diff --git a/Dockerfile b/Dockerfile
index 28ee7875d9c80324d48f3b476371d89c1b53bb25..6a8e71257bf9dc1090e70945e251e2b1c6a8b93d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -25,7 +25,7 @@ RUN if $GUI; then \
 RUN ln -s /usr/bin/python3 /usr/local/bin/python && ln -s /usr/bin/pip3 /usr/local/bin/pip
 # NumPy version is conflicting with system's gdal dep and may require venv
 ARG NUMPY_SPEC="==1.22.*"
-RUN pip install --no-cache-dir -U pip wheel mock six future deprecated "numpy$NUMPY_SPEC" \
+RUN pip install --no-cache-dir -U pip wheel mock six future tqdm deprecated "numpy$NUMPY_SPEC" \
  && pip install --no-cache-dir --no-deps keras_applications keras_preprocessing
 
 # ----------------------------------------------------------------------------
diff --git a/python/otbtf.py b/python/otbtf.py
index 860e86a7b30dc182698ec521a341daeb44d00c99..a1cf9bd442896b2d29c3986c876ce82d3ef9b6aa 100644
--- a/python/otbtf.py
+++ b/python/otbtf.py
@@ -18,17 +18,21 @@
 #
 # ==========================================================================*/
 """
-Contains stuff to help working with TensorFlow and geospatial data in the
-OTBTF framework.
+Contains stuff to help working with TensorFlow and geospatial data in the OTBTF framework.
 """
+import glob
+import json
+import os
 import threading
 import multiprocessing
 import time
 import logging
 from abc import ABC, abstractmethod
+from functools import partial
 import numpy as np
 import tensorflow as tf
 from osgeo import gdal
+from tqdm import tqdm
 
 
 # ----------------------------------------------------- Helpers --------------------------------------------------------
@@ -54,8 +58,11 @@ def read_as_np_arr(gdal_ds, as_patches=True):
         False, the shape is (1, psz_y, psz_x, nb_channels)
     :return: Numpy array of dim 4
     """
-    buffer = gdal_ds.ReadAsArray()
+    gdal_to_np_types = {1: 'uint8', 2: 'uint16', 3: 'int16', 4: 'uint32', 5: 'int32', 6: 'float32', 7: 'float64',
+                        10: 'complex64', 11: 'complex128'}
+    gdal_type = gdal_ds.GetRasterBand(1).DataType
     size_x = gdal_ds.RasterXSize
+    buffer = gdal_ds.ReadAsArray().astype(gdal_to_np_types[gdal_type])
     if len(buffer.shape) == 3:
         buffer = np.transpose(buffer, axes=(1, 2, 0))
     if not as_patches:
@@ -64,7 +71,7 @@ def read_as_np_arr(gdal_ds, as_patches=True):
     else:
         n_elems = int(gdal_ds.RasterYSize / size_x)
         size_y = size_x
-    return np.float32(buffer.reshape((n_elems, size_y, size_x, gdal_ds.RasterCount)))
+    return buffer.reshape((n_elems, size_y, size_x, gdal_ds.RasterCount))
 
 
 # -------------------------------------------------- Buffer class ------------------------------------------------------
@@ -167,7 +174,7 @@ class PatchesImagesReader(PatchesReaderBase):
     :see PatchesReaderBase
     """
 
-    def __init__(self, filenames_dict: dict, use_streaming=False):
+    def __init__(self, filenames_dict, use_streaming=False, scalar_dict=None):
         """
         :param filenames_dict: A dict() structured as follow:
             {src_name1: [src1_patches_image_1.tif, ..., src1_patches_image_N.tif],
@@ -175,6 +182,11 @@ class PatchesImagesReader(PatchesReaderBase):
              ...
              src_nameM: [srcM_patches_image_1.tif, ..., srcM_patches_image_N.tif]}
         :param use_streaming: if True, the patches are read on the fly from the disc, nothing is kept in memory.
+        :param scalar_dict: (optional) a dict containing list of scalars (int, float, str) as follow:
+            {scalar_name1: ["value_1", ..., "value_N"],
+             scalar_name2: [value_1, ..., value_N],
+             ...
+             scalar_nameM: [value1, ..., valueN]}
         """
 
         assert len(filenames_dict.values()) > 0
@@ -182,13 +194,18 @@ class PatchesImagesReader(PatchesReaderBase):
         # gdal_ds dict
         self.gdal_ds = {key: [gdal_open(src_fn) for src_fn in src_fns] for key, src_fns in filenames_dict.items()}
 
