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package h264parser
import (
"github.com/nareix/joy4/av"
"github.com/nareix/joy4/utils/bits"
"github.com/nareix/joy4/utils/bits/pio"
"fmt"
"bytes"
)
const (
NALU_SEI = 6
NALU_PPS = 7
NALU_SPS = 8
NALU_AUD = 9
)
func IsDataNALU(b []byte) bool {
typ := b[0] & 0x1f
return typ >= 1 && typ <= 5
}
/*
From: http://stackoverflow.com/questions/24884827/possible-locations-for-sequence-picture-parameter-sets-for-h-264-stream
First off, it's important to understand that there is no single standard H.264 elementary bitstream format. The specification document does contain an Annex, specifically Annex B, that describes one possible format, but it is not an actual requirement. The standard specifies how video is encoded into individual packets. How these packets are stored and transmitted is left open to the integrator.
1. Annex B
Network Abstraction Layer Units
The packets are called Network Abstraction Layer Units. Often abbreviated NALU (or sometimes just NAL) each packet can be individually parsed and processed. The first byte of each NALU contains the NALU type, specifically bits 3 through 7. (bit 0 is always off, and bits 1-2 indicate whether a NALU is referenced by another NALU).
There are 19 different NALU types defined separated into two categories, VCL and non-VCL:
VCL, or Video Coding Layer packets contain the actual visual information.
Non-VCLs contain metadata that may or may not be required to decode the video.
A single NALU, or even a VCL NALU is NOT the same thing as a frame. A frame can be ‘sliced’ into several NALUs. Just like you can slice a pizza. One or more slices are then virtually grouped into a Access Units (AU) that contain one frame. Slicing does come at a slight quality cost, so it is not often used.
Below is a table of all defined NALUs.
0 Unspecified non-VCL
1 Coded slice of a non-IDR picture VCL
2 Coded slice data partition A VCL
3 Coded slice data partition B VCL
4 Coded slice data partition C VCL
5 Coded slice of an IDR picture VCL
6 Supplemental enhancement information (SEI) non-VCL
7 Sequence parameter set non-VCL
8 Picture parameter set non-VCL
9 Access unit delimiter non-VCL
10 End of sequence non-VCL
11 End of stream non-VCL
12 Filler data non-VCL
13 Sequence parameter set extension non-VCL
14 Prefix NAL unit non-VCL
15 Subset sequence parameter set non-VCL
16 Depth parameter set non-VCL
17..18 Reserved non-VCL
19 Coded slice of an auxiliary coded picture without partitioning non-VCL
20 Coded slice extension non-VCL
21 Coded slice extension for depth view components non-VCL
22..23 Reserved non-VCL
24..31 Unspecified non-VCL
There are a couple of NALU types where having knowledge of may be helpful later.
Sequence Parameter Set (SPS). This non-VCL NALU contains information required to configure the decoder such as profile, level, resolution, frame rate.
Picture Parameter Set (PPS). Similar to the SPS, this non-VCL contains information on entropy coding mode, slice groups, motion prediction and deblocking filters.
Instantaneous Decoder Refresh (IDR). This VCL NALU is a self contained image slice. That is, an IDR can be decoded and displayed without referencing any other NALU save SPS and PPS.
Access Unit Delimiter (AUD). An AUD is an optional NALU that can be use to delimit frames in an elementary stream. It is not required (unless otherwise stated by the container/protocol, like TS), and is often not included in order to save space, but it can be useful to finds the start of a frame without having to fully parse each NALU.
NALU Start Codes
A NALU does not contain is its size. Therefore simply concatenating the NALUs to create a stream will not work because you will not know where one stops and the next begins.
The Annex B specification solves this by requiring ‘Start Codes’ to precede each NALU. A start code is 2 or 3 0x00 bytes followed with a 0x01 byte. e.g. 0x000001 or 0x00000001.
The 4 byte variation is useful for transmission over a serial connection as it is trivial to byte align the stream by looking for 31 zero bits followed by a one. If the next bit is 0 (because every NALU starts with a 0 bit), it is the start of a NALU. The 4 byte variation is usually only used for signaling random access points in the stream such as a SPS PPS AUD and IDR Where as the 3 byte variation is used everywhere else to save space.
