PeerStreamer

/*

 * Wing Commander/Xan Video Decoder

 * Copyright (C) 2003 the ffmpeg project

 *

 * 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

 */

/**

 * @file

 * Xan video decoder for Wing Commander III computer game

 * by Mario Brito (mbrito@student.dei.uc.pt)

 * and Mike Melanson (melanson@pcisys.net)

 *

 * The xan_wc3 decoder outputs PAL8 data.

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "libavutil/intreadwrite.h"

#include "avcodec.h"

#include "bytestream.h"

#define ALT_BITSTREAM_READER_LE

#include "get_bits.h"

// for av_memcpy_backptr

#include "libavutil/lzo.h"

#define RUNTIME_GAMMA 0

#define VGA__TAG MKTAG('V', 'G', 'A', ' ')

#define PALT_TAG MKTAG('P', 'A', 'L', 'T')

#define SHOT_TAG MKTAG('S', 'H', 'O', 'T')

#define PALETTE_COUNT 256

#define PALETTE_SIZE (PALETTE_COUNT * 3)

#define PALETTES_MAX 256

typedef struct XanContext {

    AVCodecContext *avctx;

    AVFrame last_frame;

    AVFrame current_frame;

    const unsigned char *buf;

    int size;

    /* scratch space */

    unsigned char *buffer1;

    int buffer1_size;

    unsigned char *buffer2;

    int buffer2_size;

    unsigned *palettes;

    int palettes_count;

    int cur_palette;

    int frame_size;

} XanContext;

static av_cold int xan_decode_init(AVCodecContext *avctx)

{

    XanContext *s = avctx->priv_data;

    s->avctx = avctx;

    s->frame_size = 0;

    avctx->pix_fmt = PIX_FMT_PAL8;

    s->buffer1_size = avctx->width * avctx->height;

    s->buffer1 = av_malloc(s->buffer1_size);

    if (!s->buffer1)

        return AVERROR(ENOMEM);

    s->buffer2_size = avctx->width * avctx->height;

    s->buffer2 = av_malloc(s->buffer2_size + 130);

    if (!s->buffer2) {

        av_freep(&s->buffer1);

        return AVERROR(ENOMEM);

    }

    return 0;

}

static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,

    int dest_len)

{

    unsigned char byte = *src++;

    unsigned char ival = byte + 0x16;

    const unsigned char * ptr = src + byte*2;

    unsigned char val = ival;

    unsigned char *dest_end = dest + dest_len;

    GetBitContext gb;

    init_get_bits(&gb, ptr, 0); // FIXME: no src size available

    while ( val != 0x16 ) {

        val = src[val - 0x17 + get_bits1(&gb) * byte];

        if ( val < 0x16 ) {

            if (dest >= dest_end)

                return 0;

            *dest++ = val;

            val = ival;

        }

    }

    return 0;

}

/**

 * unpack simple compression

 *

 * @param dest destination buffer of dest_len, must be padded with at least 130 bytes

 */

static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)

{

    unsigned char opcode;

    int size;

    unsigned char *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)

                    return;

            }

            memcpy(dest, src, size);  dest += size;  src += size;

            av_memcpy_backptr(dest, back, size2);

            dest += size2;

        } else {

            int finish = opcode >= 0xfc;

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

            memcpy(dest, src, size);  dest += size;  src += size;

            if (finish)

                return;

        }

    }

}

static inline void xan_wc3_output_pixel_run(XanContext *s,

    const unsigned char *pixel_buffer, int x, int y, int pixel_count)

{

    int stride;

    int line_inc;

    int index;

    int current_x;

    int width = s->avctx->width;

    unsigned char *palette_plane;

    palette_plane = s->current_frame.data[0];

    stride = s->current_frame.linesize[0];

    line_inc = stride - width;

    index = y * stride + x;

    current_x = x;

    while(pixel_count && (index < s->frame_size)) {

        int count = FFMIN(pixel_count, width - current_x);

        memcpy(palette_plane + index, pixel_buffer, count);

        pixel_count  -= count;

        index        += count;

        pixel_buffer += count;

        current_x    += count;

        if (current_x >= width) {

            index += line_inc;

            current_x = 0;

