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Dash-Industry-Forum / DASH-IF-Conformance

This repository provides the source code for MPEG-DASH/DASH-IF Conformance Software/Validator. It has been extended according to further standards, such as CMAF, DVB-DASH, HbbTV, and CTA WAVE.
https://conformance.dashif.org/
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track run box(trun) negative cts offset error from audio stream? #446

Open Murmur opened 5 years ago

Murmur commented 5 years ago

Is it correct to have this error from the audio representation? My understanding was moof/traf/trun/sample[0..n].CompositionTimeOffset signed 32bit(version 1) is used for video streams with B frames. Audio stream may use unsigned 32bit(version 0) trun box. Or my assumption is wrong?

(25 repetition\s) ### ### HbbTV check violated: Section E.3.1.1. "The track run box (trun) shall allow negative composition offsets in order to maintain audio visual presentation synchronization", but unsigned offsets found

I cannot make ffmpeg+mp4box use trun.version=1 for audio segments. Video segments can be created to have a negative offset values.

andyburras commented 2 years ago

Also seeing this issue of HbbTV checks not supporting trun version zero and giving:

HbbTV check violated: Section E.3.1.1. "The track run box (trun) shall allow negative composition offsets in order to maintain audio visual presentation synchronization", but unsigned offsets found

E.3.1.1 references TS 103 285. This states that negative composition offsets shall be supported (i.e. ‘trun’ boxes with version >= 1). It does not however, prohibit the use of a version zero trun combined with EditListBoxes.

jpiesing commented 2 years ago

I suspect the term HbbTV profile means the old HbbTV 1.5 profile, i.e. not HbbTV referencing DVB-DASH.