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nginx-mod-rtmp/hls/ngx_rtmp_mpegts.c
Chris Wiggins f8992e572f Automatically generate CRC for MPEG-TS packets. 
Includes descriptions from @premultiply from pull sergey-dryabzhinsky/nginx-rtmp-module#123
2017-03-27 12:06:18 +13:00

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/*
* Copyright (C) Roman Arutyunyan
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include "ngx_rtmp_mpegts.h"
#include "ngx_rtmp_mpegts_crc.h"
#include "ngx_rtmp_codec_module.h"
static u_char ngx_rtmp_mpegts_header[] = {
/* https://en.wikipedia.org/wiki/MPEG_transport_stream#Packet */
/* TS Header */
0x47, // Sync byte
0x40, 0x00, // TEI(1) + PUS(1) + TP(1) + PID(13)
0x10, // TSC(2) + AFF(1) + PF(1) + CC(4)
0x00, // adaption_field_length(8)
/* PAT */
0x00, // table_id(8)
0xb0, 0x0d, // 1011b(4) + section_length(12)
0x00, 0x01, // transport_stream_id(16)
0xc1, 0x00, 0x00, // 11b(2) + VN(5) + CNI(1), section_no(8), last_section_no(8)
/* PAT program loop */
0x00, 0x01, 0xef, 0xff, // program_number(16), reserved(3) + program_map_pid(13)
/* PAT crc (CRC-32-MPEG2) */
0x36, 0x90, 0xe2, 0x3d, // !!! Needs to be recalculated each time any bit in PAT is modified (which we dont do at the moment) !!!
/* stuffing 167 bytes */
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
/* TS Header */
0x47, // Sync byte
0x4f, 0xff, // TEI(1) + PUS(1) + TP(1) + PID(13)
0x10, // TSC(2) + AFF(1) + PF(1) + CC(4)
0x00, // adaption_field_length(8)
/* PMT */
0x02, // table_id(8)
0xb0, 0x12, // 1011b(4) + section_length(12) (section length set below. Ignore this value in here)
0x00, 0x01, // program_number(16)
0xc1, 0x00, 0x00, // 11b(2) + VN(5) + CNI(1), section_no(8), last_section_no(8)
0xe1, 0x00, // reserved(3) + PCR_PID(13)
0xf0, 0x00, // reserved(4) + program_info_length(12)
/* PMT component loop, looped through when writing header */
/* Max size of 14 bytes */
/* Also includes the PMT CRC, calculated dynamically */
0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff,
/* stuffing 157 bytes */
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};
static u_char ngx_rtmp_mpegts_header_h264[] = {
//H.264 Video, PID 0x100
0x1b, // stream_type(8)
0xe1, 0x00, // reserved(3) + elementary_PID(13)
0xf0, 0x00 // reserved(4) + ES_info_length(12)
};
static u_char ngx_rtmp_mpegts_header_mp3[] = {
//MP3 Audio, PID 0x101
0x03, // stream_type(8)
0xe1, 0x01, // reserved(3) + elementary_PID(13)
0xf0, 0x00 // reserved(4) + ES_info_length(12)
};
static u_char ngx_rtmp_mpegts_header_aac[] = {
//ADTS AAC Audio, PID 0x101
0x0f, // stream_type(8)
0xe1, 0x01, // reserved(3) + elementary_PID(13)
0xf0, 0x00 // reserved(4) + ES_info_length(12)
};
