readNBytes(i, stlBlockSizeGSI); err != nil {
return
}
// Parse GSI block
var g *gsiBlock
if g, err = parseGSIBlock(b); err != nil {
err = errors.Wrap(err, "astisub: building gsi block failed")
return
}
// Create character handler
var ch *stlCharacterHandler
if ch, err = newSTLCharacterHandler(g.characterCodeTableNumber); err != nil {
err = errors.Wrap(err, "astisub: creating stl character handler failed")
return
}
// Update metadata
// TODO Add more STL fields to metadata
o.Metadata = &Metadata{
Framerate: g.framerate,
Language: stlLanguageMapping.B(g.languageCode).(string),
STLPublisher: g.publisher,
Title: g.originalProgramTitle,
}
// Parse Text and Timing Information (TTI) blocks.
for {
// Read TTI block
if b, err = readNBytes(i, stlBlockSizeTTI); err != nil {
if err == io.EOF {
err = nil
break
}
return
}
// Parse TTI block
var t = parseTTIBlock(b, g.framerate)
if t.extensionBlockNumber != extensionBlockNumberReservedUserData {
// Create item
var i = &Item{
EndAt: t.timecodeOut - g.timecodeStartOfProgramme,
StartAt: t.timecodeIn - g.timecodeStartOfProgramme,
}
// Loop through rows
for _, text := range bytes.Split(t.text, []byte{0x8a}) {
parseTeletextRow(i, ch, func() styler { return newSTLStyler() }, text)
}
// Append item
o.Items = append(o.Items, i)
}
}
return
}
// readNBytes reads n bytes
func readNBytes(i io.Reader, c int) (o []byte, err error) {
o = make([]byte, c)
var n int
if n, err = i.Read(o); err != nil || n != len(o) {
if err != nil {
if err == io.EOF {
return
}
err = errors.Wrapf(err, "astisub: reading %d bytes failed", c)
return
}
err = fmt.Errorf("astisub: Read %d bytes, should have read %d", n, c)
return
}
return
}
// gsiBlock represents a GSI block
type gsiBlock struct {
characterCodeTableNumber uint16
codePageNumber uint32
countryOfOrigin string
creationDate time.Time
diskSequenceNumber int
displayStandardCode string
editorContactDetails string
editorName string
framerate int
languageCode string
maximumNumberOfDisplayableCharactersInAnyTextRow int
maximumNumberOfDisplayableRows int
originalEpisodeTitle string
originalProgramTitle string
publisher string
revisionDate time.Time
revisionNumber int
subtitleListReferenceCode string
timecodeFirstInCue time.Duration
timecodeStartOfProgramme time.Duration
timecodeStatus string
totalNumberOfDisks int
totalNumberOfSubtitleGroups int
totalNumberOfSubtitles int
totalNumberOfTTIBlocks int
translatedEpisodeTitle string
translatedProgramTitle string
translatorContactDetails string
translatorName string
userDefinedArea string
}
// newGSIBlock builds the subtitles GSI block
func newGSIBlock(s Subtitles) (g *gsiBlock) {
// Init
g = &gsiBlock{
characterCodeTableNumber: stlCharacterCodeTableNumberLatin,
codePageNumber: stlCodePageNumberMultilingual,
countryOfOrigin: stlCountryCodeFrance,
creationDate: Now(),
diskSequenceNumber: 1,
displayStandardCode: stlDisplayStandardCodeLevel1Teletext,
framerate: 25,
languageCode: stlLanguageCodeFrench,
maximumNumberOfDisplayableCharactersInAnyTextRow: 40,
maximumNumberOfDisplayableRows: 23,
subtitleListReferenceCode: "12345678",
timecodeStatus: stlTimecodeStatusIntendedForUse,
totalNumberOfDisks: 1,
totalNumberOfSubtitleGroups: 1,
totalNumberOfSubtitles: len(s.Items),
