Ichthyostega
d31d4295a4
Indeed — this change set is kind of sad.
Because I still admire the design of the GAVL library,
and would love to use it for processing of raw video.
However, up to now, we never got to the point of actually
doing so. For the future, I am not sure if there remains
room to rely on lib-GAVL, since FFmpeg roughly covers
a similar ground (and a lot beyond that). And providing
a plug-in for FFmpeg is unavoidable, practically speaking.
So I still retain the nominal dependency on lib-GAVL
in the Build system (since it is still packaged in Debian).
But it is pointless to rely on this library just for an
external type-def `gavl_time_t`. We owe much to this
inspiration, but it can be expected that we'll wrap
these raw time-values into a dedicated marker type
soon, and we certainly won't be exposing any C-style
interface for time calculations in future, since
we do not want anyone to side-step the Lumiera
time handling framework in favour of working
„just with plain numbers“
NOTE: lib-GAVL hompage has moved to Github:
https://github.com/bplaum/gavl
108 lines
3.8 KiB
C++
108 lines
3.8 KiB
C++
/*
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LILBGAVL.hpp - facade for integrating the GAVL media handling library
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Copyright (C)
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2008, Hermann Vosseler <Ichthyostega@web.de>
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**Lumiera** is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2 of the License, or (at your
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option) any later version. See the file COPYING for further details.
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*/
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/** @file libgavl.hpp
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** Concrete implementation of the MediaImplLib facade to work with [lib-GAVL],
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** a library for handling basic raw video data formats.
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** @todo a draft and placeholder code from 2008, at which time the intention was
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** to rely on libGAVL for processing of raw media data. This seemed like a
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** good idea at that time, but we should re-evaluate if libGAVL is maintained
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** and in actual use, before we start really relying on it.
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** @todo 2025 this code is a kind of _architecture placeholder_ — it is clear that
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** a solution can can not be _that simple_, but any viable solution will
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** rely onto an approach like outlined here: provide a façade interface,
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** which has to be implemented by any plug-in component to provide access
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** to the processing capabilities of a specific library. The access point
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** functions exposed on the facade however must be shaped by the specific
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** way how the builder and the render engine interacts with and delegates
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** back to the media-handling library. Such an interface can not be based
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** on first principles alone.
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** @todo 2025 I still retain the dependency on lib-GAVL for now, even while we
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** never got into actually using it. Simply because I still consider this
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** library exemplary, and would love to use it for real. Yet it remains
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** to be seen if the project actually gets a chance to do so, simply
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** because FFmpeg roughly covers the same ground. Presumably it turns
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** out to be a basic requirement to ship a plug-in with FFmpeg binding.
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** Furthermore, one especially tricky aspect is how to support displays
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** with extended dynamic range -- a requirement which has the potential
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** to blur the notion of »raw video«...
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** [Lib-GAVL]: https://github.com/bplaum/gavl
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*/
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#ifndef STEAM_EXTERNAL_LIBGAVL_H
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#define STEAM_EXTERNAL_LIBGAVL_H
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#include "steam/control/media-impl-lib.hpp"
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namespace steam {
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namespace external {
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using lib::Symbol;
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typedef StreamType::ImplFacade ImplFacade;
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typedef StreamType::ImplFacade::TypeTag TypeTag;
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class LibGavl;
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/**
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* Concrete media lib implementation facade
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* allowing to work with GAVL data frames and types
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* in an implementation agnostic way.
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* @note GAVL types are automagically registered into the
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* control::STypeManager on reset and thus are always available.
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* @todo 2016 evaluate if libGAVL is still active and maintained
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*/
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class ImplFacadeGAVL
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: public ImplFacade
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{
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protected:
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ImplFacadeGAVL()
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: ImplFacade("GAVL")
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{ }
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friend class LibGavl;
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public:
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virtual bool operator== (ImplFacade const& other) const;
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virtual bool operator== (StreamType const& other) const;
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virtual bool canConvert (ImplFacade const& other) const;
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virtual bool canConvert (StreamType const& other) const;
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virtual StreamType::MediaKind getKind() const;
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virtual DataBuffer* createFrame () const;
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};
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class LibGavl
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: public control::MediaImplLib
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{
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protected:
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public:
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virtual Symbol getLibID() const { return "GAVL"; }
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virtual ImplFacadeGAVL const& getImplFacade (TypeTag&);
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};
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}} // namespace steam::external
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#endif
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