公司在做编码器，需要和rtmp服务器对接，nginx-rtmp实在是太复杂，不方便调试，所以做了一个简单rtmp服务器。
参与这个项目的几个朋友，说不仅仅想实现流媒体源站功能，还想写出漂亮的代码，成为“国人软件代码之典范”。
哈哈，目标是远大的，代码得一点一点写。
https://github.com/winlinvip/simple-rtmp-server一路输入，多路（实例是12路输出）：
支持Flash推流，直接进行转码支持HLS：
主要的定位是做RTMP/HLS流媒体核心业务，支持RTMP集群（源站/边缘，或Forward方式），支持多进程和单进程，支持vhost，不支持点播。
因为简单，所以稳定；不是那个级别的稳定，是那个级别的稳定，非常稳定，没有出错的可能性。
尽管这样，也是基于state-threads的高性能服务器，一个进程一个线程，异步socket，能成为最好的流服务器。
而且，最方便的是逻辑简单，方便调试，没有异步的回调，全是同步函数。
RTMP协议收发包完整实现，510行就全部搞定。
确实很简单，发送RTMP包使用writev，一个函数就可以搞定：
[cpp]
view plain copy/**
* send out message with encoded payload to peer.
* use the message encode method to encode to payload,
* then sendout over socket.
* @msg this method will free it whatever return value.
*/
virtual int send_message(SrsMessage* msg);
实现如下：
[cpp]
view plain copyint SrsProtocol::send_message(SrsMessage* msg)
{
int ret = ERROR_SUCCESS;
if ((ret = msg->encode_packet()) != ERROR_SUCCESS) {
srs_error("encode packet to message payload failed. ret=%d", ret);
return ret;
}
srs_info("encode packet to message payload success");
// p set to current write position,
// it's ok when payload is NULL and size is 0.
char* p = (char*)msg->payload;
// always write the header event payload is empty.
do {
// generate the header.
char* pheader = NULL;
int header_size = 0;
if (p == (char*)msg->payload) {
// write new chunk stream header, fmt is 0
pheader = out_header_fmt0;
*pheader++ = 0x00 | (msg->get_perfer_cid() & 0x3F);
// chunk message header, 11 bytes
// timestamp, 3bytes, big-endian
if (msg->header.timestamp >= RTMP_EXTENDED_TIMESTAMP) {
*pheader++ = 0xFF;
*pheader++ = 0xFF;
*pheader++ = 0xFF;
} else {
pp = (char*)&msg->header.timestamp;
*pheader++ = pp[2];
*pheader++ = pp[1];
*pheader++ = pp[0];
}
// message_length, 3bytes, big-endian
pp = (char*)&msg->header.payload_length;
*pheader++ = pp[2];
*pheader++ = pp[1];
*pheader++ = pp[0];
// message_type, 1bytes
*pheader++ = msg->header.message_type;
// message_length, 3bytes, little-endian
pp = (char*)&msg->header.stream_id;
*pheader++ = pp[0];
*pheader++ = pp[1];
*pheader++ = pp[2];
*pheader++ = pp[3];
// chunk extended timestamp header, 0 or 4 bytes, big-endian
if(msg->header.timestamp >= RTMP_EXTENDED_TIMESTAMP){
pp = (char*)&msg->header.timestamp;
*pheader++ = pp[3];
*pheader++ = pp[2];
*pheader++ = pp[1];
*pheader++ = pp[0];
}
header_size = pheader - out_header_fmt0;
pheader = out_header_fmt0;
} else {
// write no message header chunk stream, fmt is 3
pheader = out_header_fmt3;
*pheader++ = 0xC0 | (msg->get_perfer_cid() & 0x3F);
// chunk extended timestamp header, 0 or 4 bytes, big-endian
if(msg->header.timestamp >= RTMP_EXTENDED_TIMESTAMP){
pp = (char*)&msg->header.timestamp;
*pheader++ = pp[3];
*pheader++ = pp[2];
*pheader++ = pp[1];
*pheader++ = pp[0];
}
header_size = pheader - out_header_fmt3;
pheader = out_header_fmt3;
}
// sendout header and payload by writev.
