PeerStreamer

- Wing Commander IV movies decoder added

@item Wing Commander IV / Xan  @tab     @tab  X

    @tab Used in Wing Commander IV.

OBJS-$(CONFIG_XAN_WC4_DECODER)         += xxan.o

    REGISTER_DECODER (XAN_WC4, xan_wc4);

#define LIBAVCODEC_VERSION_MINOR 110

/*

 * Wing Commander/Xan Video Decoder

 * Copyright (C) 2011 Konstantin Shishkov

 * based on work by Mike Melanson

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "avcodec.h"

#include "libavutil/intreadwrite.h"

#include "bytestream.h"

#define ALT_BITSTREAM_READER_LE

#include "get_bits.h"

// for av_memcpy_backptr

#include "libavutil/lzo.h"

typedef struct XanContext {

    AVCodecContext *avctx;

    AVFrame pic;

    uint8_t *y_buffer;

    uint8_t *scratch_buffer;

    int     buffer_size;

} XanContext;

static av_cold int xan_decode_init(AVCodecContext *avctx)

{

    XanContext *s = avctx->priv_data;

    s->avctx = avctx;

    avctx->pix_fmt = PIX_FMT_YUV420P;

    s->buffer_size = avctx->width * avctx->height;

    s->y_buffer = av_malloc(s->buffer_size);

    if (!s->y_buffer)

        return AVERROR(ENOMEM);

    s->scratch_buffer = av_malloc(s->buffer_size + 130);

    if (!s->scratch_buffer) {

        av_freep(&s->y_buffer);

        return AVERROR(ENOMEM);

    }

    return 0;

}

static int xan_unpack_luma(const uint8_t *src, const int src_size,

                           uint8_t *dst, const int dst_size)

{

   int tree_size, eof;

   const uint8_t *tree;

   int bits, mask;

   int tree_root, node;

   const uint8_t *dst_end = dst + dst_size;

   const uint8_t *src_end = src + src_size;

   tree_size = *src++;

   eof       = *src++;

   tree      = src - eof * 2 - 2;

   tree_root = eof + tree_size;

   src += tree_size * 2;

   node = tree_root;

   bits = *src++;

   mask = 0x80;

   for (;;) {

       int bit = !!(bits & mask);

       mask >>= 1;

       node = tree[node*2 + bit];

       if (node == eof)

           break;

       if (node < eof) {

           *dst++ = node;

           if (dst > dst_end)

               break;

           node = tree_root;

       }

       if (!mask) {

           bits = *src++;

           if (src > src_end)

               break;

           mask = 0x80;

       }

   }

   return dst != dst_end;

}

/* almost the same as in xan_wc3 decoder */

static int xan_unpack(uint8_t *dest, const int dest_len,

                      const uint8_t *src, const int src_len)

{

    uint8_t opcode;

    int size;

    uint8_t *orig_dest = dest;

    const uint8_t *src_end = src + src_len;

    const uint8_t *dest_end = dest + dest_len;

    while (dest < dest_end) {

        opcode = *src++;

        if (opcode < 0xe0) {

            int size2, back;

            if ((opcode & 0x80) == 0) {

                size  = opcode & 3;

                back  = ((opcode & 0x60) << 3) + *src++ + 1;

                size2 = ((opcode & 0x1c) >> 2) + 3;

            } else if ((opcode & 0x40) == 0) {

                size  = *src >> 6;

                back  = (bytestream_get_be16(&src) & 0x3fff) + 1;

                size2 = (opcode & 0x3f) + 4;

            } else {

                size  = opcode & 3;

                back  = ((opcode & 0x10) << 12) + bytestream_get_be16(&src) + 1;

                size2 = ((opcode & 0x0c) <<  6) + *src++ + 5;

                if (size + size2 > dest_end - dest)

                    break;

            }

            if (src + size > src_end || dest + size + size2 > dest_end)

                return -1;

            bytestream_get_buffer(&src, dest, size);

            dest += size;

            av_memcpy_backptr(dest, back, size2);

            dest += size2;

        } else {

            int finish = opcode >= 0xfc;

            size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4;

            if (src + size > src_end || dest + size > dest_end)

                return -1;

            bytestream_get_buffer(&src, dest, size);

            dest += size;

            if (finish)

                break;

        }

    }

    return dest - orig_dest;

