Customize Network Streaming

Modify the Latency and Jitter of Audio/Video Streams

You can modify the amount of time it takes for audio/video streams to begin playback by formatting the stream URL as follows: <streaming_url>?latency=<value_in_ms>&jitter=<value_in_ms>. For example, http://www.example.com/stream1?latency=-450&jitter=50

The default latency value is 0 milliseconds and the default jitter value is 300 milliseconds, which allows the audio- and video-stream buffers to fill up before playback begins; this makes playback less likely to stutter when the stream has a high bitrate or the network is slow. Using smaller latency and jitter values will not change the buffer size. Instead, it will give the buffers less time to fill up before playback begins. We recommend thoroughly testing custom latency values in a target network environment before deployment.

The "latency" value is measured as a deviation from the default latency (in milliseconds). For example, a value of -250 reduces the latency by a quarter of a second, while a value of 0 specifies the default latency. Tests have shown that usable latency values extend down to approximately -450ms (though this value may differ depending on the network environment)--while jitter values can be reduced to approximately 30ms. Reducing the latency/jitter too much will result in obvious playback stutter.

You can also increase the latency value beyond 0. This will increase the size of the streaming buffer and delay playback. Increasing latency to 10 seconds or more will likely require use of the vcdbsize and acdbsize parameters, described below, to increase the memory allocated to the buffer.

Customize the Streaming Buffer Size

You can modify the default buffer sizes associated with incoming audio/video streams. Increasing the buffer can help improve the performance of high-bitrate video streams or audio/video that is being streamed over a slow network.

Note that increasing the buffer size will also increase the playback delay (latency) when the stream begins, but decreasing the default buffer size will not shorten it.

You can modify the default buffer size by appending optional parameters to the end of a streaming URL in a BrightAuthor Video Stream or Audio Stream state (this method also applies to custom scripts). The URL parameters must be formatted as follows: <streaming_url>?buffersize=<number>&vcdbsize=<number>&acdbsize=<number>. For example, http://www.example.com/stream1?buffersize=10000000&vcdbsize=10000000&acdbsize=256000

Note that all buffer sizes are specified in bytes.

• buffersize: The size of the main buffer. Once streaming data comes into the main buffer, it is immediately split into the audio and video buffers. The default size of the main buffer is 1.5MB for HD models, 3MB for XD models, and 6MB for 4K models.

• vcdbsize: The size of the video-coded data buffer. The default size of this buffer is 3MB for HD models, 3MB for XD models, and 6MB for 4K models.

• acdbsize: The size of the audio-coded data buffer.  The default size of this buffer is 256KB for all models.