/
h264_packet.go
297 lines (242 loc) · 7.42 KB
/
h264_packet.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package codecs
import (
"bytes"
"encoding/binary"
"fmt"
)
// H264Payloader payloads H264 packets
type H264Payloader struct {
spsNalu, ppsNalu []byte
}
const (
stapaNALUType = 24
fuaNALUType = 28
fubNALUType = 29
spsNALUType = 7
ppsNALUType = 8
audNALUType = 9
fillerNALUType = 12
fuaHeaderSize = 2
stapaHeaderSize = 1
stapaNALULengthSize = 2
naluTypeBitmask = 0x1F
naluRefIdcBitmask = 0x60
fuStartBitmask = 0x80
fuEndBitmask = 0x40
outputStapAHeader = 0x78
)
// nolint:gochecknoglobals
var (
naluStartCode = []byte{0x00, 0x00, 0x01}
annexbNALUStartCode = []byte{0x00, 0x00, 0x00, 0x01}
)
func emitNalus(nals []byte, emit func([]byte)) {
start := 0
length := len(nals)
for start < length {
end := bytes.Index(nals[start:], annexbNALUStartCode)
offset := 4
if end == -1 {
end = bytes.Index(nals[start:], naluStartCode)
offset = 3
}
if end == -1 {
emit(nals[start:])
break
}
emit(nals[start : start+end])
// next NAL start position
start += end + offset
}
}
// Payload fragments a H264 packet across one or more byte arrays
func (p *H264Payloader) Payload(mtu uint16, payload []byte) [][]byte {
var payloads [][]byte
if len(payload) == 0 {
return payloads
}
emitNalus(payload, func(nalu []byte) {
if len(nalu) == 0 {
return
}
naluType := nalu[0] & naluTypeBitmask
naluRefIdc := nalu[0] & naluRefIdcBitmask
switch {
case naluType == audNALUType || naluType == fillerNALUType:
return
case naluType == spsNALUType:
p.spsNalu = nalu
return
case naluType == ppsNALUType:
p.ppsNalu = nalu
return
case p.spsNalu != nil && p.ppsNalu != nil:
// Pack current NALU with SPS and PPS as STAP-A
spsLen := make([]byte, 2)
binary.BigEndian.PutUint16(spsLen, uint16(len(p.spsNalu)))
ppsLen := make([]byte, 2)
binary.BigEndian.PutUint16(ppsLen, uint16(len(p.ppsNalu)))
stapANalu := []byte{outputStapAHeader}
stapANalu = append(stapANalu, spsLen...)
stapANalu = append(stapANalu, p.spsNalu...)
stapANalu = append(stapANalu, ppsLen...)
stapANalu = append(stapANalu, p.ppsNalu...)
if len(stapANalu) <= int(mtu) {
out := make([]byte, len(stapANalu))
copy(out, stapANalu)
payloads = append(payloads, out)
}
p.spsNalu = nil
p.ppsNalu = nil
}
// Single NALU
if len(nalu) <= int(mtu) {
out := make([]byte, len(nalu))
copy(out, nalu)
payloads = append(payloads, out)
return
}
// FU-A
maxFragmentSize := int(mtu) - fuaHeaderSize
// The FU payload consists of fragments of the payload of the fragmented
// NAL unit so that if the fragmentation unit payloads of consecutive
// FUs are sequentially concatenated, the payload of the fragmented NAL
// unit can be reconstructed. The NAL unit type octet of the fragmented
// NAL unit is not included as such in the fragmentation unit payload,
// but rather the information of the NAL unit type octet of the
// fragmented NAL unit is conveyed in the F and NRI fields of the FU
// indicator octet of the fragmentation unit and in the type field of
// the FU header. An FU payload MAY have any number of octets and MAY
// be empty.
