[vlc-devel] Append metadata to block_t

[Rémi Denis-Courmont]

	Hello,

Le perjantaina 13. heinäkuuta 2018, 14.44.47 EEST Vladimir Davydov a écrit :
> One of the ways I see is to append metadata at the begin of p_buffer (before
> media sample payload) and set some new flag to i_flags.  But it requires
> adding of new global flag like BLOCK_FLAG_CENC_ENCRYPTED.
> Something like adding to vlc_block.h :
> #define BLOCK_FLAG_CENC_ENCRYPTED 0x4000
> That is not good because flags range is pretty limited.

That will not work properly.
The decoders and packetizers need to know up-front that the ES is ciphered.

If the ciphering scheme is codec-agnostic, then some data needs to be added to 
the ES format. If it is codec-dependent, then you can use a completely new 
FourCC, like this is a new codec - or you can extend ES format.

If you use a new FourCC, you can pass the cipher data however you want within 
the block_t - it's down to an agreement between the demuxer(s), the 
packetizer(s) and the decoder(s) that support the FourCC.

If you use something generic, then currently there is no agreed solution as 
François said.

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