# Pastebin mZepxiIw
#ifdef FFMPEG_DECODER
#define DECODER_SYMBOL0(CODEC) ff_##CODEC##_decoder
#define DECODER_SYMBOL(CODEC) DECODER_SYMBOL0(CODEC)
        extern AVCodec DECODER_SYMBOL(FFMPEG_DECODER);
        avcodec_register(&DECODER_SYMBOL(FFMPEG_DECODER));

        c = &DECODER_SYMBOL(FFMPEG_DECODER);
#else
        avcodec_register_all();
        c = AVCodecInitialize(FFMPEG_CODEC);  // Done once.
#endif