dvbsubdec.c

ffmpeg源码分析

/*
 * DVB subtitle decoding for ffmpeg
 * Copyright (c) 2005 Ian Caulfield.
 *
 * 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
 */
#include "avcodec.h"
#include "dsputil.h"
#include "bitstream.h"

//#define DEBUG
//#define DEBUG_PACKET_CONTENTS
//#define DEBUG_SAVE_IMAGES

#define DVBSUB_PAGE_SEGMENT     0x10
#define DVBSUB_REGION_SEGMENT   0x11
#define DVBSUB_CLUT_SEGMENT     0x12
#define DVBSUB_OBJECT_SEGMENT   0x13
#define DVBSUB_DISPLAY_SEGMENT  0x80

static unsigned char *cm;

#ifdef DEBUG_SAVE_IMAGES
#undef fprintf
#if 0
static void png_save(const char *filename, uint8_t *bitmap, int w, int h,
                     uint32_t *rgba_palette)
{
    int x, y, v;
    FILE *f;
    char fname[40], fname2[40];
    char command[1024];

    snprintf(fname, 40, "%s.ppm", filename);

    f = fopen(fname, "w");
    if (!f) {
        perror(fname);
        exit(1);
    }
    fprintf(f, "P6\n"
            "%d %d\n"
            "%d\n",
            w, h, 255);
    for(y = 0; y < h; y++) {
        for(x = 0; x < w; x++) {
            v = rgba_palette[bitmap[y * w + x]];
            putc((v >> 16) & 0xff, f);
            putc((v >> 8) & 0xff, f);
            putc((v >> 0) & 0xff, f);
        }
    }
    fclose(f);


    snprintf(fname2, 40, "%s-a.pgm", filename);

    f = fopen(fname2, "w");
    if (!f) {
        perror(fname2);
        exit(1);
    }
    fprintf(f, "P5\n"
            "%d %d\n"
            "%d\n",
            w, h, 255);
    for(y = 0; y < h; y++) {
        for(x = 0; x < w; x++) {
            v = rgba_palette[bitmap[y * w + x]];
            putc((v >> 24) & 0xff, f);
        }
    }
    fclose(f);

    snprintf(command, 1024, "pnmtopng -alpha %s %s > %s.png 2> /dev/null", fname2, fname, filename);
    system(command);

    snprintf(command, 1024, "rm %s %s", fname, fname2);
    system(command);
}
#endif

static void png_save2(const char *filename, uint32_t *bitmap, int w, int h)
{
    int x, y, v;
    FILE *f;
    char fname[40], fname2[40];
    char command[1024];

    snprintf(fname, 40, "%s.ppm", filename);

    f = fopen(fname, "w");
    if (!f) {
        perror(fname);
        exit(1);
    }
    fprintf(f, "P6\n"
            "%d %d\n"
            "%d\n",
            w, h, 255);
    for(y = 0; y < h; y++) {
        for(x = 0; x < w; x++) {
            v = bitmap[y * w + x];
            putc((v >> 16) & 0xff, f);
            putc((v >> 8) & 0xff, f);
            putc((v >> 0) & 0xff, f);
        }
    }
    fclose(f);


    snprintf(fname2, 40, "%s-a.pgm", filename);

    f = fopen(fname2, "w");
    if (!f) {
        perror(fname2);
        exit(1);
    }
    fprintf(f, "P5\n"
            "%d %d\n"
            "%d\n",
            w, h, 255);
    for(y = 0; y < h; y++) {
        for(x = 0; x < w; x++) {
            v = bitmap[y * w + x];
            putc((v >> 24) & 0xff, f);
        }
    }
    fclose(f);

    snprintf(command, 1024, "pnmtopng -alpha %s %s > %s.png 2> /dev/null", fname2, fname, filename);
    system(command);

    snprintf(command, 1024, "rm %s %s", fname, fname2);
    system(command);
}
#endif

#define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))

typedef struct DVBSubCLUT {
    int id;

    uint32_t clut4[4];
    uint32_t clut16[16];
    uint32_t clut256[256];

    struct DVBSubCLUT *next;
} DVBSubCLUT;

static DVBSubCLUT default_clut;

typedef struct DVBSubObjectDisplay {
    int object_id;
    int region_id;

    int x_pos;
    int y_pos;

    int fgcolour;
    int bgcolour;

    struct DVBSubObjectDisplay *region_list_next;
    struct DVBSubObjectDisplay *object_list_next;
} DVBSubObjectDisplay;

typedef struct DVBSubObject {
    int id;

    int type;

    DVBSubObjectDisplay *display_list;

    struct DVBSubObject *next;
} DVBSubObject;

typedef struct DVBSubRegionDisplay {
    int region_id;

    int x_pos;
    int y_pos;

    struct DVBSubRegionDisplay *next;
} DVBSubRegionDisplay;

typedef struct DVBSubRegion {
    int id;

    int width;
    int height;
    int depth;

    int clut;
    int bgcolour;

    uint8_t *pbuf;
    int buf_size;

