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Android-RTMP直播(续二)

2016-10-15

软硬件环境

  • ubuntu 16.04
  • Android Studio 2.1.3
  • OTT BOx with android 5.1.1
  • nginx 1.11.3
  • nginx-rtmp-module
  • VLC

前言

Android RTMP直播(续)介绍了HLS协议相关的基础内容,本文将继续深入学习HLS的其它高级特性.

服务端多码率支持

nginx.conf
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#user nobody;
worker_processes auto;

rtmp_auto_push on;

error_log logs/error.log;
error_log logs/error.log notice;
error_log logs/error.log info;

#pid logs/nginx.pid;

events {
worker_connections 1024;
}

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 32x32. 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 ffmpeg -re -i rtmp://localhost:1935/$app/$name -vcodec flv -acodec copy -s 32x32
#-f flv rtmp://localhost:1935/small/${name};
#}

#application small {
# live on;
# # Video with reduced resolution comes here from ffmpeg
#}

#application webcam {
# live on;

# Stream from local webcam
# exec_static ffmpeg -f video4linux2 -i /dev/video0 -c:v libx264 -an
#-f flv rtmp://localhost:1935/webcam/mystream;
#}

# application mypush {
# live on;

# Every stream published here
# is automatically pushed to
# these two machines
#push rtmp1.example.com;
#push rtmp2.example.com:1934;
# }

# application mypull {
# live on;

# Pull all streams from remote machine
# and play locally
#pull rtmp://rtmp3.example.com pageUrl=www.example.com/index.html;
# }

# application mystaticpull {
# live on;

# Static pull is started at nginx start
#pull rtmp://rtmp4.example.com pageUrl=www.example.com/index.html name=mystream static;
# }

# video on demand
# application vod {
# play /opt/www/vod;
# }

# 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
# on_publish http://localhost:8080/publish;

# Same with playing
# on_play http://localhost:8080/play;

# Publish/play end (repeats on disconnect)
# on_done http://localhost:8080/done;

# 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 /tmp/vc;
# record_max_frames 10;
# record_interval 2m;

# Async notify about an flv recorded
# on_record_done http://localhost:8080/record_done;

#}


# HLS

# For HLS to work please create a directory in tmpfs (/tmp/hls here)
# for the fragments. The directory contents is served via HTTP (see
# http{} section in config)
#
# Incoming stream must be in H264/AAC. 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 {
live on;
hls on;
hls_path /opt/www/live;
hls_nested on;

hls_variant _low BANDWIDTH=800000;
hls_variant _mid BANDWIDTH=1200000;
hls_variant _hi BANDWIDTH=2000000;
}

# MPEG-DASH is similar to HLS

#application dash {
# live on;
# dash on;
# dash_path /tmp/dash;
#}
}
}

# HTTP can be used for accessing RTMP stats
http {

server {

listen 8081;

location / {
root /opt/www/;
}

# 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 /home/djstava/Workshop/Web/nginx-rtmp-module/;
}

location /hls {
# Serve HLS fragments
types {
application/vnd.apple.mpegurl m3u8;
video/mp2t ts;
}

root /opt/www/;
add_header Cache-Control no-cache;
}

#location /dash {
# Serve DASH fragments
# root /tmp;
# add_header Cache-Control no-cache;
#}
}
}

主要看看application hls的内容

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application hls {
live on;
hls on;
hls_path /opt/www/live;
hls_nested on;

hls_variant _low BANDWIDTH=800000;
hls_variant _mid BANDWIDTH=1200000;
hls_variant _hi BANDWIDTH=2000000;
}

这里设定当带宽分别为800k 1200k 2000k的时候,终端都播放相对应的m3u8索引文件

ffmpeg推流

这里需要利用ffmpeg推送3路不同的流,对应上面提到的低 中 高

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ffmpeg -re -i ~/Videos/xjcy.mp4 -vcodec copy -acodec copy -b:v 800k -b:a 32k -f flv rtmp://10.10.10.59/hls/livestream_low
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ffmpeg -re -i ~/Videos/xjcy.mp4 -vcodec copy -acodec copy -b:v 1200k -b:a 64k -f flv rtmp://10.10.10.59/hls/livestream_mid
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ffmpeg -re -i ~/Videos/xjcy.mp4 -vcodec copy -acodec copy -b:v 2000k -b:a 128k -f flv rtmp://10.10.10.59/hls/livestream_hi

推送开始后,hls的root目录下就会生成相应的文件内容,如下图所示

nginx_ffmpeg_variant

此时livestream.m3u8文件内容为

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#EXTM3U
#EXT-X-VERSION:3
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=800000
livestream_low/index.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=1200000
livestream_mid/index.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=2000000
livestream_hi/index.m3u8

相应的,播放链接为 http://10.10.10.59:8081/live/livestream.m3u8,播放器需要做的就是根据自身的网络状况,切换到其它的索引文件.

