The Ultimate Guide to VOD Video Renditions & Bitrates on Dacast

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As a broadcaster, it is important to understand that not all viewers will have the same internet speed. 

Why is this important, you might ask? It is important to acknowledge the variation in internet speeds so that you are providing files with the optimal bitrate to reduce buffering or lagging.

In this article, we will be covering video bitrate, multi-bitrate streaming, the value of providing multiple VOD renditions, and suggested video rendition settings.

What is Bitrate?

Bitrate is the measure of how many bits per second are transferred. A video with a higher bitrate would transfer more data at one time than a video with a lower bitrate.

When it comes to broadcasting, bitrate is often measured in megabits per second (Mbps). 

Faster internet connections can handle larger bitrate streams. Please keep in mind that the higher the bitrate you use, the more bandwidth your stream will consume. 

In order to create multiple renditions of your video, which would be copies that are a variety of sizes, you must transcode the video. Dacast uses cloud transcoding on uploaded videos.

What is Multi-Bitrate Streaming?

As we mentioned, higher internet speeds can handle streaming at a higher bitrate. On the flip side, lower internet speeds may destroy the quality of a high bitrate stream.

A solution to varying internet speeds is multi-bitrate streaming. Multi-bitrate streaming uses multiple video renditions at different bit-rates. 

Some video players that use multi-bitrate streaming allow users to choose the rendition they’d like to stream. There are also adaptive bitrate video players that automatically choose the best rendition for each viewer based on their internet speed.

Suggested Video Rendition Settings

Below is a table that documents the full details of the output for each VOD rendition.

Name Description Long Short FPS (Round Down) Max Video Bitrate Max Audio Bitrate Container Video Codec Profile Audio Codec
4k – 2160p UHD (Ultra High Definition) 3480 2160 25/30/50/60 20 Mbps 128 MP4 H264 High AAC
2k – 1440p QHD (Quad High Definition) 2560 1440 25/30/50/60 15 Mpps 128 MP4 H264 High AAC
FHD – 1080p FHD (Full HD) 1920 1080 25/30/50/60 7 Mbps 128 MP4 H264 High AAC
HD – 720p SHD (Standard HD) 1280 720 25/30/50/60 5 Mbps 128 MP4 H264 High AAC
SD – 480p FWVGA (Full Wide Video Graphics Array) 854 480 25/29.97/30/50/59.54/60 2 Mbps 128 MP4 H264 Main AAC
LD – 360p nHD (Ninth of High Definition) 640 360 25/30/50/60 1.5 Mbps 128 MP4 H264 Main AAC
ULD – 240p WQVGA (Wide Quarter Video Graphics Array) 426 240 25/30/50/60 0.5 Mbps 128 MP4 H264 Main AAC
Magic Encoding Magic Encoding N/A N/A 25/30/50/60 5 Mbps N/A MP4 H264 Main AAC
DNE – Do not encode Do Not Encode N/A N/A N/A N/A N/A N/A N/A N/A N/A

 

Other Required Live Encoder Settings

Since bitrate goes and in hand with some other aspects of videos, now is a good time to touch upon encoder settings for streaming on Dacast.

The following live encoder settings are required for live streaming with Dacast, regardless of your selected resolution and bitrate:

VIDEO CODEC H.264 (x264 may work)
FRAME RATE 25 or 30
KEYFRAME INTERVAL 2 secs (or 2x frame rate)
SCANNING Progressive
ENCODING BITRATE Constant (CBR)
AUDIO CODEC AAC
AUDIO BITRATE 128 kbps
AUDIO CHANNELS 2 (Stereo)
AUDIO SAMPLE RATE 48 kHz (48,000 Hz)

 

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