Networked AV Systems by Brad Grimes

Author:Brad Grimes
Language: eng
Format: epub
Publisher: McGraw-Hill Education
Published: 2014-08-26T16:00:00+00:00

Achieving High-Quality Compressed Images

Regardless of the method you choose to encode and compress AV content for streaming, there are ways you can optimize the content for best possible results:

• Start with a frame size that matches your output size If you capture video in the same size that you know users will be viewing it, the systems won’t have to spend CPU cycles scaling the video. Your streaming devices can concentrate on encoding and compressing the images. If in your needs analysis you identified a heterogeneous set of endpoints, match the captured frame size to the most common use case.

• Reduce image noise Encoders don’t know the difference between noise and detail. Composite video, for example, can include artifacts that look like detail information to a streaming encoder. Encoding S-video or component video will usually lead to improved image quality.

Good lighting techniques and better video cameras will reduce noise. Too much video noise can trick an encoder into detecting motion where there is none. For example, the background of a videoconference may be static (e.g., a wall), but if there is enough video noise, the encoder will think something is moving in the background and waste compression time on the wall instead of the presenter’s face.

• Select the proper audio quality If you’re streaming voice-quality audio, but you’re set up for 44.1 MHz stereo, you’re wasting bits that could be used for video or better audio compression.

• Select the proper codec As we’ve discussed, various codecs support differing streaming quality and data rates. Experiment with different codecs, settings, and applications to figure out which will deliver the experience the customer expects. For example, MPEG-4 is not the best choice for editing in most cases.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.