#define NGX_RTMP_MPEGTS_PMT_CRC_START_OFFSET 193
#define NGX_RTMP_MPEGTS_PMT_CRC_MIN_LENGTH 12
#define NGX_RTMP_MPEGTS_PMT_SECTION_LENGTH_OFFSET 195
#define NGX_RTMP_MPEGTS_PMT_LOOP_OFFSET 205
#define NGX_RTMP_MPEGTS_PID_SIZE 5
/* 700 ms PCR delay */
#define NGX_RTMP_HLS_DELAY 63000
static ngx_int_t
ngx_rtmp_mpegts_write_file(ngx_rtmp_mpegts_file_t *file, u_char *in,
size_t in_size)
{
u_char *out;
size_t out_size, n;
ssize_t rc;
static u_char buf[1024];
if (!file->encrypt) {
ngx_log_debug1(NGX_LOG_DEBUG_CORE, file->log, 0,
"mpegts: write %uz bytes", in_size);
rc = ngx_write_fd(file->fd, in, in_size);
if (rc < 0) {
return NGX_ERROR;
}
return NGX_OK;
}
/* encrypt */
ngx_log_debug1(NGX_LOG_DEBUG_CORE, file->log, 0,
"mpegts: write %uz encrypted bytes", in_size);
out = buf;
out_size = sizeof(buf);
if (file->size > 0 && file->size + in_size >= 16) {
ngx_memcpy(file->buf + file->size, in, 16 - file->size);
in += 16 - file->size;
in_size -= 16 - file->size;
AES_cbc_encrypt(file->buf, out, 16, &file->key, file->iv, AES_ENCRYPT);
out += 16;
out_size -= 16;
file->size = 0;
}
for ( ;; ) {
n = in_size & ~0x0f;
if (n > 0) {
if (n > out_size) {
n = out_size;
}
AES_cbc_encrypt(in, out, n, &file->key, file->iv, AES_ENCRYPT);
in += n;
in_size -= n;
} else if (out == buf) {
break;
}
rc = ngx_write_fd(file->fd, buf, out - buf + n);
if (rc < 0) {
return NGX_ERROR;
}
out = buf;
out_size = sizeof(buf);
}
if (in_size) {
ngx_memcpy(file->buf + file->size, in, in_size);
file->size += in_size;
}
return NGX_OK;
}
static ngx_int_t
ngx_rtmp_mpegts_write_header(ngx_rtmp_mpegts_file_t *file, ngx_rtmp_codec_ctx_t *codec_ctx, ngx_uint_t mpegts_cc)
{
ngx_int_t next_pid_offset = 0; //Used to track the number of PIDs we have and the offset in 5-byte chunks
//MPEG-TS CC is 4 bits long. Need to truncate it here.
mpegts_cc %= 0x0f;
// And then put it in the headers
ngx_rtmp_mpegts_header[3] = (ngx_rtmp_mpegts_header[3] & 0xf0) + (u_char)mpegts_cc;
ngx_rtmp_mpegts_header[191] = (ngx_rtmp_mpegts_header[191] & 0xf0) + (u_char)mpegts_cc;
//ngx_rtmp_mpegts_header
if (codec_ctx->video_codec_id)
{
//Put h264 PID in the PMT
ngx_memcpy(ngx_rtmp_mpegts_header+NGX_RTMP_MPEGTS_PMT_LOOP_OFFSET+next_pid_offset, ngx_rtmp_mpegts_header_h264, NGX_RTMP_MPEGTS_PID_SIZE);
next_pid_offset += NGX_RTMP_MPEGTS_PID_SIZE;
}
if (codec_ctx->audio_codec_id){
//Put Audio PID in the PMT
if (codec_ctx->audio_codec_id == NGX_RTMP_AUDIO_AAC) {
ngx_memcpy(ngx_rtmp_mpegts_header+NGX_RTMP_MPEGTS_PMT_LOOP_OFFSET+next_pid_offset, ngx_rtmp_mpegts_header_aac, NGX_RTMP_MPEGTS_PID_SIZE);
}
else
{
ngx_memcpy(ngx_rtmp_mpegts_header+NGX_RTMP_MPEGTS_PMT_LOOP_OFFSET+next_pid_offset, ngx_rtmp_mpegts_header_mp3, NGX_RTMP_MPEGTS_PID_SIZE);
}
