mirror of
https://github.com/aler9/gortsplib
synced 2025-10-31 10:36:26 +08:00
94 lines
2.2 KiB
Go
94 lines
2.2 KiB
Go
package rtpvp9
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import (
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"errors"
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"fmt"
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"time"
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"github.com/pion/rtp"
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"github.com/pion/rtp/codecs"
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"github.com/bluenviron/gortsplib/v3/pkg/rtptime"
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)
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// ErrMorePacketsNeeded is returned when more packets are needed.
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var ErrMorePacketsNeeded = errors.New("need more packets")
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// ErrNonStartingPacketAndNoPrevious is returned when we received a non-starting
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// packet of a fragmented frame and we didn't received anything before.
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// It's normal to receive this when decoding a stream that has been already
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// running for some time.
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var ErrNonStartingPacketAndNoPrevious = errors.New(
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"received a non-starting fragment without any previous starting fragment")
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func joinFragments(fragments [][]byte, size int) []byte {
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ret := make([]byte, size)
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n := 0
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for _, p := range fragments {
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n += copy(ret[n:], p)
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}
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return ret
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}
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// Decoder is a RTP/VP9 decoder.
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// Specification: https://datatracker.ietf.org/doc/html/draft-ietf-payload-vp9-16
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type Decoder struct {
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timeDecoder *rtptime.Decoder
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firstPacketReceived bool
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fragments [][]byte
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}
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// Init initializes the decoder.
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func (d *Decoder) Init() {
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d.timeDecoder = rtptime.NewDecoder(rtpClockRate)
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}
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// Decode decodes a VP9 frame from a RTP packet.
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func (d *Decoder) Decode(pkt *rtp.Packet) ([]byte, time.Duration, error) {
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var vpkt codecs.VP9Packet
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_, err := vpkt.Unmarshal(pkt.Payload)
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if err != nil {
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d.fragments = d.fragments[:0] // discard pending fragments
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return nil, 0, err
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}
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var frame []byte
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if vpkt.B {
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d.fragments = d.fragments[:0] // discard pending fragments
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d.firstPacketReceived = true
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if !vpkt.E {
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d.fragments = append(d.fragments, vpkt.Payload)
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return nil, 0, ErrMorePacketsNeeded
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}
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frame = vpkt.Payload
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} else {
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if len(d.fragments) == 0 {
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if !d.firstPacketReceived {
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return nil, 0, ErrNonStartingPacketAndNoPrevious
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}
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return nil, 0, fmt.Errorf("received a non-starting fragment")
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}
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d.fragments = append(d.fragments, vpkt.Payload)
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if !vpkt.E {
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return nil, 0, ErrMorePacketsNeeded
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}
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n := 0
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for _, frag := range d.fragments {
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n += len(frag)
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}
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frame = joinFragments(d.fragments, n)
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d.fragments = d.fragments[:0]
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}
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return frame, d.timeDecoder.Decode(pkt.Timestamp), nil
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}
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