PeerStreamer

/*

 * DVD subtitle decoding for ffmpeg

 * Copyright (c) 2005 Fabrice Bellard.

 *

 * 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"

//#define DEBUG

typedef struct DVDSubContext {

} DVDSubContext;

static int dvdsub_init_decoder(AVCodecContext *avctx)

{

    return 0;

}

uint16_t getbe16(const uint8_t *p)

{

    return (p[0] << 8) | p[1];

}

int get_nibble(const uint8_t *buf, int nibble_offset)

{

    return (buf[nibble_offset >> 1] >> ((1 - (nibble_offset & 1)) << 2)) & 0xf;

}

static int decode_rle(uint8_t *bitmap, int linesize, int w, int h,

                      const uint8_t *buf, int nibble_offset, int buf_size)

{

    unsigned int v;

    int x, y, len, color, nibble_end;

    uint8_t *d;

    nibble_end = buf_size * 2;

    x = 0;

    y = 0;

    d = bitmap;

    for(;;) {

        if (nibble_offset >= nibble_end)

            return -1;

        v = get_nibble(buf, nibble_offset++);

        if (v < 0x4) {

            v = (v << 4) | get_nibble(buf, nibble_offset++);

            if (v < 0x10) {

                v = (v << 4) | get_nibble(buf, nibble_offset++);

                if (v < 0x040) {

                    v = (v << 4) | get_nibble(buf, nibble_offset++);

                    if (v < 4) {

                        v |= (w - x) << 2;

                    }

                }

            }

        }

        len = v >> 2;

        if (len > (w - x))

            len = (w - x);

        color = v & 0x03;

        memset(d + x, color, len);

        x += len;

        if (x >= w) {

            y++;

            if (y >= h)

                break;

            d += linesize;

            x = 0;

            /* byte align */

            nibble_offset += (nibble_offset & 1);

        }

    }

    return 0;

}

static void guess_palette(uint32_t *rgba_palette,

                          uint8_t *palette,

                          uint8_t *alpha,

                          uint32_t subtitle_color)

{

    uint8_t color_used[16];

    int nb_opaque_colors, i, level, j, r, g, b;

    for(i = 0; i < 4; i++)

        rgba_palette[i] = 0;

    memset(color_used, 0, 16);

    nb_opaque_colors = 0;

    for(i = 0; i < 4; i++) {

        if (alpha[i] != 0 && !color_used[palette[i]]) {

            color_used[palette[i]] = 1;

            nb_opaque_colors++;

        }

    }

    if (nb_opaque_colors == 0)

        return;

    j = nb_opaque_colors;

    memset(color_used, 0, 16);

    for(i = 0; i < 4; i++) {

        if (alpha[i] != 0) {

            if (!color_used[palette[i]])  {

                level = (0xff * j) / nb_opaque_colors;

                r = (((subtitle_color >> 16) & 0xff) * level) >> 8;

                g = (((subtitle_color >> 8) & 0xff) * level) >> 8;

                b = (((subtitle_color >> 0) & 0xff) * level) >> 8;

                rgba_palette[i] = b | (g << 8) | (r << 16) | ((alpha[i] * 17) << 24);

                color_used[palette[i]] = (i + 1);

                j--;

            } else {

                rgba_palette[i] = (rgba_palette[color_used[palette[i]] - 1] & 0x00ffffff) |

                                    ((alpha[i] * 17) << 24);

            }

        }

    }

}

static int decode_dvd_subtitles(AVSubtitle *sub_header,

                                const uint8_t *buf, int buf_size)

{

    int cmd_pos, pos, cmd, x1, y1, x2, y2, offset1, offset2, next_cmd_pos;

    uint8_t palette[4], alpha[4];

    int date;

    int i;

    int is_menu = 0;

    if (buf_size < 4)

        return -1;

    sub_header->rects = NULL;

    sub_header->num_rects = 0;

    sub_header->start_display_time = 0;

    sub_header->end_display_time = 0;

    cmd_pos = getbe16(buf + 2);

    while ((cmd_pos + 4) < buf_size) {

        date = getbe16(buf + cmd_pos);

        next_cmd_pos = getbe16(buf + cmd_pos + 2);

#ifdef DEBUG

        av_log(NULL, AV_LOG_INFO, "cmd_pos=0x%04x next=0x%04x date=%d\n",

               cmd_pos, next_cmd_pos, date);

#endif

        pos = cmd_pos + 4;

        offset1 = -1;

        offset2 = -1;

        x1 = y1 = x2 = y2 = 0;

        while (pos < buf_size) {

            cmd = buf[pos++];