        }

    }

}

static inline void xan_wc3_copy_pixel_run(XanContext *s,

    int x, int y, int pixel_count, int motion_x, int motion_y)

{

    int stride;

    int line_inc;

    int curframe_index, prevframe_index;

    int curframe_x, prevframe_x;

    int width = s->avctx->width;

    unsigned char *palette_plane, *prev_palette_plane;

    palette_plane = s->current_frame.data[0];

    prev_palette_plane = s->last_frame.data[0];

    stride = s->current_frame.linesize[0];

    line_inc = stride - width;

    curframe_index = y * stride + x;

    curframe_x = x;

    prevframe_index = (y + motion_y) * stride + x + motion_x;

    prevframe_x = x + motion_x;

    while(pixel_count && (curframe_index < s->frame_size)) {

        int count = FFMIN3(pixel_count, width - curframe_x, width - prevframe_x);

        memcpy(palette_plane + curframe_index, prev_palette_plane + prevframe_index, count);

        pixel_count     -= count;

        curframe_index  += count;

        prevframe_index += count;

        curframe_x      += count;

        prevframe_x     += count;

        if (curframe_x >= width) {

            curframe_index += line_inc;

            curframe_x = 0;

        }

        if (prevframe_x >= width) {

            prevframe_index += line_inc;

            prevframe_x = 0;

        }

    }

}

static void xan_wc3_decode_frame(XanContext *s) {

    int width = s->avctx->width;

    int height = s->avctx->height;

    int total_pixels = width * height;

    unsigned char opcode;

    unsigned char flag = 0;

    int size = 0;

    int motion_x, motion_y;

    int x, y;

    unsigned char *opcode_buffer = s->buffer1;

    int opcode_buffer_size = s->buffer1_size;

    const unsigned char *imagedata_buffer = s->buffer2;

    /* pointers to segments inside the compressed chunk */

    const unsigned char *huffman_segment;

    const unsigned char *size_segment;

    const unsigned char *vector_segment;

    const unsigned char *imagedata_segment;

    huffman_segment =   s->buf + AV_RL16(&s->buf[0]);

    size_segment =      s->buf + AV_RL16(&s->buf[2]);

    vector_segment =    s->buf + AV_RL16(&s->buf[4]);

    imagedata_segment = s->buf + AV_RL16(&s->buf[6]);

    xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);

    if (imagedata_segment[0] == 2)

        xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);

    else

        imagedata_buffer = &imagedata_segment[1];

    /* use the decoded data segments to build the frame */

    x = y = 0;

    while (total_pixels) {

        opcode = *opcode_buffer++;

        size = 0;

        switch (opcode) {

        case 0:

            flag ^= 1;

            continue;

        case 1:

        case 2:

        case 3:

        case 4:

        case 5:

        case 6:

        case 7:

        case 8:

            size = opcode;

            break;

        case 12:

        case 13:

        case 14:

        case 15:

        case 16:

        case 17:

        case 18:

            size += (opcode - 10);

            break;

        case 9:

        case 19:

            size = *size_segment++;

            break;

        case 10:

        case 20:

            size = AV_RB16(&size_segment[0]);

            size_segment += 2;

            break;

        case 11:

        case 21:

            size = AV_RB24(size_segment);

            size_segment += 3;

            break;

        }

        if (opcode < 12) {

            flag ^= 1;

            if (flag) {

                /* run of (size) pixels is unchanged from last frame */

                xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);

            } else {

                /* output a run of pixels from imagedata_buffer */

                xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);

                imagedata_buffer += size;

            }

        } else {

            /* run-based motion compensation from last frame */

            motion_x = sign_extend(*vector_segment >> 4,  4);

            motion_y = sign_extend(*vector_segment & 0xF, 4);

            vector_segment++;

            /* copy a run of pixels from the previous frame */

            xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);

            flag = 0;

        }

        /* coordinate accounting */

        total_pixels -= size;

        y += (x + size) / width;

        x  = (x + size) % width;

    }

}

#if RUNTIME_GAMMA

static inline unsigned mul(unsigned a, unsigned b)

{

    return (a * b) >> 16;

}

static inline unsigned pow4(unsigned a)

{

    unsigned square = mul(a, a);

    return mul(square, square);

}

static inline unsigned pow5(unsigned a)

