103 lines
No EOL
3.6 KiB
C
103 lines
No EOL
3.6 KiB
C
#ifndef SWS_CONTEXT_HOLDER_H
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#define SWS_CONTEXT_HOLDER_H
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extern "C" {
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#include <libswscale/swscale.h>
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#include <libavutil/pixfmt.h>
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}
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struct SwsContextHolder {
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SwsContext* ctx = nullptr;
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int src_width = 0;
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int src_height = 0;
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AVPixelFormat src_format = AV_PIX_FMT_NONE;
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int dst_width = 0;
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int dst_height = 0;
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AVPixelFormat dst_format = AV_PIX_FMT_NONE;
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// Default constructor — starts with no context
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SwsContextHolder() = default;
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// Destructor — always free the context when the object is destroyed
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~SwsContextHolder() {
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reset();
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}
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// Copy constructor — disabled, context ownership must be unique
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SwsContextHolder(const SwsContextHolder&) = delete;
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// Copy assignment — disabled for the same reason
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SwsContextHolder& operator=(const SwsContextHolder&) = delete;
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// Move constructor — transfer ownership from another holder without freeing
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SwsContextHolder(SwsContextHolder&& other) noexcept
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: ctx(other.ctx),
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src_width(other.src_width), src_height(other.src_height), src_format(other.src_format),
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dst_width(other.dst_width), dst_height(other.dst_height), dst_format(other.dst_format) {
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other.ctx = nullptr; // prevent the other holder from freeing the context
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}
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// Move assignment — free current context, then take ownership from other
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SwsContextHolder& operator=(SwsContextHolder&& other) noexcept {
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if (this != &other) {
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reset(); // free whatever we currently hold
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ctx = other.ctx;
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src_width = other.src_width;
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src_height = other.src_height;
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src_format = other.src_format;
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dst_width = other.dst_width;
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dst_height = other.dst_height;
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dst_format = other.dst_format;
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other.ctx = nullptr; // prevent the other holder from freeing the context
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}
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return *this;
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}
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// Returns a valid context for the given parameters.
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// Recreates the context if any parameter has changed since the last call.
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SwsContext* get(
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int new_src_width, int new_src_height, AVPixelFormat new_src_format,
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int new_dst_width, int new_dst_height, AVPixelFormat new_dst_format
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) {
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// Reuse existing context if all parameters match
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if (ctx != nullptr &&
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src_width == new_src_width && src_height == new_src_height && src_format == new_src_format &&
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dst_width == new_dst_width && dst_height == new_dst_height && dst_format == new_dst_format) {
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return ctx;
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}
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// Parameters changed — free the old context before creating a new one
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reset();
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ctx = sws_getContext(
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new_src_width, new_src_height, new_src_format,
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new_dst_width, new_dst_height, new_dst_format,
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SWS_BILINEAR, nullptr, nullptr, nullptr
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);
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// Only store parameters if context was created successfully
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if (ctx != nullptr) {
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src_width = new_src_width;
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src_height = new_src_height;
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src_format = new_src_format;
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dst_width = new_dst_width;
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dst_height = new_dst_height;
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dst_format = new_dst_format;
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}
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return ctx;
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}
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// Free the context and reset all parameters
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void reset() {
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if (ctx != nullptr) {
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sws_freeContext(ctx);
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ctx = nullptr;
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}
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src_width = src_height = dst_width = dst_height = 0;
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src_format = dst_format = AV_PIX_FMT_NONE;
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}
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};
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#endif // SWS_CONTEXT_HOLDER_H
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