truemotion2.c

ffmpeg源码分析

/*
 * Duck/ON2 TrueMotion 2 Decoder
 * Copyright (c) 2005 Konstantin Shishkov
 *
 * This library 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 of the License, or (at your option) any later version.
 *
 * This library 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 this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 */

/**
 * @file truemotion2.c
 * Duck TrueMotion2 decoder.
 */

#include "avcodec.h"
#include "common.h"
#include "bitstream.h"
#include "dsputil.h"

#define TM2_ESCAPE 0x80000000
#define TM2_DELTAS 64
/* Huffman-coded streams of different types of blocks */
enum TM2_STREAMS{ TM2_C_HI = 0, TM2_C_LO, TM2_L_HI, TM2_L_LO,
     TM2_UPD, TM2_MOT, TM2_TYPE, TM2_NUM_STREAMS};
/* Block types */
enum TM2_BLOCKS{ TM2_HI_RES = 0, TM2_MED_RES, TM2_LOW_RES, TM2_NULL_RES,
                 TM2_UPDATE, TM2_STILL, TM2_MOTION};

typedef struct TM2Context{
    AVCodecContext *avctx;
    AVFrame pic;

    GetBitContext gb;
    DSPContext dsp;

    /* TM2 streams */
    int *tokens[TM2_NUM_STREAMS];
    int tok_lens[TM2_NUM_STREAMS];
    int tok_ptrs[TM2_NUM_STREAMS];
    int deltas[TM2_NUM_STREAMS][TM2_DELTAS];
    /* for blocks decoding */
    int D[4];
    int CD[4];
    int *last;
    int *clast;

    /* data for current and previous frame */
    int *Y1, *U1, *V1, *Y2, *U2, *V2;
    int cur;
} TM2Context;

/**
* Huffman codes for each of streams
*/
typedef struct TM2Codes{
    VLC vlc; ///< table for FFmpeg bitstream reader
    int bits;
    int *recode; ///< table for converting from code indexes to values
    int length;
} TM2Codes;

/**
* structure for gathering Huffman codes information
*/
typedef struct TM2Huff{
    int val_bits; ///< length of literal
    int max_bits; ///< maximum length of code
    int min_bits; ///< minimum length of code
    int nodes; ///< total number of nodes in tree
    int num; ///< current number filled
    int max_num; ///< total number of codes
    int *nums; ///< literals
    uint32_t *bits; ///< codes
    int *lens; ///< codelengths
} TM2Huff;

static int tm2_read_tree(TM2Context *ctx, uint32_t prefix, int length, TM2Huff *huff)
{
    if(length > huff->max_bits) {
        av_log(ctx->avctx, AV_LOG_ERROR, "Tree exceeded its given depth (%i)\n", huff->max_bits);
        return -1;
    }

    if(!get_bits1(&ctx->gb)) { /* literal */
        if (length == 0) {
            length = 1;
        }
        if(huff->num >= huff->max_num) {
            av_log(ctx->avctx, AV_LOG_DEBUG, "Too many literals\n");
            return -1;
        }
        huff->nums[huff->num] = get_bits_long(&ctx->gb, huff->val_bits);
        huff->bits[huff->num] = prefix;
        huff->lens[huff->num] = length;
        huff->num++;
        return 0;
    } else { /* non-terminal node */
        if(tm2_read_tree(ctx, prefix << 1, length + 1, huff) == -1)
            return -1;
        if(tm2_read_tree(ctx, (prefix << 1) | 1, length + 1, huff) == -1)
            return -1;
    }
    return 0;
}

static int tm2_build_huff_table(TM2Context *ctx, TM2Codes *code)
{
    TM2Huff huff;
    int res = 0;

    huff.val_bits = get_bits(&ctx->gb, 5);
    huff.max_bits = get_bits(&ctx->gb, 5);
    huff.min_bits = get_bits(&ctx->gb, 5);
    huff.nodes = get_bits_long(&ctx->gb, 17);
    huff.num = 0;

