FFmpeg/libavcodec/dvbsub.c

/*
 * DVB subtitle encoding 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include "avcodec.h"

typedef struct DVBSubtitleContext {
    int hide_state;
    int object_version;
} DVBSubtitleContext;

#define PUTBITS2(val)\
{\
    bitbuf |= (val) << bitcnt;\
    bitcnt -= 2;\
    if (bitcnt < 0) {\
        bitcnt = 6;\
        *q++ = bitbuf;\
        bitbuf = 0;\
    }\
}

static void dvb_encode_rle2(uint8_t **pq,
                            const uint8_t *bitmap, int linesize,
                            int w, int h)
{
    uint8_t *q;
    unsigned int bitbuf;
    int bitcnt;
    int x, y, len, x1, v, color;

    q = *pq;
    
    for(y = 0; y < h; y++) {
        *q++ = 0x10;
        bitbuf = 0;
        bitcnt = 6;
        
        x = 0;
        while (x < w) {
            x1 = x;
            color = bitmap[x1++];
            while (x1 < w && bitmap[x1] == color)
                x1++;
            len = x1 - x;
            if (color == 0 && len == 2) {
                PUTBITS2(0);
                PUTBITS2(0);
                PUTBITS2(1);
            } else if (len >= 3 && len <= 10) {
                v = len - 3;
                PUTBITS2(0);
                PUTBITS2((v >> 2) | 2);
                PUTBITS2(v & 3);
                PUTBITS2(color);
            } else if (len >= 12 && len <= 27) {
                v = len - 12;
                PUTBITS2(0);
                PUTBITS2(0);
                PUTBITS2(2);
                PUTBITS2(v >> 2);
                PUTBITS2(v & 3);
                PUTBITS2(color);
            } else if (len >= 29) {
                /* length = 29 ... 284 */
                if (len > 284)
                    len = 284;
                v = len - 29;
                PUTBITS2(0);
                PUTBITS2(0);
                PUTBITS2(3);
                PUTBITS2((v >> 6));
                PUTBITS2((v >> 4) & 3);
                PUTBITS2((v >> 2) & 3);
                PUTBITS2(v & 3);
                PUTBITS2(color);
            } else {
                PUTBITS2(color);
                if (color == 0) {
                    PUTBITS2(1);
                }
                len = 1;
            }
            x += len;
        }
        /* end of line */
        PUTBITS2(0);
        PUTBITS2(0);
        PUTBITS2(0);
        if (bitcnt != 6) {
            *q++ = bitbuf;
        }
        *q++ = 0xf0;
        bitmap += linesize;
    }
    *pq = q;
}

#define PUTBITS4(val)\
{\
    bitbuf |= (val) << bitcnt;\
    bitcnt -= 4;\
    if (bitcnt < 0) {\
        bitcnt = 4;\
        *q++ = bitbuf;\
        bitbuf = 0;\
    }\
}

/* some DVB decoders only implement 4 bits/pixel */
static void dvb_encode_rle4(uint8_t **pq,
                            const uint8_t *bitmap, int linesize,
                            int w, int h)
{
    uint8_t *q;
    unsigned int bitbuf;
    int bitcnt;
    int x, y, len, x1, v, color;

    q = *pq;
    
    for(y = 0; y < h; y++) {
        *q++ = 0x11;
        bitbuf = 0;
        bitcnt = 4;
        
        x = 0;
        while (x < w) {
            x1 = x;
            color = bitmap[x1++];
            while (x1 < w && bitmap[x1] == color)
                x1++;
            len = x1 - x;
            if (color == 0 && len == 2) {
                PUTBITS4(0);
                PUTBITS4(0xd);
            } else if (color == 0 && (len >= 3 && len <= 9)) {
                PUTBITS4(0);
                PUTBITS4(len - 2);
            } else if (len >= 4 && len <= 7) {
                PUTBITS4(0);
                PUTBITS4(8 + len - 4);
                PUTBITS4(color);
            } else if (len >= 9 && len <= 24) {
                PUTBITS4(0);
                PUTBITS4(0xe);
                PUTBITS4(len - 9);
                PUTBITS4(color);
            } else if (len >= 25) {
                if (len > 280)
                    len = 280;
                v = len - 25;
                PUTBITS4(0);
                PUTBITS4(0xf);
                PUTBITS4(v >> 4);
                PUTBITS4(v & 0xf);
                PUTBITS4(color);
            } else {
                PUTBITS4(color);
                if (color == 0) {
                    PUTBITS4(0xc);
                }
                len = 1;
            }
            x += len;
        }
        /* end of line */
        PUTBITS4(0);
        PUTBITS4(0);
        if (bitcnt != 4) {
            *q++ = bitbuf;
        }
        *q++ = 0xf0;
        bitmap += linesize;
    }
    *pq = q;
}