next_pid_offset += NGX_RTMP_MPEGTS_PID_SIZE;
}
//Set section length of PMT
//PMT is 13 bytes long without any programs in it. Add this in
ngx_rtmp_mpegts_header[NGX_RTMP_MPEGTS_PMT_SECTION_LENGTH_OFFSET] = 13 + next_pid_offset;
//Calculate CRC
ngx_rtmp_mpegts_crc_t crc = ngx_rtmp_mpegts_crc_init();
crc = ngx_rtmp_mpegts_crc_update(crc, ngx_rtmp_mpegts_header+NGX_RTMP_MPEGTS_PMT_CRC_START_OFFSET, NGX_RTMP_MPEGTS_PMT_CRC_MIN_LENGTH+next_pid_offset);
crc = ngx_rtmp_mpegts_crc_finalize(crc);
ngx_rtmp_mpegts_header[NGX_RTMP_MPEGTS_PMT_LOOP_OFFSET+next_pid_offset] = (crc >> 24) & 0xff;
ngx_rtmp_mpegts_header[NGX_RTMP_MPEGTS_PMT_LOOP_OFFSET+next_pid_offset+1] = (crc >> 16) & 0xff;
ngx_rtmp_mpegts_header[NGX_RTMP_MPEGTS_PMT_LOOP_OFFSET+next_pid_offset+2] = (crc >> 8) & 0xff;
ngx_rtmp_mpegts_header[NGX_RTMP_MPEGTS_PMT_LOOP_OFFSET+next_pid_offset+3] = crc & 0xff;
return ngx_rtmp_mpegts_write_file(file, ngx_rtmp_mpegts_header, sizeof(ngx_rtmp_mpegts_header));
}
static u_char *
ngx_rtmp_mpegts_write_pcr(u_char *p, uint64_t pcr)
{
*p++ = (u_char) (pcr >> 25);
*p++ = (u_char) (pcr >> 17);
*p++ = (u_char) (pcr >> 9);
*p++ = (u_char) (pcr >> 1);
*p++ = (u_char) (pcr << 7 | 0x7e);
*p++ = 0;
return p;
}
static u_char *
ngx_rtmp_mpegts_write_pts(u_char *p, ngx_uint_t fb, uint64_t pts)
{
ngx_uint_t val;
val = fb << 4 | (((pts >> 30) & 0x07) << 1) | 1;
*p++ = (u_char) val;
val = (((pts >> 15) & 0x7fff) << 1) | 1;
*p++ = (u_char) (val >> 8);
*p++ = (u_char) val;
val = (((pts) & 0x7fff) << 1) | 1;
*p++ = (u_char) (val >> 8);
*p++ = (u_char) val;
return p;
}
ngx_int_t
ngx_rtmp_mpegts_write_frame(ngx_rtmp_mpegts_file_t *file,
ngx_rtmp_mpegts_frame_t *f, ngx_buf_t *b)
{
ngx_uint_t pes_size, header_size, body_size, in_size, stuff_size, flags;
u_char packet[188], *p, *base;
ngx_int_t first, rc;
ngx_log_debug6(NGX_LOG_DEBUG_CORE, file->log, 0,
"mpegts: pid=%ui, sid=%ui, pts=%uL, "
"dts=%uL, key=%ui, size=%ui",
f->pid, f->sid, f->pts, f->dts,
(ngx_uint_t) f->key, (size_t) (b->last - b->pos));
first = 1;
while (b->pos < b->last) {
p = packet;
f->cc++;
*p++ = 0x47;
*p++ = (u_char) (f->pid >> 8);
if (first) {
p[-1] |= 0x40;
}
*p++ = (u_char) f->pid;
*p++ = 0x10 | (f->cc & 0x0f); /* payload */
if (first) {
packet[3] |= 0x20; /* adaptation */
*p++ = 7; /* size */
*p++ = 0x50; /* random access + PCR */
p = ngx_rtmp_mpegts_write_pcr(p, f->dts - NGX_RTMP_HLS_DELAY);
/* PES header */
*p++ = 0x00;
*p++ = 0x00;
*p++ = 0x01;
*p++ = (u_char) f->sid;
header_size = 5;
flags = 0x80; /* PTS */
if (f->dts != f->pts) {
header_size += 5;
flags |= 0x40; /* DTS */
}
pes_size = (b->last - b->pos) + header_size + 3;
if (pes_size > 0xffff) {
pes_size = 0;
}
*p++ = (u_char) (pes_size >> 8);
*p++ = (u_char) pes_size;