totalNumberOfTTIBlocks: len(s.Items),
}
// Add metadata
if s.Metadata != nil {
g.framerate = s.Metadata.Framerate
g.languageCode = stlLanguageMapping.A(s.Metadata.Language).(string)
g.originalProgramTitle = s.Metadata.Title
g.publisher = s.Metadata.STLPublisher
}
// Timecode first in cue
if len(s.Items) > 0 {
g.timecodeFirstInCue = s.Items[0].StartAt
}
return
}
// parseGSIBlock parses a GSI block
func parseGSIBlock(b []byte) (g *gsiBlock, err error) {
// Init
g = &gsiBlock{
characterCodeTableNumber: binary.BigEndian.Uint16(b[12:14]),
countryOfOrigin: string(bytes.TrimSpace(b[274:277])),
codePageNumber: binary.BigEndian.Uint32(append([]byte{0x0}, b[0:3]...)),
displayStandardCode: string(bytes.TrimSpace([]byte{b[11]})),
editorName: string(bytes.TrimSpace(b[309:341])),
editorContactDetails: string(bytes.TrimSpace(b[341:373])),
framerate: stlFramerateMapping.B(string(b[3:11])).(int),
languageCode: string(bytes.TrimSpace(b[14:16])),
originalEpisodeTitle: string(bytes.TrimSpace(b[48:80])),
originalProgramTitle: string(bytes.TrimSpace(b[16:48])),
publisher: string(bytes.TrimSpace(b[277:309])),
subtitleListReferenceCode: string(bytes.TrimSpace(b[208:224])),
timecodeStatus: string(bytes.TrimSpace([]byte{b[255]})),
translatedEpisodeTitle: string(bytes.TrimSpace(b[80:112])),
translatedProgramTitle: string(bytes.TrimSpace(b[112:144])),
translatorContactDetails: string(bytes.TrimSpace(b[176:208])),
translatorName: string(bytes.TrimSpace(b[144:176])),
userDefinedArea: string(bytes.TrimSpace(b[448:])),
}
// Creation date
if v := strings.TrimSpace(string(b[224:230])); len(v) > 0 {
if g.creationDate, err = time.Parse("060102", v); err != nil {
err = errors.Wrapf(err, "astisub: parsing date %s failed", v)
return
}
}
// Revision date
if v := strings.TrimSpace(string(b[230:236])); len(v) > 0 {
if g.revisionDate, err = time.Parse("060102", v); err != nil {
err = errors.Wrapf(err, "astisub: parsing date %s failed", v)
return
}
}
// Revision number
if v := strings.TrimSpace(string(b[236:238])); len(v) > 0 {
if g.revisionNumber, err = strconv.Atoi(v); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", v)
return
}
}
// Total number of TTI blocks
if v := strings.TrimSpace(string(b[238:243])); len(v) > 0 {
if g.totalNumberOfTTIBlocks, err = strconv.Atoi(v); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", v)
return
}
}
// Total number of subtitles
if v := strings.TrimSpace(string(b[243:248])); len(v) > 0 {
if g.totalNumberOfSubtitles, err = strconv.Atoi(v); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", v)
return
}
}
// Total number of subtitle groups
if v := strings.TrimSpace(string(b[248:251])); len(v) > 0 {
if g.totalNumberOfSubtitleGroups, err = strconv.Atoi(v); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", v)
return
}
}
// Maximum number of displayable characters in any text row
if v := strings.TrimSpace(string(b[251:253])); len(v) > 0 {
if g.maximumNumberOfDisplayableCharactersInAnyTextRow, err = strconv.Atoi(v); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", v)
return
}
}
// Maximum number of displayable rows
if v := strings.TrimSpace(string(b[253:255])); len(v) > 0 {