    DVBSubObjectDisplay *display_list;

    struct DVBSubRegion *next;
} DVBSubRegion;

typedef struct DVBSubContext {
    int composition_id;
    int ancillary_id;

    int time_out;
    DVBSubRegion *region_list;
    DVBSubCLUT   *clut_list;
    DVBSubObject *object_list;

    int display_list_size;
    DVBSubRegionDisplay *display_list;
} DVBSubContext;


static DVBSubObject* get_object(DVBSubContext *ctx, int object_id)
{
    DVBSubObject *ptr = ctx->object_list;

    while (ptr != NULL && ptr->id != object_id) {
        ptr = ptr->next;
    }

    return ptr;
}

static DVBSubCLUT* get_clut(DVBSubContext *ctx, int clut_id)
{
    DVBSubCLUT *ptr = ctx->clut_list;

    while (ptr != NULL && ptr->id != clut_id) {
        ptr = ptr->next;
    }

    return ptr;
}

static DVBSubRegion* get_region(DVBSubContext *ctx, int region_id)
{
    DVBSubRegion *ptr = ctx->region_list;

    while (ptr != NULL && ptr->id != region_id) {
        ptr = ptr->next;
    }

    return ptr;
}

static void delete_region_display_list(DVBSubContext *ctx, DVBSubRegion *region)
{
    DVBSubObject *object, *obj2, **obj2_ptr;
    DVBSubObjectDisplay *display, *obj_disp, **obj_disp_ptr;

    while (region->display_list != NULL) {
        display = region->display_list;

        object = get_object(ctx, display->object_id);

        if (object != NULL) {
            obj_disp = object->display_list;
            obj_disp_ptr = &object->display_list;

            while (obj_disp != NULL && obj_disp != display) {
                obj_disp_ptr = &obj_disp->object_list_next;
                obj_disp = obj_disp->object_list_next;
            }

            if (obj_disp) {
                *obj_disp_ptr = obj_disp->object_list_next;

                if (object->display_list == NULL) {
                    obj2 = ctx->object_list;
                    obj2_ptr = &ctx->object_list;

                    while (obj2 != NULL && obj2 != object) {
                        obj2_ptr = &obj2->next;
                        obj2 = obj2->next;
                    }

                    *obj2_ptr = obj2->next;

                    av_free(obj2);
                }
            }
        }

        region->display_list = display->region_list_next;

        av_free(display);
    }

}

static void delete_state(DVBSubContext *ctx)
{
    DVBSubRegion *region;
    DVBSubCLUT *clut;

    while (ctx->region_list != NULL)
    {
        region = ctx->region_list;

        ctx->region_list = region->next;

        delete_region_display_list(ctx, region);
        if (region->pbuf != NULL)
            av_free(region->pbuf);

        av_free(region);
    }

    while (ctx->clut_list != NULL)
    {
        clut = ctx->clut_list;

        ctx->clut_list = clut->next;

        av_free(clut);
    }

    /* Should already be null */
    if (ctx->object_list != NULL)
        av_log(0, AV_LOG_ERROR, "Memory deallocation error!\n");
}

static int dvbsub_init_decoder(AVCodecContext *avctx)
{
    int i, r, g, b, a = 0;
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;

    cm = cropTbl + MAX_NEG_CROP;

    memset(avctx->priv_data, 0, sizeof(DVBSubContext));

    ctx->composition_id = avctx->sub_id & 0xffff;
    ctx->ancillary_id = avctx->sub_id >> 16;

    default_clut.id = -1;
    default_clut.next = NULL;

    default_clut.clut4[0] = RGBA(  0,   0,   0,   0);
    default_clut.clut4[1] = RGBA(255, 255, 255, 255);
    default_clut.clut4[2] = RGBA(  0,   0,   0, 255);
    default_clut.clut4[3] = RGBA(127, 127, 127, 255);

    default_clut.clut16[0] = RGBA(  0,   0,   0,   0);
    for (i = 1; i < 16; i++) {
        if (i < 8) {
            r = (i & 1) ? 255 : 0;
            g = (i & 2) ? 255 : 0;
            b = (i & 4) ? 255 : 0;
        } else {
            r = (i & 1) ? 127 : 0;
            g = (i & 2) ? 127 : 0;
            b = (i & 4) ? 127 : 0;
        }
        default_clut.clut16[i] = RGBA(r, g, b, 255);
    }