{

    return mul(pow4(a), a);

}

static uint8_t gamma_corr(uint8_t in) {

    unsigned lo, hi = 0xff40, target;

    int i = 15;

    in = (in << 2) | (in >> 6);

    /*  equivalent float code:

    if (in >= 252)

        return 253;

    return round(pow(in / 256.0, 0.8) * 256);

    */

    lo = target = in << 8;

    do {

        unsigned mid = (lo + hi) >> 1;

        unsigned pow = pow5(mid);

        if (pow > target) hi = mid;

        else lo = mid;

    } while (--i);

    return (pow4((lo + hi) >> 1) + 0x80) >> 8;

}

#else

/**

 * This is a gamma correction that xan3 applies to all palette entries.

 *

 * There is a peculiarity, namely that the values are clamped to 253 -

 * it seems likely that this table was calculated by a buggy fixed-point

 * implementation, the one above under RUNTIME_GAMMA behaves like this for

 * example.

 * The exponent value of 0.8 can be explained by this as well, since 0.8 = 4/5

 * and thus pow(x, 0.8) is still easy to calculate.

 * Also, the input values are first rotated to the left by 2.

 */

static const uint8_t gamma_lookup[256] = {

    0x00, 0x09, 0x10, 0x16, 0x1C, 0x21, 0x27, 0x2C,

    0x31, 0x35, 0x3A, 0x3F, 0x43, 0x48, 0x4C, 0x50,

    0x54, 0x59, 0x5D, 0x61, 0x65, 0x69, 0x6D, 0x71,

    0x75, 0x79, 0x7D, 0x80, 0x84, 0x88, 0x8C, 0x8F,

    0x93, 0x97, 0x9A, 0x9E, 0xA2, 0xA5, 0xA9, 0xAC,

    0xB0, 0xB3, 0xB7, 0xBA, 0xBE, 0xC1, 0xC5, 0xC8,

    0xCB, 0xCF, 0xD2, 0xD5, 0xD9, 0xDC, 0xDF, 0xE3,

    0xE6, 0xE9, 0xED, 0xF0, 0xF3, 0xF6, 0xFA, 0xFD,

    0x03, 0x0B, 0x12, 0x18, 0x1D, 0x23, 0x28, 0x2D,

    0x32, 0x36, 0x3B, 0x40, 0x44, 0x49, 0x4D, 0x51,

    0x56, 0x5A, 0x5E, 0x62, 0x66, 0x6A, 0x6E, 0x72,

    0x76, 0x7A, 0x7D, 0x81, 0x85, 0x89, 0x8D, 0x90,

    0x94, 0x98, 0x9B, 0x9F, 0xA2, 0xA6, 0xAA, 0xAD,

    0xB1, 0xB4, 0xB8, 0xBB, 0xBF, 0xC2, 0xC5, 0xC9,

    0xCC, 0xD0, 0xD3, 0xD6, 0xDA, 0xDD, 0xE0, 0xE4,

    0xE7, 0xEA, 0xED, 0xF1, 0xF4, 0xF7, 0xFA, 0xFD,

    0x05, 0x0D, 0x13, 0x19, 0x1F, 0x24, 0x29, 0x2E,

    0x33, 0x38, 0x3C, 0x41, 0x45, 0x4A, 0x4E, 0x52,

    0x57, 0x5B, 0x5F, 0x63, 0x67, 0x6B, 0x6F, 0x73,

    0x77, 0x7B, 0x7E, 0x82, 0x86, 0x8A, 0x8D, 0x91,

    0x95, 0x99, 0x9C, 0xA0, 0xA3, 0xA7, 0xAA, 0xAE,

    0xB2, 0xB5, 0xB9, 0xBC, 0xBF, 0xC3, 0xC6, 0xCA,

    0xCD, 0xD0, 0xD4, 0xD7, 0xDA, 0xDE, 0xE1, 0xE4,

    0xE8, 0xEB, 0xEE, 0xF1, 0xF5, 0xF8, 0xFB, 0xFD,

    0x07, 0x0E, 0x15, 0x1A, 0x20, 0x25, 0x2A, 0x2F,

    0x34, 0x39, 0x3D, 0x42, 0x46, 0x4B, 0x4F, 0x53,

    0x58, 0x5C, 0x60, 0x64, 0x68, 0x6C, 0x70, 0x74,

    0x78, 0x7C, 0x7F, 0x83, 0x87, 0x8B, 0x8E, 0x92,

    0x96, 0x99, 0x9D, 0xA1, 0xA4, 0xA8, 0xAB, 0xAF,

    0xB2, 0xB6, 0xB9, 0xBD, 0xC0, 0xC4, 0xC7, 0xCB,

    0xCE, 0xD1, 0xD5, 0xD8, 0xDB, 0xDF, 0xE2, 0xE5,

    0xE9, 0xEC, 0xEF, 0xF2, 0xF6, 0xF9, 0xFC, 0xFD

};

#endif

static int xan_decode_frame(AVCodecContext *avctx,

                            void *data, int *data_size,

                            AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int ret, buf_size = avpkt->size;

    XanContext *s = avctx->priv_data;

    if (avctx->codec->id == CODEC_ID_XAN_WC3) {

        const uint8_t *buf_end = buf + buf_size;

        int tag = 0;

        while (buf_end - buf > 8 && tag != VGA__TAG) {

            unsigned *tmpptr;

            uint32_t new_pal;

            int size;

            int i;

            tag  = bytestream_get_le32(&buf);