-        # check number of patches in each sources
-        if len({len(ds_list) for ds_list in self.gdal_ds.values()}) != 1:
-            raise Exception("Each source must have the same number of patches images")
-
         # streaming on/off
         self.use_streaming = use_streaming
 
+        # Scalar dict (e.g. for metadata)
+        # If the scalars are not numpy.ndarray, convert them
+        self.scalar_dict = {key: [i if isinstance(i, np.ndarray) else np.asarray(i) for i in scalars]
+                            for key, scalars in scalar_dict.items()} if scalar_dict else {}
+
+        # check number of patches in each sources
+        if len({len(ds_list) for ds_list in list(self.gdal_ds.values()) + list(self.scalar_dict.values())}) != 1:
+            raise Exception("Each source must have the same number of patches images")
+
         # gdal_ds check
         nb_of_patches = {key: 0 for key in self.gdal_ds}
         self.nb_of_channels = dict()
@@ -211,8 +228,8 @@ class PatchesImagesReader(PatchesReaderBase):
 
         # if use_streaming is False, we store in memory all patches images
         if not self.use_streaming:
-            patches_list = {src_key: [read_as_np_arr(ds) for ds in self.gdal_ds[src_key]] for src_key in self.gdal_ds}
-            self.patches_buffer = {src_key: np.concatenate(patches_list[src_key], axis=0) for src_key in self.gdal_ds}
+            self.patches_buffer = {src_key: np.concatenate([read_as_np_arr(ds) for ds in src_ds], axis=0) for
+                                   src_key, src_ds in self.gdal_ds.items()}
 
     def _get_ds_and_offset_from_index(self, index):
         offset = index
@@ -230,14 +247,20 @@ class PatchesImagesReader(PatchesReaderBase):
 
     @staticmethod
     def _read_extract_as_np_arr(gdal_ds, offset):
+        gdal_to_np_types = {1: 'uint8', 2: 'uint16', 3: 'int16', 4: 'uint32', 5: 'int32', 6: 'float32', 7: 'float64',
+                            10: 'complex64', 11: 'complex128'}
         assert gdal_ds is not None
         psz = gdal_ds.RasterXSize
+        gdal_type = gdal_ds.GetRasterBand(1).DataType
         yoff = int(offset * psz)
         assert yoff + psz <= gdal_ds.RasterYSize
         buffer = gdal_ds.ReadAsArray(0, yoff, psz, psz)
         if len(buffer.shape) == 3:
             buffer = np.transpose(buffer, axes=(1, 2, 0))
-        return np.float32(buffer)
+        else:  # single-band raster
+            buffer = np.expand_dims(buffer, axis=2)
+
+        return buffer.astype(gdal_to_np_types[gdal_type])
 
     def get_sample(self, index):
         """
@@ -252,18 +275,19 @@ class PatchesImagesReader(PatchesReaderBase):
         assert index >= 0
         assert index < self.size
 
+        i, offset = self._get_ds_and_offset_from_index(index)
+        res = {src_key: scalar[i] for src_key, scalar in self.scalar_dict.items()}
         if not self.use_streaming:
-            res = {src_key: self.patches_buffer[src_key][index, :, :, :] for src_key in self.gdal_ds}
+            res.update({src_key: arr[index, :, :, :] for src_key, arr in self.patches_buffer.items()})
         else:
-            i, offset = self._get_ds_and_offset_from_index(index)
-            res = {src_key: self._read_extract_as_np_arr(self.gdal_ds[src_key][i], offset) for src_key in self.gdal_ds}
-
+            res.update({src_key: self._read_extract_as_np_arr(self.gdal_ds[src_key][i], offset)
+                        for src_key in self.gdal_ds})
         return res
 
     def get_stats(self):
         """
         Compute some statistics for each source.
-        Depending if streaming is used, the statistics are computed directly in memory, or chunk-by-chunk.
+        When streaming is used, chunk-by-chunk. Else, the statistics are computed directly in memory.
 
