[FFmpeg-devel] [RFC] Exporting virtual timelines as stream side data

Steve Lhomme robux4 at ycbcr.xyz
Thu Mar 29 15:00:03 EEST 2018

Le 27/03/2018 à 22:45, Dave Rice a écrit :
>> On Mar 27, 2018, at 4:33 PM, wm4 <nfxjfg at googlemail.com> wrote:
>> On Tue, 27 Mar 2018 16:11:11 -0400
>> Dave Rice <dave at dericed.com> wrote:
>>>> On Mar 27, 2018, at 4:01 PM, Derek Buitenhuis <derek.buitenhuis at gmail.com> wrote:
>>>> On 3/27/2018 8:52 PM, Rostislav Pehlivanov wrote:
>>>>> I think we should drop the internal crap if the tools and the API support
>>>>> it. Would also solve a lot of issues like ffmpeg.c not trimming the start
>>>>> frame (so people complain all the time about longer files).
>>>> I personally agree, but I thought I'd be diplomatic about it, since it would
>>>> technically be losing a 'feature', since it would no longer Just Work(ish)
>>>> and require user applications to apply timelines themselves - and I figured
>>>> some would argue that point.
>>> +1 I’m willing to contribute what information or samples would be needed to help with Matroska support with virtual timelines. IMO, this would be a valuable feature to have in ffmpeg.
>>> Dave Rice
>> Some explanations how this interacts with editions would be good.
> I put an example with two editions at https://archive.org/download/chapters_test/chapters_test.mkv which mimics a digitized video tape. One edition depicts the stored video encoding in its entire presentation and the other default edition plays from the video encoding selectively. When the file is played in VLC, the default edition is used to show a shortened presentation, but the other editions may be selected within the Program menu option. In the proposal there should be an option to mimic the current behavior and ignore the editions (equivalent of -ignore_editlist in mov), to use the first default edition, or to select a specific edition.

For the record, the ordered chapters with segment  linking in VLC have 
been fixed recently with this issue 

There is a lengthy set of sample files with ordered chapters and 
multiple segments. That's basically the most complex case that can exist.

I don't think the API covers segment linking, nor how libavformat would 
look around in the file system if there are available segments 
(something we do in VLC). So not sure an API for some case not covered 
would make sense.

>> Or documenting ordered chapters and segment linking in the mkv "spec"
>> at all.
> This document, http://mod16.org/hurfdurf/?p=8 <http://mod16.org/hurfdurf/?p=8>,  is unofficially a good resource on that.
> More officially the Cellar working group has this section on Linked Segments: https://tools.ietf.org/html/draft-lhomme-cellar-matroska-04#section-23 <https://tools.ietf.org/html/draft-lhomme-cellar-matroska-04#section-23>, and this one on Ordered Editions: https://tools.ietf.org/html/draft-lhomme-cellar-matroska-04#section- <https://tools.ietf.org/html/draft-lhomme-cellar-matroska-04#section->. This documentation is a work in progress so comments/reviews/suggestions are welcome (issues can be filed at https://github.com/Matroska-Org/matroska-specification <https://github.com/Matroska-Org/matroska-specification> or via https://www.ietf.org/mailman/listinfo/cellar <https://www.ietf.org/mailman/listinfo/cellar>).
> Dave Rice
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