dvbsubdec.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

        } 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 = AV_RB16(buf);
    buf += 2;
    region->height = AV_RB16(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 = AV_RB16(buf);
        buf += 2;

        object = get_object(ctx, object_id);

        if (object == NULL) {
            object = av_mallocz(sizeof(DVBSubObject));

            object->id = object_id;
            object->next = ctx->object_list;
            ctx->object_list = object;
        }

        object->type = (*buf) >> 6;

        display = av_mallocz(sizeof(DVBSubObjectDisplay));

        display->object_id = object_id;
        display->region_id = region_id;

        display->x_pos = AV_RB16(buf) & 0xfff;
        buf += 2;
        display->y_pos = AV_RB16(buf) & 0xfff;
        buf += 2;

        if ((object->type == 1 || object->type == 2) && buf+1 < buf_end) {
            display->fgcolour = *buf++;
            display->bgcolour = *buf++;
        }

        display->region_list_next = region->display_list;
        region->display_list = display;

        display->object_list_next = object->display_list;
        object->display_list = display;
    }
}

static void dvbsub_parse_page_segment(AVCodecContext *avctx,
                                        uint8_t *buf, int buf_size)
{
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;
    DVBSubRegionDisplay *display;
    DVBSubRegionDisplay *tmp_display_list, **tmp_ptr;

    uint8_t *buf_end = buf + buf_size;
    int region_id;
    int page_state;

    if (buf_size < 1)
        return;

    ctx->time_out = *buf++;
    page_state = ((*buf++) >> 2) & 3;

#ifdef DEBUG
    av_log(avctx, AV_LOG_INFO, "Page time out %ds, state %d\n", ctx->time_out, page_state);
#endif

    if (page_state == 2)
    {
        delete_state(ctx);
    }

    tmp_display_list = ctx->display_list;
    ctx->display_list = NULL;
    ctx->display_list_size = 0;

    while (buf + 5 < buf_end) {
        region_id = *buf++;
        buf += 1;

        display = tmp_display_list;
        tmp_ptr = &tmp_display_list;

        while (display != NULL && display->region_id != region_id) {
            tmp_ptr = &display->next;
            display = display->next;
        }

        if (display == NULL)
            display = av_mallocz(sizeof(DVBSubRegionDisplay));

        display->region_id = region_id;

        display->x_pos = AV_RB16(buf);
        buf += 2;
        display->y_pos = AV_RB16(buf);
        buf += 2;

        *tmp_ptr = display->next;

        display->next = ctx->display_list;
        ctx->display_list = display;
        ctx->display_list_size++;

#ifdef DEBUG
        av_log(avctx, AV_LOG_INFO, "Region %d, (%d,%d)\n", region_id, display->x_pos, display->y_pos);
#endif
    }

    while (tmp_display_list != 0) {
        display = tmp_display_list;

        tmp_display_list = display->next;

        av_free(display);
    }

}


#ifdef DEBUG_SAVE_IMAGES
static void save_display_set(DVBSubContext *ctx)
{
    DVBSubRegion *region;
    DVBSubRegionDisplay *display;
    DVBSubCLUT *clut;
    uint32_t *clut_table;
    int x_pos, y_pos, width, height;
    int x, y, y_off, x_off;
    uint32_t *pbuf;
    char filename[32];
    static int fileno_index = 0;

    x_pos = -1;
    y_pos = -1;
    width = 0;
    height = 0;

    for (display = ctx->display_list; display != NULL; display = display->next) {
        region = get_region(ctx, display->region_id);

        if (x_pos == -1) {
            x_pos = display->x_pos;
            y_pos = display->y_pos;
            width = region->width;
            height = region->height;
        } else {
            if (display->x_pos < x_pos) {
                width += (x_pos - display->x_pos);
                x_pos = display->x_pos;
            }

            if (display->y_pos < y_pos) {
                height += (y_pos - display->y_pos);
                y_pos = display->y_pos;
            }

            if (display->x_pos + region->width > x_pos + width) {
                width = display->x_pos + region->width - x_pos;
            }

            if (display->y_pos + region->height > y_pos + height) {
                height = display->y_pos + region->height - y_pos;
            }
        }
    }

    if (x_pos >= 0) {

        pbuf = av_malloc(width * height * 4);

        for (display = ctx->display_list; display != NULL; display = display->next) {
            region = get_region(ctx, display->region_id);

            x_off = display->x_pos - x_pos;
            y_off = display->y_pos - y_pos;

            clut = get_clut(ctx, region->clut);

            if (clut == 0)
                clut = &default_clut;

            switch (region->depth) {
            case 2:
                clut_table = clut->clut4;
                break;
            case 8:
                clut_table = clut->clut256;
                break;
            case 4:
            default:
                clut_table = clut->clut16;
                break;
            }

            for (y = 0; y < region->height; y++) {
                for (x = 0; x < region->width; x++) {
                    pbuf[((y + y_off) * width) + x_off + x] =
                        clut_table[region->pbuf[y * region->width + x]];
                }
            }

