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Unified-IO 2

This repo contains code for Unified-IO 2, including code to run a demo, do training, and do inference. This codebase is modified from T5X.

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Install

Install the dependencies with pip

For a TPU:

python3 -m pip install -e '.[tpu]' -f https://storage.googleapis.com/jax-releases/libtpu_releases.html -f https://storage.googleapis.com/jax-releases/jax_releases.html

For a GPU/CPU (note we have been using TPUs so GPU setups are not well tested):

python3 -m pip install -e '.' -f https://storage.googleapis.com/jax-releases/jax_cuda_releases.html

Running the demo requires additional dependencies, install them with:

python3 -m pip install -e '.[demo]' -f https://storage.googleapis.com/jax-releases/libtpu_releases.html -f https://storage.googleapis.com/jax-releases/jax_releases.html

The LLaMa tokenizer also needs to be installed, download the .model file from https://github.com/facebookresearch/llama/tree/main?tab=readme-ov-file and then update t5x/examples/unified_io/config.py so LLAMA_TOKENIZER_PATH points to the download location.

Checkpoints

We make checkpoints in the T5X format available on S3:

To download, copy the directory recursively. For example:

aws s3 --no-sign-request cp --recursive s3://ai2-prior-uio/public/uio2-checkpoints/large-3m large-3m --exclude "state*"

They should be copied to a local disk or to google file storage. Here, the --exclude "state*" flag excludes the optimizer state from the download, it can be removed if you want to continue training the checkpoint from the current optimizer state.

Demo

To run the model interactively the demo notebook can be run. Make sure the demo dependencies have been installed.

Then run the demo notebook:

jupyter notebook demo.ipynb

Set FULL_CKPT_PATH and MODEL_TYPE in the second cell to your checkpoint and the correct model size. Then the notebook can be used to start the demo.

The demo shows how to load the model, parameters, and do inference.

The demo will be slow the first time it is used because the inference function needs to be compiled, subsequent calls with similar inputs/outputs will be much faster.

Data

To train and eval on entire datasets the datasets need to be registered with seqio in seqio.TaskRegistry. See t5x/examples/unifiedio/data/tasks.py for examples. See seqio for more details on how datasets are managed by seqio. Some datasets require running a pre-processing script before they can be used.

Make sure config.MULTITASK_TFDS_DATA_DIR is updated to point to the location to store the datasets.

Datasets

We provided some initial datasets in t5x/examples/unifiedio/data/tasks.py. Our datasets are generally built one of three ways:

  1. Constructed as a tensorflow_dataset and then uploaded to the location specified in config.MULTITASK_TFDS_DATA_DIR
  2. Constructed as a set of tfrecords and uploaded to the same location
  3. Directly using a dataset from https://www.tensorflow.org/datasets/catalog/overview

Datasets built in the first or second way require running a build script before they can be used. create_data contains the needed build scripts. For example running:

python3 create_data/tfdatasets/coco_all/build.py ~/data/tfds ~/data/vqa ~/data/coco_annotations

Will upload a tfdataset of COCO data, which allows tasks such as image_generation_coco_2017 and image_caption_coco_2017 to be used. Some datasets, such as the refexp datasets, that use the public tensoflow catalog might have their own manual pre-processing steps as well which will be specified on their webpage.

UnifiedIO 2 contains a large number of tasks, for this initial release we only include a subset but will add more as we test and verify additional tasks.

Preprocessing

Pre-processing in UIO2 happens in three stages:

  1. Task-specific pre-processing constructs a prompt and builds input and outputs in the supported modalities. This stage needs to resize and pad images into the correct sizes, and provide masks to show which parts of the image are padding (typically with unified_io.data.data_utils.resize_and_pad). Audio segments need to be converted to mel-spectrograms, which can also be masked if working with noised data. This stage is implemented by various preprocessing functions in unified_io.data.preprocessing. The demo shows how to do this for raw inputs. To allow this stage to do different pre-processing during training and testing, we pass a is_training field in sequence_length dictionary to indicate whether the dataset is being used for training or testing.
  2. Next modality_processing.unified_io_preprocessor is run. This function does various task-general pre-preprocessing steps, such as tokenizing the text, and adds empty values for missing modalities so the output dataset has a consistent set of fields.
  3. Finally UnifiedIOFeatureConverter is applied, this can happen after multiple datasets have been combined into a seqio.Mixture. This function will make sure the output dataset has a consistent structure and is padded to have fixed-size tensors, as is needed for jax. This dataset can now be batched and passed directly into the loss or prediction functions of a UnifiedIO 2 model. The padding is determined by the sequence_len dictionary.

