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Added GetPTS() function.

This commit is contained in:
scruzin 2019-07-12 14:01:49 +09:30
parent 4f0a5948ed
commit aa67134969
1 changed files with 55 additions and 34 deletions
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89
container/mts/mpegts.go
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@ -33,7 +33,6 @@ import (
"fmt"
"github.com/Comcast/gots/packet"
"github.com/Comcast/gots/pes"
"github.com/pkg/errors"
"bitbucket.org/ausocean/av/container/mts/meta"
@ -379,8 +378,8 @@ var errNoPTS = errors.New("could not find PTS")
// GetPTSRange retreives the first and last PTS of an MPEGTS clip.
// If there is only one PTS, it is included twice in the pts return value.
func GetPTSRange(clip []byte, pid uint16) (pts [2]uint64, err error) {
var _pkt packet.Packet
// Find the first packet with PID pidType and PUSI.
var _pts int64
// Get the first PTS for the given PID.
var i int
for {
if i >= len(clip) {
@ -390,25 +389,14 @@ func GetPTSRange(clip []byte, pid uint16) (pts [2]uint64, err error) {
if err != nil {
return pts, errors.Wrap(err, fmt.Sprintf("could not find packet of PID: %d", pid))
}
copy(_pkt[:], pkt)
if _pkt.PayloadUnitStartIndicator() {
_pts, err = GetPTS(pkt)
if err == nil {
break
}
i += _i + PacketSize
}
// Get the payload of the packet, which will be the start of the PES packet.
payload, err := packet.Payload(&_pkt)
if err != nil {
return pts, err
}
// Get the the first PTS from the PES header.
_pes, err := pes.NewPESHeader(payload)
if err != nil {
return pts, err
}
pts[0] = _pes.PTS()
pts[0] = uint64(_pts)
pts[1] = pts[0] // Until we have find a second PTS.
// Get the last PTS searching in reverse from end of the clip.
@ -419,31 +407,64 @@ func GetPTSRange(clip []byte, pid uint16) (pts [2]uint64, err error) {
if err != nil || i <= first {
return pts, nil
}
copy(_pkt[:], pkt)
if packet.PayloadUnitStartIndicator(&_pkt) {
_pts, err = GetPTS(pkt)
if err == nil {
break
}
i = _i
}
// Get the payload of the packet.
payload, err = packet.Payload(&_pkt)
if err != nil {
return
}
// Get the the last PTS from the PES header.
_pes, err = pes.NewPESHeader(payload)
if err != nil {
return
}
pts[1] = _pes.PTS()
pts[1] = uint64(_pts)
return
}
var errNoPesPayload = errors.New("no PES payload")
var errNoPesPTS = errors.New("no PES PTS")
var errInvalidPesHeader = errors.New("invalid PES header")
var errInvalidPesPayload = errors.New("invalid PES payload")
// GetPTS returns a PTS from an MTS packet that has PES payload, or an error otherwise.
func GetPTS(pkt []byte) (pts int64, err error) {
// Bail if packet does not contain a PES.
if pkt[1]&0x040 == 0 {
err = errNoPesPayload
return
}
// Compute start of PES payload and check its length.
start := HeadSize
if pkt[3]&0x20 != 0 {
// Take into account length of the adaptation field.
start += 1 + int(pkt[4])
}
pes := pkt[start:]
if len(pes) < 9 {
err = errInvalidPesHeader
return
}
// Check that PES has a PTS.
if pes[7]&0xc0 == 0 {
err = errNoPesPTS
return
}
// Extract the PTS.
if len(pes) < 14 {
err = errInvalidPesHeader
return
}
pts = extractPTS(pes[9:14])
return
}
// extractTime extracts a PTS from the given data.
func extractPTS(d []byte) int64 {
return (int64((d[0]>>1)&0x07) << 30) | (int64(d[1]) << 22) | (int64((d[2]>>1)&0x7f) << 15) | (int64(d[3]) << 7) | int64((d[4]>>1)&0x7f)
}
var errNoMeta = errors.New("PMT does not contain meta")
// ExtractMeta returns a map of metadata from the first PMT's metaData
@ -460,7 +481,7 @@ func ExtractMeta(d []byte) (map[string]string, error) {
// metaFromPMT returns metadata, if any, from a PMT.
func metaFromPMT(d []byte) (m map[string]string, err error) {
// Get as PSI type, skipping the MTS header.
pmt := psi.PSIBytes(d[4:])
pmt := psi.PSIBytes(d[HeadSize:])
// Get the metadata descriptor.
_, desc := pmt.HasDescriptor(psi.MetadataTag)