decoder_manager.h

/*
 * Copyright (C) 2026-present ifm electronic, gmbh
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef IFM3D_RTSP_DECODER_MANAGER_H
#define IFM3D_RTSP_DECODER_MANAGER_H
 
#include <memory>
#include <optional>
#include <string>
#include <unordered_map>
#include <vector>
 
#include <ifm3d/rtsp/video_decoder.h>
 
namespace ifm3d
{
 
  class DecoderManager
  {
  public:
    explicit DecoderManager(std::optional<std::string> preferred_decoder = {});
 
    ~DecoderManager();
 
    struct DecoderInfo
    {
      /* Stable decoder name (e.g. "ffmpeg", "null"). */
      std::string name;
      /* True when the decoder can be used on the current system (e.g. the
       * ffmpeg decoder found a usable libavcodec). */
      bool available{false};
      /* True when the decoder advertises H.264 decode support. */
      bool supports_h264{false};
      /* Human-readable reason when available is false; empty otherwise. */
      std::string error;
    };
 
    static std::vector<DecoderInfo> DiscoverDecoders();
 
    /* Non-copyable, non-movable. */
    DecoderManager(const DecoderManager&) = delete;
    DecoderManager& operator=(const DecoderManager&) = delete;
    DecoderManager(DecoderManager&&) = delete;
    DecoderManager& operator=(DecoderManager&&) = delete;
 
    void LoadDecoders();
 
    std::unique_ptr<ifm3d::rtsp::VideoDecoder> CreateDecoder(
      ifm3d::rtsp::VideoCodec codec);
 
    [[nodiscard]] std::string SelectedDecoderName(
      ifm3d::rtsp::VideoCodec codec) const;
 
  private:
    void select_decoders();
 
    std::optional<std::string> _preferred_decoder;
 
    /* Registered decoder implementations, in preference order (real decoders
     * first, the null decoder last). */
    std::vector<std::unique_ptr<ifm3d::rtsp::VideoDecoderFactory>> _factories;
 
    /* Decoder selected for each codec (may be the null decoder). Empty until
     * LoadDecoders() runs. */
    std::unordered_map<ifm3d::rtsp::VideoCodec,
                       ifm3d::rtsp::VideoDecoderFactory*>
      _selected;
  };
 
} // namespace ifm3d
 
#endif /* IFM3D_RTSP_DECODER_MANAGER_H */