dvbsubdec.c

ffmpeg源码分析

    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, 4);

        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 == 0) {
                run_length = get_bits(&gb, 3);

                if (run_length == 0) {
                    (*srcbuf) += (get_bits_count(&gb) + 7) >> 3;
                    return pixels_read;
                }

                run_length += 2;

                if (map_table != NULL)
                    bits = map_table[0];
                else
                    bits = 0;

                while (run_length-- > 0 && pixels_read < dbuf_len) {
                    *destbuf++ = bits;
                    pixels_read++;
                }
            } else {
                bits = get_bits(&gb, 1);
                if (bits == 0) {
                    run_length = get_bits(&gb, 2) + 4;
                    bits = get_bits(&gb, 4);

                    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, 2);
                    if (bits == 2) {
                        run_length = get_bits(&gb, 4) + 9;
                        bits = get_bits(&gb, 4);

                        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) + 25;
                        bits = get_bits(&gb, 4);

                        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 {
                        if (map_table != NULL)
                            bits = map_table[0];
                        else
                            bits = 0;
                        *destbuf++ = bits;
                        pixels_read ++;
                    }
                }
            }
        }
    }

    if (get_bits(&gb, 8) != 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_8bit_string(uint8_t *destbuf, int dbuf_len,
                                    uint8_t **srcbuf, int buf_size,
                                    int non_mod, uint8_t *map_table)
{
    uint8_t *sbuf_end = (*srcbuf) + buf_size;
    int bits;
    int run_length;
    int pixels_read = 0;

    while (*srcbuf < sbuf_end && pixels_read < dbuf_len) {
        bits = *(*srcbuf)++;

        if (bits != 0) {
            if (non_mod != 1 || bits != 1) {
                if (map_table != NULL)
                    *destbuf++ = map_table[bits];
                else
                    *destbuf++ = bits;
            }
            pixels_read++;
        } else {
            bits = *(*srcbuf)++;
            run_length = bits & 0x7f;
            if ((bits & 0x80) == 0) {
                if (run_length == 0) {
                    return pixels_read;
                }

                if (map_table != NULL)
                    bits = map_table[0];
                else
                    bits = 0;
                while (run_length-- > 0 && pixels_read < dbuf_len) {
                    *destbuf++ = bits;
                    pixels_read++;
                }
            } else {
                bits = *(*srcbuf)++;

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

    if (*(*srcbuf)++ != 0)
        av_log(0, AV_LOG_ERROR, "DVBSub error: line overflow\n");

    return pixels_read;
}



static void dvbsub_parse_pixel_data_block(AVCodecContext *avctx, DVBSubObjectDisplay *display,
                                          uint8_t *buf, int buf_size, int top_bottom, int non_mod)
{
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;

    DVBSubRegion *region = get_region(ctx, display->region_id);
    uint8_t *buf_end = buf + buf_size;
    uint8_t *pbuf;
    int x_pos, y_pos;
    int i;

    uint8_t map2to4[] = { 0x0,  0x7,  0x8,  0xf};
    uint8_t map2to8[] = {0x00, 0x77, 0x88, 0xff};
    uint8_t map4to8[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
                         0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff};
    uint8_t *map_table;

#ifdef DEBUG
    av_log(avctx, AV_LOG_INFO, "DVB pixel block size %d, %s field:\n", buf_size,
                top_bottom ? "bottom" : "top");
#endif

#ifdef DEBUG_PACKET_CONTENTS
    for (i = 0; i < buf_size; i++)
    {
        if (i % 16 == 0)
            av_log(avctx, AV_LOG_INFO, "0x%08p: ", buf+i);

        av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
        if (i % 16 == 15)
            av_log(avctx, AV_LOG_INFO, "\n");
    }

    if (i % 16 != 0)
        av_log(avctx, AV_LOG_INFO, "\n");