To add a dataset, register it with seqio and ensure the last pre-processor is modality_processing.unified_io_preprocessor. The preceding functions should make sure the dataset has the appropriate fields for that function.

Prompts

Our entire set of prompts in t5x/examples/unified_io/data/prompt_dict, we randomly select among these prompts during training.

Visualization

We include a visualization script to show what the data looks like after post-processing:

python3 t5x/examples/unified_io/scripts/dataset_visualize.py refcoco_unc viz --override```

To get a more compact view:

python3 t5x/examples/unified_io/scripts/dataset_visualize.py refcoco_unc viz --override --gin.get_target_modalities.target_modality=[\"text\"] --gin.get_input_modalities.input_modality=[\"text\",\"image\"] --nomasks

Training

Once a checkpoint is downloaded and a dataset is ready, training can be run using train.py. Our training strategy largely follows T5X, which is configured through gin. Follow the setup from https://github.com/google-research/t5x to train on TPUs.

For example, to fine-tune the large model on refexp:

python3 t5x/train.py --gin_file=t5x/examples/unified_io/t5_1_1/large.gin --gin_file=t5x/examples/unified_io/t5_1_1/finetune/refexp.gin --gin.INITIAL_CHECKPOINT_PATH=\"/path/to/checkpoint\" --gin.MODEL_DIR=\"path/to/output_dir\" --gin.BATCH_SIZE=8

Modalities

UnifiedIO 2 can be run on a subset of the supported modality, which makes training more efficient. This can be set through the gin-configured parameters in get_input_modalities and get_target_modalities. For example, refexp.gin only turns on the image/text inputs and text outputs.

Sequence Lengths

Due to jax's fixed size tensor constraint, we by default pad all inputs and targets to the model to the maximum length supported. When training on mixtures where this is excessive, this can be tweaked by changing the sequence_lengths used by seqio For example, refexp,gin reduce the input and output sequence length since refexp has little text.

Wandb

We have modified train.py to use wandb, just make sure a WANDB_API_KEY environment variable is set. The gin configurable function utils.init_wandb should be modified or configured through gin to select the correct name/group/project/entity.

Packing

If the training mixture contains a mix of long and short examples, packing can make things more efficient. Packing will pack up to two examples together into a single input sequence, it can be turned on with this flag:

--gin.PackingStrategy.pack_max_len=(864, 1280)

During training, two examples will be attempted to be packed in a sequence with total input length of 864 input length and target length or 1280. A heuristic algorithm will try to find pairs of examples that fit this criterion as data is streamed to the training server, if none are found only one example will be used. If this happens too frequently it is a good idea to increase the max length. Statistics will be logged to wandb to track the packing efficiency.

Evaluation

Evaluation script are run using eval.py, for example:

python3 t5x/eval.py --gin_file=t5x/examples/unified_io/t5_1_1/large.gin --gin_file=t5x/examples/unified_io/t5_1_1/eval/vision_language.gin --gin.CHECKPOINT_PATH=\"large-3m\" --gin.MIXTURE_OR_TASK_NAME=\"refcoco_unc\" --gin.EVAL_OUTPUT_DIR=\"output\"

The target dataset must have metrics registered with seqio. Evaluations script can be similarly made more efficient by only using the needed modalities and choosing the sequence lengths appropriately. Note most of our official results come from collecting outputs and then running offline evaluations, the metrics here are used mostly for validation scores.

Citation

@article{lu2023uio2,
  title   = {Unified-IO 2: Scaling Autoregressive Multimodal Models with Vision, Language, Audio, and Action}, 
  author  = {Jiasen Lu and Christopher Clark and Sangho Lee and Zichen Zhang and Savya Khosla and Ryan Marten and Derek Hoiem and Aniruddha Kembhavi},
  journal = {arXiv preprint arXiv:2312.17172},
  year    = {2023},
}