if g.maximumNumberOfDisplayableRows, err = strconv.Atoi(v); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", v)
return
}
}
// Timecode start of programme
if v := strings.TrimSpace(string(b[256:264])); len(v) > 0 {
if g.timecodeStartOfProgramme, err = parseDurationSTL(v, g.framerate); err != nil {
err = errors.Wrapf(err, "astisub: parsing of stl duration %s failed", v)
return
}
}
// Timecode first in cue
if v := strings.TrimSpace(string(b[264:272])); len(v) > 0 {
if g.timecodeFirstInCue, err = parseDurationSTL(v, g.framerate); err != nil {
err = errors.Wrapf(err, "astisub: parsing of stl duration %s failed", v)
return
}
}
// Total number of disks
if v := strings.TrimSpace(string(b[272])); len(v) > 0 {
if g.totalNumberOfDisks, err = strconv.Atoi(v); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", v)
return
}
}
// Disk sequence number
if v := strings.TrimSpace(string(b[273])); len(v) > 0 {
if g.diskSequenceNumber, err = strconv.Atoi(v); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", v)
return
}
}
return
}
// bytes transforms the GSI block into []byte
func (b gsiBlock) bytes() (o []byte) {
bs := make([]byte, 4)
binary.BigEndian.PutUint32(bs, b.codePageNumber)
o = append(o, astibyte.ToLength(bs[1:], ' ', 3)...) // Code page number
o = append(o, astibyte.ToLength([]byte(stlFramerateMapping.A(b.framerate).(string)), ' ', 8)...) // Disk format code
o = append(o, astibyte.ToLength([]byte(b.displayStandardCode), ' ', 1)...) // Display standard code
binary.BigEndian.PutUint16(bs, b.characterCodeTableNumber)
o = append(o, astibyte.ToLength(bs[:2], ' ', 2)...) // Character code table number
o = append(o, astibyte.ToLength([]byte(b.languageCode), ' ', 2)...) // Language code
o = append(o, astibyte.ToLength([]byte(b.originalProgramTitle), ' ', 32)...) // Original program title
o = append(o, astibyte.ToLength([]byte(b.originalEpisodeTitle), ' ', 32)...) // Original episode title
o = append(o, astibyte.ToLength([]byte(b.translatedProgramTitle), ' ', 32)...) // Translated program title
o = append(o, astibyte.ToLength([]byte(b.translatedEpisodeTitle), ' ', 32)...) // Translated episode title
o = append(o, astibyte.ToLength([]byte(b.translatorName), ' ', 32)...) // Translator's name
o = append(o, astibyte.ToLength([]byte(b.translatorContactDetails), ' ', 32)...) // Translator's contact details
o = append(o, astibyte.ToLength([]byte(b.subtitleListReferenceCode), ' ', 16)...) // Subtitle list reference code
o = append(o, astibyte.ToLength([]byte(b.creationDate.Format("060102")), ' ', 6)...) // Creation date
o = append(o, astibyte.ToLength([]byte(b.revisionDate.Format("060102")), ' ', 6)...) // Revision date
o = append(o, astibyte.ToLength(astibyte.PadLeft([]byte(strconv.Itoa(b.revisionNumber)), '0', 2), '0', 2)...) // Revision number
o = append(o, astibyte.ToLength(astibyte.PadLeft([]byte(strconv.Itoa(b.totalNumberOfTTIBlocks)), '0', 5), '0', 5)...) // Total number of TTI blocks
o = append(o, astibyte.ToLength(astibyte.PadLeft([]byte(strconv.Itoa(b.totalNumberOfSubtitles)), '0', 5), '0', 5)...) // Total number of subtitles
o = append(o, astibyte.ToLength(astibyte.PadLeft([]byte(strconv.Itoa(b.totalNumberOfSubtitleGroups)), '0', 3), '0', 3)...) // Total number of subtitle groups