#endif

    if (region == 0)
        return;

    pbuf = region->pbuf;

    x_pos = display->x_pos;
    y_pos = display->y_pos;

    if ((y_pos & 1) != top_bottom)
        y_pos++;

    while (buf < buf_end) {
        if (x_pos > region->width || y_pos > region->height) {
            av_log(avctx, AV_LOG_ERROR, "Invalid object location!\n");
            return;
        }

        switch (*buf++) {
        case 0x10:
            if (region->depth == 8)
                map_table = map2to8;
            else if (region->depth == 4)
                map_table = map2to4;
            else
                map_table = NULL;

            x_pos += dvbsub_read_2bit_string(pbuf + (y_pos * region->width) + x_pos,
                                                region->width - x_pos, &buf, buf_size,
                                                non_mod, map_table);
            break;
        case 0x11:
            if (region->depth < 4) {
                av_log(avctx, AV_LOG_ERROR, "4-bit pixel string in %d-bit region!\n", region->depth);
                return;
            }

            if (region->depth == 8)
                map_table = map4to8;
            else
                map_table = NULL;

            x_pos += dvbsub_read_4bit_string(pbuf + (y_pos * region->width) + x_pos,
                                                region->width - x_pos, &buf, buf_size,
                                                non_mod, map_table);
            break;
        case 0x12:
            if (region->depth < 8) {
                av_log(avctx, AV_LOG_ERROR, "8-bit pixel string in %d-bit region!\n", region->depth);
                return;
            }

            x_pos += dvbsub_read_8bit_string(pbuf + (y_pos * region->width) + x_pos,
                                                region->width - x_pos, &buf, buf_size,
                                                non_mod, NULL);
            break;

        case 0x20:
            map2to4[0] = (*buf) >> 4;
            map2to4[1] = (*buf++) & 0xf;
            map2to4[2] = (*buf) >> 4;
            map2to4[3] = (*buf++) & 0xf;
            break;
        case 0x21:
            for (i = 0; i < 4; i++)
                map2to8[i] = *buf++;
            break;
        case 0x22:
            for (i = 0; i < 16; i++)
                map4to8[i] = *buf++;
            break;

        case 0xf0:
            x_pos = display->x_pos;
            y_pos += 2;
            break;
        default:
            av_log(avctx, AV_LOG_INFO, "Unknown/unsupported pixel block 0x%x\n", *(buf-1));
        }
    }

}

static void dvbsub_parse_object_segment(AVCodecContext *avctx,
                                        uint8_t *buf, int buf_size)
{
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;

    uint8_t *buf_end = buf + buf_size;
    uint8_t *block;
    int object_id;
    DVBSubObject *object;
    DVBSubObjectDisplay *display;
    int top_field_len, bottom_field_len;

    int coding_method, non_modifying_colour;

    object_id = BE_16(buf);
    buf += 2;

    object = get_object(ctx, object_id);

    if (!object)
        return;

    coding_method = ((*buf) >> 2) & 3;
    non_modifying_colour = ((*buf++) >> 1) & 1;

    if (coding_method == 0) {
        top_field_len = BE_16(buf);
        buf += 2;
        bottom_field_len = BE_16(buf);
        buf += 2;

        if (buf + top_field_len + bottom_field_len > buf_end) {
            av_log(avctx, AV_LOG_ERROR, "Field data size too large\n");
            return;
        }

        for (display = object->display_list; display != 0; display = display->object_list_next) {
            block = buf;

            dvbsub_parse_pixel_data_block(avctx, display, block, top_field_len, 0,
                                            non_modifying_colour);

            if (bottom_field_len > 0)
                block = buf + top_field_len;
            else
                bottom_field_len = top_field_len;

            dvbsub_parse_pixel_data_block(avctx, display, block, bottom_field_len, 1,
                                            non_modifying_colour);
        }

/*  } else if (coding_method == 1) {*/

    } else {
        av_log(avctx, AV_LOG_ERROR, "Unknown object coding %d\n", coding_method);
    }

}

#define SCALEBITS 10
#define ONE_HALF  (1 << (SCALEBITS - 1))
#define FIX(x)    ((int) ((x) * (1<<SCALEBITS) + 0.5))

#define YUV_TO_RGB1_CCIR(cb1, cr1)\
{\
    cb = (cb1) - 128;\
    cr = (cr1) - 128;\
    r_add = FIX(1.40200*255.0/224.0) * cr + ONE_HALF;\
    g_add = - FIX(0.34414*255.0/224.0) * cb - FIX(0.71414*255.0/224.0) * cr + \
            ONE_HALF;\
    b_add = FIX(1.77200*255.0/224.0) * cb + ONE_HALF;\
}

#define YUV_TO_RGB2_CCIR(r, g, b, y1)\
{\
    y = ((y1) - 16) * FIX(255.0/219.0);\
    r = cm[(y + r_add) >> SCALEBITS];\
    g = cm[(y + g_add) >> SCALEBITS];\
    b = cm[(y + b_add) >> SCALEBITS];\
}


static void dvbsub_parse_clut_segment(AVCodecContext *avctx,
                                        uint8_t *buf, int buf_size)
{
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;

    uint8_t *buf_end = buf + buf_size;
    int clut_id;
    DVBSubCLUT *clut;
    int entry_id, depth , full_range;
    int y, cr, cb, alpha;
    int r, g, b, r_add, g_add, b_add;

