PVC and Super Quality configuration

This guide explains how to enable low-bitrate high-definition features (PVC) for video transcoding on Media Gateway.

Media Gateway supports enabling PVC (Perceptual Video Coding) or Super Quality functions during video transcoding to achieve low-bitrate high-definition streaming. These features optimize video quality while reducing bandwidth requirements.

Enable PVC or Super Quality when creating a stream configuration template.

The following example shows a stream configuration template with PVC and Super Quality enabled:

_27

{

_27

"settings": {

_27

"transcoding": {

_27

"video": {

_27

"enabled": true,

_27

"width": 1920,

_27

"height": 1080,

_27

"fps": 30,

_27

"bitrate": 0,

_27

"advancedOptions": {

_27

"superResolution": {

_27

"enabled": true,

_27

"alphaBlending": 256

_27

},

_27

"pvc": {

_27

"enabled": true,

_27

"saveBitrateRatio": 20

_27

}

_27

}

_27

},

_27

"audio": {

_27

"enabled": true,

_27

"profile": 3

_27

}

_27

}

_27

}

_27

}

Set settings.transcoding.video.enabled to true to enable video transcoding, then configure resolution, frame rate, and bitrate based on your requirements.

Configure advancedOptions as follows:

• pvc

  • enabled": Set to true to enable PVC or false to disable (default: false)
  • saveBitrateRatio: Percentage of bitrate to save. For example, 20 means save 20% bitrate. Only applies when video.bitrate is missing or set to 0

• superResolution

  • enabled: Set to true to enable Super Quality or false to disable (default: false)
  • alphaBlending: Indicates the intensity of super quality, ranging from 1 to 256. The larger the value, the higher the intensity. The default value is 128.

Understanding how PVC interacts with different bitrate configurations is crucial for achieving optimal results. The interaction between PVC and bitrate settings affects output quality:

• When video.bitrate is missing:

  • Output bitrate follows the source stream bitrate
  • If PVC is enabled with saveBitrateRatio, output bitrate reduces proportionally from the source bitrate

• When video.bitrate is set to 0:

  • Output bitrate is automatically calculated based on resolution and frame rate (recommended network bitrate)
  • If PVC is enabled with saveBitrateRatio, output bitrate reduces proportionally from the recommended bitrate

• When video.bitrate is explicitly set:

  • Output bitrate matches the specified value
  • PVC processes the image before encoding without adjusting bitrate
  • saveBitrateRatio has no effect in this mode

• Quality considerations:

  • PVC saves bitrate according to the specified ratio
  • Actual quality improvement depends on source stream complexity
  • Simple content maintains quality at higher saving ratios
  • Complex content may degrade if the saving ratio is too high

info

Test different saving ratios with your actual content to determine optimal settings before deployment.

PVC works by preprocessing YUV images before encoding, removing details in areas less sensitive to human perception. It inherently reduces image quality as a trade-off for bitrate savings. This allows encoders to allocate limited bitrate more effectively to visually important areas.

Following are some use cases where enabling PVC is useful:

• Fixed encoding bitrate requirements
• Insufficient bitrate for acceptable quality without PVC
• Scenarios where bandwidth is severely constrained

There's no universal threshold for when bitrate becomes "insufficient". Simple content, such as presentations, can look good at lower bitrates, while complex content, like action scenes, needs more bandwidth. Following are some key factors to consider:

• Depends on both bitrate value and source content complexity
• High complexity content with low bitrate benefits most from PVC
• Requires testing with actual content to validate effectiveness

info

Enable PVC only when bitrate limitations prevent acceptable quality. Always test with representative content before production use.