在 Django 上使用 OpenCV 将视频分割为图像

Question

我有一个 REST api，我的用户可以上传 base64 编码的视频。上传后，我想将视频分割成帧来训练人工智能。这是我的序列化程序的当前版本：

# My models
class UserProfile(models.Model):
    user = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
    captureDateTime = models.CharField(_('Capture datetime'), blank=True, null=True, max_length=100)

class UserUploadedData(models.Model):
    profile = models.ForeignKey(UserProfile, on_delete=models.CASCADE)
    rawData = models.TextField(_('Raw Data'), blank=True, null=True)
    file = models.FileField(_('File'), blank=True)

    def save(self, *args, **kwargs):
        super(UserUploadedData,self).save(*args, **kwargs)

# My serializers
class UserUploadedDataSerializer(serializers.ModelSerializer):
    profile = serializers.SlugRelatedField(source="parent.id", slug_field='profile', read_only=True)
    class Meta:
        model = UserUploadedData
    fields = "__all__"

class UserProfileSerializer(serializers.Serializer):
    customerId = serializers.SlugRelatedField(source='user', queryset=get_user_model().objects.all(), many=False, slug_field='customerId')
    uploadedData = UserUploadedData(many=True)

    def __video_to_frames(self, userUploadedData):
        print("Video to frames: ")
        print(userUploadedData.file.path)
    
        # Start capturing the feed
        cap = cv2.VideoCapture(userUploadedData.file.path)
    
        # Find the number of frames
        video_length = int(cap.get(cv2.CAP_PROP_FRAME_COUNT)) - 1
        print ("Number of frames: ", video_length)
        count = 0
        print ("Converting video..\n")
        # Start converting the video
        while cap.isOpened():
            # Extract the frame
            ret, frame = cap.read()
            if not ret:
                continue
        
            if count % 12 == 0:
                # Write the results back to output location.
                filename = datetime.now().strftime('%Y.%m.%d.%H.%M.%S')
                path = "media/"+filename+"-"+str(count+1)+'.jpg'
            
                print(path)
            
                cv2.imwrite(path, frame)
            
                f = open(path, 'r')
                print(type(f))
            
                tempImageFile = ContentFile(File(f.read()))       # this is were things go wrong...  
                UserUploadedData.objects.create(profile=userUploadedData.profile, file=tempImageFile)
        
            count = count + 1
        
            # If there are no more frames left
            if (count > (video_length-1)):
                # Release the feed
                cap.release()
                break
        
    
        print ("Converting video.. done!\n")
        return

    def create(self, validated_data):
        #print(validated_data)   
        user = validated_data.get('user')
    
        profile = UserProfile.objects.create(user=user, captureDateTime=validated_data)       
        dataArray = validated_data.get('profile').get('data')
        for bioData in dataArray:
            rawData = bioData.get('rawData')
            format, mediastr = rawData.split(';base64,') 
            ext = format.split('/')[-1]
            decodedMedia = base64.b64decode(mediastr)
        
            if ext.lower() == 'mp4':
                print("Split video...")
                filename = datetime.now().strftime('temp_%Y.%m.%d.%H.%M.%S')
                tempVideoFile = ContentFile(decodedMedia, name=filename+'.'+ext)         
                object = UserUploadedData.objects.create(profile=profile, file=tempVideoFile, **bioData)
        
                # Save all converted images 
                self.__video_to_frames(object)
            else:
                print("Save image")
                filename = datetime.now().strftime('%Y.%m.%d.%H.%M.%S')
                file = ContentFile(decodedMedia, name=filename+'.'+ext)
                        
                object = UserUploadedData.objects.create(profile=profile, file=file, **bioData)        
    
        return profile

错误跟踪如下：

Number of frames:  25
Converting video..
media/2022.03.20.22.58.14-1.jpg
<class '_io.TextIOWrapper'>
Internal Server Error: /bis/v1/customer/save/
(...)
    File "C:\Users\me\Documents\Sources\python\project\app\serializers.py", line 67, in __video_to_frames
tempImageFile = ContentFile(File(f.read()))
    File "C:\Python38\lib\encodings\cp1252.py", line 23, in decode
    return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 251: character maps to <undefined>

目前，MP4 文件已正确保存，但单个图像未:(

感谢您的帮助！

Answer 1

尝试使用
文件名 = datetime.now().strftime('%Y-%m-%d-%H-%M-%S')