// decrease the sys invoke count to get higher performance.
int payload_size = msg->size - (p - (char*)msg->payload);
if (payload_size > out_chunk_size) {
payload_size = out_chunk_size;
}
// send by writev
iovec iov[2];
iov[0].iov_base = pheader;
iov[0].iov_len = header_size;
iov[1].iov_base = p;
iov[1].iov_len = payload_size;
ssize_t nwrite;
if ((ret = skt->writev(iov, 2, &nwrite)) != ERROR_SUCCESS) {
srs_error("send with writev failed. ret=%d", ret);
return ret;
}
// consume sendout bytes when not empty packet.
if (msg->payload && msg->size > 0) {
p += payload_size;
}
} while (p < (char*)msg->payload + msg->size);
return ret;
}
收RTMP包麻烦一点，需要五个函数（只有recv_message是public的）：
[cpp]
view plain copy/**
* recv a message with raw/undecoded payload from peer.
* the payload is not decoded, use srs_rtmp_expect_message<T> if requires
* specifies message.
* @pmsg, user must free it. NULL if not success.
* @remark, only when success, user can use and must free the pmsg.
*/
virtual int recv_message(SrsMessage** pmsg);
/**
* try to recv interlaced message from peer,
* return error if error occur and nerver set the pmsg,
* return success and pmsg set to NULL if no entire message got,
* return success and pmsg set to entire message if got one.
*/
virtual int recv_interlaced_message(SrsMessage** pmsg);
/**
* read the chunk basic header(fmt, cid) from chunk stream.
* user can discovery a SrsChunkStream by cid.
* @bh_size return the chunk basic header size, to remove the used bytes when finished.
*/
virtual int read_basic_header(char& fmt, int& cid, int& bh_size);
/**
* read the chunk message header(timestamp, payload_length, message_type, stream_id)
* from chunk stream and save to SrsChunkStream.
* @mh_size return the chunk message header size, to remove the used bytes when finished.
*/
virtual int read_message_header(SrsChunkStream* chunk, char fmt, int bh_size, int& mh_size);
/**
* read the chunk payload, remove the used bytes in buffer,
* if got entire message, set the pmsg.
* @payload_size read size in this roundtrip, generally a chunk size or left message size.
*/
virtual int read_message_payload(SrsChunkStream* chunk, int bh_size, int mh_size, int& payload_size, SrsMessage** pmsg);
实现如下：
[cpp]
view plain copyint SrsProtocol::recv_message(SrsMessage** pmsg)
{
*pmsg = NULL;
int ret = ERROR_SUCCESS;
while (true) {
SrsMessage* msg = NULL;
if ((ret = recv_interlaced_message(&msg)) != ERROR_SUCCESS) {
srs_error("recv interlaced message failed. ret=%d", ret);
return ret;
}
srs_verbose("entire msg received");
if (!msg) {
continue;
}
if (msg->size <= 0 || msg->header.payload_length <= 0) {
srs_trace("ignore empty message(type=%d, size=%d, time=%d, sid=%d).",
msg->header.message_type, msg->header.payload_length,
msg->header.timestamp, msg->header.stream_id);
delete msg;
continue;
}
srs_verbose("get a msg with raw/undecoded payload");
*pmsg = msg;
break;
}
return ret;
}
int SrsProtocol::recv_interlaced_message(SrsMessage** pmsg)
{
int ret = ERROR_SUCCESS;
// chunk stream basic header.
char fmt = 0;
int cid = 0;
int bh_size = 0;
if ((ret = read_basic_header(fmt, cid, bh_size)) != ERROR_SUCCESS) {
srs_error("read basic header failed. ret=%d", ret);
return ret;
}
srs_info("read basic header success. fmt=%d, cid=%d, bh_size=%d", fmt, cid, bh_size);
// get the cached chunk stream.
