static int bmp_decode_frame(AVCodecContext *avctx,

                            void *data, int *data_size,

                            uint8_t *buf, int buf_size)

{

    BMPContext *s = avctx->priv_data;

    AVFrame *picture = data;

    AVFrame *p = &s->picture;

    unsigned int fsize, hsize;

    int width, height;

    unsigned int depth;

    BiCompression comp;

    unsigned int ihsize;

    int i, j, n, linesize;

    uint32_t rgb[3];

    uint8_t *ptr;

    int dsize;

    uint8_t *buf0 = buf;



    if(buf_size < 14){

        av_log(avctx, AV_LOG_ERROR, "buf size too small (%d)\n", buf_size);

        return -1;

    }



    if(bytestream_get_byte(&buf) != 'B' ||

       bytestream_get_byte(&buf) != 'M') {

        av_log(avctx, AV_LOG_ERROR, "bad magic number\n");

        return -1;

    }



    fsize = bytestream_get_le32(&buf);

    if(buf_size < fsize){

        av_log(avctx, AV_LOG_ERROR, "not enough data (%d < %d)\n",

               buf_size, fsize);

        return -1;

    }



    buf += 2; /* reserved1 */

    buf += 2; /* reserved2 */



    hsize = bytestream_get_le32(&buf); /* header size */

    if(fsize <= hsize){

        av_log(avctx, AV_LOG_ERROR, "not enough data (%d < %d)\n",

               fsize, hsize);

        return -1;

    }



    ihsize = bytestream_get_le32(&buf);       /* more header size */

    if(ihsize + 14 > hsize){

        av_log(avctx, AV_LOG_ERROR, "invalid header size %d\n", hsize);

        return -1;

    }



    width = bytestream_get_le32(&buf);

    height = bytestream_get_le32(&buf);



    if(bytestream_get_le16(&buf) != 1){ /* planes */

        av_log(avctx, AV_LOG_ERROR, "invalid BMP header\n");

        return -1;

    }



    depth = bytestream_get_le16(&buf);



    if(ihsize > 16)

        comp = bytestream_get_le32(&buf);

    else

        comp = BMP_RGB;



    if(comp != BMP_RGB && comp != BMP_BITFIELDS){

        av_log(avctx, AV_LOG_ERROR, "BMP coding %d not supported\n", comp);

        return -1;

    }



    if(comp == BMP_BITFIELDS){

        buf += 20;

        rgb[0] = bytestream_get_le32(&buf);

        rgb[1] = bytestream_get_le32(&buf);

        rgb[2] = bytestream_get_le32(&buf);

    }



    avctx->codec_id = CODEC_ID_BMP;

    avctx->width = width;

    avctx->height = height > 0? height: -height;



    avctx->pix_fmt = PIX_FMT_NONE;



    switch(depth){

    case 32:

        if(comp == BMP_BITFIELDS){

            rgb[0] = (rgb[0] >> 15) & 3;

            rgb[1] = (rgb[1] >> 15) & 3;

            rgb[2] = (rgb[2] >> 15) & 3;



            if(rgb[0] + rgb[1] + rgb[2] != 3 ||

               rgb[0] == rgb[1] || rgb[0] == rgb[2] || rgb[1] == rgb[2]){

                break;

            }

        } else {

            rgb[0] = 2;

            rgb[1] = 1;

            rgb[2] = 0;

        }



        avctx->pix_fmt = PIX_FMT_BGR24;

        break;

    case 24:

        avctx->pix_fmt = PIX_FMT_BGR24;

        break;

    case 16:

        if(comp == BMP_RGB)

            avctx->pix_fmt = PIX_FMT_RGB555;

        break;

    default:

        av_log(avctx, AV_LOG_ERROR, "depth %d not supported\n", depth);

        return -1;

    }



    if(avctx->pix_fmt == PIX_FMT_NONE){

        av_log(avctx, AV_LOG_ERROR, "unsupported pixel format\n");

        return -1;

    }



    if(p->data[0])

        avctx->release_buffer(avctx, p);



    p->reference = 0;

    if(avctx->get_buffer(avctx, p) < 0){

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

        return -1;

    }

    p->pict_type = FF_I_TYPE;

    p->key_frame = 1;



    buf = buf0 + hsize;

    dsize = buf_size - hsize;



    /* Line size in file multiple of 4 */

    n = (avctx->width * (depth / 8) + 3) & ~3;



    if(n * avctx->height > dsize){

        av_log(avctx, AV_LOG_ERROR, "not enough data (%d < %d)\n",

               dsize, n * avctx->height);

        return -1;

    }



    if(height > 0){

        ptr = p->data[0] + (avctx->height - 1) * p->linesize[0];

        linesize = -p->linesize[0];

    } else {

        ptr = p->data[0];

        linesize = p->linesize[0];

    }



    switch(depth){

    case 24:

        for(i = 0; i < avctx->height; i++){

            memcpy(ptr, buf, n);

            buf += n;

            ptr += linesize;

        }

        break;

    case 16:

        for(i = 0; i < avctx->height; i++){

            uint16_t *src = (uint16_t *) buf;

            uint16_t *dst = (uint16_t *) ptr;



            for(j = 0; j < avctx->width; j++)

                *dst++ = le2me_16(*src++);



            buf += n;

            ptr += linesize;

        }

        break;

    case 32:

        for(i = 0; i < avctx->height; i++){

            uint8_t *src = buf;

            uint8_t *dst = ptr;



            for(j = 0; j < avctx->width; j++){

                dst[0] = src[rgb[2]];

                dst[1] = src[rgb[1]];

                dst[2] = src[rgb[0]];

                dst += 3;

                src += 4;

            }



            buf += n;

            ptr += linesize;

        }

        break;

    default:

        av_log(avctx, AV_LOG_ERROR, "BMP decoder is broken\n");

        return -1;

    }



    *picture = s->picture;

    *data_size = sizeof(AVPicture);



    return buf_size;

}
