在索引影片或影像的時候，人臉通常都能提供非常有用資訊，在這篇論文中，我們提出了一個人臉偵測系統，結合使用迴旋神經網路(Convolutional Neural Network)機器學習演算法，在以最新的壓縮規格H.264編碼的影片中進行人臉偵測。我們的系統只需要輸入壓縮資料中的DCT係數，就能夠找出人臉的位置，因此我們可以在壓縮的領域下進行人臉偵測，而不需要將影片完全解碼，如此一來，無論在編碼或者解碼影片的時候都可以用我們的系統架構去偵測人臉位置。一般而言，人臉在影像中通常都是人類視覺上比較注意並有興趣的區域，如果我們能再壓縮影片的最後一個步驟(entropy coding)之前先知道這樣的區域，我們便能改變一些編碼的參數來分配資源，例如將多一點的空間與運算時間花在這樣的區域上。我們實做了H.264中intra frame的編碼流程，並做了很多實驗來證明我們人臉偵測系統能夠有很好的性能。

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