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优化H264 rtp相关代码

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This commit is contained in:
xia-chu 2021-02-07 18:29:48 +08:00
parent 80bcf53ccf
commit 75d97b9221
2 changed files with 120 additions and 137 deletions
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182
src/Extension/H264Rtp.cpp
View File

@ -12,26 +12,31 @@
namespace mediakit{
typedef struct {
unsigned S :1;
unsigned E :1;
unsigned R :1;
unsigned type :5;
} FU;
#if defined(_WIN32)
#pragma pack(push, 1)
#endif // defined(_WIN32)
static bool MakeFU(uint8_t in, FU &fu) {
fu.S = in >> 7;
fu.E = (in >> 6) & 0x01;
fu.R = (in >> 5) & 0x01;
fu.type = in & 0x1f;
if (fu.R != 0) {
return false;
}
return true;
}
class FuFlags {
public:
#if __BYTE_ORDER == __BIG_ENDIAN
unsigned start_bit: 1;
unsigned end_bit: 1;
unsigned reserved: 1;
unsigned nal_type: 5;
#else
unsigned nal_type: 5;
unsigned reserved: 1;
unsigned end_bit: 1;
unsigned start_bit: 1;
#endif
} PACKED;
#if defined(_WIN32)
#pragma pack(pop)
#endif // defined(_WIN32)
H264RtpDecoder::H264RtpDecoder() {
_h264frame = obtainFrame();
_frame = obtainFrame();
}
H264Frame::Ptr H264RtpDecoder::obtainFrame() {
@ -44,15 +49,6 @@ bool H264RtpDecoder::inputRtp(const RtpPacket::Ptr &rtp, bool key_pos) {
return decodeRtp(rtp);
}
bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtp) {
/**
* h264帧类型
* Type==1:P/B frame
* Type==5:IDR frame
* Type==6:SEI frame
* Type==7:SPS frame
* Type==8:PPS frame
*/
/*
RTF3984 5.2节 Common Structure of the RTP Payload Format
Table 1. Summary of NAL unit types and their payload structures
@ -69,21 +65,22 @@ bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtp) {
29 FU-B Fragmentation unit 5.8
30-31 undefined -
*/
bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtp) {
auto frame = rtp->getPayload();
auto length = rtp->getPayloadSize();
auto stamp = rtp->getStampMS();
auto seq = rtp->getSeq();
int nal_type = *frame & 0x1F;
int nal_suffix = *frame & (~0x1F);
auto nal_type = *frame & 0x1F;
auto nal_suffix = *frame & (~0x1F);
if (nal_type >= 0 && nal_type < 24) {
//a full frame
_h264frame->_buffer.assign("\x00\x00\x00\x01", 4);
_h264frame->_buffer.append((char *) frame, length);
_h264frame->_pts = stamp;
auto key = _h264frame->keyFrame();
onGetH264(_h264frame);
_frame->_buffer.assign("\x00\x00\x00\x01", 4);
_frame->_buffer.append((char *) frame, length);
_frame->_pts = stamp;
auto key = _frame->keyFrame();
onGetH264(_frame);
return (key); //i frame
}
@ -106,13 +103,13 @@ bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtp) {
}
if (len > 0) {
//有有效数据
_h264frame->_buffer.assign("\x00\x00\x00\x01", 4);
_h264frame->_buffer.append((char *) ptr, len);
_h264frame->_pts = stamp;
_frame->_buffer.assign("\x00\x00\x00\x01", 4);
_frame->_buffer.append((char *) ptr, len);
_frame->_pts = stamp;
if ((ptr[0] & 0x1F) == H264Frame::NAL_IDR) {
haveIDR = true;
}
onGetH264(_h264frame);
