344 lines
11 KiB
C++
344 lines
11 KiB
C++
// RFC6184 RTP Payload Format for H.264 Video
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#include "rtp-packet.h"
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#include "rtp-payload-internal.h"
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include <errno.h>
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#define H264_NAL(v) ((v) & 0x1F)
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#define FU_START(v) ((v) & 0x80)
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#define FU_END(v) ((v) & 0x40)
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#define FU_NAL(v) ((v) & 0x1F)
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struct rtp_decode_h264_t
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{
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struct rtp_payload_t handler;
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void* cbparam;
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uint16_t seq; // rtp seq
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uint32_t timestamp;
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uint8_t* ptr;
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int size, capacity;
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int flags;
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};
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static void* rtp_h264_unpack_create(struct rtp_payload_t *handler, void* param)
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{
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struct rtp_decode_h264_t *unpacker;
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unpacker = (struct rtp_decode_h264_t *)calloc(1, sizeof(*unpacker));
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if(!unpacker)
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return NULL;
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memcpy(&unpacker->handler, handler, sizeof(unpacker->handler));
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unpacker->cbparam = param;
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unpacker->flags = -1;
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return unpacker;
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}
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static void rtp_h264_unpack_destroy(void* p)
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{
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struct rtp_decode_h264_t *unpacker;
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unpacker = (struct rtp_decode_h264_t *)p;
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if(unpacker->ptr)
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free(unpacker->ptr);
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#if defined(_DEBUG) || defined(DEBUG)
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memset(unpacker, 0xCC, sizeof(*unpacker));
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#endif
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free(unpacker);
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}
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// 5.7.1. Single-Time Aggregation Packet (STAP) (p23)
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/*
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0 1 2 3
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| RTP Header |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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|STAP-B NAL HDR | DON | NALU 1 Size |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| NALU 1 Size | NALU 1 HDR | NALU 1 Data |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
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: :
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+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| | NALU 2 Size | NALU 2 HDR |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| NALU 2 Data |
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: :
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| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| : ...OPTIONAL RTP padding |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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*/
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static int rtp_h264_unpack_stap(struct rtp_decode_h264_t *unpacker, const uint8_t* ptr, int bytes, uint32_t timestamp, int stap_b)
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{
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int r, n;
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uint16_t len;
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uint16_t don;
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r = 0;
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n = stap_b ? 3 : 1;
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if (bytes < n)
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{
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assert(0);
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return -EINVAL; // error
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}
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don = stap_b ? nbo_r16(ptr + 1) : 0;
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ptr += n; // STAP-A / STAP-B HDR + DON
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for(bytes -= n; 0 == r && bytes > 2; bytes -= len + 2)
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{
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len = nbo_r16(ptr);
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if(len + 2 > bytes || len < 2)
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{
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assert(0);
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unpacker->flags = RTP_PAYLOAD_FLAG_PACKET_LOST;
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unpacker->size = 0;
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return -EINVAL; // error
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}
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assert(H264_NAL(ptr[2]) > 0 && H264_NAL(ptr[2]) < 24);
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r = unpacker->handler.packet(unpacker->cbparam, ptr + 2, len, timestamp, unpacker->flags);
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unpacker->flags = 0;
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unpacker->size = 0;
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ptr += len + 2; // next NALU
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don = (don + 1) % 65536;
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}
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return 0 == r ? 1 : r; // packet handled
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}
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// 5.7.2. Multi-Time Aggregation Packets (MTAPs) (p27)
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/*
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0 1 2 3
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| RTP Header |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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|MTAP16 NAL HDR | decoding order number base | NALU 1 Size |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| NALU 1 Size | NALU 1 DOND | NALU 1 TS offset |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| NALU 1 HDR | NALU 1 DATA |
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+-+-+-+-+-+-+-+-+ +
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: :
