1、 為何要使用HTTP Live Streaming

可以參考wikipedia

HTTP Live Streaming（縮寫是 HLS）是一個由蘋果公司提出的基於HTTP的流媒體 網路傳輸協議。是蘋果公司QuickTime X和iPhone軟體系統的一部分。它的工作原理是把整個流分成一個個小的基於HTTP的檔案來下載，每次只下載一些。當媒體流正在播放時，客戶端可以選擇從許多不同的備用源中以不同的速率下載同樣的資源，允許流媒體會話適應不同的資料速率。在開始一個流媒體會話時，客戶端會下載一個包含元資料的extended M3U (m3u8) playlist檔案，用於尋找可用的媒體流。

HLS只請求基本的HTTP報文，與實時傳輸協議（RTP)不同，HLS可以穿過任何允許HTTP資料通過的防火牆或者代理伺服器。它也很容易使用內容分發網路來傳輸媒體流。

2、 HTTP Live Streaming技術方案

使用ffmpeg來完成對flv、mp4、mp3等格式的轉化

使用ffmpeg或segmenter完成對視訊/音訊格式檔案的切割，切割為m3u8格式及ts檔案

3、 準備工作

作業系統CentOS

3.1、準備安裝刪除已安裝包

yum erase ffmpeg x264 x264-devel

3.2、安裝各種依賴包

yum install  gcc make nasm pkgconfig wget curl curl-devel zlib-devel openssl-devel perl cpio expat-devel gettext-devel libtool mhash.x86_64 perl-Digest-SHA1.x86_64  pcre.i386 pcre.x86_64 pcre-devel.i386 pcre-devel.x86_64

3.3、安裝git

unzip git-devel.zip

cd git-devel/

autoconf

./configure

make

make install

3.4、建立安裝包目錄

mkdir ~/ffmpeg-source

4、 安裝ffmpeg及其依賴包

4.1、Yasm

cd ~/ffmpeg-source

tar xzvf yasm-1.2.0.tar.gz

cd yasm-1.2.0

./configure

make

make install

4.2、x264

cd ~/ffmpeg-source

cd x264

./configure –enable-shared

make

make install

4.3、LAME

cd ~/ffmpeg-source

tar xzvf lame-3.99.5.tar.gz

cd lame-3.99.5

./configure –enable-nasm

make

make install

4.4、libogg

cd ~/ffmpeg-source

tar xzvf libogg-1.3.0.tar.gz

cd libogg-1.3.0

./configure

make

make install

4.5、libvorbis

cd ~/ffmpeg-source

tar xzvf libvorbis-1.3.3.tar.gz

cd libvorbis-1.3.3

./configure

make

make install

4.6、libvpx

cd ~/ffmpeg-source

cd libvpx

./configure  –enable-shared

make

make install

4.7、 FAAD2

cd ~/ffmpeg-source

tar zxvf faad2-2.7.tar.gz

cd faad2-2.7

./configure

make

make install

4.8、FAAC

cd ~/ffmpeg-source

tar zxvf faac-1.28.tar.gz

cd faac-1.28

./configure

make

make install

4.9、Xvid

cd ~/ffmpeg-source

tar zxvf xvidcore-1.3.2.tar.gz

cd xvidcore/build/generic

./configure

make

make install

4.10、FFmpeg

cd ~/ffmpeg-source

cd ffmpeg

./configure  –enable-version3  –enable-libvpx –enable-libfaac –enable-libmp3lame  –enable-libvorbis –enable-libx264 –enable-libxvid –enable-shared –enable-gpl –enable-postproc –enable-nonfree –enable-avfilter –enable-pthreads

make

make install

ldconfig –v

5、 安裝nginx及nginx-rtmp-module

mkdir ~/nginx-source

cd  ~/nginx-source

tar zxvf nginx-1.2.4.tar.gz

unzip nginx-rtmp-module.zip

unzip ngx_cache_purge.zip

cd nginx-1.2.4

./configure –user=daemon –group=daemon –prefix=/usr/local/nginx-1.2.4/ –add-module=../nginx-rtmp-module-master –add-module=../nginx-rtmp-module-master/hls –add-module=../ngx_cache_purge-master  –with-http_stub_status_module –with-http_ssl_module –with-http_sub_module –with-md5=/usr/lib –with-sha1=/usr/lib –with-http_gzip_static_module

在nginx.conf中增加rtmp模組的相關配置，配置例子

rtmp {

server {

listen 1935;

chunk_size 4000;

# TV mode: one publisher, many subscribers

application mytv {

# enable live streaming

live on;

# record first 1K of stream

record all;

record_path /tmp/av;

record_max_size 1K;

# append current timestamp to each flv

record_unique on;

# publish only from localhost

allow publish 127.0.0.1;

deny publish all;

#allow play all;

}

# Transcoding (ffmpeg needed)

application big {

live on;

# On every pusblished stream run this command (ffmpeg)

# with substitutions: $app/${app}, $name/${name} for application & stream name.

#

# This ffmpeg call receives stream from this application &

# reduces the resolution down to 32×32. The stream is the published to

# ‘small’ application (see below) under the same name.

#

# ffmpeg can do anything with the stream like video/audio

# transcoding, resizing, altering container/codec params etc

#

# Multiple exec lines can be specified.

exec /usr/local/bin/ffmpeg -re -i rtmp://localhost:1935/$app/$name -vcodec flv -acodec copy -s 32×32 -f flv rtmp://localhost:1935/small/${name};