SrsChunkStream* chunk = NULL;
if (chunk_streams.find(cid) == chunk_streams.end()) {
chunk = chunk_streams[cid] = new SrsChunkStream(cid);
srs_info("cache new chunk stream: fmt=%d, cid=%d", fmt, cid);
} else {
chunk = chunk_streams[cid];
srs_info("cached chunk stream: fmt=%d, cid=%d, size=%d, message(type=%d, size=%d, time=%d, sid=%d)",
chunk->fmt, chunk->cid, (chunk->msg? chunk->msg->size : 0), chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
}
// chunk stream message header
int mh_size = 0;
if ((ret = read_message_header(chunk, fmt, bh_size, mh_size)) != ERROR_SUCCESS) {
srs_error("read message header failed. ret=%d", ret);
return ret;
}
srs_info("read message header success. "
"fmt=%d, mh_size=%d, ext_time=%d, size=%d, message(type=%d, size=%d, time=%d, sid=%d)",
fmt, mh_size, chunk->extended_timestamp, (chunk->msg? chunk->msg->size : 0), chunk->header.message_type,
chunk->header.payload_length, chunk->header.timestamp, chunk->header.stream_id);
// read msg payload from chunk stream.
SrsMessage* msg = NULL;
int payload_size = 0;
if ((ret = read_message_payload(chunk, bh_size, mh_size, payload_size, &msg)) != ERROR_SUCCESS) {
srs_error("read message payload failed. ret=%d", ret);
return ret;
}
// not got an entire RTMP message, try next chunk.
if (!msg) {
srs_info("get partial message success. chunk_payload_size=%d, size=%d, message(type=%d, size=%d, time=%d, sid=%d)",
payload_size, (msg? msg->size : (chunk->msg? chunk->msg->size : 0)), chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
return ret;
}
*pmsg = msg;
srs_info("get entire message success. chunk_payload_size=%d, size=%d, message(type=%d, size=%d, time=%d, sid=%d)",
payload_size, (msg? msg->size : (chunk->msg? chunk->msg->size : 0)), chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
return ret;
}
int SrsProtocol::read_basic_header(char& fmt, int& cid, int& bh_size)
{
int ret = ERROR_SUCCESS;
int required_size = 1;
if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
srs_error("read 1bytes basic header failed. required_size=%d, ret=%d", required_size, ret);
return ret;
}
char* p = buffer->bytes();
fmt = (*p >> 6) & 0x03;
cid = *p & 0x3f;
bh_size = 1;
if (cid > 1) {
srs_verbose("%dbytes basic header parsed. fmt=%d, cid=%d", bh_size, fmt, cid);
return ret;
}
if (cid == 0) {
required_size = 2;
if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
srs_error("read 2bytes basic header failed. required_size=%d, ret=%d", required_size, ret);
return ret;
}
cid = 64;
cid += *(++p);
bh_size = 2;
srs_verbose("%dbytes basic header parsed. fmt=%d, cid=%d", bh_size, fmt, cid);
} else if (cid == 1) {
required_size = 3;
if ((ret = buffer->ensure_buffer_bytes(skt, 3)) != ERROR_SUCCESS) {
srs_error("read 3bytes basic header failed. required_size=%d, ret=%d", required_size, ret);
return ret;
}
cid = 64;
cid += *(++p);
cid += *(++p) * 256;
bh_size = 3;
srs_verbose("%dbytes basic header parsed. fmt=%d, cid=%d", bh_size, fmt, cid);
} else {
srs_error("invalid path, impossible basic header.");
srs_assert(false);
}
return ret;
}
int SrsProtocol::read_message_header(SrsChunkStream* chunk, char fmt, int bh_size, int& mh_size)
{
int ret = ERROR_SUCCESS;
// when not exists cached msg, means get an new message,
// the fmt must be type0 which means new message.