    default_clut.clut256[0] = RGBA(  0,   0,   0,   0);
    for (i = 1; i < 256; i++) {
        if (i < 8) {
            r = (i & 1) ? 255 : 0;
            g = (i & 2) ? 255 : 0;
            b = (i & 4) ? 255 : 0;
            a = 63;
        } else {
            switch (i & 0x88) {
            case 0x00:
                r = ((i & 1) ? 85 : 0) + ((i & 0x10) ? 170 : 0);
                g = ((i & 2) ? 85 : 0) + ((i & 0x20) ? 170 : 0);
                b = ((i & 4) ? 85 : 0) + ((i & 0x40) ? 170 : 0);
                a = 255;
                break;
            case 0x08:
                r = ((i & 1) ? 85 : 0) + ((i & 0x10) ? 170 : 0);
                g = ((i & 2) ? 85 : 0) + ((i & 0x20) ? 170 : 0);
                b = ((i & 4) ? 85 : 0) + ((i & 0x40) ? 170 : 0);
                a = 127;
                break;
            case 0x80:
                r = 127 + ((i & 1) ? 43 : 0) + ((i & 0x10) ? 85 : 0);
                g = 127 + ((i & 2) ? 43 : 0) + ((i & 0x20) ? 85 : 0);
                b = 127 + ((i & 4) ? 43 : 0) + ((i & 0x40) ? 85 : 0);
                a = 255;
                break;
            case 0x88:
                r = ((i & 1) ? 43 : 0) + ((i & 0x10) ? 85 : 0);
                g = ((i & 2) ? 43 : 0) + ((i & 0x20) ? 85 : 0);
                b = ((i & 4) ? 43 : 0) + ((i & 0x40) ? 85 : 0);
                a = 255;
                break;
            }
        }
        default_clut.clut256[i] = RGBA(r, g, b, a);
    }

    return 0;
}

static int dvbsub_close_decoder(AVCodecContext *avctx)
{
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;
    DVBSubRegionDisplay *display;

    delete_state(ctx);

    while (ctx->display_list != NULL)
    {
        display = ctx->display_list;
        ctx->display_list = display->next;

        av_free(display);
    }

    return 0;
}

static int dvbsub_read_2bit_string(uint8_t *destbuf, int dbuf_len,
                                   uint8_t **srcbuf, int buf_size,
                                   int non_mod, uint8_t *map_table)
{
    GetBitContext gb;

    int bits;
    int run_length;
    int pixels_read = 0;

    init_get_bits(&gb, *srcbuf, buf_size << 8);

    while (get_bits_count(&gb) < (buf_size << 8) && pixels_read < dbuf_len) {
        bits = get_bits(&gb, 2);

        if (bits != 0) {
            if (non_mod != 1 || bits != 1) {
                if (map_table != NULL)
                    *destbuf++ = map_table[bits];
                else
                    *destbuf++ = bits;
            }
            pixels_read++;
        } else {
            bits = get_bits(&gb, 1);
            if (bits == 1) {
                run_length = get_bits(&gb, 3) + 3;
                bits = get_bits(&gb, 2);

                if (non_mod == 1 && bits == 1)
                    pixels_read += run_length;
                else {
                    if (map_table != NULL)
                        bits = map_table[bits];
                    while (run_length-- > 0 && pixels_read < dbuf_len) {
                        *destbuf++ = bits;
                        pixels_read++;
                    }
                }
            } else {
                bits = get_bits(&gb, 1);
                if (bits == 0) {
                    bits = get_bits(&gb, 2);
                    if (bits == 2) {
                        run_length = get_bits(&gb, 4) + 12;
                        bits = get_bits(&gb, 2);

                        if (non_mod == 1 && bits == 1)
                            pixels_read += run_length;
                        else {
                            if (map_table != NULL)
                                bits = map_table[bits];
                            while (run_length-- > 0 && pixels_read < dbuf_len) {
                                *destbuf++ = bits;
                                pixels_read++;
                            }
                        }
                    } else if (bits == 3) {
                        run_length = get_bits(&gb, 8) + 29;
                        bits = get_bits(&gb, 2);

                        if (non_mod == 1 && bits == 1)
                            pixels_read += run_length;
                        else {
                            if (map_table != NULL)
                                bits = map_table[bits];
                            while (run_length-- > 0 && pixels_read < dbuf_len) {
                                *destbuf++ = bits;
                                pixels_read++;
                            }
                        }
                    } else if (bits == 1) {
                        pixels_read += 2;
                        if (map_table != NULL)
                            bits = map_table[0];
                        else
                            bits = 0;
                        if (pixels_read <= dbuf_len) {
                            *destbuf++ = bits;
                            *destbuf++ = bits;
                        }
                    } else {
                        (*srcbuf) += (get_bits_count(&gb) + 7) >> 3;
                        return pixels_read;
                    }
                } else {
                    if (map_table != NULL)
                        bits = map_table[0];
                    else
                        bits = 0;
                    *destbuf++ = bits;
                    pixels_read++;
                }
            }
        }
    }

    if (get_bits(&gb, 6) != 0)
        av_log(0, AV_LOG_ERROR, "DVBSub error: line overflow\n");

    (*srcbuf) += (get_bits_count(&gb) + 7) >> 3;

    return pixels_read;
}

static int dvbsub_read_4bit_string(uint8_t *destbuf, int dbuf_len,
                                   uint8_t **srcbuf, int buf_size,
                                   int non_mod, uint8_t *map_table)
{
    GetBitContext gb;

    int bits;