o = append(o, astibyte.ToLength(astibyte.PadLeft([]byte(strconv.Itoa(b.maximumNumberOfDisplayableCharactersInAnyTextRow)), '0', 2), '0', 2)...) // Maximum number of displayable characters in any text row
o = append(o, astibyte.ToLength(astibyte.PadLeft([]byte(strconv.Itoa(b.maximumNumberOfDisplayableRows)), '0', 2), '0', 2)...) // Maximum number of displayable rows
o = append(o, astibyte.ToLength([]byte(b.timecodeStatus), ' ', 1)...) // Timecode status
o = append(o, astibyte.ToLength([]byte(formatDurationSTL(b.timecodeStartOfProgramme, b.framerate)), ' ', 8)...) // Timecode start of a programme
o = append(o, astibyte.ToLength([]byte(formatDurationSTL(b.timecodeFirstInCue, b.framerate)), ' ', 8)...) // Timecode first in cue
o = append(o, astibyte.ToLength([]byte(strconv.Itoa(b.totalNumberOfDisks)), ' ', 1)...) // Total number of disks
o = append(o, astibyte.ToLength([]byte(strconv.Itoa(b.diskSequenceNumber)), ' ', 1)...) // Disk sequence number
o = append(o, astibyte.ToLength([]byte(b.countryOfOrigin), ' ', 3)...) // Country of origin
o = append(o, astibyte.ToLength([]byte(b.publisher), ' ', 32)...) // Publisher
o = append(o, astibyte.ToLength([]byte(b.editorName), ' ', 32)...) // Editor's name
o = append(o, astibyte.ToLength([]byte(b.editorContactDetails), ' ', 32)...) // Editor's contact details
o = append(o, astibyte.ToLength([]byte{}, ' ', 75+576)...) // Spare bytes + user defined area // // Editor's contact details
return
}
// parseDurationSTL parses a STL duration
func parseDurationSTL(i string, framerate int) (d time.Duration, err error) {
// Parse hours
var hours, hoursString = 0, i[0:2]
if hours, err = strconv.Atoi(hoursString); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", hoursString)
return
}
// Parse minutes
var minutes, minutesString = 0, i[2:4]
if minutes, err = strconv.Atoi(minutesString); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", minutesString)
return
}
// Parse seconds
var seconds, secondsString = 0, i[4:6]
if seconds, err = strconv.Atoi(secondsString); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", secondsString)
return
}
// Parse frames
var frames, framesString = 0, i[6:8]
if frames, err = strconv.Atoi(framesString); err != nil {
err = errors.Wrapf(err, "astisub: atoi of %s failed", framesString)
return
}
// Set duration
d = time.Duration(hours)*time.Hour + time.Duration(minutes)*time.Minute + time.Duration(seconds)*time.Second + time.Duration(1e9*frames/framerate)*time.Nanosecond
return
}
// formatDurationSTL formats a STL duration
func formatDurationSTL(d time.Duration, framerate int) (o string) {
// Add hours
if d.Hours() < 10 {
o += "0"
}
var delta = int(math.Floor(d.Hours()))
o += strconv.Itoa(delta)
d -= time.Duration(delta) * time.Hour
// Add minutes
if d.Minutes() < 10 {
o += "0"
}
delta = int(math.Floor(d.Minutes()))
o += strconv.Itoa(delta)
d -= time.Duration(delta) * time.Minute
// Add seconds
if d.Seconds() < 10 {
o += "0"
}
delta = int(math.Floor(d.Seconds()))
o += strconv.Itoa(delta)
d -= time.Duration(delta) * time.Second
// Add frames
var frames = int(int(d.Nanoseconds()) * framerate / 1e9)
if frames < 10 {
o += "0"
}
o += strconv.Itoa(frames)
return
}
// ttiBlock represents a TTI block
type ttiBlock struct {