直播节目的录制

直播进行的同时一般都会有本地录制的需求,nginx-rtmp-module提供了这个功能,接下来实践一下.还是看nginx.conf配置文件

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application hls {
live on;
hls on;
hls_path /opt/www/live;
hls_nested on;

hls_variant _low BANDWIDTH=800000;
hls_variant _mid BANDWIDTH=1200000;
hls_variant _hi BANDWIDTH=2000000;

recorder all {
record all;
record_suffix -%Y-%m-%d-%H_%M_%S.flv;
record_max_size 200000K;
record_path /opt/www/record;
}
}

record all录制所有内容,也可以只录音频或者视频.

推流后/opt/www/record路径下就会自动生成带对应时间戳的flv文件,用vlc测试播放OK.

nginx_ffmpeg_record

时移电视

要想实现时移电视(这里指的是服务器端)的话,首先需要在服务器上保留足够的切片文件,比如说你提供1小时的时移,就意味着要有1小时的切片文件,而且索引文件中包含前1小时的切片序列.

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application hls {
live on;
hls on;
hls_path /opt/www/live;
hls_continuous on;
hls_sync 100ms;
hls_nested on;
hls_playlist_length 5m;
hls_fragment 10s;

hls_variant _low BANDWIDTH=800000;
hls_variant _mid BANDWIDTH=1200000;
hls_variant _hi BANDWIDTH=2000000;

#exec /home/djstava/Workshop/Web/nginx-1.11.3/build/test.sh;
#exec_kill_signal term;

#recorder all {
# record all;
# record_suffix -%Y-%m-%d-%H_%M_%S.flv;
# record_max_size 6200000K;
# record_path /opt/www/record;
#}
}

hls_fragment指的是切片文件的长度,这里是10秒,hls_playlist_length指的是索引文件的长度,我这里设的是5分钟.推流开始后,你到切片生成的目录,会发现*.m3u8文件包含了30个ts序列.所以,在上面这种情况下,就只能进行5分钟的时移,当播放进度到达当前直播点时则继续回到直播状态.

执行外部shell脚本

比如有个脚本test.sh,内容如下

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#!/bin/bash

on_die ()
{
# kill all children
pkill -KILL -P $$
}

trap 'on_die' TERM
ffmpeg -re -i /home/djstava/Videos/ygdx.mp4 -vcodec copy -acodec copy -f flv rtmp://10.10.10.48/hls/ygdx &
wait

我这里把它放在hls application中执行,则nginx.conf应如下

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application hls {
live on;
hls on;
hls_path /opt/www/live;
hls_continuous on;
hls_sync 100ms;
hls_nested on;
hls_playlist_length 5m;
hls_fragment 10s;

hls_variant _low BANDWIDTH=800000;
hls_variant _mid BANDWIDTH=1200000;
hls_variant _hi BANDWIDTH=2000000;

exec /home/djstava/Workshop/Web/nginx-1.11.3/build/test.sh;
exec_kill_signal term;

#recorder all {
# record all;
# record_suffix -%Y-%m-%d-%H_%M_%S.flv;
# record_max_size 6200000K;
# record_path /opt/www/record;
#}
}

当hls服务正常启动时(如上面写过的ffmpeg推流动作),外部脚本test.sh也被执行了.脚本中捕捉了退出的中断信号,也就说,如果ffmpeg推流动作中断了,那么test.sh脚本也就不再执行了.

制作RAMDISK

为了提高HLS的读写效率,可以把切片和索引文件操作放在内存中进行.

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mount -t tmpfs -o size=512m tmpfs /opt/www/live

参考文献

1 https://github.com/arut/nginx-rtmp-module/wiki/Directives

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