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hls.go
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hls.go
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package main
import (
"encoding/binary"
"flag"
"fmt"
"io"
"log"
"net/http"
"os"
"regexp"
"strconv"
"sync"
"time"
"hls/adts"
"hls/mpegts"
)
// values used are taken from an example working server (Wowza, if I recall correctly)
const PROGRAM_NUMBER = 1
const PROGRAM_MAP_PID = 4095
const STREAM_PACKET_IDENTIFIER = 257
const STREAM_ID = 192
const ESD_PID = 258
type packet = [188]byte
type chunk struct {
index uint64
duration uint64
data []byte
}
func main() {
redirect := flag.String("r", "", "redirect url for non-existent pages")
minimum := flag.Uint("m", 0, "minimum number of active streams required for server to be deemed healthy")
flag.Parse()
args := flag.Args()
addr := args[0]
base := args[1]
list := args[2:]
directory := startdirectory(base, list)
server(addr, directory, *redirect, *minimum)
}
type directory struct {
mutex sync.Mutex
streams map[string]*stream
}
func startdirectory(base string, streams []string) *directory {
d := &directory{streams: map[string]*stream{}}
go func() {
ticker := time.NewTicker(time.Second)
defer ticker.Stop()
for {
d.mutex.Lock()
for _, s := range streams {
if _, ok := d.streams[s]; !ok {
d.streams[s] = start(base, s)
}
}
for k, v := range d.streams {
select {
default:
case <-v.done:
delete(d.streams, k)
}
}
d.mutex.Unlock()
select {
case <-ticker.C:
}
}
}()
return d
}
func (d *directory) find(s string) *stream {
d.mutex.Lock()
defer d.mutex.Unlock()
return d.streams[s]
}
func (d *directory) list() (list []string) {
d.mutex.Lock()
defer d.mutex.Unlock()
for k, v := range d.streams {
if v.ok() {
list = append(list, k)
}
}
return
}
type stream struct {
mutex sync.Mutex
list []chunk
done chan bool
}
func (s *stream) bandwidth() uint {
return 52850
}
func (s *stream) chunk(i uint64) []byte {
s.mutex.Lock()
defer s.mutex.Unlock()
for _, c := range s.list {
if c.index == i {
return c.data
}
}
return nil
}
func (s *stream) ok() bool {
s.mutex.Lock()
defer s.mutex.Unlock()
return len(s.list) > 2
}
func (s *stream) index() (list [][2]uint64) {
s.mutex.Lock()
defer s.mutex.Unlock()
if len(s.list) < 3 {
return
}
for _, c := range s.list {
list = append(list, [2]uint64{c.index, c.duration})
}
for len(list) > 3 {
list = list[1:]
}
return
}
func start(base, name string) (s *stream) {
s = &stream{done: make(chan bool)}
go func() {
url := base + "/" + name
defer func() {
time.Sleep(20 * time.Second) // delay before retrying
close(s.done)
}()
in := open(url)
if in == nil {
return
}
index := uint64(time.Now().Unix()) / 10
adjust := 3120 * uint64(time.Second)
a2m := adtsToMPEGTS(uint64(time.Now().UnixNano())+adjust, 10, true)
data := make([]byte, 0, 100000)
for c := range in {
out, err := a2m(c)
if err != nil {
s.mutex.Lock()
s.list = nil
s.mutex.Unlock()
return
}
for _, o := range out {
if ts := mpegts.TS(o); ts.TEI() {
//log.Printf("Chunk %d for %s, %d bytes\n", index, name, len(data))
if len(data) > 0 {
s.mutex.Lock()
s.list = append(s.list, chunk{index: index, duration: marker(o).duration(), data: data})
for len(s.list) > 10 {
s.list = s.list[1:]
}
s.mutex.Unlock()
index++
}
data = make([]byte, 0, 100000)
} else {
data = append(data, o[:]...)
