Method convert

src/video.cpp:138–182

  class avcodec_software_encode_device_t: public platf::avcodec_encode_device_t {
  public:
    int convert(platf::img_t &img) override {
      // If we need to add aspect ratio padding, we need to scale into an intermediate output buffer
      bool requires_padding = (sw_frame->width != sws_output_frame->width || sw_frame->height != sws_output_frame->height);

      // Setup the input frame using the caller's img_t
      sws_input_frame->data[0] = img.data;
      sws_input_frame->linesize[0] = img.row_pitch;

      // Perform color conversion and scaling to the final size
      auto status = sws_scale_frame(sws.get(), requires_padding ? sws_output_frame.get() : sw_frame.get(), sws_input_frame.get());
      if (status < 0) {
        char string[AV_ERROR_MAX_STRING_SIZE];
        BOOST_LOG(error) << "Couldn't scale frame: "sv << av_make_error_string(string, AV_ERROR_MAX_STRING_SIZE, status);
        return -1;
      }

      // If we require aspect ratio padding, copy the output frame into the final padded frame
      if (requires_padding) {
        auto fmt_desc = av_pix_fmt_desc_get((AVPixelFormat) sws_output_frame->format);
        auto planes = av_pix_fmt_count_planes((AVPixelFormat) sws_output_frame->format);
        for (int plane = 0; plane < planes; plane++) {
          auto shift_h = plane == 0 ? 0 : fmt_desc->log2_chroma_h;
          auto shift_w = plane == 0 ? 0 : fmt_desc->log2_chroma_w;
          auto offset = ((offsetW >> shift_w) * fmt_desc->comp[plane].step) + (offsetH >> shift_h) * sw_frame->linesize[plane];

          // Copy line-by-line to preserve leading padding for each row
          for (int line = 0; line < sws_output_frame->height >> shift_h; line++) {
            memcpy(sw_frame->data[plane] + offset + (line * sw_frame->linesize[plane]), sws_output_frame->data[plane] + (line * sws_output_frame->linesize[plane]), (size_t) (sws_output_frame->width >> shift_w) * fmt_desc->comp[plane].step);
          }
        }
      }

      // If frame is not a software frame, it means we still need to transfer from main memory
      // to vram memory
      if (frame->hw_frames_ctx) {
        auto status = av_hwframe_transfer_data(frame, sw_frame.get(), 0);
        if (status < 0) {
          char string[AV_ERROR_MAX_STRING_SIZE];
          BOOST_LOG(error) << "Failed to transfer image data to hardware frame: "sv << av_make_error_string(string, AV_ERROR_MAX_STRING_SIZE, status);
          return -1;
        }
      }

      return 0;
    }

    int set_frame(AVFrame *frame, AVBufferRef *hw_frames_ctx) override {
      this->frame = frame;