H264码流NALU解析

包

package h264
 
import (
    ;sync;
 
    log ;github.com/sirupsen/logrus;
)
 
const (
    DEFAULT_CAP int = 1024 * 1024 * 4
 
    // NALU类型
    NALU_TYPE_SLICE    = 1
    NALU_TYPE_DPA      = 2
    NALU_TYPE_DPB      = 3
    NALU_TYPE_DPC      = 4
    NALU_TYPE_IDR      = 5
    NALU_TYPE_SEI      = 6
    NALU_TYPE_SPS      = 7
    NALU_TYPE_PPS      = 8
    NALU_TYPE_AUD      = 9
    NALU_TYPE_EOSEQ    = 10
    NALU_TYPE_EOSTREAM = 11
    NALU_TYPE_FILL     = 12
 
    // 优先级
    NALU_PRIORITY_DISPOSABLE = 0
    NALU_PRIRITY_LOW         = 1
    NALU_PRIORITY_HIGH       = 2
    NALU_PRIORITY_HIGHEST    = 3
)
 
type NaluHead struct {
    StartCodeLen int
    Forbidden    int
    Reference    int
    UnitType     int
}
 
type H264Buffer struct {
    mutex       sync.Mutex
    data        []byte
    dataMaxSize int
    rPtr        int
    naluHeads   []*NaluHead // NALU块信息
    iFrameIndex []int       // I帧索引列表
}
 
func NewH264Buffer(cap int) *H264Buffer {
    return &H264Buffer{
        data:        make([]byte, 0, cap),
        dataMaxSize: cap,
        rPtr:        0,
        naluHeads:   make([]*NaluHead, 0),
        iFrameIndex: make([]int, 0),
    }
}
 
func (buf *H264Buffer) Push(d []byte) {
    buf.mutex.Lock()
    defer buf.mutex.Unlock()
    log.Info(;H264Buffer push data;)
    if len(d) > buf.dataMaxSize {
        return
    }
    // 计算超出的字节数
    over := len(buf.data) ; len(d) - buf.dataMaxSize
    if over > 0 {
        // 左移超出的字节数
        buf.data = buf.data[over:]
        buf.rPtr = buf.rPtr - over
    }
    buf.data = append(buf.data, d...)
    // 更新nalu信息
    buf.updateNALU()
    log.Info(;I frame indexs: ;, buf.iFrameIndex)
}
 
func (buf *H264Buffer) getNALUHead(headIdx int) *NaluHead {
    return &NaluHead{
        Forbidden: int(buf.data[headIdx] >> 7),
        Reference: int((buf.data[headIdx] << 1) >> 6),
        UnitType:  int((buf.data[headIdx] << 3) >> 3),
    }
}
 
func (buf *H264Buffer) updateNALU() {
    buf.naluHeads = make([]*NaluHead, 0)
    buf.iFrameIndex = make([]int, 0)
    for i := 0; i < len(buf.data)-5; i;; {
        if buf.data[i] == 0 && buf.data[i;1] == 0 {
            if buf.data[i;2] == 1 {
                head := buf.getNALUHead(i ; 3)
                head.StartCodeLen = 3
                // 起始码长度为3的情况
                buf.naluHeads = append(buf.naluHeads, head)
                if head.UnitType == NALU_TYPE_IDR {
                    buf.iFrameIndex = append(buf.iFrameIndex, i)
                }
            }
            if buf.data[i;2] == 0 && buf.data[i;3] == 1 {
                head := buf.getNALUHead(i ; 4)
                head.StartCodeLen = 4
                // 起始码长度为4的情况
                buf.naluHeads = append(buf.naluHeads, head)
                if head.UnitType == NALU_TYPE_IDR {
                    buf.iFrameIndex = append(buf.iFrameIndex, i)
                }
            }
        }
    }
}
 
func (buf *H264Buffer) NaluInfo() {
    buf.mutex.Lock()
    defer buf.mutex.Unlock()
    log.Info(;|Index	|	Forbidden	|	Reference	|	UnitType|;)
    for i, v := range buf.naluHeads {
        reference := ;UNKNOW;
        switch v.Reference {
        case NALU_PRIORITY_DISPOSABLE:
            reference = ;DISPOSABLE;
        case NALU_PRIRITY_LOW:
            reference = ;LOW;
        case NALU_PRIORITY_HIGH:
            reference = ;HIGH;
        case NALU_PRIORITY_HIGHEST:
            reference = ;HIGHEST;
        }
        naluType := ;UNKNOW;
        switch v.UnitType {
        case NALU_TYPE_SLICE:
            naluType = ;SLICE;
        case NALU_TYPE_DPA:
            naluType = ;DPA;
        case NALU_TYPE_DPB:
            naluType = ;DPB;
        case NALU_TYPE_DPC:
            naluType = ;DPC;
        case NALU_TYPE_IDR:
            naluType = ;IDR;
        case NALU_TYPE_SEI:
            naluType = ;SEI;
        case NALU_TYPE_SPS:
            naluType = ;SPS;
        case NALU_TYPE_PPS:
            naluType = ;PPS;
        case NALU_TYPE_AUD:
            naluType = ;AUD;
        case NALU_TYPE_EOSEQ:
            naluType = ;EOSEQ;
        case NALU_TYPE_EOSTREAM:
            naluType = ;EOSTREAM;
        case NALU_TYPE_FILL:
            naluType = ;FILL;
        }
        log.Info(;|Index: ;, i, ;		| StartCodeLen: ;, v.StartCodeLen, ;	| Forbidden: ;, v.Forbidden,
            ;	| Reference: ;, reference, ;	| UnitType: ;, naluType)
    }
}
 
func (buf *H264Buffer) Pop() []byte {
    buf.mutex.Lock()
    defer buf.mutex.Unlock()
    d := buf.data[buf.rPtr:]
    buf.rPtr = len(buf.data) - 1
    return d
}
 
func (buf *H264Buffer) PopLastGOP() []byte {
    buf.mutex.Lock()
    defer buf.mutex.Unlock()
    if len(buf.iFrameIndex) == 0 {
        log.Info(;no I Frame;)
        return make([]byte, 0)
    }
    idx := buf.iFrameIndex[len(buf.iFrameIndex)-1]
    d := buf.data[idx:]
    log.Info(;GOP size: ;, len(d))
    return d
}

func main() {
    d, err := ioutil.ReadFile(;sintel.h264;)
    if err != nil {
        log.Fatal(err)
    }
    buffer := h264.NewH264Buffer(h264.DEFAULT_CAP)
    buffer.Push(d)
    buffer.NaluInfo()
}