On Tue, Sep 1, 2015 at 11:57 AM, David Singer <sin...@apple.com> wrote:
> > > On Sep 1, 2015, at 11:36 , Kevin Marks <kevinma...@gmail.com> wrote: > > > I suppose the browser could generate this data the first time it reads > through the video. It would use a lot less memory. Though that sounds like > a problem for the browsers to solve, not the standard. > > > > There is no *generation* on the browser side; these tables are part of > the file format. > > > > Well, when it imports stream-oriented media it has to construct these in > memory, but they can be saved out again. I know that in theory this made > its way into the mp4 format, but I'm not sure how much of it is real. > > Two different questions: > a) do the QuickTime movie file format and the MP4 format contain these > tables? Yes. > b) if I open another format, what happens? > > For case (a), the situation may be more nuanced if Movie Fragments are in > use (you then get the tables for each fragment of the movie, though they > are easily coalesced as they arrive). > > For case (b), classic QuickTime used to ‘convert to movie’ in memory, > building the tables. The situation is more nuanced on more recent engines. > > I think the point of the discussion is that one cannot dismiss trick modes > such as reverse play as being unimplementable. The other point for me is that given http://aomedia.org/ announcing plans to create a new video file format to fix everything, that this time we actually learn from this history and make one that is editable and seekable again.