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Amazon Kinesis Video Streams Consumer Library For Python

Introduction

The Amazon Kinesis Video Stream Consumer Library for Python reads in streaming bytes from Amazon Kinesis Video Streams (KVS) made available via a KVS GetMedia or GetMediaForFragmentList API call response. The library parses these raw bytes into individual MKV fragments and forwards to call-backs in the user’s application.

Fragments are returned as raw bytes and a searchable DOM like structure by parsing with EMBLite by MideTechnology.

In addition, the KvsFragementProcessor class provides the following functions for post-processing of parsed MKV fragments:

1. get_fragment_tags(): Extract MKV tags from the fragment.
2. save_fragment_as_local_mkv(): Saves the fragment as stand-alone MKV file on local disk.
3. get_frames_as_ndarray(): Returns a selectable ratio of frames in the fragment as a list of NDArray objects.
4. save_frames_as_jpeg(): Returns a selectable ratio of frames in the fragment as a JPEGs to local disk.

Getting started

A complete example of how to consume the Amazon Kinesis Video Stream Consumer Library for Python is provided in the kvs_consumer_library_example module.

To deploy this example:

1. Make sure you have an active stream running in KVS. The example takes fragments off the live edge of the stream so if none are being received the consumer will gracefully exit. If you prefer to parse previous stored fragments, you will need to update the StartSelector used in the kvs_consumer_library_example.

2. Clone and CD into this repository

git clone https://github.com/aws-samples/amazon-kinesis-video-streams-consumer-library-for-python.git
cd amazon-kinesis-video-streams-consumer-library-for-python

3. Install Python Dependencies:

python3 -m pip install -r requirements.txt

4. Open the cloned repository with your favourite IDE

5. In kvs_consumer_library_example.py, update the KVS stream parameters:
   a. REGION and
   b. KVS_STREAM01_NAME

6. Run the example code:

python3 kvs_consumer_library_example.py

This assumes default client authentication and so your host machine must have a valid AWS credentials file or receive temporary credentials by other means. User IAM or temporary credentials must have AmazonKinesisVideoStreamsReadOnlyAccess or some per stream specific equivalent of these permissions.

Assuming authenticating is successful then the consumer library will be reading in the nominated KVS stream and returning parsed MKV fragments to the on_fragment_arrived() callback where a series of post-processing of the fragment and enclosed frames is completed.

Check the on_fragment_arrived function and see the post processing features. The save MKV and save frames functions are commented out so you don't fill up too much disk but easy to uncomment to test these features as well.

Summary Workflow

1. Define a on_fragment_arrived() and on_read_stream_complete() and on_stream_read_exception() call-backs in user application logic.
2. Initialize the KVS Media and / or Archive Media clients,
3. Make a call to KVS Media GetMedia and / or KVS Archive Media GetMediaForFragmentList for the given stream,
4. Initialize and run this KVS Consumer library thread providing the response from the GetMedia or GetMediaForFragmentList call,
5. Fragments will then be parsed and delivered to the call-backs for processing as per the example code provided.

Timing and Async Considerations

To keep the examples and base solution as simple as possible, the fragment processing library provided is threaded to run outside of the main process but it returns received fragments to the main application process call-backs and isn't using any asynchronous programming techniques. Therefore, any processing time taken in the on_fragment_arrived() callback will be blocking for the KVS consumer library fragment processing function. If the processing takes longer (or close to) than the fragment duration then the stream processing will slip behind the live edge of the media and introduce additional latency.

If performing long or external blocking processes in the on_fragment_arrived() callback, it is the responsibility of the developer to thread or develop async solutions to prevent extended blocking of the consumer library fragment processing.

Security

See CONTRIBUTING for more information.

License

This library is licensed under the MIT-0 License. See the LICENSE file.

Credits:

EMBLite by MideTechnology is an external EBML parser used to decode the MKV fragents in this library. For convenance, a slightly modified version of EMBLite is shipped with the KvsConsumerLibrary but adding credit where its due.
EMBLite MIT License: https://github.com/MideTechnology/ebmlite/blob/development/LICENSE