madam.core module¶

class madam.core.Asset(essence, **metadata)[source]¶

Bases: object

Represents a digital asset.

An Asset is an immutable value object whose contents consist of essence and metadata. Essence represents the actual data of a media file, such as the color values of an image, whereas the metadata describes the essence.

Assets should not be instantiated directly. Instead, use read() to retrieve an Asset representing your content.

essence¶

Represents the actual content of the asset.

The essence of an MP3 file, for example, is only comprised of the actual audio data, whereas metadata such as ID3 tags are stored separately as metadata.

class madam.core.AssetStorage[source]¶

Bases: collections.abc.MutableMapping

Represents a data store for Asset objects.

The persistence guarantees for stored data may differ based on the respective storage implementation.

clear() → None. Remove all items from D.¶

filter(**kwargs)[source]¶: Returns a sequence of asset keys whose assets match the criteria that are specified by the passed arguments. :param kwargs: Criteria defined as keys and values :return: Sequence of asset keys

filter_by_tags(*tags)[source]¶

Returns a set of all asset keys in this storage that have at least the specified tags.

Parameters:	tags – Mandatory tags of an asset to be included in result
Returns:	Keys of the assets whose tags are a superset of the specified tags

get(k[, d]) → D[k] if k in D, else d. d defaults to None.¶

items() → a set-like object providing a view on D's items¶

keys() → a set-like object providing a view on D's keys¶

pop(k[, d]) → v, remove specified key and return the corresponding value.¶: If key is not found, d is returned if given, otherwise KeyError is raised.

popitem() → (k, v), remove and return some (key, value) pair¶: as a 2-tuple; but raise KeyError if D is empty.

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D¶

update([E, ]**F) → None. Update D from mapping/iterable E and F.¶: If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v

values() → an object providing a view on D's values¶

class madam.core.InMemoryStorage[source]¶

Bases: madam.core.AssetStorage

Represents a non-persistent storage backend for Asset objects.

Assets are not serialized, but stored in memory.

clear() → None. Remove all items from D.¶

filter(**kwargs)¶: Returns a sequence of asset keys whose assets match the criteria that are specified by the passed arguments. :param kwargs: Criteria defined as keys and values :return: Sequence of asset keys

filter_by_tags(*tags)¶

Returns a set of all asset keys in this storage that have at least the specified tags.

Parameters:	tags – Mandatory tags of an asset to be included in result
Returns:	Keys of the assets whose tags are a superset of the specified tags

get(k[, d]) → D[k] if k in D, else d. d defaults to None.¶

items() → a set-like object providing a view on D's items¶

keys() → a set-like object providing a view on D's keys¶

pop(k[, d]) → v, remove specified key and return the corresponding value.¶: If key is not found, d is returned if given, otherwise KeyError is raised.

popitem() → (k, v), remove and return some (key, value) pair¶: as a 2-tuple; but raise KeyError if D is empty.

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D¶

update([E, ]**F) → None. Update D from mapping/iterable E and F.¶: If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v

values() → an object providing a view on D's values¶

class madam.core.Madam[source]¶

Bases: object

Represents an instance of the library.

get_processor(file)[source]¶

Returns a processor that can read the data in the specified file.

Parameters:	file – file-like object to be parsed.
Returns:	Processor object that can handle the data in the specified file, or None if no suitable processor could be found.

read(file, additional_metadata=None)[source]¶

Reads the specified file and returns its contents as an Asset object.

Parameters:	file – file-like object to be parsed additional_metadata (dict) – optional metadata for the resulting asset. Existing metadata entries extracted from the file will be overwritten.
Returns:	Asset representing the specified file
Raises:	UnsupportedFormatError – if the file format cannot be recognized or is not supported TypeError – if the file is None
Example:

>>> import io
>>> from madam import Madam
>>> madam = Madam()
>>> file = io.BytesIO(b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\x01\x00\x00\x00\x01'
... b'\x08\x06\x00\x00\x00\x1f\x15\xc4\x89\x00\x00\x00\nIDATx\x9cc\x00\x01\x00\x00\x05\x00'
... b'\x01\r\n-\xb4\x00\x00\x00\x00IEND\xaeB`\x82')
>>> asset = madam.read(file)

write(asset, file)[source]¶

Write the Asset object to the specified file.