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+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| | NALU 2 SIZE | NALU 2 DOND |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| NALU 2 TS offset | NALU 2 HDR | NALU 2 DATA |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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: :
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| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| : ...OPTIONAL RTP padding |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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*/
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static int rtp_h264_unpack_mtap(struct rtp_decode_h264_t *unpacker, const uint8_t* ptr, int bytes, uint32_t timestamp, int n)
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{
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int r;
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//uint16_t dond;
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uint16_t donb;
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uint16_t len;
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uint32_t ts;
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r = 0;
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if (bytes < 3)
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{
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assert(0);
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return -EINVAL; // error
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}
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donb = nbo_r16(ptr + 1);
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ptr += 3; // MTAP16/MTAP24 HDR + DONB
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for(bytes -= 3; 0 == r && n + 3 < bytes; bytes -= len + 2)
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{
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len = nbo_r16(ptr);
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if(len + 2 > bytes || len < 1 /*DOND*/ + n /*TS offset*/ + 1 /*NALU*/)
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{
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assert(0);
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unpacker->flags = RTP_PAYLOAD_FLAG_PACKET_LOST;
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unpacker->size = 0;
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return -EINVAL; // error
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}
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//dond = (ptr[2] + donb) % 65536;
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ts = (uint16_t)nbo_r16(ptr + 3);
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if (3 == n) ts = (ts << 8) | ptr[5]; // MTAP24
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// if the NALU-time is larger than or equal to the RTP timestamp of the packet,
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// then the timestamp offset equals (the NALU - time of the NAL unit - the RTP timestamp of the packet).
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// If the NALU - time is smaller than the RTP timestamp of the packet,
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// then the timestamp offset is equal to the NALU - time + (2 ^ 32 - the RTP timestamp of the packet).
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ts += timestamp; // wrap 1 << 32
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assert(H264_NAL(ptr[n + 3]) > 0 && H264_NAL(ptr[n + 3]) < 24);
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r = unpacker->handler.packet(unpacker->cbparam, ptr + 2 + 1 + n, len - 1 - n, ts, unpacker->flags);
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unpacker->flags = 0;
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unpacker->size = 0;
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ptr += len + 2; // next NALU
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}
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return 0 == r ? 1 : r; // packet handled
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}
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// 5.8. Fragmentation Units (FUs) (p29)
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/*
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0 1 2 3
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| FU indicator | FU header | DON |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
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| FU payload |
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| |
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| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| : ...OPTIONAL RTP padding |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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*/
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static int rtp_h264_unpack_fu(struct rtp_decode_h264_t *unpacker, const uint8_t* ptr, int bytes, uint32_t timestamp, int fu_b)
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{
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int r, n;
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uint8_t fuheader;
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//uint16_t don;
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r = 0;
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n = fu_b ? 4 : 2;
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if (bytes < n || unpacker->size + bytes - n > RTP_PAYLOAD_MAX_SIZE)
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{
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assert(0);
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return -EINVAL; // error
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}
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if (unpacker->size + bytes - n + 1 /*NALU*/ > unpacker->capacity)
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{
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void* p = NULL;
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int size = unpacker->size + bytes + 1;
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size += size / 4 > 128000 ? size / 4 : 128000;
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p = realloc(unpacker->ptr, size);
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if (!p)
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{
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// set packet lost flag
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unpacker->flags = RTP_PAYLOAD_FLAG_PACKET_LOST;
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unpacker->size = 0;
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return -ENOMEM; // error
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}
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unpacker->ptr = (uint8_t*)p;
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unpacker->capacity = size;
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}
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fuheader = ptr[1];
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//don = nbo_r16(ptr + 2);
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if (FU_START(fuheader))
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{
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#if 0
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if (unpacker->size > 0)
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{
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unpacker->flags |= RTP_PAYLOAD_FLAG_PACKET_CORRUPT;
