Hardware decoding using ffmpeg in STAVPlay

[rockinggit]

Hello,

I have compiled ffmpeg for nacl and trying to use hardware docoding with RTSP stream.
I have used below flags included while compiling ffmpeg.
--enable-hwaccel=h264 & --enable-hwaccels

and followed hw_decode.cc example given in ffmpeg/doc/example.

I always get NULL return value avcodec_get_hw_config on TV.

const AVCodecHWConfig *config = avcodec_get_hw_config(codec, i);

Do i need any other library for enabling hw decoding.

Below is code snippet..
//==============================================
enum AVHWDeviceType type;
type = av_hwdevice_find_type_by_name("vaapi"); //Tried this step with vaapi, vdpau both

for (auto i = 0;; i++) {
        const AVCodecHWConfig *config = avcodec_get_hw_config(codec, i); //This step fails.
        if (!config) {
            return NULL; 
        }
        if (config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX &&
            config->device_type == type) {
            hw_pix_fmt = config->pix_fmt;
            break;
        }
    }

//==============================================

Any help is highly appreciated.

Thanks,