Making mosaic images with ffmpeg
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#pragma once
extern "C" {
#include <libavutil/mem.h>
}
#include <stdexcept>
#include <memory>
namespace av {
// Generic error class
struct error : public std::runtime_error {
using runtime_error::runtime_error;
};
// Type of a freeing function (for wrapper)
template <typename T>
using deleter = void(*)(T*);
// Kind of unique_ptr, but with const-semantics
template <typename T, typename D = deleter<T>>
struct wrapper {
wrapper(T * data_ = nullptr, D deleter_ = D())
: data(data_)
, deleter(deleter_)
{}
wrapper(wrapper && o)
: data(o.data)
, deleter(o.deleter)
{ o.release(); }
wrapper & operator=(wrapper && o) {
data = o.data;
deleter = o.deleter;
o.release();
return *this;
}
wrapper(wrapper const & o) = delete;
wrapper & operator=(wrapper const & o) = delete;
~wrapper(){ reset(); }
T * get() { return data; }
T const * get() const { return data; }
T & operator*() { return *get(); }
T const & operator*() const { return *get(); }
T * operator->() { return get(); }
T const * operator->() const { return get(); }
T * release() { auto t = data; data = nullptr; return t; }
void reset() { if(data && deleter) deleter(data); data = nullptr; }
operator bool() const { return get(); }
private:
T * data;
D deleter;
};
// Allocator
template <typename T>
struct allocator {
using value_type = T;
using size_type = size_t;
T* allocate(size_type n) const {
auto ptr = av_malloc(n * sizeof(T));
if(!ptr) throw std::bad_alloc();
return static_cast<T*>(ptr);
}
void deallocate(T* ptr, size_type /*n*/) const noexcept {
av_free(ptr);
}
};
template <typename T, typename S>
bool operator==(allocator<T> const &, allocator<S> const &) noexcept { return true; }
template <typename T, typename S>
bool operator!=(allocator<T> const &, allocator<S> const &) noexcept { return false; }
}