dvdsubdec.c

来自「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」· C语言 代码 · 共 520 行 · 第 1/2 页

                av_log(NULL, AV_LOG_INFO, "x1=%d x2=%d y1=%d y2=%d\n",
                       x1, x2, y1, y2);
#endif
                pos += 6;
                break;
            case 0x06:
                if ((buf_size - pos) < 4)
                    goto fail;
                offset1 = AV_RB16(buf + pos);
                offset2 = AV_RB16(buf + pos + 2);
#ifdef DEBUG
                av_log(NULL, AV_LOG_INFO, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
#endif
                pos += 4;
                break;
            case 0x86:
                if ((buf_size - pos) < 8)
                    goto fail;
                offset1 = AV_RB32(buf + pos);
                offset2 = AV_RB32(buf + pos + 4);
#ifdef DEBUG
                av_log(NULL, AV_LOG_INFO, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
#endif
                pos += 8;
                break;

            case 0x83:
                /* HD set palette */
                if ((buf_size - pos) < 768)
                    goto fail;
                yuv_palette = buf + pos;
                pos += 768;
                break;
            case 0x84:
                /* HD set contrast (alpha) */
                if ((buf_size - pos) < 256)
                    goto fail;
                for (i = 0; i < 256; i++)
                    alpha[i] = 0xFF - buf[pos+i];
                pos += 256;
                break;

            case 0xff:
                goto the_end;
            default:
#ifdef DEBUG
                av_log(NULL, AV_LOG_INFO, "unrecognised subpicture command 0x%x\n", cmd);
#endif
                goto the_end;
            }
        }
    the_end:
        if (offset1 >= 0) {
            int w, h;
            uint8_t *bitmap;

            /* decode the bitmap */
            w = x2 - x1 + 1;
            if (w < 0)
                w = 0;
            h = y2 - y1;
            if (h < 0)
                h = 0;
            if (w > 0 && h > 0) {
                if (sub_header->rects != NULL) {
                    for (i = 0; i < sub_header->num_rects; i++) {
                        av_free(sub_header->rects[i].bitmap);
                        av_free(sub_header->rects[i].rgba_palette);
                    }
                    av_freep(&sub_header->rects);
                    sub_header->num_rects = 0;
                }

                bitmap = av_malloc(w * h);
                sub_header->rects = av_mallocz(sizeof(AVSubtitleRect));
                sub_header->num_rects = 1;
                sub_header->rects[0].bitmap = bitmap;
                decode_rle(bitmap, w * 2, w, (h + 1) / 2,
                           buf, offset1, buf_size, is_8bit);
                decode_rle(bitmap + w, w * 2, w, h / 2,
                           buf, offset2, buf_size, is_8bit);
                if (is_8bit) {
                    if (yuv_palette == 0)
                        goto fail;
                    sub_header->rects[0].rgba_palette = av_malloc(256 * 4);
                    sub_header->rects[0].nb_colors = 256;
                    yuv_a_to_rgba(yuv_palette, alpha, sub_header->rects[0].rgba_palette, 256);
                } else {
                    sub_header->rects[0].rgba_palette = av_malloc(4 * 4);
                    sub_header->rects[0].nb_colors = 4;
                    guess_palette(sub_header->rects[0].rgba_palette,
                                  colormap, alpha, 0xffff00);
                }
                sub_header->rects[0].x = x1;
                sub_header->rects[0].y = y1;
                sub_header->rects[0].w = w;
                sub_header->rects[0].h = h;
                sub_header->rects[0].linesize = w;
            }
        }
        if (next_cmd_pos == cmd_pos)
            break;
        cmd_pos = next_cmd_pos;
    }
    if (sub_header->num_rects > 0)
        return is_menu;
 fail:
    if (sub_header->rects != NULL) {
        for (i = 0; i < sub_header->num_rects; i++) {
            av_free(sub_header->rects[i].bitmap);
            av_free(sub_header->rects[i].rgba_palette);
        }
        av_freep(&sub_header->rects);
        sub_header->num_rects = 0;
    }
    return -1;
}

static int is_transp(const uint8_t *buf, int pitch, int n,
                     const uint8_t *transp_color)
{
    int i;
    for(i = 0; i < n; i++) {
        if (!transp_color[*buf])
            return 0;
        buf += pitch;
    }
    return 1;
}