if (!chunk->msg && fmt != RTMP_FMT_TYPE0) {
ret = ERROR_RTMP_CHUNK_START;
srs_error("chunk stream start, "
"fmt must be %d, actual is %d. ret=%d", RTMP_FMT_TYPE0, fmt, ret);
return ret;
}
// when exists cache msg, means got an partial message,
// the fmt must not be type0 which means new message.
if (chunk->msg && fmt == RTMP_FMT_TYPE0) {
ret = ERROR_RTMP_CHUNK_START;
srs_error("chunk stream exists, "
"fmt must not be %d, actual is %d. ret=%d", RTMP_FMT_TYPE0, fmt, ret);
return ret;
}
// create msg when new chunk stream start
if (!chunk->msg) {
srs_assert(fmt == RTMP_FMT_TYPE0);
chunk->msg = new SrsMessage();
srs_verbose("create message for new chunk, fmt=%d, cid=%d", fmt, chunk->cid);
}
// read message header from socket to buffer.
static char mh_sizes[] = {11, 7, 1, 0};
mh_size = mh_sizes[(int)fmt];
srs_verbose("calc chunk message header size. fmt=%d, mh_size=%d", fmt, mh_size);
int required_size = bh_size + mh_size;
if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
srs_error("read %dbytes message header failed. required_size=%d, ret=%d", mh_size, required_size, ret);
return ret;
}
char* p = buffer->bytes() + bh_size;
// parse the message header.
// see also: ngx_rtmp_recv
if (fmt <= RTMP_FMT_TYPE2) {
int32_t timestamp_delta;
char* pp = (char*)×tamp_delta;
pp[2] = *p++;
pp[1] = *p++;
pp[0] = *p++;
pp[3] = 0;
if (fmt == RTMP_FMT_TYPE0) {
// 6.1.2.1. Type 0
// For a type-0 chunk, the absolute timestamp of the message is sent
// here.
chunk->header.timestamp = timestamp_delta;
} else {
// 6.1.2.2. Type 1
// 6.1.2.3. Type 2
// For a type-1 or type-2 chunk, the difference between the previous
// chunk's timestamp and the current chunk's timestamp is sent here.
chunk->header.timestamp += timestamp_delta;
}
// fmt: 0
// timestamp: 3 bytes
// If the timestamp is greater than or equal to 16777215
// (hexadecimal 0x00ffffff), this value MUST be 16777215, and the
// ‘extended timestamp header’ MUST be present. Otherwise, this value
// SHOULD be the entire timestamp.
//
// fmt: 1 or 2
// timestamp delta: 3 bytes
// If the delta is greater than or equal to 16777215 (hexadecimal
// 0x00ffffff), this value MUST be 16777215, and the ‘extended
// timestamp header’ MUST be present. Otherwise, this value SHOULD be
// the entire delta.