         :return statistics dict
         """
@@ -314,6 +338,7 @@ class IteratorBase(ABC):
     """
     Base class for iterators
     """
+
     @abstractmethod
     def __init__(self, patches_reader: PatchesReaderBase):
         pass
@@ -361,17 +386,24 @@ class Dataset:
     :see Buffer
     """
 
-    def __init__(self, patches_reader: PatchesReaderBase, buffer_length: int = 128,
-                 Iterator: IteratorBase = RandomIterator):
+    def __init__(self, patches_reader: PatchesReaderBase = None, buffer_length: int = 128,
+                 Iterator=RandomIterator, max_nb_of_samples=None):
         """
         :param patches_reader: The patches reader instance
         :param buffer_length: The number of samples that are stored in the buffer
         :param Iterator: The iterator class used to generate the sequence of patches indices.
+        :param max_nb_of_samples: Optional, max number of samples to consider
         """
-
         # patches reader
         self.patches_reader = patches_reader
-        self.size = self.patches_reader.get_size()
+
+        # If necessary, limit the nb of samples
+        logging.info('Number of samples: %s', self.patches_reader.get_size())
+        if max_nb_of_samples and self.patches_reader.get_size() > max_nb_of_samples:
+            logging.info('Reducing number of samples to %s', max_nb_of_samples)
+            self.size = max_nb_of_samples
+        else:
+            self.size = self.patches_reader.get_size()
 
         # iterator
         self.iterator = Iterator(patches_reader=self.patches_reader)
@@ -404,8 +436,21 @@ class Dataset:
                                                          output_types=self.output_types,
                                                          output_shapes=self.output_shapes).repeat(1)
 
+    def to_tfrecords(self, output_dir, n_samples_per_shard=100, drop_remainder=True):
+        """
+        Save the dataset into TFRecord files
+
+        :param output_dir: output directory
+        :param n_samples_per_shard: number of samples per TFRecord file
+        :param drop_remainder: drop remainder samples
+        """
+        tfrecord = TFRecords(output_dir)
+        tfrecord.ds2tfrecord(self, n_samples_per_shard=n_samples_per_shard, drop_remainder=drop_remainder)
+
     def get_stats(self) -> dict:
         """
+        Compute dataset statistics
+
         :return: the dataset statistics, computed by the patches reader
         """
         with self.mining_lock:
@@ -502,8 +547,8 @@ class DatasetFromPatchesImages(Dataset):
     :see Dataset
     """
 
-    def __init__(self, filenames_dict: dict, use_streaming: bool = False, buffer_length: int = 128,
-                 Iterator: IteratorBase = RandomIterator):
+    def __init__(self, filenames_dict, use_streaming=False, buffer_length: int = 128,
+                 Iterator=RandomIterator):
         """
         :param filenames_dict: A dict() structured as follow:
             {src_name1: [src1_patches_image1, ..., src1_patches_imageN1],
@@ -518,3 +563,204 @@ class DatasetFromPatchesImages(Dataset):
         patches_reader = PatchesImagesReader(filenames_dict=filenames_dict, use_streaming=use_streaming)
 
