我有一个名为“Post”的模型,它将引用图像和视频。我为缩略图存储添加了 ImageSpecField 并创建了一个函数,它从上传的视频中提取所需的帧。生成缩略图时有什么方法可以使用此功能吗?因为现在 ImageSpecField 只能使用 FileField 作为输入。
我曾尝试创建一个继承自 ImageSpecField 的新类,但我很快意识到这行不通,因为此类仅在服务器启动时实例化,因此将此函数放在它的构造函数中是行不通的。
import cv2 as cv
from django.conf import settings
from django.db import models
from imagekit.processors import ResizeToFit
from imagekit.models import ImageSpecField
def video_to_image(source, frame):
vid_cap = cv.VideoCapture(settings.MEDIA_ROOT + source.__str__())
vid_cap.set(cv.CAP_PROP_POS_FRAMES, frame)
success, image = vid_cap.read()
vid_cap.release()
return image
class Post(models.Model):
IMAGE = 'I'
VIDEO = 'V'
FILE_TYPES = [
(IMAGE, 'Image'),
(VIDEO, 'Video')
]
file_type = models.CharField(max_length=1, choices=FILE_TYPES)
file = models.FileField(upload_to='post_images')
thumbnail_frame = models.IntegerField(default=0)
image_thumbnail = ImageSpecField(source='file',
processors=[ResizeToFit(width=200, height=200)],
format='JPEG',
options={'quality': 60})
我希望 imagekit 从视频生成缩略图,并能够通过 ImageSpecField 获取它。
最佳答案
好吧,我想我终于明白了。我设法通过创建另一个字段 - thumbnail_source_image 并根据上传的文件类型执行以下操作来实现它:
- 对于图像 - 将 thumbnail_source_image 设置为与文件字段相同的值
- 对于视频 - 从给定的毫秒视频生成图像,将其保存到与文件相同的位置,并将其设置为 thumbnail_source_image
我正在使用魔术库获取文件类型。
但是这种方法有一个小问题——要让 Django 生成文件路径,我们必须在我们的模型上调用 save() 方法。这迫使我们向数据库发出两个请求,而不是一个。
utils.py 文件:
import cv2 as cv
def save_frame_from_video(video_path, millisecond, frame_file_path):
vidcap = cv.VideoCapture(video_path)
vidcap.set(cv.CAP_PROP_POS_MSEC, millisecond)
success, image = vidcap.read()
# save image to temp file
cv.imwrite(frame_file_path, image)
vidcap.release()
models.py 文件:
import os
from django.conf import settings
from django.db import models
from imagekit.processors import ResizeToFit
from imagekit.models import ImageSpecField
from .utils import save_frame_from_video
class Post(models.Model):
image_types = ['image/jpeg', 'image/gif', 'image/png']
video_types = ['video/webm']
IMAGE = 'I'
VIDEO = 'V'
TYPES = [
(IMAGE, 'Image'),
(VIDEO, 'Video'),
]
type = models.CharField(max_length=1, choices=TYPES, blank=True)
file = models.FileField(upload_to='post_files/%Y/%m/%d/')
thumbnail_millisecond = models.IntegerField(default=0)
thumbnail_source_image = models.ImageField(upload_to='post_files/%Y/%m/%d/', null=True, blank=True)
image_thumbnail = ImageSpecField(source='thumbnail_source_image',
processors=[
ResizeToFit(150,
150,
mat_color=(230, 230, 230)),
],
format='JPEG',
options={'quality': 80})
def _set_type(self):
# max bytes to read for file type detection
read_size = 5 * (1024 * 1024) # 5MB
# read mime type of file
from magic import from_buffer
mime = from_buffer(self.file.read(read_size), mime=True)
if mime in self.image_types:
self.type = self.IMAGE
elif mime in self.video_types:
self.type = self.VIDEO
def _set_thumbnail_source_image(self):
if self.type == self.IMAGE:
self.thumbnail_source_image = self.file
elif self.type == self.VIDEO:
# create thumbnail source file
image_path = os.path.splitext(self.file.path)[0] + '_thumbnail_src_image.jpg'
save_frame_from_video(self.file.path, int(self.thumbnail_millisecond), image_path)
# generate path relative to media root, because this is the version that ImageField accepts
media_image_path = os.path.relpath(image_path, settings.MEDIA_ROOT)
self.thumbnail_source_image = media_image_path
def save(self, *args, **kwargs):
if self.type == '':
self._set_type()
# if there is no source image
if not bool(self.thumbnail_source_image):
# we need to save first, for django to generate path for file in "file" field
super().save(*args, **kwargs)
self._set_thumbnail_source_image()
super().save(*args, **kwargs)
关于python - 使用 imagekit 和 opencv 创建视频缩略图,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/57867278/