import subprocess
import json
def get_aspect_ratios(video_file):
cmd = 'ffprobe -i "{}" -v quiet -print_format json -show_format -show_streams'.format(video_file)
# jsonstr = subprocess.getoutput(cmd)
jsonstr = subprocess.check_output(cmd, shell=True, encoding='utf-8')
r = json.loads(jsonstr)
# look for "codec_type": "video". take the 1st one if there are mulitple
video_stream_info = [x for x in r['streams'] if x['codec_type']=='video'][0]
if 'display_aspect_ratio' in video_stream_info and video_stream_info['display_aspect_ratio']!="0:1":
a,b = video_stream_info['display_aspect_ratio'].split(':')
dar = int(a)/int(b)
else:
# some video do not have the info of 'display_aspect_ratio'
w,h = video_stream_info['width'], video_stream_info['height']
dar = int(w)/int(h)
## not sure if we should use this
#cw,ch = video_stream_info['coded_width'], video_stream_info['coded_height']
#sar = int(cw)/int(ch)
if 'sample_aspect_ratio' in video_stream_info and video_stream_info['sample_aspect_ratio']!="0:1":
# some video do not have the info of 'sample_aspect_ratio'
a,b = video_stream_info['sample_aspect_ratio'].split(':')
sar = int(a)/int(b)
else:
sar = dar
par = dar/sar
return dar, sar, par
存储纵横比是以像素为单位的图像宽高比,可以很容易地从视频文件中计算出来。在
显示纵横比是在屏幕上显示时图像的宽高比(以厘米或英寸为单位),根据像素纵横比和存储纵横比的组合计算。在
SAR×PAR= DAR。在
例如,一个640×480的VGA图像的SAR为640/480=4:3,如果在4:3显示(DAR=4:3)显示为正方形像素,则为1:1的PAR。相比之下,720×576d-1pal图像的SAR为720/576=5:4,但显示在4:3显示器上(DAR=4:3)。在Source
因此,使用OpenCV可以得到SAR(像素尺寸的比率),但我怀疑您能否从中获得一个常量显示纵横比(因为它与显示相关)。在
你可以做的是当displaying图像时,你可以得到window property,它有一个标志WND_PROP_ASPECT_RATIO。在
我相信这适用于大多数视频(需要ffprobe,它与ffmpeg一起提供)
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