*p++ = 0x80; /* H222 */
*p++ = (u_char) flags;
*p++ = (u_char) header_size;
p = ngx_rtmp_mpegts_write_pts(p, flags >> 6, f->pts +
NGX_RTMP_HLS_DELAY);
if (f->dts != f->pts) {
p = ngx_rtmp_mpegts_write_pts(p, 1, f->dts +
NGX_RTMP_HLS_DELAY);
}
first = 0;
}
body_size = (ngx_uint_t) (packet + sizeof(packet) - p);
in_size = (ngx_uint_t) (b->last - b->pos);
if (body_size <= in_size) {
ngx_memcpy(p, b->pos, body_size);
b->pos += body_size;
} else {
stuff_size = (body_size - in_size);
if (packet[3] & 0x20) {
/* has adaptation */
base = &packet[5] + packet[4];
p = ngx_movemem(base + stuff_size, base, p - base);
ngx_memset(base, 0xff, stuff_size);
packet[4] += (u_char) stuff_size;
} else {
/* no adaptation */
packet[3] |= 0x20;
p = ngx_movemem(&packet[4] + stuff_size, &packet[4],
p - &packet[4]);
packet[4] = (u_char) (stuff_size - 1);
if (stuff_size >= 2) {
packet[5] = 0;
ngx_memset(&packet[6], 0xff, stuff_size - 2);
}
}
ngx_memcpy(p, b->pos, in_size);
b->pos = b->last;
}
rc = ngx_rtmp_mpegts_write_file(file, packet, sizeof(packet));
if (rc != NGX_OK) {
return rc;
}
}
return NGX_OK;
}
ngx_int_t
ngx_rtmp_mpegts_init_encryption(ngx_rtmp_mpegts_file_t *file,
u_char *key, size_t key_len, uint64_t iv)
{
if (AES_set_encrypt_key(key, key_len * 8, &file->key)) {
return NGX_ERROR;
}
ngx_memzero(file->iv, 8);
file->iv[8] = (u_char) (iv >> 56);
file->iv[9] = (u_char) (iv >> 48);
file->iv[10] = (u_char) (iv >> 40);
file->iv[11] = (u_char) (iv >> 32);
file->iv[12] = (u_char) (iv >> 24);
file->iv[13] = (u_char) (iv >> 16);
file->iv[14] = (u_char) (iv >> 8);
file->iv[15] = (u_char) (iv);
file->encrypt = 1;
return NGX_OK;
}
ngx_int_t
ngx_rtmp_mpegts_open_file(ngx_rtmp_mpegts_file_t *file, u_char *path,
ngx_log_t *log, ngx_rtmp_codec_ctx_t *codec_ctx, ngx_uint_t mpegts_cc)
{
file->log = log;
file->fd = ngx_open_file(path, NGX_FILE_WRONLY, NGX_FILE_TRUNCATE,
NGX_FILE_DEFAULT_ACCESS);
if (file->fd == NGX_INVALID_FILE) {
ngx_log_error(NGX_LOG_ERR, log, ngx_errno,
"hls: error creating fragment file");
return NGX_ERROR;
}
file->size = 0;
if (ngx_rtmp_mpegts_write_header(file, codec_ctx, mpegts_cc) != NGX_OK) {
ngx_log_error(NGX_LOG_ERR, log, ngx_errno,
"hls: error writing fragment header");
ngx_close_file(file->fd);
return NGX_ERROR;
}
return NGX_OK;
}
ngx_int_t
ngx_rtmp_mpegts_close_file(ngx_rtmp_mpegts_file_t *file)
{
u_char buf[16];
ssize_t rc;
if (file->encrypt) {
ngx_memset(file->buf + file->size, 16 - file->size, 16 - file->size);
AES_cbc_encrypt(file->buf, buf, 16, &file->key, file->iv, AES_ENCRYPT);
rc = ngx_write_fd(file->fd, buf, 16);
if (rc < 0) {
return NGX_ERROR;
}
}
ngx_close_file(file->fd);
return NGX_OK;
}
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