static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    ZmbvContext * const c = avctx->priv_data;

    int zret = Z_OK; 

    int len = buf_size;

    int hi_ver, lo_ver, ret;



    if (c->pic.data[0])

            avctx->release_buffer(avctx, &c->pic);



    c->pic.reference = 3;

    c->pic.buffer_hints = FF_BUFFER_HINTS_VALID;

    if ((ret = avctx->get_buffer(avctx, &c->pic)) < 0) {

        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

        return ret;

    }



    

    c->flags = buf[0];

    buf++; len--;

    if (c->flags & ZMBV_KEYFRAME) {

        void *decode_intra = NULL;

        c->decode_intra= NULL;

        hi_ver = buf[0];

        lo_ver = buf[1];

        c->comp = buf[2];

        c->fmt = buf[3];

        c->bw = buf[4];

        c->bh = buf[5];



        buf += 6;

        len -= 6;

        av_log(avctx, AV_LOG_DEBUG,

               "Flags=%X ver=%i.%i comp=%i fmt=%i blk=%ix%i\n",

               c->flags,hi_ver,lo_ver,c->comp,c->fmt,c->bw,c->bh);

        if (hi_ver != 0 || lo_ver != 1) {

            av_log_ask_for_sample(avctx, "Unsupported version %i.%i\n",

                                  hi_ver, lo_ver);

            return AVERROR_PATCHWELCOME;

        }

        if (c->bw == 0 || c->bh == 0) {

            av_log_ask_for_sample(avctx, "Unsupported block size %ix%i\n",

                                  c->bw, c->bh);

            return AVERROR_PATCHWELCOME;

        }

        if (c->comp != 0 && c->comp != 1) {

            av_log_ask_for_sample(avctx, "Unsupported compression type %i\n",

                                  c->comp);

            return AVERROR_PATCHWELCOME;

        }



        switch (c->fmt) {

        case ZMBV_FMT_8BPP:

            c->bpp = 8;

            decode_intra = zmbv_decode_intra;

            c->decode_xor = zmbv_decode_xor_8;

            break;

        case ZMBV_FMT_15BPP:

        case ZMBV_FMT_16BPP:

            c->bpp = 16;

            decode_intra = zmbv_decode_intra;

            c->decode_xor = zmbv_decode_xor_16;

            break;

#ifdef ZMBV_ENABLE_24BPP

        case ZMBV_FMT_24BPP:

            c->bpp = 24;

            decode_intra = zmbv_decode_intra;

            c->decode_xor = zmbv_decode_xor_24;

            break;

#endif 

        case ZMBV_FMT_32BPP:

            c->bpp = 32;

            decode_intra = zmbv_decode_intra;

            c->decode_xor = zmbv_decode_xor_32;

            break;

        default:

            c->decode_xor = NULL;

            av_log_ask_for_sample(avctx, "Unsupported (for now) format %i\n",

                                  c->fmt);

            return AVERROR_PATCHWELCOME;

        }



        zret = inflateReset(&c->zstream);

        if (zret != Z_OK) {

            av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", zret);

            return -1;

        }



        c->cur  = av_realloc_f(c->cur, avctx->width * avctx->height,  (c->bpp / 8));

        c->prev = av_realloc_f(c->prev, avctx->width * avctx->height,  (c->bpp / 8));

        c->bx = (c->width + c->bw - 1) / c->bw;

        c->by = (c->height+ c->bh - 1) / c->bh;

        if (!c->cur || !c->prev)

            return -1;

        c->decode_intra= decode_intra;

    }



    if (c->decode_intra == NULL) {

        av_log(avctx, AV_LOG_ERROR, "Error! Got no format or no keyframe!\n");

        return AVERROR_INVALIDDATA;

    }



    if (c->comp == 0) { 

        memcpy(c->decomp_buf, buf, len);

        c->decomp_size = 1;

    } else { 

        c->zstream.total_in = c->zstream.total_out = 0;

        c->zstream.next_in = (uint8_t*)buf;

        c->zstream.avail_in = len;

        c->zstream.next_out = c->decomp_buf;

        c->zstream.avail_out = c->decomp_size;

        zret = inflate(&c->zstream, Z_SYNC_FLUSH);

        if (zret != Z_OK && zret != Z_STREAM_END) {

            av_log(avctx, AV_LOG_ERROR, "inflate error %d\n", zret);

            return AVERROR_INVALIDDATA;

        }

        c->decomp_len = c->zstream.total_out;

    }

    if (c->flags & ZMBV_KEYFRAME) {

        c->pic.key_frame = 1;

        c->pic.pict_type = AV_PICTURE_TYPE_I;

        c->decode_intra(c);

    } else {

        c->pic.key_frame = 0;

        c->pic.pict_type = AV_PICTURE_TYPE_P;

        if (c->decomp_len)

            c->decode_xor(c);

    }



    

    {

        uint8_t *out, *src;

        int i, j;



        out = c->pic.data[0];

        src = c->cur;

        switch (c->fmt) {

        case ZMBV_FMT_8BPP:

            for (j = 0; j < c->height; j++) {

                for (i = 0; i < c->width; i++) {

                    out[i * 3 + 0] = c->pal[(*src) * 3 + 0];

                    out[i * 3 + 1] = c->pal[(*src) * 3 + 1];

                    out[i * 3 + 2] = c->pal[(*src) * 3 + 2];

                    src++;

                }

                out += c->pic.linesize[0];

            }

            break;

        case ZMBV_FMT_15BPP:

            for (j = 0; j < c->height; j++) {

                for (i = 0; i < c->width; i++) {

                    uint16_t tmp = AV_RL16(src);

                    src += 2;

                    out[i * 3 + 0] = (tmp & 0x7C00) >> 7;

                    out[i * 3 + 1] = (tmp & 0x03E0) >> 2;

                    out[i * 3 + 2] = (tmp & 0x001F) << 3;

                }

                out += c->pic.linesize[0];

            }

            break;

        case ZMBV_FMT_16BPP:

            for (j = 0; j < c->height; j++) {

                for (i = 0; i < c->width; i++) {

                    uint16_t tmp = AV_RL16(src);

                    src += 2;

                    out[i * 3 + 0] = (tmp & 0xF800) >> 8;

                    out[i * 3 + 1] = (tmp & 0x07E0) >> 3;

                    out[i * 3 + 2] = (tmp & 0x001F) << 3;

                }

                out += c->pic.linesize[0];

            }

            break;

#ifdef ZMBV_ENABLE_24BPP

        case ZMBV_FMT_24BPP:

            for (j = 0; j < c->height; j++) {

                memcpy(out, src, c->width * 3);

                src += c->width * 3;

                out += c->pic.linesize[0];

            }

            break;

#endif 

        case ZMBV_FMT_32BPP:

            for (j = 0; j < c->height; j++) {

                for (i = 0; i < c->width; i++) {

                    uint32_t tmp = AV_RL32(src);

                    src += 4;

                    AV_WB24(out+(i*3), tmp);

                }

                out += c->pic.linesize[0];

            }

            break;

        default:

            av_log(avctx, AV_LOG_ERROR, "Cannot handle format %i\n", c->fmt);

        }

        FFSWAP(uint8_t *, c->cur, c->prev);

    }

    *data_size = sizeof(AVFrame);

    *(AVFrame*)data = c->pic;



    

    return buf_size;

}