/* return 0 if empty rectangle, 1 if non empty */
static int find_smallest_bounding_rectangle(AVSubtitle *s)
{
    uint8_t transp_color[256];
    int y1, y2, x1, x2, y, w, h, i;
    uint8_t *bitmap;

    if (s->num_rects == 0 || s->rects == NULL || s->rects[0].w <= 0 || s->rects[0].h <= 0)
        return 0;

    memset(transp_color, 0, 256);
    for(i = 0; i < s->rects[0].nb_colors; i++) {
        if ((s->rects[0].rgba_palette[i] >> 24) == 0)
            transp_color[i] = 1;
    }
    y1 = 0;
    while (y1 < s->rects[0].h && is_transp(s->rects[0].bitmap + y1 * s->rects[0].linesize,
                                  1, s->rects[0].w, transp_color))
        y1++;
    if (y1 == s->rects[0].h) {
        av_freep(&s->rects[0].bitmap);
        s->rects[0].w = s->rects[0].h = 0;
        return 0;
    }

    y2 = s->rects[0].h - 1;
    while (y2 > 0 && is_transp(s->rects[0].bitmap + y2 * s->rects[0].linesize, 1,
                               s->rects[0].w, transp_color))
        y2--;
    x1 = 0;
    while (x1 < (s->rects[0].w - 1) && is_transp(s->rects[0].bitmap + x1, s->rects[0].linesize,
                                        s->rects[0].h, transp_color))
        x1++;
    x2 = s->rects[0].w - 1;
    while (x2 > 0 && is_transp(s->rects[0].bitmap + x2, s->rects[0].linesize, s->rects[0].h,
                                  transp_color))
        x2--;
    w = x2 - x1 + 1;
    h = y2 - y1 + 1;
    bitmap = av_malloc(w * h);
    if (!bitmap)
        return 1;
    for(y = 0; y < h; y++) {
        memcpy(bitmap + w * y, s->rects[0].bitmap + x1 + (y1 + y) * s->rects[0].linesize, w);
    }
    av_freep(&s->rects[0].bitmap);
    s->rects[0].bitmap = bitmap;
    s->rects[0].linesize = w;
    s->rects[0].w = w;
    s->rects[0].h = h;
    s->rects[0].x += x1;
    s->rects[0].y += y1;
    return 1;
}

static int dvdsub_close_decoder(AVCodecContext *avctx)
{
    return 0;
}

#ifdef DEBUG
#undef fprintf
static void ppm_save(const char *filename, uint8_t *bitmap, int w, int h,
                     uint32_t *rgba_palette)
{
    int x, y, v;
    FILE *f;

    f = fopen(filename, "w");
    if (!f) {
        perror(filename);
        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);
}
#endif

static int dvdsub_decode(AVCodecContext *avctx,
                         void *data, int *data_size,
                         uint8_t *buf, int buf_size)
{
    AVSubtitle *sub = (void *)data;
    int is_menu;

    is_menu = decode_dvd_subtitles(sub, buf, buf_size);

    if (is_menu < 0) {
    no_subtitle:
        *data_size = 0;

        return buf_size;
    }
    if (!is_menu && find_smallest_bounding_rectangle(sub) == 0)
        goto no_subtitle;

#if defined(DEBUG)
    av_log(NULL, AV_LOG_INFO, "start=%d ms end =%d ms\n",
           sub->start_display_time,
           sub->end_display_time);
    ppm_save("/tmp/a.ppm", sub->rects[0].bitmap,
             sub->rects[0].w, sub->rects[0].h, sub->rects[0].rgba_palette);
#endif

    *data_size = 1;
    return buf_size;
}

AVCodec dvdsub_decoder = {
    "dvdsub",
    CODEC_TYPE_SUBTITLE,
    CODEC_ID_DVD_SUBTITLE,
    0,
    dvdsub_init_decoder,
    NULL,
    dvdsub_close_decoder,
    dvdsub_decode,
};