Advanced Shaping Settings

The following table lists the advanced tuning settings for Transport Stream Shaping. These settings are only available when Transport Stream Shaping is enabled.

Caution

Changing these settings can have a negative impact on the video performance and/or network performance.

Tip

Advanced Setting	Description/Values
Transport Stream Bitrate	(Transport Stream Shaping must be enabled) Type in the Maximum Transport Stream (TS) Bitrate in kbps for the outbound stream, for example, 3000. Kraken automatically generates a minimum value based on the Video Bitrate, Audio Bitrate and whether or not there is KLV metadata. This minimum value may be used by default, or you may set the Maximum TS Bitrate to a higher value (but not lower). Note If KLV metadata pass-through is enabled, 200 kbps will be added to the Maximum TS Bitrate value by default. If your site is utilizing KLV streams that are higher than 200 kbps, you should increase the Maximum TS Bitrate value to make room for the KLV stream. For example, to use a 1 Mbps KLV stream, you should increase the Maximum TS Bitrate by 800 kbps to allocate enough room in the Kraken output stream for the KLV, Audio and Video. Tip If the encoder is overrunning the ceiling bitrate and you have room in the channel to spare, you can increase this value, which allows more room in the channel for higher spikes in the encoder. By default, the Web Interface tries to set this to 20% above the expected aggregate bitrate of the elementary streams. For instance, it adds the Video Bitrate, Audio Bitrate, and expected KLV bitrate and adds 20%. This can be increased, but should probably not drop below 12%. You need at least 3% and sometimes more for the TS packetization and PSI tables, etc.
Shaping Video Max Bitrate	Type in the maximum video bitrate for shaping the outbound stream, as a percentage. Range = 50% - 150% Note Increasing this above 80% will increase the quality, but also increases the probability that the encoder will overrun the ceiling. At higher bitrates, it should be possible to increase this to 85%. Tip You can try setting this to 90% or higher to see where you start observing problems due to overrunning the network buffers. In most situations, you should not exceed 100%. The optimal setting is reached when this value is as close to 100% as possible without overrunning the buffers. This depends on a large number of factors, including Bitrate, Frame Rate, GOP size, Resolution, scene complexity, and VBV size.
Shaping Video Target Bitrate	Type in the target video bitrate for shaping the outbound stream, as a percentage. Range = 50% - 150% Tip As a general rule, keep this at 70% for all operating points. It should be lower than the Shaping Video Max Bitrate and lower than 100%. 70% is fairly optimal for the Kraken’s encoder.
Depth of VBV	Type in or adjust the slider to specify the value in milliseconds for the Video Buffering Verifier (VBV) depth. Range = 500 - 3000ms Note The VBV is a theoretical MPEG video buffer model used to ensure that an encoded video stream can be correctly buffered and played back at the decoder device. By definition, the VBV will not overflow nor underflow when its input is a compliant MPEG stream. Tip This is the depth of the CBR buffer in the decoder VBV model in milliseconds. A value that you should strive for is 1000ms; lower values may decrease the rate at which the encoder overruns the network buffers at lower bitrates. Increasing this parameter increases latency and also increases quality. It should not be lowered below 1000ms. A good quality encoder will make intra frames 12- 15 times larger than non-intra frames. At 30fps, this means half of the stream bitrate is consumed for a single video frame. Since it must fit inside the VBV, the optimal point for our low delay application is 1000ms.
Depth of Network Shaping Buffer	Type in or adjust the slider to specify the value in milliseconds for the network shaping buffer depth. Range = 500 - 3000ms Note This is the depth in milliseconds of the network traffic shaper’s buffers. Since a good quality encoder will generate an intra frame consuming approximately 50% of the available bitrate in one frame, this is the interval over which the bitrate spike of the intra frame is sent out over the network to keep it inside the channel bitrate. If the encoder overshoots this buffer, because the bitrate is too low for the resolution, frame rate, and/or scene complexity, the encoder will overrun this buffer. As a result, a decoder will receive a corrupt stream.