[vlc-devel] [PATCH 3/4] avformat mux: Mark keyframe blocks as such.

[Luca Barbato]

On 16/08/13 13:40, Rafaël Carré wrote:
> libavformat developers can and will change this buffering behaviour so I
> doubt we can rely on it.

Actually we can provide a simple avoption called flush-before-keyframe,
but once you have multitrack allowed in webm you are back to square one
(same thing with common segmented formats)

> If it's useful to know if a webm container packet comes with a keyframe
> then I guess avformat should be modified to include that information.

Your problem here is that you want AVIO to get notified about an
information the I/O layer might not really find useful.

The whole thing is a huge hack to cope with:

- client shortcoming due specification constraint (they would not
  expect what we are feeding them with)

- flying pig syndrome (aka make what the specification explicitly
forbids just because you can)

Since I do like making pigs fly I'll help out the best I can, but is
good to be aware about it =) (and pester the browser people to relax the
specification and/or have something less crazy than webrtc for plain
real-time one-directional streaming).

Patch on libav-devel about it coming soon.

lu