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30 Chapter 2
Each track in a media file must have its own hint track. For example, a movie with one audio
and one video track must have two hint tracks: one for the audio track and one for the
video track.
When you use QuickTime Player to export a movie as a hinted movie, QuickTime adds all the
necessary hint tracks automatically.
To export a QuickTime movie as a hinted movie with QuickTime Player:
1 Open QuickTime Player on a Mac OS X, Mac OS, or Windows computer.
2 Open the QuickTime movie you want to hint.
3 Choose Export from the File menu.
4 Choose “Movie to Hinted Movie” from the pop-up menu, then type a new filename.
5 Click Save.
Improving the Performance of Hinted Movies
When you export a hinted movie from QuickTime Player, you can compress video and sound
using either the native RTP payload encoder or the generic QuickTime payload encoder. To
select QuickTime, click Options in the QuickTime Player Export dialog, then click the Track
Hinter Settings button.
The QuickTime payload encoder parses media samples into equal-sized packets. If a video
frame takes up 10 packets, and one is lost, the whole frame is discarded. Payload encoders
native to a specific codec take advantage of specific knowledge of the media format to parse
the data into packets in a more compact way. They can recover a partial frame if a video
packet is lost.
Generally, native payload encoding is preferred. Check with your codec manufacturer for
specific guidelines regarding payload encoding.
Use care and experimentation when choosing between native and QuickTime payload
encoders.
Session Description Protocol (SDP) Files
A Session Description Protocol (SDP) file contains information about the format, timing, and
authorship of the streamed media. For live streaming, SDP files are created on the capture-
and-encoding computer by QuickTime Broadcaster or other broadcast software. For
broadcasts of prerecorded media, an SDP file is automatically created on your streaming
server. To stream either live or prerecorded media, an SDP file must be present in the media
directory you’ve designated in Streaming Server Admin.
LL0329.book Page 30 Wednesday, November 20, 2002 2:09 PM