avcodec_open2返回错误代码-22

JNIEXPORT int JNICALL Java_com_example_testlive_MainActivity_Init( JNIEnv* env, jobject thiz)
{
    //avcodec_init();
    avcodec_register_all();
    // Register all formats and codecs
    av_register_all();
    LOGI("register");
    // Find the decoder for the video stream
    pCodec=avcodec_find_decoder(CODEC_ID_H264);
    if(pCodec == NULL)
    {
        LOGI("avcodec_find_decoder failed");
        return -1; // Codec not found
    }
    else
    {
        pCodecCtx=avcodec_alloc_context3(pCodec);
        if (pCodecCtx == NULL)
        {
            LOGI("avcodec_alloc_context3 failed");
        }
 
        pCodecCtx->time_base.num = 1; //
        pCodecCtx->time_base.den = 25;
        pCodecCtx->bit_rate = 0; //
        pCodecCtx->frame_number = 1; //
        pCodecCtx->codec_type = CODEC_ID_H264;
        pCodecCtx->width = 704; //
        pCodecCtx->height = 576;      
    }
    // Open codec
    LOGI("avcodec_find_decoder susscess");
    //av_dict_set(&optionsDict, "b", "2.5M", 0);
    //pCodec->capabilities=CODEC_CAP_DELAY;
    if(pCodec->capabilities&CODEC_CAP_TRUNCATED)
    pCodecCtx->flags|= CODEC_FLAG_TRUNCATED;
    int ret = 0;
    if((ret = avcodec_open2(pCodecCtx, pCodec, NULL))<0)
    {
        LOGI("avcodec_open2 failed");      
        return ret; // Could not open codec      ******************程序执行到这里返回-22************
    }
    // Allocate video frame
    pFrame=avcodec_alloc_frame();
 
    // Allocate an AVFrame structure
    pFrameRGBA=avcodec_alloc_frame();
    if(pFrameRGBA==NULL)
    {
        LOGI("avcodec_alloc_frame failed");      
        return -1;
    }
    //get the scaling context
    sws_ctx = sws_getContext
    (
        pCodecCtx->width,
        pCodecCtx->height,
        pCodecCtx->pix_fmt,
        pCodecCtx->width,
        pCodecCtx->height,
        AV_PIX_FMT_RGBA,
        SWS_BILINEAR,
        NULL,
        NULL,
        NULL
    );
 
    // Assign appropriate parts of bitmap to image planes in pFrameRGBA
    // Note that pFrameRGBA is an AVFrame, but AVFrame is a superset
    // of AVPicture
    //avpicture_fill((AVPicture *)pFrameRGBA, buffer, AV_PIX_FMT_RGBA,
    //     pCodecCtx->width, pCodecCtx->height);
 
    return 0;
}
我发现把CODEC_ID_H264换成CODEC_ID_MPEG4就成功了，为什么呢？我需要的是CODEC_ID_H264啊，
 
avcodec_find_decoder(CODEC_ID_MPEG4);//CODEC_ID_H264

CODEC_ID_H264---->AV_CODEC_ID_H264,版本问题