onGetH264(_frame);
}
ptr += len;
}
@ -121,38 +118,44 @@ bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtp) {
case 28: {
//FU-A
FU fu;
MakeFU(frame[1], fu);
if (fu.S) {
FuFlags *fu = (FuFlags *) (frame + 1);
if (fu->start_bit) {
//该帧的第一个rtp包 FU-A start
_h264frame->_buffer.assign("\x00\x00\x00\x01", 4);
_h264frame->_buffer.push_back(nal_suffix | fu.type);
_h264frame->_buffer.append((char *) frame + 2, length - 2);
_h264frame->_pts = stamp;
//预留空间，防止频繁扩容拷贝
_frame->_buffer.reserve(_max_frame_size);
_frame->_buffer.assign("\x00\x00\x00\x01", 4);
_frame->_buffer.push_back(nal_suffix | fu->nal_type);
_frame->_buffer.append((char *) frame + 2, length - 2);
_frame->_pts = stamp;
//该函数return时，保存下当前sequence,以便下次对比seq是否连续
_lastSeq = seq;
return _h264frame->keyFrame();
_last_seq = seq;
return _frame->keyFrame();
}
if (seq != (uint16_t)(_lastSeq + 1) && seq != 0) {
if (seq != (uint16_t) (_last_seq + 1)) {
//中间的或末尾的rtp包，其seq必须连续(如果回环了则判定为连续)，否则说明rtp丢包，那么该帧不完整，必须得丢弃
_h264frame->_buffer.clear();
WarnL << "rtp丢包: " << seq << " != " << _lastSeq << " + 1,该帧被废弃";
_frame->_buffer.clear();
WarnL << "rtp丢包: " << seq << " != " << _last_seq << " + 1,该帧被废弃";
return false;
}
if (!fu.E) {
if (!fu->end_bit) {
//该帧的中间rtp包 FU-A mid
_h264frame->_buffer.append((char *) frame + 2, length - 2);
_frame->_buffer.append((char *) frame + 2, length - 2);
//该函数return时，保存下当前sequence,以便下次对比seq是否连续
_lastSeq = seq;
_last_seq = seq;
return false;
}
//该帧最后一个rtp包 FU-A end
_h264frame->_buffer.append((char *) frame + 2, length - 2);
_h264frame->_pts = stamp;
onGetH264(_h264frame);
_frame->_buffer.append((char *) frame + 2, length - 2);
_frame->_pts = stamp;
//计算最大的帧
auto frame_size = _frame->size();
if (frame_size > _max_frame_size) {
_max_frame_size = frame_size;
}
onGetH264(_frame);
return false;
}
@ -161,9 +164,6 @@ bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtp) {
// 25 STAP-B 单一时间的组合包
// 26 MTAP16 多个时间的组合包
// 27 MTAP24 多个时间的组合包
// 0 udef
// 30 udef
// 31 udef
WarnL << "不支持的rtp类型:" << (int) nal_type << " " << seq;
return false;
}
@ -173,24 +173,15 @@ bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtp) {
void H264RtpDecoder::onGetH264(const H264Frame::Ptr &frame) {
//rtsp没有dts，那么根据pts排序算法生成dts
_dts_generator.getDts(frame->_pts,frame->_dts);
//写入环形缓存
RtpCodec::inputFrame(frame);
_h264frame = obtainFrame();
_frame = obtainFrame();
}
////////////////////////////////////////////////////////////////////////
H264RtpEncoder::H264RtpEncoder(uint32_t ui32Ssrc,
uint32_t ui32MtuSize,
uint32_t ui32SampleRate,
uint8_t ui8PayloadType,
uint8_t ui8Interleaved) :
RtpInfo(ui32Ssrc,
ui32MtuSize,
ui32SampleRate,
ui8PayloadType,
ui8Interleaved) {
H264RtpEncoder::H264RtpEncoder(uint32_t ssrc, uint32_t mtu, uint32_t sample_rate, uint8_t pt, uint8_t interleaved)
: RtpInfo(ssrc, mtu, sample_rate, pt, interleaved) {
}
void H264RtpEncoder::inputFrame(const Frame::Ptr &frame) {