Emulation Prevention Bytes
Start codes work because the four byte sequences 0x000000, 0x000001, 0x000002 and 0x000003 are illegal within a non-RBSP NALU. So when creating a NALU, care is taken to escape these values that could otherwise be confused with a start code. This is accomplished by inserting an ‘Emulation Prevention’ byte 0x03, so that 0x000001 becomes 0x00000301.
When decoding, it is important to look for and ignore emulation prevention bytes. Because emulation prevention bytes can occur almost anywhere within a NALU, it is often more convenient in documentation to assume they have already been removed. A representation without emulation prevention bytes is called Raw Byte Sequence Payload (RBSP).
Example
Let's look at a complete example.
0x0000 | 00 00 00 01 67 64 00 0A AC 72 84 44 26 84 00 00
0x0010 | 03 00 04 00 00 03 00 CA 3C 48 96 11 80 00 00 00
0x0020 | 01 68 E8 43 8F 13 21 30 00 00 01 65 88 81 00 05
0x0030 | 4E 7F 87 DF 61 A5 8B 95 EE A4 E9 38 B7 6A 30 6A
0x0040 | 71 B9 55 60 0B 76 2E B5 0E E4 80 59 27 B8 67 A9
0x0050 | 63 37 5E 82 20 55 FB E4 6A E9 37 35 72 E2 22 91
0x0060 | 9E 4D FF 60 86 CE 7E 42 B7 95 CE 2A E1 26 BE 87
0x0070 | 73 84 26 BA 16 36 F4 E6 9F 17 DA D8 64 75 54 B1
0x0080 | F3 45 0C 0B 3C 74 B3 9D BC EB 53 73 87 C3 0E 62
0x0090 | 47 48 62 CA 59 EB 86 3F 3A FA 86 B5 BF A8 6D 06
0x00A0 | 16 50 82 C4 CE 62 9E 4E E6 4C C7 30 3E DE A1 0B
0x00B0 | D8 83 0B B6 B8 28 BC A9 EB 77 43 FC 7A 17 94 85
0x00C0 | 21 CA 37 6B 30 95 B5 46 77 30 60 B7 12 D6 8C C5
0x00D0 | 54 85 29 D8 69 A9 6F 12 4E 71 DF E3 E2 B1 6B 6B
0x00E0 | BF 9F FB 2E 57 30 A9 69 76 C4 46 A2 DF FA 91 D9
0x00F0 | 50 74 55 1D 49 04 5A 1C D6 86 68 7C B6 61 48 6C
0x0100 | 96 E6 12 4C 27 AD BA C7 51 99 8E D0 F0 ED 8E F6
0x0110 | 65 79 79 A6 12 A1 95 DB C8 AE E3 B6 35 E6 8D BC
0x0120 | 48 A3 7F AF 4A 28 8A 53 E2 7E 68 08 9F 67 77 98
0x0130 | 52 DB 50 84 D6 5E 25 E1 4A 99 58 34 C7 11 D6 43
0x0140 | FF C4 FD 9A 44 16 D1 B2 FB 02 DB A1 89 69 34 C2
0x0150 | 32 55 98 F9 9B B2 31 3F 49 59 0C 06 8C DB A5 B2
0x0160 | 9D 7E 12 2F D0 87 94 44 E4 0A 76 EF 99 2D 91 18
0x0170 | 39 50 3B 29 3B F5 2C 97 73 48 91 83 B0 A6 F3 4B
0x0180 | 70 2F 1C 8F 3B 78 23 C6 AA 86 46 43 1D D7 2A 23
0x0190 | 5E 2C D9 48 0A F5 F5 2C D1 FB 3F F0 4B 78 37 E9
0x01A0 | 45 DD 72 CF 80 35 C3 95 07 F3 D9 06 E5 4A 58 76
0x01B0 | 03 6C 81 20 62 45 65 44 73 BC FE C1 9F 31 E5 DB
0x01C0 | 89 5C 6B 79 D8 68 90 D7 26 A8 A1 88 86 81 DC 9A
0x01D0 | 4F 40 A5 23 C7 DE BE 6F 76 AB 79 16 51 21 67 83
0x01E0 | 2E F3 D6 27 1A 42 C2 94 D1 5D 6C DB 4A 7A E2 CB
0x01F0 | 0B B0 68 0B BE 19 59 00 50 FC C0 BD 9D F5 F5 F8
0x0200 | A8 17 19 D6 B3 E9 74 BA 50 E5 2C 45 7B F9 93 EA