// According to the RFC, the first octet is skipped due to redundant information
naluIndex := 1
naluLength := len(nalu) - naluIndex
naluRemaining := naluLength
if min(maxFragmentSize, naluRemaining) <= 0 {
return
}
for naluRemaining > 0 {
currentFragmentSize := min(maxFragmentSize, naluRemaining)
out := make([]byte, fuaHeaderSize+currentFragmentSize)
// +---------------+
// |0|1|2|3|4|5|6|7|
// +-+-+-+-+-+-+-+-+
// |F|NRI| Type |
// +---------------+
out[0] = fuaNALUType
out[0] |= naluRefIdc
// +---------------+
// |0|1|2|3|4|5|6|7|
// +-+-+-+-+-+-+-+-+
// |S|E|R| Type |
// +---------------+
out[1] = naluType
if naluRemaining == naluLength {
// Set start bit
out[1] |= 1 << 7
} else if naluRemaining-currentFragmentSize == 0 {
// Set end bit
out[1] |= 1 << 6
}
copy(out[fuaHeaderSize:], nalu[naluIndex:naluIndex+currentFragmentSize])
payloads = append(payloads, out)
naluRemaining -= currentFragmentSize
naluIndex += currentFragmentSize
}
})
return payloads
}
// H264Packet represents the H264 header that is stored in the payload of an RTP Packet
type H264Packet struct {
IsAVC bool
fuaBuffer []byte
videoDepacketizer
}
func (p *H264Packet) doPackaging(buf, nalu []byte) []byte {
if p.IsAVC {
buf = binary.BigEndian.AppendUint32(buf, uint32(len(nalu)))
buf = append(buf, nalu...)
return buf
}
buf = append(buf, annexbNALUStartCode...)
buf = append(buf, nalu...)
return buf
}
// IsDetectedFinalPacketInSequence returns true of the packet passed in has the
// marker bit set indicated the end of a packet sequence
func (p *H264Packet) IsDetectedFinalPacketInSequence(rtpPacketMarketBit bool) bool {
return rtpPacketMarketBit
}
// Unmarshal parses the passed byte slice and stores the result in the H264Packet this method is called upon
func (p *H264Packet) Unmarshal(payload []byte) ([]byte, error) {
if p.zeroAllocation {
return payload, nil
}
return p.parseBody(payload)
}
func (p *H264Packet) parseBody(payload []byte) ([]byte, error) {
if len(payload) == 0 {
return nil, fmt.Errorf("%w: %d <=0", errShortPacket, len(payload))
}
// NALU Types
// https://tools.ietf.org/html/rfc6184#section-5.4
naluType := payload[0] & naluTypeBitmask
switch {
case naluType > 0 && naluType < 24:
return p.doPackaging(nil, payload), nil
case naluType == stapaNALUType:
currOffset := int(stapaHeaderSize)
result := []byte{}
for currOffset < len(payload) {
naluSize := int(binary.BigEndian.Uint16(payload[currOffset:]))
currOffset += stapaNALULengthSize
if len(payload) < currOffset+naluSize {
return nil, fmt.Errorf("%w STAP-A declared size(%d) is larger than buffer(%d)", errShortPacket, naluSize, len(payload)-currOffset)
}
result = p.doPackaging(result, payload[currOffset:currOffset+naluSize])
currOffset += naluSize
}
return result, nil
case naluType == fuaNALUType:
if len(payload) < fuaHeaderSize {
return nil, errShortPacket
}
if p.fuaBuffer == nil {
p.fuaBuffer = []byte{}
}
p.fuaBuffer = append(p.fuaBuffer, payload[fuaHeaderSize:]...)
if payload[1]&fuEndBitmask != 0 {
naluRefIdc := payload[0] & naluRefIdcBitmask
fragmentedNaluType := payload[1] & naluTypeBitmask
nalu := append([]byte{}, naluRefIdc|fragmentedNaluType)
nalu = append(nalu, p.fuaBuffer...)
p.fuaBuffer = nil
return p.doPackaging(nil, nalu), nil
}
return []byte{}, nil
}
return nil, fmt.Errorf("%w: %d", errUnhandledNALUType, naluType)
}
// H264PartitionHeadChecker checks H264 partition head.
//
// Deprecated: replaced by H264Packet.IsPartitionHead()
type H264PartitionHeadChecker struct{}
// IsPartitionHead checks if this is the head of a packetized nalu stream.
//
// Deprecated: replaced by H264Packet.IsPartitionHead()
func (*H264PartitionHeadChecker) IsPartitionHead(packet []byte) bool {
return (&H264Packet{}).IsPartitionHead(packet)
}
// IsPartitionHead checks if this is the head of a packetized nalu stream.
func (*H264Packet) IsPartitionHead(payload []byte) bool {
if len(payload) < 2 {
return false
}
if payload[0]&naluTypeBitmask == fuaNALUType ||
payload[0]&naluTypeBitmask == fubNALUType {
return payload[1]&fuStartBitmask != 0
}
return true
}