Live stream question

[Abhijit Deodhar]

Hi,

When using a live stream,  I read that we need to encode and packetize the video stream into chunks/segments to enable streaming over HLS protocol.

My question is in the case of live stream, are the chunks stored on disk before being sent out over the wire via HLS protocol? or does the packetization happen completely in-memory and on the fly without any disk I/O?

if storage is required, what kind of storage is recommended for Ant server?

Regards

Abhijit

[Selim Emre]

Hi abhideodhar,

We are storing all of chunks/segments in disk currently. Saving these files on in-memory is not meaningful. Also, a scalable solution is hard for this method.

If you concern about latency, we are developing LL-DASH(CMAF), you can use LL-DASH.  Using disk with streaming makes it improves performance, easy to scale and decrease to error possibility.

Best Regards,

Selim

[Abhijit Deodhar]

Thanks for the reply Selim. 

If chunks are stored on disk, then it will add to the latency. I want to know how Ant Media Server minimizes this latency? I read about CMAF and smaller chunk sizes with chunked encoding and chunked transfer, but if the origin server needs to store few chunks on disk before forwarding them, then does it not affect the latency compared to in-memory operations?

What kind of storage is used for the chunks - is it an object storage or any file-system? What is the typical object size/file size of these chunks? How do you tune it to ensure that the storage layer does not add too much latency to the live stream? Any recommendations for the same?

 

If there are any relevant articles/blogs/documents, I would be interested to learn more about it.

Thanks

Abhijit

[Selim Emre]

Hi,

The main reason for latency is not related to writing to disk, but HLS protocol layer latency. If you are using SSD for harddisk hardware, no need to concern about latency for disk processes. 

CMAF chunk size is related to the stream video bitrate parameter. If you provide me stream video bitrate parameter, I can give more clear details about chunks. Also, no need for extra configurations for storage. You can achieve 3-4 sec latency with LL-DASH. We will add a blog post about LL-DASH.

I hope, it's clear.

Best Regards,

Selim

[Abhijit Deodhar]

Thanks Selim!

I am looking at an IP camera input stream which is typically 2Mb/s to 4Mb/s per camera.

What would be the chunk size for each video segment for such a stream?

Looking forward to the blog post...

Thanks

Abhijit

[Selim Emre]

Hi Abhideodhar,

Have a good day. According to my tests chunk sizes will be between 500-1000 kbps. We look forward to announcing this feature.

Best Regards,

Selim