[vlc-devel] x264_encoder_open return NULL, Why?

[Michael]

Hello: I have a issue

    X264_t *m_h;
    X264_param_t m_param;
    x264_param_default(&m_param);

    m_param.i_width = nWidth;
    m_param.i_height = nHeight;
    m_param.i_frame_reference = 4;
    m_param.i_bframe = 2;
    m_param.rc.i_bitrate = nBit_rate * 1000;
    m_param.rc.i_rc_method = X264_RC_CRF;  
    m_param.rc.f_rate_tolerance = 1.0f;
    m_param.rc.i_vbv_buffer_size = nBit_rate * 1000;
    m_param.rc.f_vbv_buffer_init = 0.9f;
    m_param.rc.i_vbv_max_bitrate = nBit_rate *1000;

    m_h = x264_encoder_open(&m_param);

   m_h NULL, why？
   Thanks for help.