DALI Release 1.18.0

Using DALI 1.18.0

To upgrade to DALI 1.18.0 from an older version of DALI, follow the installation and usage information in the DALI User Guide.

Note: The internal DALI C++ API used for operator’s implementation, and the C++ API that enables using DALI as a library from native code, is not yet officially supported. Hence these APIs may change in the next release without advance notice.

Key Features and Enhancements

This DALI release includes the following key features and enhancements:
  • Unified batch representation in the GPU and CPU stages of the pipeline (effort towards conditional execution) (#4253, #4236, #4220, #4189).
  • Added support to specify the fill_value argument for each sample in the fn.erase operator (#4182).
  • Added support for the memory video file in FramesDecoder (#4184).
  • Moved the audio_resample operator out of experimental module (#4194).

Fixed Issues

Here are the fixed issues in this release:
  • Fixed an unnecessary synchronization in MakeContiguous. (#4248).
  • Fixed the Python tool to create the webdataset index (#4226).
  • Added a fix to prevent DALI from allocating GPU memory when constructing CPU TensorList (#4203).
  • Fixed a PyTorch example to comply with the new PyTroch (#4213).

Breaking Changes

There are no breaking changes in this release.

Deprecated Features

There are no deprecated features in this release.

Known Issues

This DALI release includes the following known issues:

  • The video loader operator requires that the key frames occur, at a minimum, every 10 to 15 frames of the video stream.

    If the key frames occur at a frequency that is less than 10-15 frames, the returned frames might be out of sync.

  • The experimental VideoReaderDecoder does not support open GOP.

    It will not report an error and might produce invalid frames. VideoReader uses a heuristic approach to detect open GOP and should work in most common cases.

  • The DALI TensorFlow plug-in might not be compatible with TensorFlow versions 1.15.0 and later.

    To use DALI with the TensorFlow version that does not have the prebuilt plug-in binary that is shipped with DALI, ensure that the compiler that is used to build TensorFlow exists on the system during the plug-in installation. (Depending on the particular version, you can use GCC 4.8.4, GCC 4.8.5, or GCC 5.4.)

  • In experimental debug and eager modes, the GPU external source is not properly synchronized with DALI internal streams.

    As a workaround, you can manually synchronize the device before returning the data from the callback.

  • Due to some known issues with meltdown/spectra mitigations and DALI, DALI shows the best performance when running in Docker with escalated privileges, for example:
    • privileged=yes in Extra Settings for AWS data points
    • --privileged or --security-opt seccomp=unconfined for bare Docker