#ifdef DEBUG

            av_log(NULL, AV_LOG_INFO, "cmd=%02x\n", cmd);

#endif

            switch(cmd) {

            case 0x00:

                /* menu subpicture */

                is_menu = 1;

                break;

            case 0x01:

                /* set start date */

                sub_header->start_display_time = (date << 10) / 90;

                break;

            case 0x02:

                /* set end date */

                sub_header->end_display_time = (date << 10) / 90;

                break;

            case 0x03:

                /* set palette */

                if ((buf_size - pos) < 2)

                    goto fail;

                palette[3] = buf[pos] >> 4;

                palette[2] = buf[pos] & 0x0f;

                palette[1] = buf[pos + 1] >> 4;

                palette[0] = buf[pos + 1] & 0x0f;

                pos += 2;

                break;

            case 0x04:

                /* set alpha */

                if ((buf_size - pos) < 2)

                    goto fail;

                alpha[3] = buf[pos] >> 4;

                alpha[2] = buf[pos] & 0x0f;

                alpha[1] = buf[pos + 1] >> 4;

                alpha[0] = buf[pos + 1] & 0x0f;

                pos += 2;

#ifdef DEBUG

            av_log(NULL, AV_LOG_INFO, "alpha=%x%x%x%x\n", alpha[0],alpha[1],alpha[2],alpha[3]);

#endif

                break;

            case 0x05:

                if ((buf_size - pos) < 6)

                    goto fail;

                x1 = (buf[pos] << 4) | (buf[pos + 1] >> 4);

                x2 = ((buf[pos + 1] & 0x0f) << 8) | buf[pos + 2];

                y1 = (buf[pos + 3] << 4) | (buf[pos + 4] >> 4);

                y2 = ((buf[pos + 4] & 0x0f) << 8) | buf[pos + 5];

#ifdef DEBUG

                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 = getbe16(buf + pos);

                offset2 = getbe16(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 0xff:

            default:

                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].rgba_palette = av_malloc(4 * 4);

                decode_rle(bitmap, w * 2, w, h / 2,

                           buf, offset1 * 2, buf_size);

                decode_rle(bitmap + w, w * 2, w, h / 2,

                           buf, offset2 * 2, buf_size);

                guess_palette(sub_header->rects[0].rgba_palette,

                              palette, 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].nb_colors = 4;

                sub_header->rects[0].linesize = w;

                sub_header->rects[0].bitmap = bitmap;

            }

        }

        if (next_cmd_pos == cmd_pos)

            break;

        cmd_pos = next_cmd_pos;

    }

    if (sub_header->num_rects > 0)

        return is_menu;

 fail:

    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,

    sizeof(DVDSubContext),

    dvdsub_init_decoder,

    NULL,

    dvdsub_close_decoder,

    dvdsub_decode,

};

/* parser definition */

typedef struct DVDSubParseContext {

    uint8_t *packet;

    int packet_len;

    int packet_index;

} DVDSubParseContext;

static int dvdsub_parse_init(AVCodecParserContext *s)

{

    return 0;

}

static int dvdsub_parse(AVCodecParserContext *s,

                        AVCodecContext *avctx,

                        uint8_t **poutbuf, int *poutbuf_size,

                        const uint8_t *buf, int buf_size)

{

    DVDSubParseContext *pc = s->priv_data;

    if (pc->packet_index == 0) {

        if (buf_size < 2)

            return 0;

        pc->packet_len = (buf[0] << 8) | buf[1];

        av_freep(&pc->packet);

        pc->packet = av_malloc(pc->packet_len);

    }

    if (pc->packet) {

        if (pc->packet_index + buf_size <= pc->packet_len) {

            memcpy(pc->packet + pc->packet_index, buf, buf_size);

            pc->packet_index += buf_size;

            if (pc->packet_index >= pc->packet_len) {

                *poutbuf = pc->packet;

                *poutbuf_size = pc->packet_len;

                pc->packet_index = 0;

                return buf_size;

            }

        } else {

            /* erroneous size */

            pc->packet_index = 0;

        }

    }

    *poutbuf = NULL;

    *poutbuf_size = 0;

    return buf_size;

}

static void dvdsub_parse_close(AVCodecParserContext *s)

{

    DVDSubParseContext *pc = s->priv_data;

    av_freep(&pc->packet);

}

AVCodecParser dvdsub_parser = {

    { CODEC_ID_DVD_SUBTITLE },

    sizeof(DVDSubParseContext),

    dvdsub_parse_init,

    dvdsub_parse,

    dvdsub_parse_close,

};