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

#define RGB_TO_Y_CCIR(r, g, b) \
((FIX(0.29900*219.0/255.0) * (r) + FIX(0.58700*219.0/255.0) * (g) + \
  FIX(0.11400*219.0/255.0) * (b) + (ONE_HALF + (16 << SCALEBITS))) >> SCALEBITS)

#define RGB_TO_U_CCIR(r1, g1, b1, shift)\
(((- FIX(0.16874*224.0/255.0) * r1 - FIX(0.33126*224.0/255.0) * g1 +         \
     FIX(0.50000*224.0/255.0) * b1 + (ONE_HALF << shift) - 1) >> (SCALEBITS + shift)) + 128)

#define RGB_TO_V_CCIR(r1, g1, b1, shift)\
(((FIX(0.50000*224.0/255.0) * r1 - FIX(0.41869*224.0/255.0) * g1 -           \
   FIX(0.08131*224.0/255.0) * b1 + (ONE_HALF << shift) - 1) >> (SCALEBITS + shift)) + 128)

static inline void putbe16(uint8_t **pq, uint16_t v)
{
    uint8_t *q;
    q = *pq;
    *q++ = v >> 8;
    *q++ = v;
    *pq = q;
}

static int encode_dvb_subtitles(DVBSubtitleContext *s, 
                                uint8_t *outbuf, AVSubtitle *h)
{
    uint8_t *q, *pseg_len;
    int page_id, region_id, clut_id, object_id, i, bpp_index, page_state;


    q = outbuf;

    page_id = 1;
    region_id = 0;
    clut_id = 0;
    object_id = 0;
    if (h->nb_colors <= 4) {
        /* 2 bpp, some decoders do not support it correctly */
        bpp_index = 0;
    } else if (h->nb_colors <= 16) {
        /* 4 bpp, standard encoding */
        bpp_index = 1;
    } else {
        return -1;
    }

    *q++ = 0x00; /* subtitle_stream_id */

    /* page composition segment */

    *q++ = 0x0f; /* sync_byte */
    *q++ = 0x10; /* segment_type */
    putbe16(&q, page_id);
    pseg_len = q;
    q += 2; /* segment length */
    *q++ = 30; /* page_timeout (seconds) */
    if (s->hide_state)
        page_state = 0; /* normal case */
    else
        page_state = 2; /* mode change */
    /* page_version = 0 + page_state */
    *q++ = s->object_version | (page_state << 2) | 3; 
    *q++ = region_id;
    *q++ = 0xff; /* reserved */
    putbe16(&q, 0); /* left pos */
    putbe16(&q, 0); /* top pos */

    putbe16(&pseg_len, q - pseg_len - 2);

    if (!s->hide_state) {
        /* CLUT segment */
        
        *q++ = 0x0f; /* sync byte */
        *q++ = 0x12; /* CLUT definition segment */
        putbe16(&q, page_id);
        pseg_len = q;
        q += 2; /* segment length */
        *q++ = clut_id;
        *q++ = (0 << 4) | 0xf; /* version = 0 */
        
        for(i = 0; i < h->nb_colors; i++) {
            *q++ = i; /* clut_entry_id */
            *q++ = (1 << (7 - bpp_index)) | (0xf << 1) | 1; /* 2 bits/pixel full range */
            {
                int a, r, g, b;
                a = (h->rgba_palette[i] >> 24) & 0xff;
                r = (h->rgba_palette[i] >> 16) & 0xff;
                g = (h->rgba_palette[i] >> 8) & 0xff;
                b = (h->rgba_palette[i] >> 0) & 0xff;
                
