ARM转码

ARM下，譬如raspberry pi，转码音频还是可行的。ffmpeg转码音频的CPU占用50%。

编译

使用系统的ffmpeg转码时，需要禁止srs编译ffmpeg，同时打开transcode选项：--with-transcode --without-ffmpeg，这样就不会编译ffmpeg，但是编译了直播转码功能。参考：Build

配置文件

使用下面的配置：

listen              1935;
http_stream {
    enabled         on;
    listen          8080;
    dir             ./objs/nginx/html;
}
vhost __defaultVhost__ {
    transcode {
        enabled     on;
        ffmpeg      ./objs/ffmpeg/bin/ffmpeg;
        engine arm_aonly {
            enabled         on;
            vcodec          copy;
            acodec          aac;
            abitrate        48;
            asample_rate    44100;
            achannels       2;
            aparams {
                strict experimental;
            }
            output          rtmp://127.0.0.1:[port]/[app]?vhost=hls/[stream];
        }
    }
}

vhost hls {
    hls {
        enabled         on;
        hls_path        ./objs/nginx/html;
        hls_fragment    10;
        hls_window      60;
    }
}

运行

启动后CPU占用：

top - 07:07:07 up 38 min,  2 users,  load average: 0.96, 0.58, 0.44
Tasks:  74 total,   3 running,  71 sleeping,   0 stopped,   0 zombie
%Cpu(s): 53.2 us, 14.9 sy,  0.0 ni, 28.2 id,  0.0 wa,  0.0 hi,  3.6 si,  0.0 st
KiB Mem:    383156 total,   168808 used,   214348 free,    11704 buffers
KiB Swap:   102396 total,        0 used,   102396 free,   117676 cached

  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
 3592 winlin    20   0 41620  13m 3880 R  52.1  3.5   1:32.72 ./objs/ffmpeg/bin/ffmpeg 
-f flv -i rtmp://127.0.0.1:1935/l 
 3591 winlin    20   0  3400 1464 1056 R  17.4  0.4   0:29.06 ./objs/srs -c console.conf

启动的转码进程：

winlin@raspberrypi:~/srs$ ps aux|grep ffmpeg
winlin    3592 51.2  3.4  41620 13408 pts/0    R+   07:04   1:43 ./objs/ffmpeg/bin/ffmpeg 
-f flv -i rtmp://127.0.0.1:1935/live?vhost=__defaultVhost__/livestream -vcodec copy 
-acodec aac -b:a 48000 -ar 44100 -ac 2 -strict experimental -f flv 
-y rtmp://127.0.0.1:1935/live?vhost=hls/livestream

生成的文件：

winlin@raspberrypi:~/srs$ ll objs/nginx/html/live/
total 6.1M
-rw-r--r-- 1 winlin winlin 936K Apr  5 07:07 livestream-21.ts
-rw-r--r-- 1 winlin winlin 935K Apr  5 07:08 livestream-22.ts
-rw-r--r-- 1 winlin winlin 155K Apr  5 07:08 livestream-23.ts
-rw-r--r-- 1 winlin winlin 833K Apr  5 07:08 livestream-24.ts
-rw-r--r-- 1 winlin winlin 905K Apr  5 07:08 livestream-25.ts
-rw-r--r-- 1 winlin winlin 934K Apr  5 07:08 livestream-26.ts
-rw-r--r-- 1 winlin winlin 933K Apr  5 07:08 livestream-27.ts
-rw-r--r-- 1 winlin winlin 529K Apr  5 07:09 livestream-28.ts.tmp
-rw-r--r-- 1 winlin winlin  155 Apr  5 06:43 livestream.html
-rw-r--r-- 1 winlin winlin  339 Apr  5 07:08 livestream.m3u8