@ -198,48 +189,39 @@ void H264RtpEncoder::inputFrame(const Frame::Ptr &frame) {
auto len = frame->size() - frame->prefixSize();
auto pts = frame->pts();
auto nal_type = H264_TYPE(ptr[0]);
auto max_size = getMaxSize() - 2;
auto packet_size = getMaxSize() - 2;
//末尾5bit为nalu type，固定为28(FU-A)
auto fu_char_0 = (ptr[0] & (~0x1F)) | 28;
auto fu_char_1 = nal_type;
FuFlags *fu_flags = (FuFlags *) (&fu_char_1);
fu_flags->start_bit = 1;
//超过MTU则按照FU-A模式打包
if (len > max_size + 1) {
//最高位bit为forbidden_zero_bit,
//后面2bit为nal_ref_idc(帧重要程度),00:可以丢,11:不能丢
//末尾5bit为nalu type，固定为28(FU-A)
unsigned char nal_fu_a = (*((unsigned char *) ptr) & (~0x1F)) | 28;
unsigned char s_e_r_flags;
bool fu_a_start = true;
bool mark_bit = false;
if (len > packet_size + 1) {
size_t offset = 1;
while (!mark_bit) {
if (len <= offset + max_size) {
while (!fu_flags->end_bit) {
if (!fu_flags->start_bit && len <= offset + packet_size) {
//FU-A end
mark_bit = true;
max_size = len - offset;
s_e_r_flags = (1 << 6) | nal_type;
} else if (fu_a_start) {
//FU-A start
s_e_r_flags = (1 << 7) | nal_type;
} else {
//FU-A mid
s_e_r_flags = nal_type;
packet_size = len - offset;
fu_flags->end_bit = 1;
}
{
//传入nullptr先不做payload的内存拷贝
auto rtp = makeRtp(getTrackType(), nullptr, max_size + 2, mark_bit, pts);
auto rtp = makeRtp(getTrackType(), nullptr, packet_size + 2, fu_flags->end_bit, pts);
//rtp payload 负载部分
uint8_t *payload = rtp->getPayload();
//FU-A 第1个字节
payload[0] = nal_fu_a;
payload[0] = fu_char_0;
//FU-A 第2个字节
payload[1] = s_e_r_flags;
payload[1] = fu_char_1;
//H264 数据
memcpy(payload + 2, (unsigned char *) ptr + offset, max_size);
memcpy(payload + 2, (uint8_t *) ptr + offset, packet_size);
//输入到rtp环形缓存
RtpCodec::inputRtp(rtp, fu_a_start && nal_type == H264Frame::NAL_IDR);
}
offset += max_size;
fu_a_start = false;
RtpCodec::inputRtp(rtp, fu_flags->start_bit && nal_type == H264Frame::NAL_IDR);
offset += packet_size;
fu_flags->start_bit = 0;
}
} else {
//如果帧长度不超过mtu, 则按照Single NAL unit packet per H.264 方式打包

25
src/Extension/H264Rtp.h
View File

@ -48,8 +48,9 @@ private:
H264Frame::Ptr obtainFrame();
private:
uint16_t _lastSeq = 0;
H264Frame::Ptr _h264frame;
uint16_t _last_seq = 0;
size_t _max_frame_size = 0;
H264Frame::Ptr _frame;
DtsGenerator _dts_generator;
};
@ -61,17 +62,17 @@ public:
typedef std::shared_ptr<H264RtpEncoder> Ptr;
/**
* @param ui32Ssrc ssrc
* @param ui32MtuSize mtu大小
* @param ui32SampleRate 采样率，强制为90000
* @param ui8PayloadType pt类型
* @param ui8Interleaved rtsp interleaved
* @param ssrc ssrc
* @param mtu mtu大小
* @param sample_rate 采样率，强制为90000
* @param pt pt类型
* @param interleaved rtsp interleaved
*/
H264RtpEncoder(uint32_t ui32Ssrc,
uint32_t ui32MtuSize = 1400,
uint32_t ui32SampleRate = 90000,
uint8_t ui8PayloadType = 96,
uint8_t ui8Interleaved = TrackVideo * 2);
H264RtpEncoder(uint32_t ssrc,
uint32_t mtu = 1400,
uint32_t sample_rate = 90000,
uint8_t pt = 96,
uint8_t interleaved = TrackVideo * 2);
~H264RtpEncoder() {}
/**