                *q++ = RGB_TO_Y_CCIR(r, g, b);
                *q++ = RGB_TO_V_CCIR(r, g, b, 0);
                *q++ = RGB_TO_U_CCIR(r, g, b, 0);
                *q++ = 255 - a;
            }
        }

        putbe16(&pseg_len, q - pseg_len - 2);
    }
    /* region composition segment */

    *q++ = 0x0f; /* sync_byte */
    *q++ = 0x11; /* segment_type */
    putbe16(&q, page_id);
    pseg_len = q;
    q += 2; /* segment length */
    *q++ = region_id;
    *q++ = (s->object_version << 4) | (0 << 3) | 0x07; /* version , no fill */
    putbe16(&q, 720); /* region width */
    putbe16(&q, 576); /* region height */
    *q++ = ((1 + bpp_index) << 5) | ((1 + bpp_index) << 2) | 0x03; 
    *q++ = clut_id;
    *q++ = 0; /* 8 bit fill colors */
    *q++ = 0x03; /* 4 bit and 2 bit fill colors */
    
    if (!s->hide_state) {
        putbe16(&q, object_id);
        *q++ = (0 << 6) | (0 << 4) | ((h->x >> 8) & 0xf);  
        *q++ = h->x;
        *q++ = 0xf0 | ((h->y >> 8) & 0xf);
        *q++ = h->y;
    }
    
    putbe16(&pseg_len, q - pseg_len - 2);

    if (!s->hide_state) {
        
    /* Object Data segment */

    *q++ = 0x0f; /* sync byte */
    *q++ = 0x13;
    putbe16(&q, page_id);
    pseg_len = q;
    q += 2; /* segment length */
    
    putbe16(&q, object_id);
    *q++ = (s->object_version << 4) | (0 << 2) | (0 << 1) | 1; /* version = 0,
                                                               onject_coding_method,
                                                               non_modifying_color_flag */
    {
        uint8_t *ptop_field_len, *pbottom_field_len, *top_ptr, *bottom_ptr;
        void (*dvb_encode_rle)(uint8_t **pq,
                                const uint8_t *bitmap, int linesize,
                                int w, int h);
        ptop_field_len = q;
        q += 2;
        pbottom_field_len = q;
        q += 2;

        if (bpp_index == 0)
            dvb_encode_rle = dvb_encode_rle2;
        else
            dvb_encode_rle = dvb_encode_rle4;
            
        top_ptr = q;
        dvb_encode_rle(&q, h->bitmap, h->w * 2, h->w, h->h >> 1);
        bottom_ptr = q;
        dvb_encode_rle(&q, h->bitmap + h->w, h->w * 2, h->w, h->h >> 1);

        putbe16(&ptop_field_len, bottom_ptr - top_ptr);
        putbe16(&pbottom_field_len, q - bottom_ptr);
    }

    putbe16(&pseg_len, q - pseg_len - 2);
    }

    /* end of display set segment */

    *q++ = 0x0f; /* sync_byte */
    *q++ = 0x80; /* segment_type */
    putbe16(&q, page_id);
    pseg_len = q;
    q += 2; /* segment length */

    putbe16(&pseg_len, q - pseg_len - 2);

    *q++ = 0xff; /* end of PES data */

    s->object_version = (s->object_version + 1) & 0xf;
    s->hide_state = !s->hide_state;
    return q - outbuf;
}

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

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

static int dvbsub_encode(AVCodecContext *avctx,
                       unsigned char *buf, int buf_size, void *data)
{
    DVBSubtitleContext *s = avctx->priv_data;
    AVSubtitle *sub = data;
    int ret;

    ret = encode_dvb_subtitles(s, buf, sub);
    return ret;
}

AVCodec dvbsub_encoder = {
    "dvbsub",
    CODEC_TYPE_SUBTITLE,
    CODEC_ID_DVB_SUBTITLE,
    sizeof(DVBSubtitleContext),
    dvbsub_init_decoder,
    dvbsub_encode,
    dvbsub_close_decoder,
};