}

static int xan_decode_chroma(AVCodecContext *avctx, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    XanContext *s = avctx->priv_data;

    uint8_t *U, *V;

    unsigned chroma_off;

    int val, uval, vval;

    int i, j;

    const uint8_t *src, *src_end;

    const uint8_t *table;

    int mode, offset, dec_size;

    chroma_off = AV_RL32(buf + 4);

    if (!chroma_off)

        return 0;

    if (chroma_off + 10 >= avpkt->size) {

        av_log(avctx, AV_LOG_ERROR, "Invalid chroma block position\n");

        return -1;

    }

    src    = avpkt->data + 4 + chroma_off;

    table  = src + 2;

    mode   = bytestream_get_le16(&src);

    offset = bytestream_get_le16(&src) * 2;

    if (src - avpkt->data >= avpkt->size - offset) {

        av_log(avctx, AV_LOG_ERROR, "Invalid chroma block offset\n");

        return -1;

    }

    memset(s->scratch_buffer, 0, s->buffer_size);

    dec_size = xan_unpack(s->scratch_buffer, s->buffer_size, src + offset,

                          avpkt->size - offset - (src - avpkt->data));

    if (dec_size < 0) {

        av_log(avctx, AV_LOG_ERROR, "Chroma unpacking failed\n");

        return -1;

    }

    U = s->pic.data[1];

    V = s->pic.data[2];

    src     = s->scratch_buffer;

    src_end = src + dec_size;

    if (mode) {

        for (j = 0; j < avctx->height >> 1; j++) {

            for (i = 0; i < avctx->width >> 1; i++) {

                val = *src++;

                if (val) {

                    val  = AV_RL16(table + (val << 1));

                    uval = (val >> 3) & 0xF8;

                    vval = (val >> 8) & 0xF8;

                    U[i] = uval | (uval >> 5);

                    V[i] = vval | (vval >> 5);

                }

                if (src == src_end)

                    return 0;

            }

            U += s->pic.linesize[1];

            V += s->pic.linesize[2];

        }

    } else {

        uint8_t *U2 = U + s->pic.linesize[1];

        uint8_t *V2 = V + s->pic.linesize[2];

        for (j = 0; j < avctx->height >> 2; j++) {

            for (i = 0; i < avctx->width >> 1; i += 2) {

                val = *src++;

                if (val) {

                    val  = AV_RL16(table + (val << 1));

                    uval = (val >> 3) & 0xF8;

                    vval = (val >> 8) & 0xF8;

                    U[i] = U[i+1] = U2[i] = U2[i+1] = uval | (uval >> 5);

                    V[i] = V[i+1] = V2[i] = V2[i+1] = vval | (vval >> 5);

                }

            }

            U  += s->pic.linesize[1] * 2;

            V  += s->pic.linesize[2] * 2;

            U2 += s->pic.linesize[1] * 2;

            V2 += s->pic.linesize[2] * 2;

        }

    }

    return 0;

}

static int xan_decode_frame_type0(AVCodecContext *avctx, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    XanContext *s = avctx->priv_data;

    uint8_t *ybuf, *prev_buf, *src = s->scratch_buffer;

    unsigned  chroma_off, corr_off;

    int cur, last, size;

    int i, j;

    int ret;

    corr_off   = AV_RL32(buf + 8);

    chroma_off = AV_RL32(buf + 4);

    if ((ret = xan_decode_chroma(avctx, avpkt)) != 0)

        return ret;

    size = avpkt->size - 4;

    if (corr_off >= avpkt->size) {

        av_log(avctx, AV_LOG_WARNING, "Ignoring invalid correction block position\n");

        corr_off = 0;

    }

    if (corr_off)

        size = corr_off;

    if (chroma_off)

        size = FFMIN(size, chroma_off);

    ret = xan_unpack_luma(buf + 12, size, src, s->buffer_size >> 1);

    if (ret) {

        av_log(avctx, AV_LOG_ERROR, "Luma decoding failed\n");

        return ret;

    }

    ybuf = s->y_buffer;

    last = *src++;

    ybuf[0] = last << 1;

    for (j = 1; j < avctx->width - 1; j += 2) {

        cur = (last + *src++) & 0x1F;

        ybuf[j]   = last + cur;

        ybuf[j+1] = cur << 1;

        last = cur;