commentFlag byte
cumulativeStatus byte
extensionBlockNumber int
justificationCode byte
subtitleGroupNumber int
subtitleNumber int
text []byte
timecodeIn time.Duration
timecodeOut time.Duration
verticalPosition int
}
// newTTIBlock builds an item TTI block
func newTTIBlock(i *Item, idx int) (t *ttiBlock) {
// Init
t = &ttiBlock{
commentFlag: stlCommentFlagTextContainsSubtitleData,
cumulativeStatus: stlCumulativeStatusSubtitleNotPartOfACumulativeSet,
extensionBlockNumber: 255,
justificationCode: stlJustificationCodeLeftJustifiedText,
subtitleGroupNumber: 0,
subtitleNumber: idx,
timecodeIn: i.StartAt,
timecodeOut: i.EndAt,
verticalPosition: 20,
}
// Add text
var lines []string
for _, l := range i.Lines {
lines = append(lines, l.String())
}
t.text = []byte(strings.Join(lines, "\n"))
return
}
// parseTTIBlock parses a TTI block
func parseTTIBlock(p []byte, framerate int) *ttiBlock {
return &ttiBlock{
commentFlag: p[15],
cumulativeStatus: p[4],
extensionBlockNumber: int(uint8(p[3])),
justificationCode: p[14],
subtitleGroupNumber: int(uint8(p[0])),
subtitleNumber: int(binary.LittleEndian.Uint16(p[1:3])),
text: p[16:128],
timecodeIn: parseDurationSTLBytes(p[5:9], framerate),
timecodeOut: parseDurationSTLBytes(p[9:13], framerate),
verticalPosition: int(uint8(p[13])),
}
}
// bytes transforms the TTI block into []byte
func (t *ttiBlock) bytes(g *gsiBlock) (o []byte) {
o = append(o, byte(uint8(t.subtitleGroupNumber))) // Subtitle group number
var b = make([]byte, 2)
binary.LittleEndian.PutUint16(b, uint16(t.subtitleNumber))
o = append(o, b...) // Subtitle number
o = append(o, byte(uint8(t.extensionBlockNumber))) // Extension block number
o = append(o, t.cumulativeStatus) // Cumulative status
o = append(o, formatDurationSTLBytes(t.timecodeIn, g.framerate)...) // Timecode in
o = append(o, formatDurationSTLBytes(t.timecodeOut, g.framerate)...) // Timecode out
o = append(o, byte(uint8(t.verticalPosition))) // Vertical position
o = append(o, t.justificationCode) // Justification code
o = append(o, t.commentFlag) // Comment flag
o = append(o, astibyte.ToLength(encodeTextSTL(string(t.text)), '\x8f', 112)...) // Text field
return
}
// formatDurationSTLBytes formats a STL duration in bytes
func formatDurationSTLBytes(d time.Duration, framerate int) (o []byte) {
// Add hours
var hours = int(math.Floor(d.Hours()))
o = append(o, byte(uint8(hours)))
d -= time.Duration(hours) * time.Hour
// Add minutes
var minutes = int(math.Floor(d.Minutes()))
o = append(o, byte(uint8(minutes)))
d -= time.Duration(minutes) * time.Minute
// Add seconds
var seconds = int(math.Floor(d.Seconds()))
o = append(o, byte(uint8(seconds)))
d -= time.Duration(seconds) * time.Second
// Add frames
var frames = int(int(d.Nanoseconds()) * framerate / 1e9)
o = append(o, byte(uint8(frames)))
return
}
// parseDurationSTLBytes parses a STL duration in bytes
func parseDurationSTLBytes(b []byte, framerate int) time.Duration {
return time.Duration(uint8(b[0]))*time.Hour + time.Duration(uint8(b[1]))*time.Minute + time.Duration(uint8(b[2]))*time.Second + time.Duration(1e9*int(uint8(b[3]))/framerate)*time.Nanosecond
}
type stlCharacterHandler struct {
accent string
c uint16
m *astimap.Map
}