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unpacker->handler.packet(unpacker->cbparam, unpacker->ptr, unpacker->size, unpacker->timestamp, unpacker->flags);
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unpacker->flags = 0;
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unpacker->size = 0; // reset
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}
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#endif
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unpacker->size = 1; // NAL unit type byte
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unpacker->ptr[0] = (ptr[0]/*indicator*/ & 0xE0) | (fuheader & 0x1F);
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assert(H264_NAL(unpacker->ptr[0]) > 0 && H264_NAL(unpacker->ptr[0]) < 24);
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}
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else
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{
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if (0 == unpacker->size)
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{
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unpacker->flags = RTP_PAYLOAD_FLAG_PACKET_LOST;
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return 0; // packet discard
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}
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assert(unpacker->size > 0);
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}
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unpacker->timestamp = timestamp;
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if (bytes > n)
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{
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assert(unpacker->capacity >= unpacker->size + bytes - n);
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memmove(unpacker->ptr + unpacker->size, ptr + n, bytes - n);
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unpacker->size += bytes - n;
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}
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if(FU_END(fuheader))
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{
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if(unpacker->size > 0)
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r = unpacker->handler.packet(unpacker->cbparam, unpacker->ptr, unpacker->size, timestamp, unpacker->flags);
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unpacker->flags = 0;
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unpacker->size = 0; // reset
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}
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return 0 == r ? 1 : r; // packet handled
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}
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static int rtp_h264_unpack_input(void* p, const void* packet, int bytes)
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{
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int r;
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uint8_t nalt;
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struct rtp_packet_t pkt;
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struct rtp_decode_h264_t *unpacker;
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unpacker = (struct rtp_decode_h264_t *)p;
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if(!unpacker || 0 != rtp_packet_deserialize(&pkt, packet, bytes) || pkt.payloadlen < 1)
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return -EINVAL;
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if (-1 == unpacker->flags)
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{
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unpacker->flags = 0;
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unpacker->seq = (uint16_t)(pkt.rtp.seq - 1); // disable packet lost
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}
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if ((uint16_t)pkt.rtp.seq != (uint16_t)(unpacker->seq + 1))
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{
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unpacker->flags = RTP_PAYLOAD_FLAG_PACKET_LOST;
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unpacker->size = 0; // discard previous packets
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}
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unpacker->seq = (uint16_t)pkt.rtp.seq;
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nalt = ((unsigned char *)pkt.payload)[0];
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switch(nalt & 0x1F)
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{
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case 0: // reserved
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case 31: // reserved
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assert(0);
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return 0; // packet discard
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case 24: // STAP-A
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return rtp_h264_unpack_stap(unpacker, (const uint8_t*)pkt.payload, pkt.payloadlen, pkt.rtp.timestamp, 0);
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case 25: // STAP-B
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return rtp_h264_unpack_stap(unpacker, (const uint8_t*)pkt.payload, pkt.payloadlen, pkt.rtp.timestamp, 1);
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case 26: // MTAP16
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return rtp_h264_unpack_mtap(unpacker, (const uint8_t*)pkt.payload, pkt.payloadlen, pkt.rtp.timestamp, 2);
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case 27: // MTAP24
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return rtp_h264_unpack_mtap(unpacker, (const uint8_t*)pkt.payload, pkt.payloadlen, pkt.rtp.timestamp, 3);
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case 28: // FU-A
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return rtp_h264_unpack_fu(unpacker, (const uint8_t*)pkt.payload, pkt.payloadlen, pkt.rtp.timestamp, 0);
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case 29: // FU-B
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return rtp_h264_unpack_fu(unpacker, (const uint8_t*)pkt.payload, pkt.payloadlen, pkt.rtp.timestamp, 1);
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default: // 1-23 NAL unit
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r = unpacker->handler.packet(unpacker->cbparam, (const uint8_t*)pkt.payload, pkt.payloadlen, pkt.rtp.timestamp, unpacker->flags);
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unpacker->flags = 0;
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unpacker->size = 0;
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return 0 == r ? 1 : r; // packet handled
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}
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}
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struct rtp_payload_decode_t *rtp_h264_decode()
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{
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static struct rtp_payload_decode_t unpacker = {
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rtp_h264_unpack_create,
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rtp_h264_unpack_destroy,
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rtp_h264_unpack_input,
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};
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return &unpacker;
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}
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