            size = bytestream_get_be32(&buf);

            size = FFMIN(size, buf_end - buf);

            switch (tag) {

            case PALT_TAG:

                if (size < PALETTE_SIZE)

                    return AVERROR_INVALIDDATA;

                if (s->palettes_count >= PALETTES_MAX)

                    return AVERROR_INVALIDDATA;

                tmpptr = av_realloc(s->palettes, (s->palettes_count + 1) * AVPALETTE_SIZE);

                if (!tmpptr)

                    return AVERROR(ENOMEM);

                s->palettes = tmpptr;

                tmpptr += s->palettes_count * AVPALETTE_COUNT;

                for (i = 0; i < PALETTE_COUNT; i++) {

#if RUNTIME_GAMMA

                    int r = gamma_corr(*buf++);

                    int g = gamma_corr(*buf++);

                    int b = gamma_corr(*buf++);

#else

                    int r = gamma_lookup[*buf++];

                    int g = gamma_lookup[*buf++];

                    int b = gamma_lookup[*buf++];

#endif

                    *tmpptr++ = (r << 16) | (g << 8) | b;

                }

                s->palettes_count++;

                break;

            case SHOT_TAG:

                if (size < 4)

                    return AVERROR_INVALIDDATA;

                new_pal = bytestream_get_le32(&buf);

                if (new_pal < s->palettes_count) {

                    s->cur_palette = new_pal;

                } else

                    av_log(avctx, AV_LOG_ERROR, "Invalid palette selected\n");

                break;

            case VGA__TAG:

                break;

            default:

                buf += size;

                break;

            }

        }

        buf_size = buf_end - buf;

    }

    if ((ret = avctx->get_buffer(avctx, &s->current_frame))) {

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

        return ret;

    }

    s->current_frame.reference = 3;

    if (!s->frame_size)

        s->frame_size = s->current_frame.linesize[0] * s->avctx->height;

    memcpy(s->current_frame.data[1], s->palettes + s->cur_palette * AVPALETTE_COUNT, AVPALETTE_SIZE);

    s->buf = buf;

    s->size = buf_size;

    xan_wc3_decode_frame(s);

    /* release the last frame if it is allocated */

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

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

    *data_size = sizeof(AVFrame);

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

    /* shuffle frames */

    FFSWAP(AVFrame, s->current_frame, s->last_frame);

    /* always report that the buffer was completely consumed */

    return buf_size;

}

static av_cold int xan_decode_end(AVCodecContext *avctx)

{

    XanContext *s = avctx->priv_data;

    /* release the frames */

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

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

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

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

    av_freep(&s->buffer1);

    av_freep(&s->buffer2);

    av_freep(&s->palettes);

    return 0;

}

AVCodec ff_xan_wc3_decoder = {

    "xan_wc3",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_XAN_WC3,

    sizeof(XanContext),

    xan_decode_init,

    NULL,

    xan_decode_end,

    xan_decode_frame,

    CODEC_CAP_DR1,

    .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),

};