stash/vendor/github.com/asticode/go-astits/data_sdt.go
cj c1a096a1a6
Caption support (#2462)
Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>
2022-05-06 11:59:28 +10:00

108 lines
3 KiB
Go

package astits
import (
"fmt"
"github.com/asticode/go-astikit"
)
// Running statuses
const (
RunningStatusNotRunning = 1
RunningStatusPausing = 3
RunningStatusRunning = 4
RunningStatusServiceOffAir = 5
RunningStatusStartsInAFewSeconds = 2
RunningStatusUndefined = 0
)
// SDTData represents an SDT data
// Page: 33 | Chapter: 5.2.3 | Link: https://www.dvb.org/resources/public/standards/a38_dvb-si_specification.pdf
// (barbashov) the link above can be broken, alternative: https://dvb.org/wp-content/uploads/2019/12/a038_tm1217r37_en300468v1_17_1_-_rev-134_-_si_specification.pdf
type SDTData struct {
OriginalNetworkID uint16
Services []*SDTDataService
TransportStreamID uint16
}
// SDTDataService represents an SDT data service
type SDTDataService struct {
Descriptors []*Descriptor
HasEITPresentFollowing bool // When true indicates that EIT present/following information for the service is present in the current TS
HasEITSchedule bool // When true indicates that EIT schedule information for the service is present in the current TS
HasFreeCSAMode bool // When true indicates that access to one or more streams may be controlled by a CA system.
RunningStatus uint8
ServiceID uint16
}
// parseSDTSection parses an SDT section
func parseSDTSection(i *astikit.BytesIterator, offsetSectionsEnd int, tableIDExtension uint16) (d *SDTData, err error) {
// Create data
d = &SDTData{TransportStreamID: tableIDExtension}
// Get next bytes
var bs []byte
if bs, err = i.NextBytesNoCopy(2); err != nil {
err = fmt.Errorf("astits: fetching next bytes failed: %w", err)
return
}
// Original network ID
d.OriginalNetworkID = uint16(bs[0])<<8 | uint16(bs[1])
// Reserved for future use
i.Skip(1)
// Loop until end of section data is reached
for i.Offset() < offsetSectionsEnd {
// Create service
s := &SDTDataService{}
// Get next bytes
if bs, err = i.NextBytesNoCopy(2); err != nil {
err = fmt.Errorf("astits: fetching next bytes failed: %w", err)
return
}
// Service ID
s.ServiceID = uint16(bs[0])<<8 | uint16(bs[1])
// Get next byte
var b byte
if b, err = i.NextByte(); err != nil {
err = fmt.Errorf("astits: fetching next byte failed: %w", err)
return
}
// EIT schedule flag
s.HasEITSchedule = uint8(b&0x2) > 0
// EIT present/following flag
s.HasEITPresentFollowing = uint8(b&0x1) > 0
// Get next byte
if b, err = i.NextByte(); err != nil {
err = fmt.Errorf("astits: fetching next byte failed: %w", err)
return
}
// Running status
s.RunningStatus = uint8(b) >> 5
// Free CA mode
s.HasFreeCSAMode = uint8(b&0x10) > 0
// We need to rewind since the current byte is used by the descriptor as well
i.Skip(-1)
// Descriptors
if s.Descriptors, err = parseDescriptors(i); err != nil {
err = fmt.Errorf("astits: parsing descriptors failed: %w", err)
return
}
// Append service
d.Services = append(d.Services, s)
}
return
}