func newSTLCharacterHandler(characterCodeTable uint16) (*stlCharacterHandler, error) {
if v, ok := stlCharacterCodeTables[characterCodeTable]; ok {
return &stlCharacterHandler{
c: characterCodeTable,
m: v,
}, nil
}
return nil, fmt.Errorf("astisub: table doesn't exist for character code table %d", characterCodeTable)
}
// TODO Use this instead of encodeTextSTL => use in teletext process like for decode
// TODO Test
func (h *stlCharacterHandler) encode(i []byte) byte {
return ' '
}
func (h *stlCharacterHandler) decode(i byte) (o []byte) {
k := int(i)
if !h.m.InA(k) {
return
}
v := h.m.B(k).(string)
if len(h.accent) > 0 {
o = norm.NFC.Bytes([]byte(v + h.accent))
h.accent = ""
return
} else if h.c == stlCharacterCodeTableNumberLatin && k >= 0xc0 && k <= 0xcf {
h.accent = v
return
}
return []byte(v)
}
type stlStyler struct {
boxing *bool
italics *bool
underline *bool
}
func newSTLStyler() *stlStyler {
return &stlStyler{}
}
func (s *stlStyler) parseSpacingAttribute(i byte) {
switch i {
case 0x80:
s.italics = astiptr.Bool(true)
case 0x81:
s.italics = astiptr.Bool(false)
case 0x82:
s.underline = astiptr.Bool(true)
case 0x83:
s.underline = astiptr.Bool(false)
case 0x84:
s.boxing = astiptr.Bool(true)
case 0x85:
s.boxing = astiptr.Bool(false)
}
}
func (s *stlStyler) hasBeenSet() bool {
return s.italics != nil || s.boxing != nil || s.underline != nil
}
func (s *stlStyler) hasChanged(sa *StyleAttributes) bool {
return s.boxing != sa.STLBoxing || s.italics != sa.STLItalics || s.underline != sa.STLUnderline
}
func (s *stlStyler) propagateStyleAttributes(sa *StyleAttributes) {
sa.propagateSTLAttributes()
}
func (s *stlStyler) update(sa *StyleAttributes) {
if s.boxing != nil && s.boxing != sa.STLBoxing {
sa.STLBoxing = s.boxing
}
if s.italics != nil && s.italics != sa.STLItalics {
sa.STLItalics = s.italics
}
if s.underline != nil && s.underline != sa.STLUnderline {
sa.STLUnderline = s.underline
}
}
// WriteToSTL writes subtitles in .stl format
func (s Subtitles) WriteToSTL(o io.Writer) (err error) {
// Do not write anything if no subtitles
if len(s.Items) == 0 {
err = ErrNoSubtitlesToWrite
return
}
// Write GSI block
var g = newGSIBlock(s)
if _, err = o.Write(g.bytes()); err != nil {
err = errors.Wrap(err, "astisub: writing gsi block failed")
return
}
// Loop through items
for idx, item := range s.Items {
// Write tti block
if _, err = o.Write(newTTIBlock(item, idx+1).bytes(g)); err != nil {
err = errors.Wrapf(err, "astisub: writing tti block #%d failed", idx+1)
return
}
}
return
}
// TODO Remove below
// STL unicode diacritic
var stlUnicodeDiacritic = astimap.NewMap(byte('\x00'), "\x00").
Set(byte('\xc1'), "\u0300"). // Grave accent
Set(byte('\xc2'), "\u0301"). // Acute accent
Set(byte('\xc3'), "\u0302"). // Circumflex
Set(byte('\xc4'), "\u0303"). // Tilde
Set(byte('\xc5'), "\u0304"). // Macron
Set(byte('\xc6'), "\u0306"). // Breve
Set(byte('\xc7'), "\u0307"). // Dot
Set(byte('\xc8'), "\u0308"). // Umlaut
Set(byte('\xca'), "\u030a"). // Ring
Set(byte('\xcb'), "\u0327"). // Cedilla
Set(byte('\xcd'), "\u030B"). // Double acute accent
Set(byte('\xce'), "\u0328"). // Ogonek
Set(byte('\xcf'), "\u030c") // Caron
// STL unicode mapping
var stlUnicodeMapping = astimap.NewMap(byte('\x00'), "\x00").