    }

    ybuf[j]  = last << 1;

    prev_buf = ybuf;

    ybuf += avctx->width;

    for (i = 1; i < avctx->height; i++) {

        last = ((prev_buf[0] >> 1) + *src++) & 0x1F;

        ybuf[0] = last << 1;

        for (j = 1; j < avctx->width - 1; j += 2) {

            cur = ((prev_buf[j + 1] >> 1) + *src++) & 0x1F;

            ybuf[j]   = last + cur;

            ybuf[j+1] = cur << 1;

            last = cur;

        }

        ybuf[j] = last << 1;

        prev_buf = ybuf;

        ybuf += avctx->width;

    }

    if (corr_off) {

        int corr_end, dec_size;

        corr_end = avpkt->size;

        if (chroma_off > corr_off)

            corr_end = chroma_off;

        dec_size = xan_unpack(s->scratch_buffer, s->buffer_size,

                              avpkt->data + 8 + corr_off,

                              corr_end - corr_off);

        if (dec_size < 0)

            dec_size = 0;

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

            s->y_buffer[i*2+1] = (s->y_buffer[i*2+1] + (s->scratch_buffer[i] << 1)) & 0x3F;

    }

    src  = s->y_buffer;

    ybuf = s->pic.data[0];

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

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

            ybuf[i] = (src[i] << 2) | (src[i] >> 3);

        src  += avctx->width;

        ybuf += s->pic.linesize[0];

    }

    return 0;

}

static int xan_decode_frame_type1(AVCodecContext *avctx, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    XanContext *s = avctx->priv_data;

    uint8_t *ybuf, *src = s->scratch_buffer;

    int cur, last;

    int i, j;

    int ret;

    if ((ret = xan_decode_chroma(avctx, avpkt)) != 0)

        return ret;

    ret = xan_unpack_luma(buf + 16, avpkt->size - 16, src,

                          s->buffer_size >> 1);

    if (ret) {

        av_log(avctx, AV_LOG_ERROR, "Luma decoding failed\n");

        return ret;

    }

    ybuf = s->y_buffer;

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

        last = (ybuf[0] + (*src++ << 1)) & 0x3F;

        ybuf[0] = last;

        for (j = 1; j < avctx->width - 1; j += 2) {

            cur = (ybuf[j + 1] + (*src++ << 1)) & 0x3F;

            ybuf[j]   = (last + cur) >> 1;

            ybuf[j+1] = cur;

            last = cur;

        }

        ybuf[j] = last;

        ybuf += avctx->width;

    }

    src = s->y_buffer;

    ybuf = s->pic.data[0];

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

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

            ybuf[i] = (src[i] << 2) | (src[i] >> 3);

        src  += avctx->width;

        ybuf += s->pic.linesize[0];

    }

    return 0;

}

static int xan_decode_frame(AVCodecContext *avctx,

                            void *data, int *data_size,

                            AVPacket *avpkt)

{

    XanContext *s = avctx->priv_data;

    int ftype;

    int ret;

    s->pic.reference = 1;

    s->pic.buffer_hints = FF_BUFFER_HINTS_VALID |

                          FF_BUFFER_HINTS_PRESERVE |

                          FF_BUFFER_HINTS_REUSABLE;

    if ((ret = avctx->reget_buffer(avctx, &s->pic))) {

        av_log(s->avctx, AV_LOG_ERROR, "reget_buffer() failed\n");

        return ret;

    }

    ftype = AV_RL32(avpkt->data);

    switch (ftype) {

    case 0:

        ret = xan_decode_frame_type0(avctx, avpkt);

        break;

    case 1:

        ret = xan_decode_frame_type1(avctx, avpkt);

        break;

    default:

        av_log(avctx, AV_LOG_ERROR, "Unknown frame type %d\n", ftype);

        return -1;

    }

    if (ret)

        return ret;

    *data_size = sizeof(AVFrame);

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

    return avpkt->size;

}

static av_cold int xan_decode_end(AVCodecContext *avctx)

{

    XanContext *s = avctx->priv_data;

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

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

    av_freep(&s->y_buffer);

    av_freep(&s->scratch_buffer);

    return 0;

}

AVCodec ff_xan_wc4_decoder = {

    "xan_wc4",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_XAN_WC4,

    sizeof(XanContext),

    xan_decode_init,

    NULL,

    xan_decode_end,

    xan_decode_frame,

    CODEC_CAP_DR1,

    .long_name = NULL_IF_CONFIG_SMALL("Wing Commander IV / Xxan"),

};