0x0210 | 5A F9 A9 30 B1 6F 5B 36 24 1E 8D 55 57 F4 CC 67
0x0220 | B2 65 6A A9 36 26 D0 06 B8 E2 E3 73 8B D1 C0 1C
0x0230 | 52 15 CA B5 AC 60 3E 36 42 F1 2C BD 99 77 AB A8
0x0240 | A9 A4 8E 9C 8B 84 DE 73 F0 91 29 97 AE DB AF D6
0x0250 | F8 5E 9B 86 B3 B3 03 B3 AC 75 6F A6 11 69 2F 3D
0x0260 | 3A CE FA 53 86 60 95 6C BB C5 4E F3
This is a complete AU containing 3 NALUs. As you can see, we begin with a Start code followed by an SPS (SPS starts with 67). Within the SPS, you will see two Emulation Prevention bytes. Without these bytes the illegal sequence 0x000000 would occur at these positions. Next you will see a start code followed by a PPS (PPS starts with 68) and one final start code followed by an IDR slice. This is a complete H.264 stream. If you type these values into a hex editor and save the file with a .264 extension, you will be able to convert it to this image:
Lena
Annex B is commonly used in live and streaming formats such as transport streams, over the air broadcasts, and DVDs. In these formats it is common to repeat the SPS and PPS periodically, usually preceding every IDR thus creating a random access point for the decoder. This enables the ability to join a stream already in progress.
2. AVCC
The other common method of storing an H.264 stream is the AVCC format. In this format, each NALU is preceded with its length (in big endian format). This method is easier to parse, but you lose the byte alignment features of Annex B. Just to complicate things, the length may be encoded using 1, 2 or 4 bytes. This value is stored in a header object. This header is often called ‘extradata’ or ‘sequence header’. Its basic format is as follows:
bits
8 version ( always 0x01 )
8 avc profile ( sps[0][1] )
8 avc compatibility ( sps[0][2] )
8 avc level ( sps[0][3] )
6 reserved ( all bits on )
2 NALULengthSizeMinusOne
3 reserved ( all bits on )
5 number of SPS NALUs (usually 1)
repeated once per SPS:
16 SPS size
variable SPS NALU data
8 number of PPS NALUs (usually 1)
repeated once per PPS
16 PPS size
variable PPS NALU data
Using the same example above, the AVCC extradata will look like this:
0x0000 | 01 64 00 0A FF E1 00 19 67 64 00 0A AC 72 84 44
0x0010 | 26 84 00 00 03 00 04 00 00 03 00 CA 3C 48 96 11
0x0020 | 80 01 00 07 68 E8 43 8F 13 21 30
You will notice SPS and PPS is now stored out of band. That is, separate from the elementary stream data. Storage and transmission of this data is the job of the file container, and beyond the scope of this document. Notice that even though we are not using start codes, emulation prevention bytes are still inserted.