    /* check for correct codes parameters */
    if((huff.val_bits < 1) || (huff.val_bits > 32) ||
       (huff.max_bits < 0) || (huff.max_bits > 32)) {
        av_log(ctx->avctx, AV_LOG_ERROR, "Incorrect tree parameters - literal length: %i, max code length: %i\n",
               huff.val_bits, huff.max_bits);
        return -1;
    }
    if((huff.nodes < 0) || (huff.nodes > 0x10000)) {
        av_log(ctx->avctx, AV_LOG_ERROR, "Incorrect number of Huffman tree nodes: %i\n", huff.nodes);
        return -1;
    }
    /* one-node tree */
    if(huff.max_bits == 0)
        huff.max_bits = 1;

    /* allocate space for codes - it is exactly ceil(nodes / 2) entries */
    huff.max_num = (huff.nodes + 1) >> 1;
    huff.nums = av_mallocz(huff.max_num * sizeof(int));
    huff.bits = av_mallocz(huff.max_num * sizeof(uint32_t));
    huff.lens = av_mallocz(huff.max_num * sizeof(int));

    if(tm2_read_tree(ctx, 0, 0, &huff) == -1)
        res = -1;

    if(huff.num != huff.max_num) {
        av_log(ctx->avctx, AV_LOG_ERROR, "Got less codes than expected: %i of %i\n",
               huff.num, huff.max_num);
        res = -1;
    }

    /* convert codes to vlc_table */
    if(res != -1) {
        int i;

        res = init_vlc(&code->vlc, huff.max_bits, huff.max_num,
                    huff.lens, sizeof(int), sizeof(int),
                    huff.bits, sizeof(uint32_t), sizeof(uint32_t), 0);
        if(res < 0) {
            av_log(ctx->avctx, AV_LOG_ERROR, "Cannot build VLC table\n");
            res = -1;
        } else
            res = 0;
        if(res != -1) {
            code->bits = huff.max_bits;
            code->length = huff.max_num;
            code->recode = av_malloc(code->length * sizeof(int));
            for(i = 0; i < code->length; i++)
                code->recode[i] = huff.nums[i];
        }
    }
    /* free allocated memory */
    av_free(huff.nums);
    av_free(huff.bits);
    av_free(huff.lens);

    return res;
}

static void tm2_free_codes(TM2Codes *code)
{
    if(code->recode)
        av_free(code->recode);
    if(code->vlc.table)
        free_vlc(&code->vlc);
}

static inline int tm2_get_token(GetBitContext *gb, TM2Codes *code)
{
    int val;
    val = get_vlc2(gb, code->vlc.table, code->bits, 1);
    return code->recode[val];
}

static inline int tm2_read_header(TM2Context *ctx, uint8_t *buf)
{
    uint32_t magic;
    uint8_t *obuf;
    int length;

    obuf = buf;

    magic = LE_32(buf);
    buf += 4;

    if(magic == 0x00000100) { /* old header */
/*      av_log (ctx->avctx, AV_LOG_ERROR, "TM2 old header: not implemented (yet)\n"); */
        return 40;
    } else if(magic == 0x00000101) { /* new header */
        int w, h, size, flags, xr, yr;

        length = LE_32(buf);
        buf += 4;

        init_get_bits(&ctx->gb, buf, 32 * 8);
        size = get_bits_long(&ctx->gb, 31);
        h = get_bits(&ctx->gb, 15);
        w = get_bits(&ctx->gb, 15);
        flags = get_bits_long(&ctx->gb, 31);
        yr = get_bits(&ctx->gb, 9);
        xr = get_bits(&ctx->gb, 9);

        return 40;
    } else {
        av_log (ctx->avctx, AV_LOG_ERROR, "Not a TM2 header: 0x%08X\n", magic);
        return -1;
    }

    return (buf - obuf);
}

static int tm2_read_deltas(TM2Context *ctx, int stream_id) {
    int d, mb;
    int i, v;

    d = get_bits(&ctx->gb, 9);
    mb = get_bits(&ctx->gb, 5);