Parameters:	asset – Asset that contains the data to be written file – file-like object to be written
Example:

>>> import io
>>> import os
>>> from madam import Madam
>>> from madam.core import Asset
>>> gif_asset = Asset(essence=io.BytesIO(b'GIF89a\x01\x00\x01\x00\x00\x00\x00;'), mime_type='image/gif')
>>> madam = Madam()
>>> with open(os.devnull, 'wb') as file:
...     madam.write(gif_asset, file)
>>> wav_asset = Asset(
...     essence=io.BytesIO(b'RIFF$\x00\x00\x00WAVEfmt \x10\x00\x00\x00\x01\x00\x01\x00D\xac'
...             b'\x00\x00\x88X\x01\x00\x02\x00\x10\x00data\x00\x00\x00\x00'),
...     mime_type='video/mp4')
>>> with open(os.devnull, 'wb') as file:
...     madam.write(wav_asset, file)

class madam.core.MetadataProcessor[source]¶

Bases: object

Represents an entity that can manipulate metadata.

Every MetadataProcessor needs to have a no-args __init__ method in order to be registered correctly.

combine(file, metadata)[source]¶

Returns a byte stream whose contents represent the specified file where the specified metadata was added.

Parameters:	metadata – Mapping of the metadata format to the metadata dict file – Container file
Returns:	file-like object with combined content
Return type:	io.BytesIO

formats¶: The metadata formats which are supported. :return: supported metadata formats :rtype: tuple

read(file)[source]¶

Reads the file and returns the metadata.

The metadata that is returned is grouped by type. The keys are specified by format.

Parameters:	file – File-like object to be read
Returns:	Metadata contained in the file
Return type:	dict
Raises:	UnsupportedFormatError – if the data is corrupt or its format is not supported

strip(file)[source]¶

Removes all metadata of the supported type from the specified file.

Parameters:	file – file-like that should get stripped of the metadata
Returns:	file-like object without metadata
Return type:	io.BytesIO

exception madam.core.OperatorError[source]¶

Bases: Exception

Represents an error that is raised whenever an error occurs in an operator().

with_traceback()¶: Exception.with_traceback(tb) – set self.__traceback__ to tb and return self.

class madam.core.Pipeline[source]¶

Bases: object

Represents a processing pipeline for Asset objects.

The pipeline can be configured to hold a list of asset processing operators, all of which are applied to one or more assets when calling the process() method.

add(operator)[source]¶

Appends the specified operator to the processing chain.

Parameters:	operator – Operator to be added

process(*assets)[source]¶

Applies the operators in this pipeline on the specified assets.

Parameters:	assets – Assets to be processed
Returns:	Generator with processed assets

class madam.core.Processor[source]¶

Bases: object

Represents an entity that can create Asset objects from binary data.

Every Processor needs to have a no-args __init__ method in order to be registered correctly.

can_read(file)[source]¶

Returns whether the specified MIME type is supported by this processor.

Parameters:	file – file-like object to be tested
Returns:	whether the data format of the specified file is supported or not

read(file)[source]¶

Returns an Asset object whose essence is identical to the contents of the specified file.

Parameters:	file – file-like object to be read
Returns:	Asset with essence
Raises:	UnsupportedFormatError – if the specified data format is not supported

class madam.core.ShelveStorage(path)[source]¶

Bases: madam.core.AssetStorage

Represents a persistent storage backend for Asset objects. Asset keys must be strings.

ShelveStorage uses a file on the file system to serialize Assets.

clear() → None. Remove all items from D.¶

filter(**kwargs)¶: Returns a sequence of asset keys whose assets match the criteria that are specified by the passed arguments. :param kwargs: Criteria defined as keys and values :return: Sequence of asset keys

filter_by_tags(*tags)¶

Returns a set of all asset keys in this storage that have at least the specified tags.

Parameters:	tags – Mandatory tags of an asset to be included in result
Returns:	Keys of the assets whose tags are a superset of the specified tags

get(k[, d]) → D[k] if k in D, else d. d defaults to None.¶

items() → a set-like object providing a view on D's items¶

keys() → a set-like object providing a view on D's keys¶

pop(k[, d]) → v, remove specified key and return the corresponding value.¶: If key is not found, d is returned if given, otherwise KeyError is raised.

popitem() → (k, v), remove and return some (key, value) pair¶: as a 2-tuple; but raise KeyError if D is empty.

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D¶

update([E, ]**F) → None. Update D from mapping/iterable E and F.¶: If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v

values() → an object providing a view on D's values¶

exception madam.core.UnsupportedFormatError[source]¶

Bases: Exception

Represents an error that is raised whenever file content with unknown type is encountered.

with_traceback()¶: Exception.with_traceback(tb) – set self.__traceback__ to tb and return self.

madam.core.operator(function)[source]¶

Decorator function for methods that process assets.

Usually, it will be used with operations in a Processor implementation to make the methods configurable before applying the method to an asset.

Only keyword arguments are allowed for configuration.

Example for using a decorated convert method:

convert_to_opus = processor.convert(mime_type='audio/opus')
convert_to_opus(asset)

Parameters:	function – Method to decorate
Returns:	Configurable method