[vlc-devel] [PATCH 00/17] RFC Split block_t into 2 different data containers

[Rémi Denis-Courmont]

Le keskiviikkona 24. huhtikuuta 2019, 16.57.15 EEST Thomas Guillem a écrit :
> Hello TypX,
> 
> I also 2 other issues with this RFC:
>  - Drop of flags in vlc_data_t: sadly, there will be no ways for accesses to
> report a discontinuity.

That's a feature. You cannot have flags in a byte stream as you've reminded 
already.

> I know it is broken in VLC 3.0 since flags are lost
> in stream filters, but there are a lot of requests to bring back the
> ability for accesses to notify a discontinuity.

That was not "broken in VLC 3.0". The only stream_t function that could 
preserve packet boundaries, and thus flags, is vlc_stream_ReadBlock() which was 
introduced in 3.0, much later than stream filters.

Besides, even before streams filters existed, the stream buffering code in the 
core did much the same as stream filters do today. This is really as old as the 
stream_t abstraction.

So there never was an option to pass flags there. In particular, what V4L2 
access does is just cargo cult from the V4L2 access_demux.

> We should fix it for 4.0
> and therefore keep this flag.

I completely disagree. That is an impossible/inconsistent requirement.

If you have packets with flags, don't use the the stream abstraction. Even if 
that worked through stream filters, it would confuse the demuxers behind it. So 
you need tight coupling anyway.

-- 
Реми Дёни-Курмон
http://www.remlab.net/