[FFmpeg-devel] [NUT-devel] [PATCH] nut: Add per frame sidedata and metadata

[Michael Niedermayer]

On Wed, Mar 27, 2013 at 05:14:23PM +0100, Luca Barbato wrote:
> On 27/03/13 15:41, Michael Niedermayer wrote:
> >  reserved_count[frame_code] (v)
> > -    MUST be <256.
> > +    Muxers conforming to this version of the specification MUST set it to
> > +    !!(flags[frame_code] & FLAG_SIDEDATA)
> > +    Demuxers MUST support any value from 0 to 255
> > +    These rules are to ensure extensibility of the format.
> 
> Would enjoy a better explanation.
> Such as "muxer supporting FLAG_SIDEDATA MUST set the reserved_count to 1
> if side data is in used in order to be compatible with older demuxers"

ok, added


> 
> > +
> > +sidedata_size[frame_code] (v)
> > +    Size in bytes at the end inside data which represent frame sidedata and
> > +    frame metadata.
> 
> metadata and sidedata are different items, I'm not exactly cool in
> lumping everything in the same serialized dictionary.

i see what you mean, ill post a different suggestion in a moment


> 
> > +
> > +side_data
> > +    This data structure is used both in frames for per frame side and metadata
> > +    as well as info tags for metadata covering the whole file, a stream
> > +    chapter or other.
> > +    Metadata is data that is about the actual data and generally not essential
> > +    for correct presentation
> > +    Sidedata is semantically part of the data and essential for its correct
> > +    presentation. The same syntax is used by both for simplicity.
> > +    The use of sidedata should be avoided and the information be put inside
> > +    the codec bitstream, if its syntax supports carrying such information.
> 
> This statement should be omitted.

ok


> 
> > +    Types of per frame side data:
> > +    "Channels", "ChannelLayout", "SampleRate", "Width", "Height"
> > +        This frame changes the number of channels, the channel layout, ... to
> > +        the given value (v)
> > +        If used in any frame of a stream then every keyframe of the stream
> > +        SHOULD carry such sidedata to allow seeking.
> > +    "Extradata", "Palette"
> > +        This frame changes the codec_specific_data or palette to the given
> > +        value (vb)
> > +        If used in any frame of a stream then every keyframe of the stream
> > +        SHOULD carry such sidedata to allow seeking.
> > +    "CodecSpecificSide<num>"
> > +        Codec specific side data, equivalent to matroskas BlockAdditional (vb)
> > +        the "<num>" should be replaced by a number identifying the type of
> > +        side data, it is equivalent/equal to BlockAddId in matroska.
> > +    "SkipStart", "SkipEnd"
> > +        The decoder should skip/drop the specified number of samples at the
> > +        start/end of this frame (v)
> > +    "UserData<identifer here>"
> > +        User specific side data, the "<identifer here>" should be replaced
> > +        by a globally unique identifer of the project that
> > +        uses/creates/understands the side data. For example "UserDataFFmpeg"
> 
> I'm not certain serializing type and enumeration this way would work
> that well.

its easy extendible and quite flexible, it also uses existing syntax

Thanks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many that live deserve death. And some that die deserve life. Can you give
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even the very wise cannot see all ends. -- Gandalf
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