         super().__init__(patches_reader=patches_reader, buffer_length=buffer_length, Iterator=Iterator)
+
+
+class TFRecords:
+    """
+    This class allows to convert Dataset objects to TFRecords and to load them in dataset tensorflows format.
+    """
+
+    def __init__(self, path):
+        """
+        :param path: Can be a directory where TFRecords must be saved/loaded or a single TFRecord path
+        """
+        if os.path.isdir(path) or not os.path.exists(path):
+            self.dirpath = path
+            os.makedirs(self.dirpath, exist_ok=True)
+            self.tfrecords_pattern_path = os.path.join(self.dirpath, "*.records")
+        else:
+            self.dirpath = os.path.dirname(path)
+            self.tfrecords_pattern_path = path
+        self.output_types_file = os.path.join(self.dirpath, "output_types.json")
+        self.output_shape_file = os.path.join(self.dirpath, "output_shape.json")
+        self.output_shape = self.load(self.output_shape_file) if os.path.exists(self.output_shape_file) else None
+        self.output_types = self.load(self.output_types_file) if os.path.exists(self.output_types_file) else None
+
+    @staticmethod
+    def _bytes_feature(value):
+        """
+        Convert a value to a type compatible with tf.train.Example.
+        :param value: value
+        :return a bytes_list from a string / byte.
+        """
+        if isinstance(value, type(tf.constant(0))):
+            value = value.numpy()  # BytesList won't unpack a string from an EagerTensor.
+        return tf.train.Feature(bytes_list=tf.train.BytesList(value=[value]))
+
+    def ds2tfrecord(self, dataset, n_samples_per_shard=100, drop_remainder=True):
+        """
+        Convert and save samples from dataset object to tfrecord files.
+        :param dataset: Dataset object to convert into a set of tfrecords
+        :param n_samples_per_shard: Number of samples per shard
+        :param drop_remainder: Whether additional samples should be dropped. Advisable if using multiworkers training.
+                               If True, all TFRecords will have `n_samples_per_shard` samples
+        """
+        logging.info("%s samples", dataset.size)
+
+        nb_shards = (dataset.size // n_samples_per_shard)
+        if not drop_remainder and dataset.size % n_samples_per_shard > 0:
+            nb_shards += 1
+
+        self.convert_dataset_output_shapes(dataset)
+
+        def _convert_data(data):
+            """
+            Convert data
+            """
+            data_converted = {}
+
+            for k, d in data.items():
+                data_converted[k] = d.name
+
+            return data_converted
+
+        self.save(_convert_data(dataset.output_types), self.output_types_file)
+
+        for i in tqdm(range(nb_shards)):
+
+            if (i + 1) * n_samples_per_shard <= dataset.size:
+                nb_sample = n_samples_per_shard
+            else:
+                nb_sample = dataset.size - i * n_samples_per_shard
+
+            filepath = os.path.join(self.dirpath, f"{i}.records")
+            with tf.io.TFRecordWriter(filepath) as writer:
+                for s in range(nb_sample):
+                    sample = dataset.read_one_sample()
+                    serialized_sample = {name: tf.io.serialize_tensor(fea) for name, fea in sample.items()}
+                    features = {name: self._bytes_feature(serialized_tensor) for name, serialized_tensor in
+                                serialized_sample.items()}
+                    tf_features = tf.train.Features(feature=features)
+                    example = tf.train.Example(features=tf_features)
+                    writer.write(example.SerializeToString())
+
+    @staticmethod
+    def save(data, filepath):
+        """
+        Save data to pickle format.
+        :param data: Data to save json format
+        :param filepath: Output file name
+        """
+
+        with open(filepath, 'w') as f:
+            json.dump(data, f, indent=4)
+
+    @staticmethod
+    def load(filepath):
+        """
+        Return data from pickle format.
+        :param filepath: Input file name
+        """
+        with open(filepath, 'r') as f:
+            return json.load(f)
+
+    def convert_dataset_output_shapes(self, dataset):
+        """
+        Convert and save numpy shape to tensorflow shape.
+        :param dataset: Dataset object containing output shapes
+        """
+        output_shapes = {}
+
+        for key in dataset.output_shapes.keys():
+            output_shapes[key] = (None,) + dataset.output_shapes[key]
+
+        self.save(output_shapes, self.output_shape_file)
+
+    @staticmethod
+    def parse_tfrecord(example, features_types, target_keys, preprocessing_fn=None, **kwargs):
+        """
+        Parse example object to sample dict.
+        :param example: Example object to parse
+        :param features_types: List of types for each feature
+        :param target_keys: list of keys of the targets
+        :param preprocessing_fn: Optional. A preprocessing function that takes input, target as args and returns