    if((d < 1) || (d > TM2_DELTAS) || (mb < 1) || (mb > 32)) {
        av_log(ctx->avctx, AV_LOG_ERROR, "Incorrect delta table: %i deltas x %i bits\n", d, mb);
        return -1;
    }

    for(i = 0; i < d; i++) {
        v = get_bits_long(&ctx->gb, mb);
        if(v & (1 << (mb - 1)))
            ctx->deltas[stream_id][i] = v - (1 << mb);
        else
            ctx->deltas[stream_id][i] = v;
    }
    for(; i < TM2_DELTAS; i++)
        ctx->deltas[stream_id][i] = 0;

    return 0;
}

static int tm2_read_stream(TM2Context *ctx, uint8_t *buf, int stream_id) {
    int i;
    int cur = 0;
    int skip = 0;
    int len, toks;
    TM2Codes codes;

    /* get stream length in dwords */
    len = BE_32(buf); buf += 4; cur += 4;
    skip = len * 4 + 4;

    if(len == 0)
        return 4;

    toks = BE_32(buf); buf += 4; cur += 4;
    if(toks & 1) {
        len = BE_32(buf); buf += 4; cur += 4;
        if(len == TM2_ESCAPE) {
            len = BE_32(buf); buf += 4; cur += 4;
        }
        if(len > 0) {
            init_get_bits(&ctx->gb, buf, (skip - cur) * 8);
            if(tm2_read_deltas(ctx, stream_id) == -1)
                return -1;
            buf += ((get_bits_count(&ctx->gb) + 31) >> 5) << 2;
            cur += ((get_bits_count(&ctx->gb) + 31) >> 5) << 2;
        }
    }
    /* skip unused fields */
    if(BE_32(buf) == TM2_ESCAPE) {
        buf += 4; cur += 4; /* some unknown length - could be escaped too */
    }
    buf += 4; cur += 4;
    buf += 4; cur += 4; /* unused by decoder */

    init_get_bits(&ctx->gb, buf, (skip - cur) * 8);
    if(tm2_build_huff_table(ctx, &codes) == -1)
        return -1;
    buf += ((get_bits_count(&ctx->gb) + 31) >> 5) << 2;
    cur += ((get_bits_count(&ctx->gb) + 31) >> 5) << 2;

    toks >>= 1;
    /* check if we have sane number of tokens */
    if((toks < 0) || (toks > 0xFFFFFF)){
        av_log(ctx->avctx, AV_LOG_ERROR, "Incorrect number of tokens: %i\n", toks);
        tm2_free_codes(&codes);
        return -1;
    }
    ctx->tokens[stream_id] = av_realloc(ctx->tokens[stream_id], toks * sizeof(int));
    ctx->tok_lens[stream_id] = toks;
    len = BE_32(buf); buf += 4; cur += 4;
    if(len > 0) {
        init_get_bits(&ctx->gb, buf, (skip - cur) * 8);
        for(i = 0; i < toks; i++)
            ctx->tokens[stream_id][i] = tm2_get_token(&ctx->gb, &codes);
    } else {
        for(i = 0; i < toks; i++)
            ctx->tokens[stream_id][i] = codes.recode[0];
    }
    tm2_free_codes(&codes);

    return skip;
}

static inline int GET_TOK(TM2Context *ctx,int type) {
    if(ctx->tok_ptrs[type] >= ctx->tok_lens[type]) {
        av_log(ctx->avctx, AV_LOG_ERROR, "Read token from stream %i out of bounds (%i>=%i)\n", type, ctx->tok_ptrs[type], ctx->tok_lens[type]);
        return 0;
    }
    if(type <= TM2_MOT)
        return ctx->deltas[type][ctx->tokens[type][ctx->tok_ptrs[type]++]];
    return ctx->tokens[type][ctx->tok_ptrs[type]++];
}

