651649 - Ogg skeleton presentation time doesn't take into account Vorbis

Status: RESOLVED INACTIVE

(Core :: Audio/Video: Playback, defect)

Description

[Chris Pearce [:cpearce (Not reading bugmail)]]

The definition of presentation time at http://wiki.xiph.org/Ogg_Skeleton_4 is:

"the presentation time: this is the actual cut-in time and all logical bitstreams are meant to start presenting from this time onwards, not from the time their data starts, which may be some time before that [...]"

Our implementation of Ogg skeleton presentation time doesn't drop Vorbis samples up to the presentation time, only Theora frames. I missed this when reviewing the original presentation time patch. :(

For example, content/media/test/bug556821.ogv has a presentation time, and oggz-info reports Content-duration of 2.425s (which I verified is correct using OggIndex), but Firefox finds the duration as 2.551s.

Comment 1

[cajbir (:cajbir)]

(In reply to comment #0)
>
> For example, content/media/test/bug556821.ogv has a presentation time, and
> oggz-info reports Content-duration of 2.425s (which I verified is correct
> using OggIndex), but Firefox finds the duration as 2.551s.

What version of oggz-info are you using? It gives a duration of 2.392 for me with version 1.1.1. Which is the correct duration?

Comment 2

[Chris Pearce [:cpearce (Not reading bugmail)]]

I was using oggz-info 0.9.9, which is the latest release with prebuilt win32 binaries.

I calculated the duration as 2.425s like so:

$ OggIndex content/media/test/bug556821.ogv
Writing output to 'content/media/test/bug556821.indexed.ogv'
WARNING: Lost sync decoding packets on theora page 1
WARNING: Fewer packets finished on theora page 1 than expected.
WARNING: Ogg page lengths don't sum to file length!
Vorbis/31415 index uses 62 bytes, compresses to 48 (77.4194%), duration [123274,125387] ms
Theora/1323396749 index uses 82 bytes, compresses to 52 (63.4146%), duration [122889,125825] ms
Skeleton 4.0 track with keyframe indexes uses 495 bytes, 0.251138% overhead

---

So the timelines of the streams in ms are:

Vorbis: [123274,125387]
Theora: [122889,125825]

oggz-info 0.9.9 reports the presentation-time as 123.400. So the duration is:
max(125825,125387) - 123400 == 2425

So unless oggz-info 0.9.9 is misreporting the presentation time, the duration should be 2425ms.

Comment 3

[Nils Ohlmeier [:drno]]

Mass closing do to inactivity.
Feel free to re-open if still needed.