+                                           a tuple (input_preprocessed, target_preprocessed)
+        :param kwargs: some keywords arguments for preprocessing_fn
+        """
+        read_features = {key: tf.io.FixedLenFeature([], dtype=tf.string) for key in features_types}
+        example_parsed = tf.io.parse_single_example(example, read_features)
+
+        for key in read_features.keys():
+            example_parsed[key] = tf.io.parse_tensor(example_parsed[key], out_type=features_types[key])
+
+        # Differentiating inputs and outputs
+        input_parsed = {key: value for (key, value) in example_parsed.items() if key not in target_keys}
+        target_parsed = {key: value for (key, value) in example_parsed.items() if key in target_keys}
+
+        if preprocessing_fn:
+            input_parsed, target_parsed = preprocessing_fn(input_parsed, target_parsed, **kwargs)
+
+        return input_parsed, target_parsed
+
+    def read(self, batch_size, target_keys, n_workers=1, drop_remainder=True, shuffle_buffer_size=None,
+             preprocessing_fn=None, **kwargs):
+        """
+        Read all tfrecord files matching with pattern and convert data to tensorflow dataset.
+        :param batch_size: Size of tensorflow batch
+        :param target_keys: Keys of the target, e.g. ['s2_out']
+        :param n_workers: number of workers, e.g. 4 if using 4 GPUs
+                                             e.g. 12 if using 3 nodes of 4 GPUs
+        :param drop_remainder: whether the last batch should be dropped in the case it has fewer than
+                               `batch_size` elements. True is advisable when training on multiworkers.
+                               False is advisable when evaluating metrics so that all samples are used
+        :param shuffle_buffer_size: if None, shuffle is not used. Else, blocks of shuffle_buffer_size
+                                    elements are shuffled using uniform random.
+        :param preprocessing_fn: Optional. A preprocessing function that takes input, target as args and returns
+                                   a tuple (input_preprocessed, target_preprocessed)
+        :param kwargs: some keywords arguments for preprocessing_fn
+        """
+        options = tf.data.Options()
+        if shuffle_buffer_size:
+            options.experimental_deterministic = False  # disable order, increase speed
+        options.experimental_distribute.auto_shard_policy = tf.data.experimental.AutoShardPolicy.AUTO  # for multiworker
+        parse = partial(self.parse_tfrecord, features_types=self.output_types, target_keys=target_keys,
+                        preprocessing_fn=preprocessing_fn, **kwargs)
+
+        # TODO: to be investigated :
+        # 1/ num_parallel_reads useful ? I/O bottleneck of not ?
+        # 2/ num_parallel_calls=tf.data.experimental.AUTOTUNE useful ?
+        # 3/ shuffle or not shuffle ?
+        matching_files = glob.glob(self.tfrecords_pattern_path)
+        logging.info('Searching TFRecords in %s...', self.tfrecords_pattern_path)
+        logging.info('Number of matching TFRecords: %s', len(matching_files))
+        matching_files = matching_files[:n_workers * (len(matching_files) // n_workers)]  # files multiple of workers
+        nb_matching_files = len(matching_files)
+        if nb_matching_files == 0:
+            raise Exception("At least one worker has no TFRecord file in {}. Please ensure that the number of TFRecord "
+                            "files is greater or equal than the number of workers!".format(self.tfrecords_pattern_path))
+        logging.info('Reducing number of records to : %s', nb_matching_files)
+        dataset = tf.data.TFRecordDataset(matching_files)  # , num_parallel_reads=2)  # interleaves reads from xxx files
+        dataset = dataset.with_options(options)  # uses data as soon as it streams in, rather than in its original order
+        dataset = dataset.map(parse, num_parallel_calls=tf.data.experimental.AUTOTUNE)
+        if shuffle_buffer_size:
+            dataset = dataset.shuffle(buffer_size=shuffle_buffer_size)
+        dataset = dataset.batch(batch_size, drop_remainder=drop_remainder)
+        dataset = dataset.prefetch(buffer_size=tf.data.experimental.AUTOTUNE)
+        # TODO voir si on met le prefetch avant le batch cf https://keras.io/examples/keras_recipes/tfrecord/
+
+        return dataset
+
+    def read_one_sample(self, target_keys):
+        """
+        Read one tfrecord file matching with pattern and convert data to tensorflow dataset.
+        :param target_key: Key of the target, e.g. 's2_out'
+        """
+        matching_files = glob.glob(self.tfrecords_pattern_path)
+        one_file = matching_files[0]
+        parse = partial(self.parse_tfrecord, features_types=self.output_types, target_keys=target_keys)
+        dataset = tf.data.TFRecordDataset(one_file)
+        dataset = dataset.map(parse)
+        dataset = dataset.batch(1)
+
+        sample = iter(dataset).get_next()
+        return sample