static int bmp_decode_frame(AVCodecContext *avctx,

                            void *data, int *data_size,

                            AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->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;

    const 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), trying to decode anyway\n",

               buf_size, fsize);

        fsize = buf_size;

    }



    buf += 2; /* reserved1 */

    buf += 2; /* reserved2 */



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

    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;

    }



    /* sometimes file size is set to some headers size, set a real size in that case */

    if(fsize == 14 || fsize == ihsize + 14)

        fsize = buf_size - 2;



    if(fsize <= hsize){

        av_log(avctx, AV_LOG_ERROR, "declared file size is less than header size (%d < %d)\n",

               fsize, hsize);

        return -1;

    }



    switch(ihsize){

    case  40: // windib v3

    case  64: // OS/2 v2

    case 108: // windib v4

    case 124: // windib v5

        width = bytestream_get_le32(&buf);

        height = bytestream_get_le32(&buf);

        break;

    case  12: // OS/2 v1

        width  = bytestream_get_le16(&buf);

        height = bytestream_get_le16(&buf);

        break;

    default:

        av_log(avctx, AV_LOG_ERROR, "unsupported BMP file, patch welcome\n");

        return -1;

    }



    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 == 40)

        comp = bytestream_get_le32(&buf);

    else

        comp = BMP_RGB;



    if(comp != BMP_RGB && comp != BMP_BITFIELDS && comp != BMP_RLE4 && comp != BMP_RLE8){

        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->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;

        if(comp == BMP_BITFIELDS)

            avctx->pix_fmt = rgb[1] == 0x07E0 ? PIX_FMT_RGB565 : PIX_FMT_RGB555;

        break;

    case 8:

        if(hsize - ihsize - 14 > 0)

            avctx->pix_fmt = PIX_FMT_PAL8;

        else

            avctx->pix_fmt = PIX_FMT_GRAY8;

        break;

    case 1:

    case 4:

        if(hsize - ihsize - 14 > 0){

            avctx->pix_fmt = PIX_FMT_PAL8;

        }else{

            av_log(avctx, AV_LOG_ERROR, "Unknown palette for %d-colour BMP\n", 1<<depth);

            return -1;

        }

        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 = AV_PICTURE_TYPE_I;

    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 && comp != BMP_RLE4 && comp != BMP_RLE8){

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

               dsize, n * avctx->height);

        return -1;

    }



    // RLE may skip decoding some picture areas, so blank picture before decoding

    if(comp == BMP_RLE4 || comp == BMP_RLE8)

        memset(p->data[0], 0, avctx->height * p->linesize[0]);



    if(depth == 4 || depth == 8)

        memset(p->data[1], 0, 1024);



    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];

    }



    if(avctx->pix_fmt == PIX_FMT_PAL8){

        int colors = 1 << depth;

        if(ihsize >= 36){

            int t;

            buf = buf0 + 46;

            t = bytestream_get_le32(&buf);

            if(t < 0 || t > (1 << depth)){

                av_log(avctx, AV_LOG_ERROR, "Incorrect number of colors - %X for bitdepth %d\n", t, depth);

            }else if(t){

                colors = t;

            }

        }

        buf = buf0 + 14 + ihsize; //palette location

        if((hsize-ihsize-14) < (colors << 2)){ // OS/2 bitmap, 3 bytes per palette entry

            for(i = 0; i < colors; i++)

                ((uint32_t*)p->data[1])[i] = bytestream_get_le24(&buf);

        }else{

            for(i = 0; i < colors; i++)

                ((uint32_t*)p->data[1])[i] = bytestream_get_le32(&buf);

        }

        buf = buf0 + hsize;

    }

    if(comp == BMP_RLE4 || comp == BMP_RLE8){

        if(height < 0){

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

            p->linesize[0] = -p->linesize[0];

        }

        ff_msrle_decode(avctx, (AVPicture*)p, depth, buf, dsize);

        if(height < 0){

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

            p->linesize[0] = -p->linesize[0];

        }

    }else{

        switch(depth){

        case 1:

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

                int j;

                for (j = 0; j < n; j++) {

                    ptr[j*8+0] =  buf[j] >> 7;

                    ptr[j*8+1] = (buf[j] >> 6) & 1;

                    ptr[j*8+2] = (buf[j] >> 5) & 1;

                    ptr[j*8+3] = (buf[j] >> 4) & 1;

                    ptr[j*8+4] = (buf[j] >> 3) & 1;

                    ptr[j*8+5] = (buf[j] >> 2) & 1;

                    ptr[j*8+6] = (buf[j] >> 1) & 1;

                    ptr[j*8+7] =  buf[j]       & 1;

                }

                buf += n;

                ptr += linesize;

            }

            break;

        case 8:

        case 24:

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

                memcpy(ptr, buf, n);

                buf += n;

                ptr += linesize;

            }

            break;

        case 4:

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

                int j;

                for(j = 0; j < n; j++){

                    ptr[j*2+0] = (buf[j] >> 4) & 0xF;

                    ptr[j*2+1] = buf[j] & 0xF;

                }

                buf += n;

                ptr += linesize;

            }

            break;

        case 16:

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

                const uint16_t *src = (const uint16_t *) buf;

                uint16_t *dst = (uint16_t *) ptr;



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

                    *dst++ = av_le2ne16(*src++);



                buf += n;

                ptr += linesize;

            }

            break;

        case 32:

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

                const 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;

}
