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Mpeg flags for DRM support at newer encoding API - was: RFC: V4L2 MPEG Encoding API: Part 2

Hans Verkuil wrote:
On Tuesday 02 May 2006 22:34, Mauro Carvalho Chehab wrote:
Em Seg, 2006-05-01 às 00:40 +0200, Hans Verkuil escreveu:
Audio controls
==============

V4L2_CID_COMP_AUDIO_COPYRIGHT
Set whether the material has copyright or not.
BOOL: possible values: 1 = has copyright, 0 = does not have
copyright

V4L2_CID_COMP_AUDIO_ORIGINAL
Set if the material is original or a copy.
BOOL: possible values: 1 = original, 0 = copy


Stream controls
===============

The first copyright control maps to a stream property in the
ISO/IEC 11172-1 standard. The second is device specific and lists
the various stream types that the device can produce.

V4L2_CID_COMP_STREAM_COPYRIGHT
BOOL
0=Stream is not copyrighted
1=Stream is copyrighted
Although we are not discussing DRM implementation at kernel, those
flags are meant to help on DRM controls. I'm not sure if we should or
not implement it.

For the record, these flags have NOTHING to do with DRM. They cannot be used to implement DRM. They just mark the stream as having copyright and are the MPEG equivalent of saying 'Copyright by...'. There is no encryption involved, nor can it be used for that. All MPEG programs like xine, mplayer, etc. and also all commercial programs for whatever platform will and must accept MPEG streams with this bit. There is simply NO DRM INVOLVED. I still don't know how you get this idea into your head :-(

ISO-13818-1, 2.4.3.7, describes that Copyright bit like this..

a PES packet shall have a Copyright Indicator. 1 Bit

copyright -- This is a 1 bit field. When set to '1' it indicates that the material of the associated PES packet
payload is protected by copyright. When set to '0' it is not defined whether the material is protected by
copyright. A copyright descriptor described in 2.6.8 on page 71 is associated with the elementary stream
which contains this PES packet and the copyright flag is set to '1' the descriptor applies to the material
contained in this PES packet.

additional_copy_info -- This 7 bit field contains private data relating to copyright information.


2.6.2.4 describes the copyright descriptor thus ..


2.6.24 Copyright descriptor
The copyright_descriptor provides a method to enable audio-visual works identification. This
copyright_descriptor applies to programs or program elements within programs.

copyright_descriptor() {
   descriptor_tag                        8 uimsbf
   descriptor_length                 8 uimsbf
   copyright_identifier             32 uimsbf
   for (i = 0; i < N ; i++ ){
   additional_copyright_info     8 bslbf
   }
}


Manu

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