我正在做一个项目，它从服务器获取视频 URL，然后播放它。视频播放完成后，它会向服务器请求另一个链接，并在收到 URL 后播放它。
我正在使用 mplayer 播放视频。我的新要求是，当视频播放到 50% 时，我的设备应该请求新的链接。
如何获取视频的播放状态？
播放视频时我得到的日志是......
fa@FriendlyELEC:~/Desktop/MediaFiles$ mplayer video.mp4
MPlayer2 2.0-728-g2c378c7-4+b1 (C) 2000-2012 MPlayer Team
Cannot open file '/home/fa/.mplayer/input.conf': No such file or directory
Failed to open /home/fa/.mplayer/input.conf.
Cannot open file '/etc/mplayer/input.conf': No such file or directory
Failed to open /etc/mplayer/input.conf.
Playing video.mp4.
Detected file format: QuickTime / MOV (libavformat)
[lavf] stream 0: video (h264), -vid 0
Clip info:
major_brand: dash
minor_version: 0
compatible_brands: iso6avc1mp41
creation_time: 2016-01-27 09:00:27
Load subtitles in .
[vdpau] Error when calling vdp_device_create_x11: 25
[VO_XV] It seems there is no Xvideo support for your video card available.
[VO_XV] Run 'xvinfo' to verify its Xv support and read
[VO_XV] DOCS/HTML/en/video.html#xv!
[VO_XV] See 'mplayer -vo help' for other (non-xv) video out drivers.
[VO_XV] Try -vo x11.
[ass] auto-open
Selected video codec: H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 [libavcodec]
Audio: no sound
Starting playback...
VIDEO: 1920x1080 23.976 fps 1902.3 kbps (237.8 kB/s)
VO: [x11] 1920x1080 => 1920x1080 Planar YV12
[swscaler @ 0xb5d30980]No accelerated colorspace conversion found from yuv420p to bgra.
[swscaler @ 0xb5d30980]using unscaled yuv420p -> bgra special converter
Colorspace details not fully supported by selected vo.
V: 54.0 0/ 0 7% 163% 0.0% 0 0
我想了解五：
V: 54.0 0/ 0 7% 163% 0.0% 0 0