Playback Issue 02: Sequential Track Playback General

Overview of Playback Issue

Playback of tracks is the regular operation. Specific aspects for media profiles beyond the requirements here should be submitted as separate issues.

References and Background

to be added

Definitions

Required Capabilities

The support for a media profile, signaled by the compatibility brand, indicates that the track of a media profile can be played back if the data is sequentially provided to the track buffer.

Action/Stimulus

For a track buffer that supports a media profile, **Sequential Playback" of a CMAF Track k, consisting of a sequence if CMAF Header and CMAF Fragments refers to the following action:

• The track buffer is initialized with the CMAF header of the track k
• The first CMAF Fragment of the CMAF track is appended to the track buffer
• The playback is initialized at wall-clock time Ti and the first sample of the first fragment with presentation time tf[k,i=1]=0 is played back at wall-clock time Tp
• The next fragment i=2 with presentation time tf[k,i=2] is appended to the track buffer prior to Ti + tf[k,i=2] - tf[k,i=1]
• The following fragments i with presentation time tf[k,i] are appended sequentially to the track buffer prior to Ti + tf[k,i] - tf[k,i-1]

Expected Observation

The playback shall be continuous and time-accurate.

Testable Requirements

General

• Each sample j in fragment i in the track k shall be played back the presentation time, i.e. at time Tp + t[k,i,j] (We likely need some margins)

Video

tbd

Audio

tbd

Media Profiles may add additional requirements for seamless switching.

Comments and Guidelines

tbd