MPlayer saves wrong aspect ratio image as screenshoot

[Kimio Miyamura]

Summary of the bug:
When trying to make screenshot of DVD sized mp4(720x480), the following command create 720x480 sized jpeg image. Even though it should be saved as a 854x480 sized image.
Also, tested 720x404 sized movie or 720x396 sized movie, the command created 720x480 sized jpeg image.
Currently, 640x480 sized movie only produce correct sized screenshot image.
It is not correspond with format of image. With -vo png, wrong sized png image are created.
I'm using 2 bash script which create contact sheet of movie. One of script uses MPlayer only. And another one can switch ffmpeg and MPlayer. The issue have found script which use MPlayer only. Then tried another one by switching ffmpeg to MPlayer. Then the issue was reproduced.
Note that the latter script creates fine contact sheet when using ffmpeg.
How to reproduce:

mplayer -ao null -vf pp=ac -vf pp=ac/lb -vo jpeg:outdir=./ -ss 102 -frames 1 '/Users/username/Movies/More Than You Know.mp4'

MPlayer SVN-r37183-4.2.1 (C) 2000-2014 MPlayer Team
Can't init Apple Remote.

Playing /Users/username/Movies/More Than You Know.mp4.
libavformat version 55.37.102 (internal)
libavformat file format detected.
[lavf] stream 0: video (h264), -vid 0
[lavf] stream 1: audio (aac), -aid 0, -alang und
VIDEO: [H264] 720x480 24bpp 29.970 fps 2286.9 kbps (279.2 kbyte/s)
Clip info:

major_brand: isom
minor_version: 512
compatible_brands: isomiso2avc1mp41
encoder: Lavf54.63.104

Load subtitles in /Users/username/Movies/
jpeg: Progressive JPEG disabled.
jpeg: Baseline JPEG enabled.
Opening video filter: [pp=ac/lb]
Opening video filter: [scale]
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
libavcodec version 55.60.103 (internal)
Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
==========================================================================
==========================================================================
Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders
AUDIO: 44100 Hz, 6 ch, floatle, 177.1 kbit/2.09% (ratio: 22133->1058400)
Selected audio codec: [ffaac] afm: ffmpeg (FFmpeg AAC (MPEG-2/MPEG-4 Audio))
==========================================================================
AO: [null] 44100Hz 2ch floatle (4 bytes per sample)
Starting playback...
[PP] Using external postprocessing filter, max q = 6.
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
[swscaler @ 0x10e28a170]bicubic scaler, from yuv420p to rgb24 using MMXEXT
[swscaler @ 0x10e28a170]using unscaled yuv420p -> rgb24 special converter
VO: [jpeg] 720x480 => 854x480 RGB 24-bit
jpeg: output directory: ./
A: 103.0 V: 103.1 A-V: -0.024 ct: 0.001 0/ 0 ??% ??% ??,?% 0 0

Exiting... (End of file)