        }

        snprintf(filename, 32, "dvbs.%d", fileno_index);

        png_save2(filename, pbuf, width, height);

        av_free(pbuf);
    }

    fileno_index++;
}
#endif

static int dvbsub_display_end_segment(AVCodecContext *avctx, uint8_t *buf,
                                        int buf_size, AVSubtitle *sub)
{
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;

    DVBSubRegion *region;
    DVBSubRegionDisplay *display;
    AVSubtitleRect *rect;
    DVBSubCLUT *clut;
    uint32_t *clut_table;
    int i;

    sub->rects = NULL;
    sub->start_display_time = 0;
    sub->end_display_time = ctx->time_out * 1000;
    sub->format = 0;

    sub->num_rects = ctx->display_list_size;

    if (sub->num_rects > 0)
        sub->rects = av_mallocz(sizeof(AVSubtitleRect) * sub->num_rects);

    i = 0;

    for (display = ctx->display_list; display != NULL; display = display->next) {
        region = get_region(ctx, display->region_id);
        rect = &sub->rects[i];

        if (region == NULL)
            continue;

        rect->x = display->x_pos;
        rect->y = display->y_pos;
        rect->w = region->width;
        rect->h = region->height;
        rect->nb_colors = 16;
        rect->linesize = region->width;

        clut = get_clut(ctx, region->clut);

        if (clut == NULL)
            clut = &default_clut;

        switch (region->depth) {
        case 2:
            clut_table = clut->clut4;
            break;
        case 8:
            clut_table = clut->clut256;
            break;
        case 4:
        default:
            clut_table = clut->clut16;
            break;
        }

        rect->rgba_palette = av_malloc((1 << region->depth) * sizeof(uint32_t));
        memcpy(rect->rgba_palette, clut_table, (1 << region->depth) * sizeof(uint32_t));

        rect->bitmap = av_malloc(region->buf_size);
        memcpy(rect->bitmap, region->pbuf, region->buf_size);

        i++;
    }

    sub->num_rects = i;

#ifdef DEBUG_SAVE_IMAGES
    save_display_set(ctx);
#endif

    return 1;
}

static int dvbsub_decode(AVCodecContext *avctx,
                         void *data, int *data_size,
                         uint8_t *buf, int buf_size)
{
    DVBSubContext *ctx = (DVBSubContext*) avctx->priv_data;
    AVSubtitle *sub = (AVSubtitle*) data;
    uint8_t *p, *p_end;
    int segment_type;
    int page_id;
    int segment_length;

#ifdef DEBUG_PACKET_CONTENTS
    int i;

    av_log(avctx, AV_LOG_INFO, "DVB sub 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

    if (buf_size <= 2)
        return -1;

    p = buf;
    p_end = buf + buf_size;

    while (p < p_end && *p == 0x0f)
    {
        p += 1;
        segment_type = *p++;
        page_id = AV_RB16(p);
        p += 2;
        segment_length = AV_RB16(p);
        p += 2;

        if (page_id == ctx->composition_id || page_id == ctx->ancillary_id) {
            switch (segment_type) {
            case DVBSUB_PAGE_SEGMENT:
                dvbsub_parse_page_segment(avctx, p, segment_length);
                break;
            case DVBSUB_REGION_SEGMENT:
                dvbsub_parse_region_segment(avctx, p, segment_length);
                break;
            case DVBSUB_CLUT_SEGMENT:
                dvbsub_parse_clut_segment(avctx, p, segment_length);
                break;
            case DVBSUB_OBJECT_SEGMENT:
                dvbsub_parse_object_segment(avctx, p, segment_length);
                break;
            case DVBSUB_DISPLAY_SEGMENT:
                *data_size = dvbsub_display_end_segment(avctx, p, segment_length, sub);
                break;
            default:
#ifdef DEBUG
                av_log(avctx, AV_LOG_INFO, "Subtitling segment type 0x%x, page id %d, length %d\n",
                        segment_type, page_id, segment_length);
#endif
                break;
            }
        }

        p += segment_length;
    }

    if (p != p_end)
    {
#ifdef DEBUG
        av_log(avctx, AV_LOG_INFO, "Junk at end of packet\n");
#endif
        return -1;
    }

    return buf_size;
}


AVCodec dvbsub_decoder = {
    "dvbsub",
    CODEC_TYPE_SUBTITLE,
    CODEC_ID_DVB_SUBTITLE,
    sizeof(DVBSubContext),
    dvbsub_init_decoder,
    NULL,
    dvbsub_close_decoder,
    dvbsub_decode,
};