Additionally, there is a new variable called NALULengthSizeMinusOne. This confusingly named variable tells us how many bytes to use to store the length of each NALU. So, if NALULengthSizeMinusOne is set to 0, then each NALU is preceded with a single byte indicating its length. Using a single byte to store the size, the max size of a NALU is 255 bytes. That is obviously pretty small. Way too small for an entire key frame. Using 2 bytes gives us 64k per NALU. It would work in our example, but is still a pretty low limit. 3 bytes would be perfect, but for some reason is not universally supported. Therefore, 4 bytes is by far the most common, and it is what we used here:
0x0000 | 00 00 02 41 65 88 81 00 05 4E 7F 87 DF 61 A5 8B
0x0010 | 95 EE A4 E9 38 B7 6A 30 6A 71 B9 55 60 0B 76 2E
0x0020 | B5 0E E4 80 59 27 B8 67 A9 63 37 5E 82 20 55 FB
0x0030 | E4 6A E9 37 35 72 E2 22 91 9E 4D FF 60 86 CE 7E
0x0040 | 42 B7 95 CE 2A E1 26 BE 87 73 84 26 BA 16 36 F4
0x0050 | E6 9F 17 DA D8 64 75 54 B1 F3 45 0C 0B 3C 74 B3
0x0060 | 9D BC EB 53 73 87 C3 0E 62 47 48 62 CA 59 EB 86
0x0070 | 3F 3A FA 86 B5 BF A8 6D 06 16 50 82 C4 CE 62 9E
0x0080 | 4E E6 4C C7 30 3E DE A1 0B D8 83 0B B6 B8 28 BC
0x0090 | A9 EB 77 43 FC 7A 17 94 85 21 CA 37 6B 30 95 B5
0x00A0 | 46 77 30 60 B7 12 D6 8C C5 54 85 29 D8 69 A9 6F
0x00B0 | 12 4E 71 DF E3 E2 B1 6B 6B BF 9F FB 2E 57 30 A9
0x00C0 | 69 76 C4 46 A2 DF FA 91 D9 50 74 55 1D 49 04 5A
0x00D0 | 1C D6 86 68 7C B6 61 48 6C 96 E6 12 4C 27 AD BA
0x00E0 | C7 51 99 8E D0 F0 ED 8E F6 65 79 79 A6 12 A1 95
0x00F0 | DB C8 AE E3 B6 35 E6 8D BC 48 A3 7F AF 4A 28 8A
0x0100 | 53 E2 7E 68 08 9F 67 77 98 52 DB 50 84 D6 5E 25
0x0110 | E1 4A 99 58 34 C7 11 D6 43 FF C4 FD 9A 44 16 D1
0x0120 | B2 FB 02 DB A1 89 69 34 C2 32 55 98 F9 9B B2 31
0x0130 | 3F 49 59 0C 06 8C DB A5 B2 9D 7E 12 2F D0 87 94
0x0140 | 44 E4 0A 76 EF 99 2D 91 18 39 50 3B 29 3B F5 2C
0x0150 | 97 73 48 91 83 B0 A6 F3 4B 70 2F 1C 8F 3B 78 23
0x0160 | C6 AA 86 46 43 1D D7 2A 23 5E 2C D9 48 0A F5 F5
0x0170 | 2C D1 FB 3F F0 4B 78 37 E9 45 DD 72 CF 80 35 C3
0x0180 | 95 07 F3 D9 06 E5 4A 58 76 03 6C 81 20 62 45 65
0x0190 | 44 73 BC FE C1 9F 31 E5 DB 89 5C 6B 79 D8 68 90
0x01A0 | D7 26 A8 A1 88 86 81 DC 9A 4F 40 A5 23 C7 DE BE
0x01B0 | 6F 76 AB 79 16 51 21 67 83 2E F3 D6 27 1A 42 C2
0x01C0 | 94 D1 5D 6C DB 4A 7A E2 CB 0B B0 68 0B BE 19 59
0x01D0 | 00 50 FC C0 BD 9D F5 F5 F8 A8 17 19 D6 B3 E9 74
0x01E0 | BA 50 E5 2C 45 7B F9 93 EA 5A F9 A9 30 B1 6F 5B
0x01F0 | 36 24 1E 8D 55 57 F4 CC 67 B2 65 6A A9 36 26 D0
0x0200 | 06 B8 E2 E3 73 8B D1 C0 1C 52 15 CA B5 AC 60 3E
0x0210 | 36 42 F1 2C BD 99 77 AB A8 A9 A4 8E 9C 8B 84 DE
0x0220 | 73 F0 91 29 97 AE DB AF D6 F8 5E 9B 86 B3 B3 03
0x0230 | B3 AC 75 6F A6 11 69 2F 3D 3A CE FA 53 86 60 95
0x0240 | 6C BB C5 4E F3
An advantage to this format is the ability to configure the decoder at the start and jump into the middle of a stream. This is a common use case where the media is available on a random access medium such as a hard drive, and is therefore used in common container formats such as MP4 and MKV.