#ifdef DEBUG_PACKET_CONTENTS
    int i;

    av_log(avctx, AV_LOG_INFO, "DVB clut packet:\n");

    for (i=0; i < buf_size; i++)
    {
        av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
        if (i % 16 == 15)
            av_log(avctx, AV_LOG_INFO, "\n");
    }

    if (i % 16 != 0)
        av_log(avctx, AV_LOG_INFO, "\n");

#endif

    clut_id = *buf++;
    buf += 1;

    clut = get_clut(ctx, clut_id);

    if (clut == NULL) {
        clut = av_malloc(sizeof(DVBSubCLUT));

        memcpy(clut, &default_clut, sizeof(DVBSubCLUT));

        clut->id = clut_id;

        clut->next = ctx->clut_list;
        ctx->clut_list = clut;
    }

    while (buf + 4 < buf_end)
    {
        entry_id = *buf++;

        depth = (*buf) & 0xe0;

        if (depth == 0) {
            av_log(avctx, AV_LOG_ERROR, "Invalid clut depth 0x%x!\n", *buf);
            return;
        }

        full_range = (*buf++) & 1;

        if (full_range) {
            y = *buf++;
            cr = *buf++;
            cb = *buf++;
            alpha = *buf++;
        } else {
            y = buf[0] & 0xfc;
            cr = (((buf[0] & 3) << 2) | ((buf[1] >> 6) & 3)) << 4;
            cb = (buf[1] << 2) & 0xf0;
            alpha = (buf[1] << 6) & 0xc0;

            buf += 2;
        }

        if (y == 0)
            alpha = 0xff;

        YUV_TO_RGB1_CCIR(cb, cr);
        YUV_TO_RGB2_CCIR(r, g, b, y);

#ifdef DEBUG
        av_log(avctx, AV_LOG_INFO, "clut %d := (%d,%d,%d,%d)\n", entry_id, r, g, b, alpha);
#endif

        if (depth & 0x80)
            clut->clut4[entry_id] = RGBA(r,g,b,255 - alpha);
        if (depth & 0x40)
            clut->clut16[entry_id] = RGBA(r,g,b,255 - alpha);
        if (depth & 0x20)
            clut->clut256[entry_id] = RGBA(r,g,b,255 - alpha);
    }
}


static void dvbsub_parse_region_segment(AVCodecContext *avctx,
                                        uint8_t *buf, int buf_size)
{
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;

    uint8_t *buf_end = buf + buf_size;
    int region_id, object_id;
    DVBSubRegion *region;
    DVBSubObject *object;
    DVBSubObjectDisplay *display;
    int fill;

    if (buf_size < 10)
        return;

    region_id = *buf++;

    region = get_region(ctx, region_id);

    if (region == NULL)
    {
        region = av_mallocz(sizeof(DVBSubRegion));

        region->id = region_id;

        region->next = ctx->region_list;
        ctx->region_list = region;
    }

    fill = ((*buf++) >> 3) & 1;

    region->width = BE_16(buf);
    buf += 2;
    region->height = BE_16(buf);
    buf += 2;

    if (region->width * region->height != region->buf_size) {
        if (region->pbuf != 0)
            av_free(region->pbuf);

        region->buf_size = region->width * region->height;

        region->pbuf = av_malloc(region->buf_size);

        fill = 1;
    }

    region->depth = 1 << (((*buf++) >> 2) & 7);
    region->clut = *buf++;

    if (region->depth == 8)
        region->bgcolour = *buf++;
    else {
        buf += 1;

        if (region->depth == 4)
            region->bgcolour = (((*buf++) >> 4) & 15);
        else
            region->bgcolour = (((*buf++) >> 2) & 3);
    }

#ifdef DEBUG
    av_log(avctx, AV_LOG_INFO, "Region %d, (%dx%d)\n", region_id, region->width, region->height);
#endif

    if (fill) {
        memset(region->pbuf, region->bgcolour, region->buf_size);
#ifdef DEBUG
        av_log(avctx, AV_LOG_INFO, "Fill region (%d)\n", region->bgcolour);
#endif
    }

    delete_region_display_list(ctx, region);

    while (buf + 5 < buf_end) {
        object_id = BE_16(buf);
        buf += 2;