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Dash-Industry-Forum / Guidelines-TimingModel

DASH-IF implementation guidelines: the DASH timing model
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Structure of a DASH presentation #15

Closed irajs closed 4 years ago

irajs commented 4 years ago

Change from "" to "":

This schema contains various extension points for 3rd parties to This schema defines various extension mechanisms for 3rd parties

Services SHALL NOT make use of the [MPEG2TS] container format. to This IOP only supports services using the [ISOBMFF] container format.

[MPEGCMAF] is the modern successor to [ISOBMFF]. DASH services SHALL use [MPEGCMAF] compatible data containers. To ensure backward compatibility with legacy services, clients SHOULD also support [ISOBMFF] that does not conform to [MPEGCMAF]. to [MPEGCMAF] is the constrained media format based on [ISOBMFF], specifically designed for adaptive streaming. This IOP uses [MPEGCMAF] compatible data containers.

There are strong parallels between [MPEGDASH] and HLS, both being adaptive streaming technologies that in their modern form use a mutually compatible container format ([MPEGCMAF]). to Note: HLS V? and later also support ([MPEGCMAF]). Therefore, under certain constraints, the content encoded in ([MPEGCMAF]) can be delivered using MPD or HLS m3u8 manifest format.

Note: [MPEGDASH] has the concept of "segment" (URL-addressable media object) and "subsegment" (byte range of URL-addressable media object), whereas [MPEGCMAF] does not make such a distinction. IOP uses [MPEGCMAF] segment terminology, with the term segment in IOP being equivalent to "CMAF segment" which in turns means "DASH media segment or media subsegment" to Note: [MPEGDASH] has the concept of "segment" (URL-addressable media object) and "subsegment" (byte range of URL-addressable media object), whereas [MPEGCMAF] does not make such a distinction. IOP uses [MPEGCMAF] segment terminology, with the term segment in IOP being equivalent to "CMAF segment" which in turns means "DASH media segment or media subsegment", depending the employed DASH profile.

The following SHALL requirement (or equivalent) should be added in the Media Segment section: -Services SHALL NOT make use of the [MPEG2TS] container format. -DASH services SHALL use [MPEGCMAF] compatible data containers. -To ensure backward compatibility with legacy services, clients SHOULD also support [ISOBMFF] that does not conform to [MPEGCMAF].

haudiobe commented 4 years ago

Note: [MPEGDASH] has the concept of "segment" (URL-addressable media object) and "subsegment" (byte range of URL-addressable media object), whereas [MPEGCMAF] does not make such a distinction. IOP uses [MPEGCMAF] segment terminology, with the term segment in IOP being equivalent to "CMAF segment" which in turns means "DASH media segment or media subsegment", depending the employed DASH profile.

CMAF surely makes the distinction, it has CMAF Fragments and CMAF Segments.

haudiobe commented 4 years ago

The following SHALL requirement (or equivalent) should be added in the Media Segment section: -Services SHALL NOT make use of the [MPEG2TS] container format. -DASH services SHALL use [MPEGCMAF] compatible data containers. -To ensure backward compatibility with legacy services, clients SHOULD also support [ISOBMFF] that does not conform to [MPEGCMAF].

The above is unclear and not helpful. Impossible to do any conformance on this. Suggest to completely remove

haudiobe commented 4 years ago

(v5 editing: 08/07/2019) Comments meaningful - can be implemented.

irajs commented 4 years ago

the text of this section was updated accordingly. The SHALL requirements yet to be implemented in other sections.

sandersaares commented 4 years ago

I think all the important parts are taken care of with August update, so I close the issue now. The parts that were not integrated into the rest were rather minor and not critical to the text. If upon re-reading it still feels something is absent, let's address it separately.