Как заставить FFMPEG кодировать H264 с использованием libx264?

Question

Пример кодирования FFMPEG не удается создать видео H264. MPEG1 работает нормально, хотя.

Вставка кода здесь также

     * @file
     * video encoding with libavcodec API example
     *
     * @example encode_video.c
     */
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <libavcodec/avcodec.h>
    #include <libavutil/opt.h>
    #include <libavutil/imgutils.h>
    static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
                       FILE *outfile)
    {
        int ret;
        /* send the frame to the encoder */
        if (frame)
            printf("Send frame %3"PRId64"\n", frame->pts);
        ret = avcodec_send_frame(enc_ctx, frame);
        if (ret < 0) {
            fprintf(stderr, "Error sending a frame for encoding\n");
            exit(1);
        }
        while (ret >= 0) {
            ret = avcodec_receive_packet(enc_ctx, pkt);
            if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
                return;
            else if (ret < 0) {
                fprintf(stderr, "Error during encoding\n");
                exit(1);
            }
            printf("Write packet %3"PRId64" (size=%5d)\n", pkt->pts, pkt->size);
            fwrite(pkt->data, 1, pkt->size, outfile);
            av_packet_unref(pkt);
        }
    }

    int main(int argc, char **argv)
    {
        const char *filename, *codec_name;
        const AVCodec *codec;
        AVCodecContext *c= NULL;
        int i, ret, x, y;
        FILE *f;
        AVFrame *frame;
        AVPacket *pkt;
        uint8_t endcode[] = { 0, 0, 1, 0xb7 };
        if (argc <= 2) {
            fprintf(stderr, "Usage: %s <output file> <codec name>\n", argv[0]);
            exit(0);
        }
        filename = argv[1];
        codec_name = argv[2];
        /* find the mpeg1video encoder */
        codec = avcodec_find_encoder_by_name(codec_name);
        if (!codec) {
            fprintf(stderr, "Codec '%s' not found\n", codec_name);
            exit(1);
        }
        c = avcodec_alloc_context3(codec);
        if (!c) {
            fprintf(stderr, "Could not allocate video codec context\n");
            exit(1);
        }
        pkt = av_packet_alloc();
        if (!pkt)
            exit(1);
        /* put sample parameters */
        c->bit_rate = 400000;
        /* resolution must be a multiple of two */
        c->width = 352;
        c->height = 288;
        /* frames per second */
        c->time_base = (AVRational){1, 25};
        c->framerate = (AVRational){25, 1};
        /* emit one intra frame every ten frames
         * check frame pict_type before passing frame
         * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
         * then gop_size is ignored and the output of encoder
         * will always be I frame irrespective to gop_size
         */
        c->gop_size = 10;
        c->max_b_frames = 1;
        c->pix_fmt = AV_PIX_FMT_YUV420P;
        if (codec->id == AV_CODEC_ID_H264)
            av_opt_set(c->priv_data, "preset", "slow", 0);
        /* open it */
        ret = avcodec_open2(c, codec, NULL);
        if (ret < 0) {
            fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
            exit(1);
        }
        f = fopen(filename, "wb");
        if (!f) {
            fprintf(stderr, "Could not open %s\n", filename);
            exit(1);
        }
        frame = av_frame_alloc();
        if (!frame) {
            fprintf(stderr, "Could not allocate video frame\n");
            exit(1);
        }
        frame->format = c->pix_fmt;
        frame->width  = c->width;
        frame->height = c->height;
        ret = av_frame_get_buffer(frame, 32);
        if (ret < 0) {
            fprintf(stderr, "Could not allocate the video frame data\n");
            exit(1);
        }
        /* encode 1 second of video */
        for (i = 0; i < 25; i++) {
            fflush(stdout);
            /* make sure the frame data is writable */
            ret = av_frame_make_writable(frame);
            if (ret < 0)
                exit(1);
            /* prepare a dummy image */
            /* Y */
            for (y = 0; y < c->height; y++) {
                for (x = 0; x < c->width; x++) {
                    frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
                }
            }
            /* Cb and Cr */
            for (y = 0; y < c->height/2; y++) {
                for (x = 0; x < c->width/2; x++) {
                    frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
                    frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
                }
            }
            frame->pts = i;
            /* encode the image */
            encode(c, frame, pkt, f);
        }
        /* flush the encoder */
        encode(c, NULL, pkt, f);
        /* add sequence end code to have a real MPEG file */
        if (codec->id == AV_CODEC_ID_MPEG1VIDEO || codec->id == AV_CODEC_ID_MPEG2VIDEO)
            fwrite(endcode, 1, sizeof(endcode), f);
        fclose(f);
        avcodec_free_context(&c);
        av_frame_free(&frame);
        av_packet_free(&pkt);
        return 0;
    }

Код не выполняется при вызове кодирования, и каждый avcodec_receive_packet вызов возвращает AVERROR(EAGAIN)

Что мне здесь не хватает?