Avoid sending VLA in every packet

[Ramil980]

Hi @algesten,

At the moment, VLA is added to every packet in a frame. However, based on the libwebrtc implementation, it should only be included in the first packet of the frame. This PR fixes that behavior

[algesten]

We don't use VLA yet, but this seems reasonable. @xnorpx do you agree?

[xnorpx]

@algesten I think it looks resonable. But this would not work if we had if a user brought their own RTP header extension?

[algesten]

@algesten I think it looks resonable. But this would not work if we had if a user brought their own RTP header extension?

What do you mean?

[xnorpx]

@algesten I think it looks resonable. But this would not work if we had if a user brought their own RTP header extension?

What do you mean?

  let mut pkt_ext_vals = ext_vals.clone();
            if !first {
                pkt_ext_vals.user_values.remove::<VideoLayersAllocation>();
            }

I read it as it will remove VideoLayesAllocation if it's not the first package.

If I create my own say DD header extension which should also only be on the first packet (similar to VLA)

I do not contribute this back to str0m, how can I avoid to get it attached to all packets in the frame?