chunk->extended_timestamp = (timestamp_delta >= RTMP_EXTENDED_TIMESTAMP);
if (chunk->extended_timestamp) {
chunk->header.timestamp = RTMP_EXTENDED_TIMESTAMP;
}
if (fmt <= RTMP_FMT_TYPE1) {
pp = (char*)&chunk->header.payload_length;
pp[2] = *p++;
pp[1] = *p++;
pp[0] = *p++;
pp[3] = 0;
chunk->header.message_type = *p++;
if (fmt == 0) {
pp = (char*)&chunk->header.stream_id;
pp[0] = *p++;
pp[1] = *p++;
pp[2] = *p++;
pp[3] = *p++;
srs_verbose("header read completed. fmt=%d, mh_size=%d, ext_time=%d, time=%d, payload=%d, type=%d, sid=%d",
fmt, mh_size, chunk->extended_timestamp, chunk->header.timestamp, chunk->header.payload_length,
chunk->header.message_type, chunk->header.stream_id);
} else {
srs_verbose("header read completed. fmt=%d, mh_size=%d, ext_time=%d, time=%d, payload=%d, type=%d",
fmt, mh_size, chunk->extended_timestamp, chunk->header.timestamp, chunk->header.payload_length,
chunk->header.message_type);
}
} else {
srs_verbose("header read completed. fmt=%d, mh_size=%d, ext_time=%d, time=%d",
fmt, mh_size, chunk->extended_timestamp, chunk->header.timestamp);
}
} else {
srs_verbose("header read completed. fmt=%d, size=%d, ext_time=%d",
fmt, mh_size, chunk->extended_timestamp);
}
if (chunk->extended_timestamp) {
mh_size += 4;
required_size = bh_size + mh_size;
srs_verbose("read header ext time. fmt=%d, ext_time=%d, mh_size=%d", fmt, chunk->extended_timestamp, mh_size);
if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
srs_error("read %dbytes message header failed. required_size=%d, ret=%d", mh_size, required_size, ret);
return ret;
}
char* pp = (char*)&chunk->header.timestamp;
pp[3] = *p++;
pp[2] = *p++;
pp[1] = *p++;
pp[0] = *p++;
srs_verbose("header read ext_time completed. time=%d", chunk->header.timestamp);
}
// valid message
if (chunk->header.payload_length < 0) {
ret = ERROR_RTMP_MSG_INVLIAD_SIZE;
srs_error("RTMP message size must not be negative. size=%d, ret=%d",
chunk->header.payload_length, ret);
return ret;
}
// copy header to msg
chunk->msg->header = chunk->header;
return ret;
}
int SrsProtocol::read_message_payload(SrsChunkStream* chunk, int bh_size, int mh_size, int& payload_size, SrsMessage** pmsg)
{
int ret = ERROR_SUCCESS;
// empty message
if (chunk->header.payload_length == 0) {
// need erase the header in buffer.
buffer->erase(bh_size + mh_size);
srs_trace("get an empty RTMP "
"message(type=%d, size=%d, time=%d, sid=%d)", chunk->header.message_type,
chunk->header.payload_length, chunk->header.timestamp, chunk->header.stream_id);
*pmsg = chunk->msg;
chunk->msg = NULL;
return ret;
}
srs_assert(chunk->header.payload_length > 0);
// the chunk payload size.
payload_size = chunk->header.payload_length - chunk->msg->size;
if (payload_size > in_chunk_size) {
payload_size = in_chunk_size;
}
srs_verbose("chunk payload size is %d, message_size=%d, received_size=%d, in_chunk_size=%d",
payload_size, chunk->header.payload_length, chunk->msg->size, in_chunk_size);
// create msg payload if not initialized
if (!chunk->msg->payload) {
chunk->msg->payload = new int8_t[chunk->header.payload_length];
memset(chunk->msg->payload, 0, chunk->header.payload_length);
srs_verbose("create empty payload for RTMP message. size=%d", chunk->header.payload_length);
}
// read payload to buffer
int required_size = bh_size + mh_size + payload_size;
if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
srs_error("read payload failed. required_size=%d, ret=%d", required_size, ret);
return ret;
}
memcpy(chunk->msg->payload + chunk->msg->size, buffer->bytes() + bh_size + mh_size, payload_size);
buffer->erase(bh_size + mh_size + payload_size);
chunk->msg->size += payload_size;
srs_verbose("chunk payload read complted. bh_size=%d, mh_size=%d, payload_size=%d", bh_size, mh_size, payload_size);
// got entire RTMP message?
if (chunk->header.payload_length == chunk->msg->size) {
*pmsg = chunk->msg;
chunk->msg = NULL;
srs_verbose("get entire RTMP message(type=%d, size=%d, time=%d, sid=%d)",
chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
return ret;
}
srs_verbose("get partial RTMP message(type=%d, size=%d, time=%d, sid=%d), partial size=%d",
chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id,
chunk->msg->size);
return ret;
}
NGINX-RTMP对应的代码无数地方无数行，复杂得无与伦比。
http://blog.csdn
.NET/win_lin/article/details/12844375