}

application small {

live on;

# Video with reduced resolution comes here from ffmpeg

}

application mypush {

live on;

# Every stream published here

# is automatically pushed to

# these two machines

}

application mypull {

live on;

# Pull all streams from remote machine

# and play locally

}

# video on demand

application vod {

play /var/flvs;

}

application vod2 {

play /var/mp4s;

}

# Many publishers, many subscribers

# no checks, no recording

application videochat {

live on;

# The following notifications receive all

# the session variables as well as

# particular call arguments in HTTP POST

# request

# Make HTTP request & use HTTP retcode

# to decide whether to allow publishing

# from this connection or not

# Same with playing

# Publish/play end (repeats on disconnect)

# All above mentioned notifications receive

# standard connect() arguments as well as

# play/publish ones. If any arguments are sent

# with GET-style syntax to play & publish

# these are also included.

# Example URL:

#   rtmp://localhost/myapp/mystream?a=b&c=d

# record 10 video keyframes (no audio) every 2 minutes

record keyframes;

record_path /var/vc;

record_max_frames 10;

record_interval 2m;

# Async notify about an flv recorded

}

# HLS

# HLS requires libavformat & should be configured as a separate

# NGINX module in addition to nginx-rtmp-module:

# ./configure … –add-module=/path/to/nginx-rtmp-module/hls …

# For HLS to work please create a directory in tmpfs (/tmp/app here)

# for the fragments. The directory contents is served via HTTP (see

# http{} section in config)

#

# Incoming stream must be in H264/AAC/MP3. For iPhones use baseline H264

# profile (see ffmpeg example).

# This example creates RTMP stream from movie ready for HLS:

#

# ffmpeg -loglevel verbose -re -i movie.avi  -vcodec libx264

#    -vprofile baseline -acodec libmp3lame -ar 44100 -ac 1

#    -f flv rtmp://localhost:1935/hls/movie

#

# If you need to transcode live stream use ‘exec’ feature.

#

application hls {

hls on;

hls_path /var/app;

hls_fragment 5s;

}

}

}

# HTTP can be used for accessing RTMP stats

http {

server {

listen      8080;

# This URL provides RTMP statistics in XML

location /stat {

rtmp_stat all;

# Use this stylesheet to view XML as web page

# in browser

rtmp_stat_stylesheet stat.xsl;

}

location /stat.xsl {

# XML stylesheet to view RTMP stats.

# Copy stat.xsl wherever you want

# and put the full directory path here

root /path/to/stat.xsl/;

}

location /hls {

# Serve HLS fragments

alias /var/app;

}

}

}

6、 安裝segmenter

cd  svn/trunk

gcc -Wall -g segmenter.c -o segmenter -lavformat -lavcodec -lavutil -std=c99

cp segmenter /usr/bin/

從優酷上下載一個視訊檔案，假定為baluobu.flv

找個mp3檔案，假定為10year.mp3

mkdir /var/flvs /var/mp4s /var/vc /var/app /var/app/10year /var/app/baluobu

使用ffmpeg將測試視訊和音訊轉為mpeg ts格式檔案

ffmpeg -i /var/flvs/baluobu.flv  -f mpegts -acodec libmp3lame -ar 48000 -ab 128k -vcodec libx264 -b 96k -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 5 -trellis 1 -refs 1 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 200k -maxrate 96k -bufsize 96k -rc_eq ‘blurCplx^(1-qComp)’ -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 -aspect 320:240 -g 30 -async 2 /var/app/baluobu/baluobu.ts

ffmpeg -i /var/flvs/10year.mp3  -f mpegts -acodec libmp3lame -ar 48000 -ab 128k -vcodec libx264 -b 96k -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 5 -trellis 1 -refs 1 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 200k -maxrate 96k -bufsize 96k -rc_eq ‘blurCplx^(1-qComp)’ -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 -aspect 320:240 -g 30 -async 2 /var/app/10year/10year.ts

cd /var/app/10year

segmenter -i 10year.ts -d 5 -o 10year -x 10year.m3u8

cd /var/app/baluobu

segmenter -i baluobu.ts -d 5 -o buluobu -x baluobu.m3u8

7、測試

簡單起見使用VLC測試。

如果無問題，說明已經正常配置成功了HTTP Live Streaming（HLS）服務

可以再iOS裝置上使用safari訪問以上地址

或者在android機器上安裝vplayer後訪問以上地址

如果需要通過網頁形式提供線上視訊，需要在nginx的mime.types檔案中新增如下MIME型別：

.m3u8 application/x-mpegURL
.ts video/MP2T

同時在HTML5頁面中使用video標籤包含視訊的m3u8檔案

8、開發說明

iOS已經原生支援HTTP Live Streaming（HLS），只需要使用MPMoviePlayerController播放以上地址即可

Android 3.x以後通過新增的NuPlayer類才支援HTTP Live streaming，而且功能也較弱，為簡化處理，可以使用

nginx-rtmp-module 本身也支援RTMP協議，從而也可以基於nginx來搭建線上直播系統。