Set(byte('\x8a'), "\u000a"). // Line break
Set(byte('\xa8'), "\u00a4"). // ¤
Set(byte('\xa9'), "\u2018"). // ‘
Set(byte('\xaa'), "\u201C"). // “
Set(byte('\xab'), "\u00AB"). // «
Set(byte('\xac'), "\u2190"). // ←
Set(byte('\xad'), "\u2191"). // ↑
Set(byte('\xae'), "\u2192"). // →
Set(byte('\xaf'), "\u2193"). // ↓
Set(byte('\xb4'), "\u00D7"). // ×
Set(byte('\xb8'), "\u00F7"). // ÷
Set(byte('\xb9'), "\u2019"). // ’
Set(byte('\xba'), "\u201D"). // ”
Set(byte('\xbc'), "\u00BC"). // ¼
Set(byte('\xbd'), "\u00BD"). // ½
Set(byte('\xbe'), "\u00BE"). // ¾
Set(byte('\xbf'), "\u00BF"). // ¿
Set(byte('\xd0'), "\u2015"). // ―
Set(byte('\xd1'), "\u00B9"). // ¹
Set(byte('\xd2'), "\u00AE"). // ®
Set(byte('\xd3'), "\u00A9"). // ©
Set(byte('\xd4'), "\u2122"). // ™
Set(byte('\xd5'), "\u266A"). // ♪
Set(byte('\xd6'), "\u00AC"). // ¬
Set(byte('\xd7'), "\u00A6"). // ¦
Set(byte('\xdc'), "\u215B"). // ⅛
Set(byte('\xdd'), "\u215C"). // ⅜
Set(byte('\xde'), "\u215D"). // ⅝
Set(byte('\xdf'), "\u215E"). // ⅞
Set(byte('\xe0'), "\u2126"). // Ohm Ω
Set(byte('\xe1'), "\u00C6"). // Æ
Set(byte('\xe2'), "\u0110"). // Đ
Set(byte('\xe3'), "\u00AA"). // ª
Set(byte('\xe4'), "\u0126"). // Ħ
Set(byte('\xe6'), "\u0132"). // IJ
Set(byte('\xe7'), "\u013F"). // Ŀ
Set(byte('\xe8'), "\u0141"). // Ł
Set(byte('\xe9'), "\u00D8"). // Ø
Set(byte('\xea'), "\u0152"). // Œ
Set(byte('\xeb'), "\u00BA"). // º
Set(byte('\xec'), "\u00DE"). // Þ
Set(byte('\xed'), "\u0166"). // Ŧ
Set(byte('\xee'), "\u014A"). // Ŋ
Set(byte('\xef'), "\u0149"). // ʼn
Set(byte('\xf0'), "\u0138"). // ĸ
Set(byte('\xf1'), "\u00E6"). // æ
Set(byte('\xf2'), "\u0111"). // đ
Set(byte('\xf3'), "\u00F0"). // ð
Set(byte('\xf4'), "\u0127"). // ħ
Set(byte('\xf5'), "\u0131"). // ı
Set(byte('\xf6'), "\u0133"). // ij
Set(byte('\xf7'), "\u0140"). // ŀ
Set(byte('\xf8'), "\u0142"). // ł
Set(byte('\xf9'), "\u00F8"). // ø
Set(byte('\xfa'), "\u0153"). // œ
Set(byte('\xfb'), "\u00DF"). // ß
Set(byte('\xfc'), "\u00FE"). // þ
Set(byte('\xfd'), "\u0167"). // ŧ
Set(byte('\xfe'), "\u014B"). // ŋ
Set(byte('\xff'), "\u00AD") // Soft hyphen
// encodeTextSTL encodes the STL text
func encodeTextSTL(i string) (o []byte) {
i = string(norm.NFD.Bytes([]byte(i)))
for _, c := range i {
if stlUnicodeMapping.InB(string(c)) {
o = append(o, stlUnicodeMapping.A(string(c)).(byte))
} else if stlUnicodeDiacritic.InB(string(c)) {
o = append(o[:len(o)-1], stlUnicodeDiacritic.A(string(c)).(byte), o[len(o)-1])
} else {
o = append(o, byte(c))
}
}
return
}