*/
var StartCodeBytes = []byte{0,0,1}
var AUDBytes = []byte{0,0,0,1,0x9,0xf0,0,0,0,1} // AUD
func CheckNALUsType(b []byte) (typ int) {
_, typ = SplitNALUs(b)
return
}
const (
NALU_RAW = iota
NALU_AVCC
NALU_ANNEXB
)
func SplitNALUs(b []byte) (nalus [][]byte, typ int) {
if len(b) < 4 {
return [][]byte{b}, NALU_RAW
}
val3 := pio.U24BE(b)
val4 := pio.U32BE(b)
// maybe AVCC
if val4 <= uint32(len(b)) {
_val4 := val4
_b := b[4:]
nalus := [][]byte{}
for {
nalus = append(nalus, _b[:_val4])
_b = _b[_val4:]
if len(_b) < 4 {
break
}
_val4 = pio.U32BE(_b)
_b = _b[4:]
if _val4 > uint32(len(_b)) {
break
}
}
if len(_b) == 0 {
return nalus, NALU_AVCC
}
}
// is Annex B
if val3 == 1 || val4 == 1 {
_val3 := val3
_val4 := val4
start := 0
pos := 0
for {
if start != pos {
nalus = append(nalus, b[start:pos])
}
if _val3 == 1 {
pos += 3
} else if _val4 == 1 {
pos += 4
}
start = pos
if start == len(b) {
break
}
_val3 = 0
_val4 = 0
for pos < len(b) {
if pos+2 < len(b) && b[pos] == 0 {
_val3 = pio.U24BE(b[pos:])
if _val3 == 0 {
if pos+3 < len(b) {
_val4 = uint32(b[pos+3])
if _val4 == 1 {
break
}
}
} else if _val3 == 1 {
break
}
pos++
} else {
pos++
}
}
}
typ = NALU_ANNEXB
return
}
return [][]byte{b}, NALU_RAW
}
type SPSInfo struct {
ProfileIdc uint
LevelIdc uint
MbWidth uint
MbHeight uint
CropLeft uint
CropRight uint
CropTop uint
CropBottom uint
Width uint
Height uint
}
func ParseSPS(data []byte) (self SPSInfo, err error) {
r := &bits.GolombBitReader{R: bytes.NewReader(data)}
if _, err = r.ReadBits(8); err != nil {
return
}
if self.ProfileIdc, err = r.ReadBits(8); err != nil {
return
}
// constraint_set0_flag-constraint_set6_flag,reserved_zero_2bits
if _, err = r.ReadBits(8); err != nil {
return
}
// level_idc
if self.LevelIdc, err = r.ReadBits(8); err != nil {
return
}
// seq_parameter_set_id
if _, err = r.ReadExponentialGolombCode(); err != nil {
return
}
if self.ProfileIdc == 100 || self.ProfileIdc == 110 ||
self.ProfileIdc == 122 || self.ProfileIdc == 244 ||
self.ProfileIdc == 44 || self.ProfileIdc == 83 ||
self.ProfileIdc == 86 || self.ProfileIdc == 118 {
var chroma_format_idc uint
if chroma_format_idc, err = r.ReadExponentialGolombCode(); err != nil {
return
}
if chroma_format_idc == 3 {
// residual_colour_transform_flag
if _, err = r.ReadBit(); err != nil {
return
}
}
// bit_depth_luma_minus8
if _, err = r.ReadExponentialGolombCode(); err != nil {
return
}
// bit_depth_chroma_minus8
if _, err = r.ReadExponentialGolombCode(); err != nil {
return
}
// qpprime_y_zero_transform_bypass_flag
if _, err = r.ReadBit(); err != nil {
return
}
var seq_scaling_matrix_present_flag uint
if seq_scaling_matrix_present_flag, err = r.ReadBit(); err != nil {
return
}
if seq_scaling_matrix_present_flag != 0 {
for i := 0; i < 8; i++ {
var seq_scaling_list_present_flag uint
if seq_scaling_list_present_flag, err = r.ReadBit(); err != nil {
return
}
if seq_scaling_list_present_flag != 0 {
var sizeOfScalingList uint
if i < 6 {
sizeOfScalingList = 16
} else {
sizeOfScalingList = 64
}
lastScale := uint(8)
nextScale := uint(8)
for j := uint(0); j < sizeOfScalingList; j++ {
if nextScale != 0 {
var delta_scale uint
if delta_scale, err = r.ReadSE(); err != nil {
return
}
nextScale = (lastScale + delta_scale + 256) % 256
}
if nextScale != 0 {
lastScale = nextScale
}
}
}
}
}
}
