snprintf(args, sizeof(args),
		"buffer=video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d[in];"
		"[in]hflip[out];"
		"[out]buffersink",
		dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt, 1, 1,
		dec_ctx->sample_aspect_ratio.num,
		dec_ctx->sample_aspect_ratio.den);