Opened 6 years ago

Last modified 6 years ago

#1 new defect

Temporal scalability in VP8

Reported by: bernard_aboba@… Owned by: draft-ietf-payload-vp8@…
Priority: major Milestone: milestone1
Component: vp8 Version:
Severity: Active WG Document Keywords:
Cc:

Description

Section 1 states:

In summary, the payload format described in this document enables a number of features in VP8, including:

· Temporal scalability.

However, Section 6 doesn’t include information on format parameters or O/A considerations relating to temporal scaling.

It appears that VP8 transports all temporal layers in a single RTP session utilizing a single SSRC (e.g. Single Session Transport), so that RFC 5583 does not apply, correct?

Other than the max-fr parameter, is there anything that provides an indication of the capabilities of the receiver? Or is the encoder free to utilize any configuration that fits within the max-fr parameter?

For example, if the Offer includes max-fr=60, does that mean that the receiver is prepared to handle any of the following?

  1. T0 = 60 fps (no temporal scalability)
  2. T0 = 30 fps, T1 = 30 fps
  3. T0 = 15 fps, T1 = 15 fps, T2=30 fps
  4. T0 = 7.5 fps, T1 = 7.5 fps, T2 = 15 fps, T3 = 30 fps


Change History (1)

comment:1 Changed 6 years ago by harald@…

As far as I understand, the temporal scalability is enabled by the features described in section 4.2, and all receivers of this format are required to handle all combinations of parameters used here.

Thus, there is no need for signalling the actual scalability parameters used; it's an unilateral encoder choice.

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