// log2_max_frame_num_minus4
if _, err = r.ReadExponentialGolombCode(); err != nil {
return
}
var pic_order_cnt_type uint
if pic_order_cnt_type, err = r.ReadExponentialGolombCode(); err != nil {
return
}
if pic_order_cnt_type == 0 {
// log2_max_pic_order_cnt_lsb_minus4
if _, err = r.ReadExponentialGolombCode(); err != nil {
return
}
} else if pic_order_cnt_type == 1 {
// delta_pic_order_always_zero_flag
if _, err = r.ReadBit(); err != nil {
return
}
// offset_for_non_ref_pic
if _, err = r.ReadSE(); err != nil {
return
}
// offset_for_top_to_bottom_field
if _, err = r.ReadSE(); err != nil {
return
}
var num_ref_frames_in_pic_order_cnt_cycle uint
if num_ref_frames_in_pic_order_cnt_cycle, err = r.ReadExponentialGolombCode(); err != nil {
return
}
for i := uint(0); i < num_ref_frames_in_pic_order_cnt_cycle; i++ {
if _, err = r.ReadSE(); err != nil {
return
}
}
}
// max_num_ref_frames
if _, err = r.ReadExponentialGolombCode(); err != nil {
return
}
// gaps_in_frame_num_value_allowed_flag
if _, err = r.ReadBit(); err != nil {
return
}
if self.MbWidth, err = r.ReadExponentialGolombCode(); err != nil {
return
}
self.MbWidth++
if self.MbHeight, err = r.ReadExponentialGolombCode(); err != nil {
return
}
self.MbHeight++
var frame_mbs_only_flag uint
if frame_mbs_only_flag, err = r.ReadBit(); err != nil {
return
}
if frame_mbs_only_flag == 0 {
// mb_adaptive_frame_field_flag
if _, err = r.ReadBit(); err != nil {
return
}
}
// direct_8x8_inference_flag
if _, err = r.ReadBit(); err != nil {
return
}
var frame_cropping_flag uint
if frame_cropping_flag, err = r.ReadBit(); err != nil {
return
}
if frame_cropping_flag != 0 {
if self.CropLeft, err = r.ReadExponentialGolombCode(); err != nil {
return
}
if self.CropRight, err = r.ReadExponentialGolombCode(); err != nil {
return
}
if self.CropTop, err = r.ReadExponentialGolombCode(); err != nil {
return
}
if self.CropBottom, err = r.ReadExponentialGolombCode(); err != nil {
return
}
}
self.Width = (self.MbWidth * 16) - self.CropLeft*2 - self.CropRight*2
self.Height = ((2 - frame_mbs_only_flag) * self.MbHeight * 16) - self.CropTop*2 - self.CropBottom*2
return
}
type CodecData struct {
Record []byte
RecordInfo AVCDecoderConfRecord
SPSInfo SPSInfo
}
func (self CodecData) Type() av.CodecType {
return av.H264
}
func (self CodecData) AVCDecoderConfRecordBytes() []byte {
return self.Record
}
func (self CodecData) SPS() []byte {
return self.RecordInfo.SPS[0]
}
func (self CodecData) PPS() []byte {
return self.RecordInfo.PPS[0]
}
func (self CodecData) Width() int {
return int(self.SPSInfo.Width)
}
func (self CodecData) Height() int {
return int(self.SPSInfo.Height)
}
func NewCodecDataFromAVCDecoderConfRecord(record []byte) (self CodecData, err error) {
self.Record = record
if _, err = (&self.RecordInfo).Unmarshal(record); err != nil {
return
}
if len(self.RecordInfo.SPS) == 0 {
err = fmt.Errorf("h264parser: no SPS found in AVCDecoderConfRecord")
return
}
if len(self.RecordInfo.PPS) == 0 {
err = fmt.Errorf("h264parser: no PPS found in AVCDecoderConfRecord")
return
}
if self.SPSInfo, err = ParseSPS(self.RecordInfo.SPS[0]); err != nil {
err = fmt.Errorf("h264parser: parse SPS failed(%s)", err)
return
}
return
}
func NewCodecDataFromSPSAndPPS(sps, pps []byte) (self CodecData, err error) {
recordinfo := AVCDecoderConfRecord{}
