If you're more familiar with IT infrastructure or video production technologies than with video encoding, creating high-quality streams may seem daunting. Learn best practices for creating high-quality encoded source video for the Wowza Video™ service.
Source encode
When using Wowza Video, you create one stream rendition, also called a source encode. Wowza Video will automatically transcode your live stream to create many different output formats and sizes so your viewers can watch on a wide variety of devices and networks.
Wowza Video can't generate any output renditions that are of higher quality than what it receives from the video source, so prepare the highest quality source you can support. The higher the resolution of the source video, the more output renditions Wowza Video makes available for your viewers.
Incoming stream formats
Wowza Video supports encoders compatible with standard protocols, such as H.264 encoders that use RTMP or RTSP/RTP protocols. H.264 encoding presets can be contained in any of a number of formats (.MOV, .MP4, .F4V, etc.).
| Accepted encode formats | Accepted audio formats |
|---|---|
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Calculating source encoding presets
When preparing a source encode, use the following rules of thumb to make sure the size of the encode doesn't exceed your available bandwidth.
- Determine the bandwidth for your source encode.
- Allow 40% of your total bandwidth for overhead.
Example
- You have a 10 Mbps connection between your encoder and Wowza Video.
- Allowing 40% for overhead, your total encoding presets should not exceed 6 Mbps total, or 3 Mbps each.
- You could easily create a source encode of 1080p quality (1920x1080) at the maximum video bitrate (6000 Kbps) with an audio bitrate of 128 Kbps.
Recommended encoding presets
When preparing your source, you will need to specify audio and video settings for your stream. Shown below are recommended encoding presets that are typical for Wowza Video. In your camera or source encoder, you'll be able to configure some or all of the attributes described here.
For more information on each of these settings, please see Advanced encoding settings.
| Baseline | Main | High | ||||
| Resolution | 240p | 360p | 480p | 720p | 1080p | 4K |
| Frame size | 426x240 | 640x360 | 854x480 | 1280x720 | 1920x1080 | 3840x2160 |
| Supported video bitrate | 300 - 700 Kbps | 400 - 1200 Kbps | 512 - 2000 Kbps | 1600 - 4000 Kbps | 3200 - 6000 Kbps | 8000 - 20,000 Kbps |
| Recommended video bitrate | 512 Kbps | 1024 Kbps | 1600 Kbps | 2640 Kbps | 4400 Kbps | 12,000 Kbps |
Advanced encoding settings
There are many audio and video settings that control how your stream is prepared and delivered. Below is a list of the most common settings and how they will impact your stream.
| Setting | Description and Notes | Sample values |
|---|---|---|
| Aspect ratio | The ratio of the width to the height of your video. Wowza Video streams videos with different aspect ratios and frame sizes based on the device and platform. Should be divisible by 8. |
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| Audio bitrate | The amount of data being transferred into audio. A higher bitrate generally means better audio quality. |
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| Audio sample rate | The number of samples of audio recorded every second, measure in Hertz (Hz). |
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| Bits per pixel | The color depth of the video. Also impacted by the amount of motion in your video, with higher pixel count required for active videos. |
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| Bitrate (constant or variable) |
Constant bitrate (CBR) encoding is faster, but results in lower quality for complex video. VBR encoding adjusts the bitrate depending on the complexity of the content. |
VBR: constrain to 110% of target bitrate to maintain video quality |
| Frame rate | The speed at which images appear, measured in frames per second (fps). Wowza Video uses the source encode frame rate for all output renditions. Wowza Video supports a maximum rate of 60fps. |
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| Frame size | The size of a single video frame: width x height, measured in pixels. Wowza Video streams videos with different aspect ratios and frame sizes based on the device and platform. |
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| Keyframes | The full frame of the image in a video. Subsequent frames only contain the information that has changed. |
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| Profile | Determines how the H.264 codec compresses the stream. Consider your audience when selecting the profile. For example, will most users be watching on a mobile device? |
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| Video bitrate | The amount of data in 1 second of video, typically measured in kilobits per second, or Kbps. Higher bitrates can contain more data, but you must have the bandwidth to accommodate it. | The formula for calculating bitrate is: bits/pixel x (width x height) x frame rate)/1000 |
Testing your encoding setup
The Wowza Video standard support plan offers a 48-hour turnaround during business hours, so make sure to test your entire setup at least three business days before your event. It's also recommended to make sure your video source is ready to stream at least two hours before the scheduled start time and to start the video source at least 15 minutes before the event begins.
To test your entire setup:
- Run the primary and backup encoders with a test stream for at least 30 minutes each.
- Preview the stream on a variety of screens and devices.
- View the stream on your Wowza Video hosted page, if you have one.
- View the stream on external players and websites, if you're using them.
- If you're recording, check that the recording captures supported audio and video as expected.
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