}
}
}
}()
return
}
type marker [188]byte
func dummy(timestamp, duration uint64) (dummy marker) {
dummy[1] = 0x80 //set TEI bit
binary.BigEndian.PutUint64(dummy[2:], timestamp)
binary.BigEndian.PutUint64(dummy[2+8:], duration)
return
}
func (m marker) timestamp() uint64 {
return binary.BigEndian.Uint64(m[2:])
}
func (m marker) duration() uint64 {
return binary.BigEndian.Uint64(m[2+8:])
}
func (m marker) time() time.Time {
ts := m.timestamp()
sec := ts / uint64(time.Second)
ns := ts % uint64(time.Second)
return time.Unix(int64(sec), int64(ns))
}
func adtsProgramSpecificInformation() func() []packet {
var program_number uint16 = PROGRAM_NUMBER
var program_map_pid uint16 = PROGRAM_MAP_PID
var pid uint16 = STREAM_PACKET_IDENTIFIER
var esdpid uint16 = ESD_PID
//esd := []byte{14,3,192,3,32} ???
// NAK & \r \255 \255 I D 3 ' ' 255 ID 3 ' ' \0 SI
// program descriptors and elementary stream info data - just taken from a working server
dsc := []byte{0x25, 255, 255, 73, 68, 51, 32, 255, 73, 68, 51, 32, 0, 3, 0, 1}
esd := []byte{0x15, 38, 13, 255, 255, 73, 68, 51, 32, 255, 73, 68, 51, 32, 0, 15}
return mpegts.ProgramSpecificInformation(program_number, program_map_pid, pid, dsc, esd, esdpid)
}
func adtsToMPEGTS(start uint64, interval uint, marker bool) func(adts.Frame) ([]packet, error) {
patpmt := adtsProgramSpecificInformation()
pes := packetizedElementaryStream(STREAM_PACKET_IDENTIFIER, STREAM_ID)
var totalFramesProcessed uint64
var framesSincePAT uint
var fps float64
var sfq uint
var tic uint64
return func(frame adts.Frame) (out []packet, err error) {
if sfq == 0 {
sfq = frame.SamplingFrequency()
if sfq == 0 {
return nil, fmt.Errorf("SamplingFrequency is zero")
}
fps = frame.FramesPerSecond()
tic = frame.FrameLengthNano()
}
if frame.SamplingFrequency() != sfq {
return nil, fmt.Errorf("SamplingFrequency changed")
}
if frame.NumberAACFramesMinusOne() != 0 {
return nil, fmt.Errorf("NumberAACFrames is greater than one")
}
// if we have more than (approximately) <interval> seconds of audio then reset count to trigger PAT/PMT
if framesSincePAT > (uint(fps) * interval) {
// and also send a dummy packet (if requested) with some metadata about the chunk which has just finished
if marker {
out = append(out, dummy(start+tic*totalFramesProcessed, uint64(framesSincePAT)*tic)) // timestamp, duration
}
framesSincePAT = 0
}
// will send a PAT/PMT at the start and every <interval> seconds thereafter
if framesSincePAT == 0 {
out = append(out, patpmt()...)
}
// we kep things simple and send one audio frame per PES packet (which can span multiple 188-byte network packets)
out = append(out, pes(frame, start+tic*totalFramesProcessed)...)
