Controlling HLS disk cache life time

Nimble Streamer can be used for HLS re-streaming for both VOD and live modes. For VOD we primarily use disk cache. By default each chunk is stored for a day after the last request.

You may control a life time of VOD disk cache chunks via vod_cache_timeout parameter.  If you want chunks to be stored for 2 days, just set up this:

General settings are stored in /etc/nimble/nimble.conf. Just add this string in the config file:

vod_cache_timeout = 48

You may control server by changing other configuration parameters. Once you make a change you need to re-start Nimble by running

sudo service nimble restart

Once the service is re-started, Nimble will start requests to origin services via the user agent specified in the config.

Please learn more about latest VOD cache control features here.

Related documentation

Nimble HTTP Streamer, VOD re-streaming cache control, Nimble Streamer overview video, Nimble configs explained, HLS re-streaming set up, HDS re-streaming, Smooth Streaming support, Progressive download re-streaming, WMSPanel Slideshare

Nimble Streamer disk cache for VOD re-streaming

One of the major use cases for Nimble Streamer is the re-streaming of HLS and Smooth Streaming. Our customers use it to off-load their origin servers by moving light-weight Nimble edges closer to their audience.

Currently Nimble has a RAM-based cache for live re-streaming and a disk cache for VOD re-streaming.
Let's see how disk cache works for delivery of VOD content.

1. A viewer requests a playlist, Nimble downloads its and determines whether it's live or VOD.
2. The playlist is sent back to the viewer.
3. A viewer requests a new chunk from the previously downloaded playlist.
4. If there is no pre-downloaded chunk, it's being requested from the origin.
5. Once downloaded, it's being placed to disk cache.
6. If the disk cache is full, the chunk is stored into RAM if possible.
7. The chunk is being stored on disk for 24 hours then removed.

Live caching will be done in similar way, but it will be primarily stored in RAM and then on disk in case of overflow.

The following parameters are added info config file to allow some fine tuning of disk cache:

• cache_path is a path to the file cache storage, with default value /var/cache/nimble.
• max_disk_cache_size is a size of file cache measured in MB with 4096 MB by default.

This gives an ability to effectively deliver VOD content to any edges from any type of origin.

Please also learn more about latest VOD cache control features here.

You can also take a look at the video where Jan Ozer of Streaming Learning Center and Yury Udovichenko of Softvelum discuss pros and cons of dynamic packetizing of live, VOD and DVR content. It gives more details about Nimble Streamer VOD streaming.

Related documentation

Nimble Streamer, VOD re-streaming cache control, MP4 transmuxing to HLS VOD streaming,, HLS re-streaming set up, Smooth Streaming support,  HLS caching for effective re-streaming, HTTP pseudo-streaming progressive download, Progressive download re-streaming,