recordinfo.AVCProfileIndication = sps[1]
recordinfo.ProfileCompatibility = sps[2]
recordinfo.AVCLevelIndication = sps[3]
recordinfo.SPS = [][]byte{sps}
recordinfo.PPS = [][]byte{pps}
recordinfo.LengthSizeMinusOne = 3
buf := make([]byte, recordinfo.Len())
recordinfo.Marshal(buf)
self.RecordInfo = recordinfo
self.Record = buf
if self.SPSInfo, err = ParseSPS(sps); err != nil {
return
}
return
}
type AVCDecoderConfRecord struct {
AVCProfileIndication uint8
ProfileCompatibility uint8
AVCLevelIndication uint8
LengthSizeMinusOne uint8
SPS [][]byte
PPS [][]byte
}
var ErrDecconfInvalid = fmt.Errorf("h264parser: AVCDecoderConfRecord invalid")
func (self *AVCDecoderConfRecord) Unmarshal(b []byte) (n int, err error) {
if len(b) < 7 {
err = ErrDecconfInvalid
return
}
self.AVCProfileIndication = b[1]
self.ProfileCompatibility = b[2]
self.AVCLevelIndication = b[3]
self.LengthSizeMinusOne = b[4]&0x03
spscount := int(b[5]&0x1f)
n += 6
for i := 0; i < spscount; i++ {
if len(b) < n+2 {
err = ErrDecconfInvalid
return
}
spslen := int(pio.U16BE(b[n:]))
n += 2
if len(b) < n+spslen {
err = ErrDecconfInvalid
return
}
self.SPS = append(self.SPS, b[n:n+spslen])
n += spslen
}
if len(b) < n+1 {
err = ErrDecconfInvalid
return
}
ppscount := int(b[n])
n++
for i := 0; i < ppscount; i++ {
if len(b) < n+2 {
err = ErrDecconfInvalid
return
}
ppslen := int(pio.U16BE(b[n:]))
n += 2
if len(b) < n+ppslen {
err = ErrDecconfInvalid
return
}
self.PPS = append(self.PPS, b[n:n+ppslen])
n += ppslen
}
return
}
func (self AVCDecoderConfRecord) Len() (n int) {
n = 7
for _, sps := range self.SPS {
n += 2+len(sps)
}
for _, pps := range self.PPS {
n += 2+len(pps)
}
return
}
func (self AVCDecoderConfRecord) Marshal(b []byte) (n int) {
b[0] = 1
b[1] = self.AVCProfileIndication
b[2] = self.ProfileCompatibility
b[3] = self.AVCLevelIndication
b[4] = self.LengthSizeMinusOne|0xfc
b[5] = uint8(len(self.SPS))|0xe0
n += 6
for _, sps := range self.SPS {
pio.PutU16BE(b[n:], uint16(len(sps)))
n += 2
copy(b[n:], sps)
n += len(sps)
}
b[n] = uint8(len(self.PPS))
n++
for _, pps := range self.PPS {
pio.PutU16BE(b[n:], uint16(len(pps)))
n += 2
copy(b[n:], pps)
n += len(pps)
}
return
}
type SliceType uint
func (self SliceType) String() string {
switch self {
case SLICE_P:
return "P"
case SLICE_B:
return "B"
case SLICE_I:
return "I"
}
return ""
}
const (
SLICE_P = iota+1
SLICE_B
SLICE_I
)
func ParseSliceHeaderFromNALU(packet []byte) (sliceType SliceType, err error) {
if len(packet) <= 1 {
err = fmt.Errorf("h264parser: packet too short to parse slice header")
return
}
nal_unit_type := packet[0]&0x1f
switch nal_unit_type {
case 1,2,5,19:
// slice_layer_without_partitioning_rbsp
// slice_data_partition_a_layer_rbsp
default:
err = fmt.Errorf("h264parser: nal_unit_type=%d has no slice header", nal_unit_type)
return
}
r := &bits.GolombBitReader{R: bytes.NewReader(packet[1:])}
// first_mb_in_slice
if _, err = r.ReadExponentialGolombCode(); err != nil {
return
}
// slice_type
var u uint
if u, err = r.ReadExponentialGolombCode(); err != nil {
return
}
switch u {
case 0,3,5,8:
sliceType = SLICE_P
case 1,6:
sliceType = SLICE_B
case 2,4,7,9:
sliceType = SLICE_I
default:
err = fmt.Errorf("h264parser: slice_type=%d invalid", u)
return
}
return
}
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