totalFramesProcessed++
framesSincePAT++
return
}
}
func stdin(out chan adts.Frame) {
f := os.Stdin
defer close(out)
fn := adts.ADTS()
for {
buff := make([]byte, 8192)
n, err := f.Read(buff)
if err != nil {
return
}
fn(buff[:n], func(frame []byte, sync bool) bool {
if !sync {
panic("sync")
}
out <- frame
return true
})
}
}
// could probably go into MPEG-TS library
func packetizedElementaryStream(packetID uint16, streamID uint8) func([]byte, uint64) []packet {
cc := uint8(0) // increments with each invocation of the returned closure
//dai := true
//sid := uint8(STREAM_ID)
//pid := uint16(STREAM_PACKET_IDENTIFIER)
return func(data []byte, time uint64) (out []packet) {
pcr := mpegts.Nano90KHz(time)
oph := mpegts.OptionalPESHeader(make([]byte, 8), true, pcr) // 'true' is DAI (Data alignment indicator) - could be an arg
pes := mpegts.PESPacket(streamID, oph, data)
siz := uint(176)
if len(pes) < 176 {
siz = uint(len(pes))
}
af := mpegts.AdaptationField(make([]byte, 184-siz), false, true, false, mpegts.AFPCR(pcr))
out = append(out, mpegts.TransportStreamPacket(true, false, packetID, cc%16, af, pes[0:siz]))
pes = pes[siz:]
cc++
for len(pes) >= 184 {
out = append(out, mpegts.TransportStreamPacket(false, false, packetID, cc%16, nil, pes[:184]))
pes = pes[184:]
cc++
}
if len(pes) > 0 {
out = append(out, mpegts.TransportStreamPacket(false, false, packetID, cc%16, nil, pes))
cc++
}
return
}
}
func open(endpoint string) chan []byte {
headers := map[string]string{}
client := &http.Client{
//CheckRedirect: redirectPolicyFunc,
}
req, err := http.NewRequest("GET", endpoint, nil)
//req.Header.Add("Icy-MetaData", "1")
resp, err := client.Do(req)
if err != nil {
//log.Println(endpoint, err)
return nil
}
if resp.StatusCode != 200 {
resp.Body.Close()
return nil
}
for k, _ := range resp.Header {
if len(k) < 5 {
continue
}
switch k {
case "Content-Type":
headers[k] = resp.Header[k][0]
default:
if k[0:4] == "Icy-" || k[0:4] == "Ice-" {
headers[k] = resp.Header[k][0]
}
}
}
ch := make(chan []byte)
metaint := uint(0)
if ice_metadata, ok := headers["Icy-Metaint"]; ok {
if p, err := strconv.Atoi(ice_metadata); err != nil || p < 0 {
//log.Println("icy-metaint must be a positive integer", ice_metadata)
resp.Body.Close()
return nil
} else {
metaint = uint(p)
}
}
demux := demuxmeta(metaint)
go func() {
defer resp.Body.Close()
defer close(ch)
chunk := 8192
fn := adts.ADTS()
for {
buff := make([]byte, chunk)
if nread, _ := io.ReadFull(resp.Body, buff); nread != chunk {
//log.Println(endpoint, "short read", nread, chunk)
return
}
cromulent := true
demux(buff, func(b []byte, m bool) {
if m {
//log.Println(string(b))
} else {
fn(b, func(frame []byte, sync bool) bool {
if cromulent && sync {
ch <- frame
return true
}
cromulent = false
return false
})
}
})
if !cromulent {
return
}
}
}()
return ch
}
func demuxmeta(mint uint) func([]byte, func([]byte, bool)) {
// handle degenerate case
if mint == 0 {
return func(buff []byte, f func([]byte, bool)) {
f(buff, false)
}
}
stat := 0 // state: 0 - data, 1 - metaint byte, 2 - metadata
todo := mint // remaining bytes for this state
meta := make([]byte, 0) // metadata buffer
return func(buff []byte, f func([]byte, bool)) {
for len(buff) > 0 {
switch stat {
case 0: // not in metadata
if uint(len(buff)) < todo {
f(buff, false)
todo -= uint(len(buff))
return
}
f(buff[:todo], false)
buff = buff[todo:] // may be empty - caught by for{} condition
todo = 0
stat = 1
case 1: // read metalen byte
todo = uint(buff[0]) << 4 // * 16
meta = make([]byte, 0, 4096) // greater then 255*16
buff = buff[1:]
stat = 2
case 2: // in metadata
if uint(len(buff)) < todo {
meta = append(meta, buff[:]...)
todo -= uint(len(buff))
return
}
meta := append(meta, buff[:todo]...)
