stream()

audb.stream(name, table, *, version=None, map=None, batch_size=16, shuffle=False, buffer_size=100000, only_metadata=False, bit_depth=None, channels=None, format=None, mixdown=False, sampling_rate=None, full_path=True, cache_root=None, num_workers=1, timeout=-1, verbose=True)[source]

Stream table and media files of a database.

Loads only the first batch_size rows of a table into memory, and downloads only the related media files, if any media files are requested.

By setting bit_depth, channels, format, mixdown, and sampling_rate we can request a specific flavor of the database. In that case media files are automatically converted to the desired properties (see also audb.Flavor).

Parameters

  • name (str) – name of database

  • table (str) – name of table

  • version (Optional[str]) – version string, latest if None

  • map (Optional[Dict[str, Union[str, Sequence[str]]]]) – map scheme or scheme fields to column values. For example if your table holds a column speaker with speaker IDs, which is assigned to a scheme that contains a dict mapping speaker IDs to age and gender entries, map={'speaker': ['age', 'gender']} will replace the column with two new columns that map ID values to age and gender, respectively. To also keep the original column with speaker IDS, you can do map={'speaker': ['speaker', 'age', 'gender']}

  • batch_size (int) – number of table rows to return in one iteration

  • shuffle (bool) – if True, it first reads buffer_size rows from the table and selects batch_size randomly from them

  • buffer_size (int) – number of table rows to be loaded when shuffle is True

  • only_metadata (bool) – load only header and tables of database

  • bit_depth (Optional[int]) – bit depth, one of 16, 24, 32

  • channels (Union[int, Sequence[int], None]) – channel selection, see audresample.remix(). Note that media files with too few channels will be first upsampled by repeating the existing channels. E.g. channels=[0, 1] upsamples all mono files to stereo, and channels=[1] returns the second channel of all multi-channel files and all mono files

  • format (Optional[str]) – file format, one of 'flac', 'wav'

  • mixdown (bool) – apply mono mix-down

  • sampling_rate (Optional[int]) – sampling rate in Hz, one of 8000, 16000, 22500, 44100, 48000

  • full_path (bool) – replace relative with absolute file paths

  • cache_root (Optional[str]) – cache folder where databases are stored. If not set audb.default_cache_root() is used

  • num_workers (Optional[int]) – number of parallel jobs or 1 for sequential processing. If None will be set to the number of processors on the machine multiplied by 5

  • timeout (float) – maximum wait time if another thread or process is already accessing the database. If timeout is reached, None is returned. If timeout < 0 the method will block until the database can be accessed

  • verbose (bool) – show debug messages

Return type

DatabaseIterator

Returns

database object

Raises

  • ValueError – if table is requested that is not part of the database

  • ValueError – if a non-supported bit_depth, format, or sampling_rate is requested

  • RuntimeError – if a flavor is requested, but the database contains media files, that don’t contain audio, e.g. text files

Examples

>>> import numpy as np
>>> np.random.seed(1)
>>> db = audb.stream(
...     "emodb",
...     "files",
...     version="1.4.1",
...     batch_size=4,
...     shuffle=True,
...     only_metadata=True,
...     full_path=False,
...     verbose=False,
... )
>>> next(db)
                                 duration  speaker transcription
file
wav/14a05Fb.wav 0 days 00:00:03.128687500       14           a05
wav/15a05Eb.wav 0 days 00:00:03.993562500       15           a05
wav/12a05Nd.wav    0 days 00:00:03.185875       12           a05
wav/13a07Na.wav 0 days 00:00:01.911687500       13           a07