time to notice each artifact; thus, the image quality per frame must be higher to provide the same perceived quality.
ÆConsequently, you should try to use the source frame rate if possible, and no less than half the source frame rate, unless you target real‐time streaming to dial‐up modem users.
ÆRaising frame rates generally pays off more than raising frame sizes in improving the user experience.
NEGOTIATING FRAME DROPPING
‐Some codecs optionally or automatically reduce frame rate in order to maintain the quality of difficult frames and keep within the target average data rate. This process generally takes the form of a control that sets the minimum image quality per frame. If the bits that the codec would normally allocate to a given frame aren’t sufficient to hit the target quality, it raises the data rate for the frame to the minimum required for quality; then drops one or more frames that follow to keep the average data rate on target.
ÆWhether this process is appropriate depends on the content.
ÆVarious factors come into play here:
‐Keyframe rate
‐Sample rate
‐Channels
Delivery methods for video
The method you use to compress content depends greatly on how you plan to deliver it.
ÆDisc‐based delivery
‐Disc playback keeps getting better even as the focus of the industry moves to network delivery.
‐Disc‐based delivery works well, and the available data rates are radically higher than those for web video.
ÆDownloadable files
‐The most basic type of video on the web is a simple, downloadable file.
‐The advantage of downloadable files is that users don’t expect real‐time playback during the download.
