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/**
* @file gst_video/h264.c H.264 Packetization
*
* Copyright (C) 2010 Creytiv.com
*/
#include <string.h>
#include <re.h>
#include <rem.h>
#include <baresip.h>
#include "gst_video.h"
/** NAL unit types (RFC 3984, Table 1) */
enum {
H264_NAL_UNKNOWN = 0,
/* 1-23 NAL unit Single NAL unit packet per H.264 */
H264_NAL_SLICE = 1,
H264_NAL_DPA = 2,
H264_NAL_DPB = 3,
H264_NAL_DPC = 4,
H264_NAL_IDR_SLICE = 5,
H264_NAL_SEI = 6,
H264_NAL_SPS = 7,
H264_NAL_PPS = 8,
H264_NAL_AUD = 9,
H264_NAL_END_SEQUENCE = 10,
H264_NAL_END_STREAM = 11,
H264_NAL_FILLER_DATA = 12,
H264_NAL_SPS_EXT = 13,
H264_NAL_AUX_SLICE = 19,
H264_NAL_STAP_A = 24, /**< Single-time aggregation packet */
H264_NAL_STAP_B = 25, /**< Single-time aggregation packet */
H264_NAL_MTAP16 = 26, /**< Multi-time aggregation packet */
H264_NAL_MTAP24 = 27, /**< Multi-time aggregation packet */
H264_NAL_FU_A = 28, /**< Fragmentation unit */
H264_NAL_FU_B = 29, /**< Fragmentation unit */
};
const uint8_t gst_video_h264_level_idc = 0x0c;
/*
* Find the NAL start sequence in a H.264 byte stream
*
* @note: copied from ffmpeg source
*/
static const uint8_t *h264_find_startcode(const uint8_t *p, const uint8_t *end)
{
const uint8_t *a = p + 4 - ((long)p & 3);
for (end -= 3; p < a && p < end; p++ ) {
if (p[0] == 0 && p[1] == 0 && p[2] == 1)
return p;
}
for (end -= 3; p < end; p += 4) {
uint32_t x = *(const uint32_t*)(void *)p;
if ( (x - 0x01010101) & (~x) & 0x80808080 ) {
if (p[1] == 0 ) {
if ( p[0] == 0 && p[2] == 1 )
return p;
if ( p[2] == 0 && p[3] == 1 )
return p+1;
}
if ( p[3] == 0 ) {
if ( p[2] == 0 && p[4] == 1 )
return p+2;
if ( p[4] == 0 && p[5] == 1 )
return p+3;
}
}
}
for (end += 3; p < end; p++) {
if (p[0] == 0 && p[1] == 0 && p[2] == 1)
return p;
}
return end + 3;
}
static int rtp_send_data(const uint8_t *hdr, size_t hdr_sz,
const uint8_t *buf, size_t sz, bool eof,
videnc_packet_h *pkth, void *arg)
{
return pkth(eof, hdr, hdr_sz, buf, sz, arg);
}
static int h264_nal_send(bool first, bool last,
bool marker, uint32_t ihdr, const uint8_t *buf,
size_t size, size_t maxsz,
videnc_packet_h *pkth, void *arg)
{
uint8_t hdr = (uint8_t)ihdr;
int err = 0;
if (first && last && size <= maxsz) {
err = rtp_send_data(&hdr, 1, buf, size, marker,
pkth, arg);
}
else {
uint8_t fu_hdr[2];
const uint8_t type = hdr & 0x1f;
const uint8_t nri = hdr & 0x60;
const size_t sz = maxsz - 2;
fu_hdr[0] = nri | H264_NAL_FU_A;
fu_hdr[1] = first ? (1<<7 | type) : type;
while (size > sz) {
err |= rtp_send_data(fu_hdr, 2, buf, sz, false,
pkth, arg);
buf += sz;
size -= sz;
fu_hdr[1] &= ~(1 << 7);
}
if (last)
fu_hdr[1] |= 1<<6; /* end bit */
err |= rtp_send_data(fu_hdr, 2, buf, size, marker && last,
pkth, arg);
}
return err;
}
int gst_video_h264_packetize(const uint8_t *buf, size_t len,
size_t pktsize,
videnc_packet_h *pkth, void *arg)
{
const uint8_t *start = buf;
const uint8_t *end = start + len;
const uint8_t *r;
int err = 0;
r = h264_find_startcode(buf, end);
while (r < end) {
const uint8_t *r1;
/* skip zeros */
while (!*(r++))
;
r1 = h264_find_startcode(r, end);
err |= h264_nal_send(true, true, (r1 >= end), r[0],
r+1, r1-r-1, pktsize,
pkth, arg);
r = r1;
}
return err;
}
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