f(meta, true)
buff = buff[todo:]
todo = mint
stat = 0
}
}
}
}
func server(addr string, directory *directory, redirect string, minimum uint) {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Server", "Anarcast")
if r.URL.Path == "/" {
if redirect != "" {
http.Redirect(w, r, redirect, http.StatusSeeOther)
} else {
w.WriteHeader(http.StatusOK)
w.Write([]byte("Hello, World!\n"))
}
return
}
if r.URL.Path == "/healthy" {
if len(directory.list()) < int(minimum) {
w.WriteHeader(http.StatusNotFound)
return
}
w.WriteHeader(http.StatusOK)
return
}
re := regexp.MustCompile(`^/([A-Za-z0-9.-_]+)/(|playlist.m3u8|chunklist.m3u8|(\d+).ts)$`)
match := re.FindStringSubmatch(r.URL.Path)
if len(match) != 4 {
if redirect != "" {
http.Redirect(w, r, redirect, http.StatusSeeOther)
} else {
w.WriteHeader(http.StatusNotFound)
w.Write([]byte("Sorry\n"))
}
return
}
mountpoint := match[1]
stream := directory.find(mountpoint)
if stream == nil || stream.index() == nil {
w.WriteHeader(http.StatusNotFound)
return
}
//log.Println(mountpoint, match[3])
switch match[2] {
case "": // eg.: http://hls.example.com/streamname/ - so send the playlist
fallthrough
case "playlist.m3u8":
w.Header().Set("Content-Type", "application/vnd.apple.mpegurl")
w.Header().Set("Transfer-Encoding", "chunked")
w.Header().Set("Connection", "keep-alive")
fmt.Fprintf(w, "#EXTM3U\n")
fmt.Fprintf(w, "#EXT-X-VERSION:3\n")
fmt.Fprintf(w, "#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=%d,CODECS=\"mp4a.40.2\"\n", stream.bandwidth())
fmt.Fprintf(w, "chunklist.m3u8\n")
case "chunklist.m3u8":
list := stream.index()
if len(list) < 3 {
w.WriteHeader(http.StatusNotFound)
return
}
w.Header().Set("Access-Control-Allow-Credentials", "true")
w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, GET, POST, HEAD")
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Expose-Headers", "Date, Server, Content-Type, Content-Length")
w.Header().Set("Access-Control-Allow-Headers", "Content-Type, User-Agent, If-Modified-Since, Cache-Control, Range")
w.Header().Set("Cache-Control", "no-cache")
w.Header().Set("Content-Type", "application/vnd.apple.mpegurl")
w.WriteHeader(http.StatusOK)
fmt.Fprintln(w, "#EXTM3U")
fmt.Fprintln(w, "#EXT-X-VERSION:3")
fmt.Fprintln(w, "#EXT-X-TARGETDURATION:12") // >= max segment length
fmt.Fprintln(w, "#EXT-X-MEDIA-SEQUENCE: ", list[0][0])
for _, v := range list {
fmt.Fprintf(w, "#EXTINF:%.2f\n%d.ts\n", float64(v[1])/1000000000, v[0])
}
default:
index, err := strconv.Atoi(match[3])
if err != nil {
w.WriteHeader(http.StatusNotFound)
return
}
chunk := stream.chunk(uint64(index))
if len(chunk) < 1 {
w.WriteHeader(http.StatusNotFound)
return
}
w.Header().Set("Access-Control-Expose-Headers", "Date, Server, Content-Type, Content-Length")
w.Header().Set("Cache-Control", "no-cache")
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Allow-Credentials", "true")
w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, GET, POST, HEAD")
w.Header().Set("Access-Control-Allow-Headers", "Content-Type, User-Agent, If-Modified-Since, Cache-Control, Range")
w.Header().Set("Content-Length", fmt.Sprintf("%d", len(chunk)))
w.Header().Set("Content-Type", "video/MP2T")
w.WriteHeader(http.StatusOK)
w.Write(chunk)
}
})
log.Fatal(http.ListenAndServe(addr, nil))
}