/* blocks decoding routines */

/* common Y, U, V pointers initialisation */
#define TM2_INIT_POINTERS() \
    int *last, *clast; \
    int *Y, *U, *V;\
    int Ystride, Ustride, Vstride;\
\
    Ystride = ctx->avctx->width;\
    Vstride = (ctx->avctx->width + 1) >> 1;\
    Ustride = (ctx->avctx->width + 1) >> 1;\
    Y = (ctx->cur?ctx->Y2:ctx->Y1) + by * 4 * Ystride + bx * 4;\
    V = (ctx->cur?ctx->V2:ctx->V1) + by * 2 * Vstride + bx * 2;\
    U = (ctx->cur?ctx->U2:ctx->U1) + by * 2 * Ustride + bx * 2;\
    last = ctx->last + bx * 4;\
    clast = ctx->clast + bx * 4;

#define TM2_INIT_POINTERS_2() \
    int *Yo, *Uo, *Vo;\
    int oYstride, oUstride, oVstride;\
\
    TM2_INIT_POINTERS();\
    oYstride = Ystride;\
    oVstride = Vstride;\
    oUstride = Ustride;\
    Yo = (ctx->cur?ctx->Y1:ctx->Y2) + by * 4 * oYstride + bx * 4;\
    Vo = (ctx->cur?ctx->V1:ctx->V2) + by * 2 * oVstride + bx * 2;\
    Uo = (ctx->cur?ctx->U1:ctx->U2) + by * 2 * oUstride + bx * 2;

/* recalculate last and delta values for next blocks */
#define TM2_RECALC_BLOCK(CHR, stride, last, CD) {\
    CD[0] = (CHR[1] - 128) - last[1];\
    CD[1] = (int)CHR[stride + 1] - (int)CHR[1];\
    last[0] = (int)CHR[stride + 0] - 128;\
    last[1] = (int)CHR[stride + 1] - 128;}

/* common operations - add deltas to 4x4 block of luma or 2x2 blocks of chroma */
static inline void tm2_apply_deltas(TM2Context *ctx, int* Y, int stride, int *deltas, int *last)
{
    int ct, d;
    int i, j;

    for(j = 0; j < 4; j++){
        ct = ctx->D[j];
        for(i = 0; i < 4; i++){
            d = deltas[i + j * 4];
            ct += d;
            last[i] += ct;
            Y[i] = clip_uint8(last[i]);
        }
        Y += stride;
        ctx->D[j] = ct;
    }
}

static inline void tm2_high_chroma(int *data, int stride, int *last, int *CD, int *deltas)
{
    int i, j;
    for(j = 0; j < 2; j++){
        for(i = 0; i < 2; i++){
            CD[j] += deltas[i + j * 2];
            last[i] += CD[j];
            data[i] = last[i] + 128;
        }
        data += stride;
    }
}

static inline void tm2_low_chroma(int *data, int stride, int *clast, int *CD, int *deltas, int bx)
{
    int t;
    int l;
    int prev;

    if(bx > 0)
        prev = clast[-3];
    else
        prev = 0;
    t = (CD[0] + CD[1]) >> 1;
    l = (prev - CD[0] - CD[1] + clast[1]) >> 1;
    CD[1] = CD[0] + CD[1] - t;
    CD[0] = t;
    clast[0] = l;

    tm2_high_chroma(data, stride, clast, CD, deltas);
}

static inline void tm2_hi_res_block(TM2Context *ctx, AVFrame *pic, int bx, int by)
{
    int i;
    int deltas[16];
    TM2_INIT_POINTERS();

    /* hi-res chroma */
    for(i = 0; i < 4; i++) {
        deltas[i] = GET_TOK(ctx, TM2_C_HI);
        deltas[i + 4] = GET_TOK(ctx, TM2_C_HI);
    }
    tm2_high_chroma(U, Ustride, clast, ctx->CD, deltas);
    tm2_high_chroma(V, Vstride, clast + 2, ctx->CD + 2, deltas + 4);

    /* hi-res luma */
    for(i = 0; i < 16; i++)
        deltas[i] = GET_TOK(ctx, TM2_L_HI);

    tm2_apply_deltas(ctx, Y, Ystride, deltas, last);
}

static inline void tm2_med_res_block(TM2Context *ctx, AVFrame *pic, int bx, int by)
{