yading@10: /*
yading@10:  * DivX (XSUB) subtitle encoder
yading@10:  * Copyright (c) 2005 DivX, Inc.
yading@10:  * Copyright (c) 2009 Bjorn Axelsson
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #include "avcodec.h"
yading@10: #include "bytestream.h"
yading@10: #include "put_bits.h"
yading@10: 
yading@10: /**
yading@10:  * Number of pixels to pad left and right.
yading@10:  *
yading@10:  * The official encoder pads the subtitles with two pixels on either side,
yading@10:  * but until we find out why, we won't do it (we will pad to have width
yading@10:  * divisible by 2 though).
yading@10:  */
yading@10: #define PADDING 0
yading@10: #define PADDING_COLOR 0
yading@10: 
yading@10: /**
yading@10:  * Encode a single color run. At most 16 bits will be used.
yading@10:  * @param len   length of the run, values > 255 mean "until end of line", may not be < 0.
yading@10:  * @param color color to encode, only the lowest two bits are used and all others must be 0.
yading@10:  */
yading@10: static void put_xsub_rle(PutBitContext *pb, int len, int color)
yading@10: {
yading@10:     if (len <= 255)
yading@10:         put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len);
yading@10:     else
yading@10:         put_bits(pb, 14, 0);
yading@10:     put_bits(pb, 2, color);
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Encode a 4-color bitmap with XSUB rle.
yading@10:  *
yading@10:  * The encoded bitmap may be wider than the source bitmap due to padding.
yading@10:  */
yading@10: static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap,
yading@10:                            int linesize, int w, int h)
yading@10: {
yading@10:     int x0, x1, y, len, color = PADDING_COLOR;
yading@10: 
yading@10:     for (y = 0; y < h; y++) {
yading@10:         x0 = 0;
yading@10:         while (x0 < w) {
yading@10:             // Make sure we have enough room for at least one run and padding
yading@10:             if (pb->size_in_bits - put_bits_count(pb) < 7*8)
yading@10:                 return -1;
yading@10: 
yading@10:             x1 = x0;
yading@10:             color = bitmap[x1++] & 3;
yading@10:             while (x1 < w && (bitmap[x1] & 3) == color)
yading@10:                 x1++;
yading@10:             len = x1 - x0;
yading@10:             if (PADDING && x0 == 0) {
yading@10:                 if (color == PADDING_COLOR) {
yading@10:                     len += PADDING;
yading@10:                     x0  -= PADDING;
yading@10:                 } else
yading@10:                     put_xsub_rle(pb, PADDING, PADDING_COLOR);
yading@10:             }
yading@10: 
yading@10:             // Run can't be longer than 255, unless it is the rest of a row
yading@10:             if (x1 == w && color == PADDING_COLOR) {
yading@10:                 len += PADDING + (w&1);
yading@10:             } else
yading@10:                 len = FFMIN(len, 255);
yading@10:             put_xsub_rle(pb, len, color);
yading@10: 
yading@10:             x0 += len;
yading@10:         }
yading@10:         if (color != PADDING_COLOR && (PADDING + (w&1)))
yading@10:             put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR);
yading@10: 
yading@10:         avpriv_align_put_bits(pb);
yading@10: 
yading@10:         bitmap += linesize;
yading@10:     }
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int make_tc(uint64_t ms, int *tc)
yading@10: {
yading@10:     static const int tc_divs[3] = { 1000, 60, 60 };
yading@10:     int i;
yading@10:     for (i=0; i<3; i++) {
yading@10:         tc[i] = ms % tc_divs[i];
yading@10:         ms /= tc_divs[i];
yading@10:     }
yading@10:     tc[3] = ms;
yading@10:     return ms > 99;
yading@10: }
yading@10: 
yading@10: static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,
yading@10:                        int bufsize, const AVSubtitle *h)
yading@10: {
yading@10:     uint64_t startTime = h->pts / 1000; // FIXME: need better solution...
yading@10:     uint64_t endTime = startTime + h->end_display_time - h->start_display_time;
yading@10:     int start_tc[4], end_tc[4];
yading@10:     uint8_t *hdr = buf + 27; // Point behind the timestamp
yading@10:     uint8_t *rlelenptr;
yading@10:     uint16_t width, height;
yading@10:     int i;
yading@10:     PutBitContext pb;
yading@10: 
yading@10:     if (bufsize < 27 + 7*2 + 4*3) {
yading@10:         av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");
yading@10:         return -1;
yading@10:     }
yading@10: 
yading@10:     // TODO: support multiple rects
yading@10:     if (h->num_rects != 1)
yading@10:         av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);
yading@10: 
yading@10:     // TODO: render text-based subtitles into bitmaps
yading@10:     if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) {
yading@10:         av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");
yading@10:         return -1;
yading@10:     }
yading@10: 
yading@10:     // TODO: color reduction, similar to dvdsub encoder
yading@10:     if (h->rects[0]->nb_colors > 4)
yading@10:         av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);
yading@10: 
yading@10:     // TODO: Palette swapping if color zero is not transparent
yading@10:     if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff)
yading@10:         av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");
yading@10: 
yading@10:     if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {
yading@10:         av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");
yading@10:         return -1;
yading@10:     }
yading@10: 
yading@10:     snprintf(buf, 28,
yading@10:         "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",
yading@10:         start_tc[3], start_tc[2], start_tc[1], start_tc[0],
yading@10:         end_tc[3],   end_tc[2],   end_tc[1],   end_tc[0]);
yading@10: 
yading@10:     // Width and height must probably be multiples of 2.
yading@10:     // 2 pixels required on either side of subtitle.
yading@10:     // Possibly due to limitations of hardware renderers.
yading@10:     // TODO: check if the bitmap is already padded
yading@10:     width  = FFALIGN(h->rects[0]->w, 2) + PADDING * 2;
yading@10:     height = FFALIGN(h->rects[0]->h, 2);
yading@10: 
yading@10:     bytestream_put_le16(&hdr, width);
yading@10:     bytestream_put_le16(&hdr, height);
yading@10:     bytestream_put_le16(&hdr, h->rects[0]->x);
yading@10:     bytestream_put_le16(&hdr, h->rects[0]->y);
yading@10:     bytestream_put_le16(&hdr, h->rects[0]->x + width);
yading@10:     bytestream_put_le16(&hdr, h->rects[0]->y + height);
yading@10: 
yading@10:     rlelenptr = hdr; // Will store length of first field here later.
yading@10:     hdr+=2;
yading@10: 
yading@10:     // Palette
yading@10:     for (i=0; i<4; i++)
yading@10:         bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]);
yading@10: 
yading@10:     // Bitmap
yading@10:     // RLE buffer. Reserve 2 bytes for possible padding after the last row.
yading@10:     init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2);
yading@10:     if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0],
yading@10:                         h->rects[0]->pict.linesize[0]*2,
yading@10:                         h->rects[0]->w, (h->rects[0]->h + 1) >> 1))
yading@10:         return -1;
yading@10:     bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field
yading@10: 
yading@10:     if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0],
yading@10:                         h->rects[0]->pict.linesize[0]*2,
yading@10:                         h->rects[0]->w, h->rects[0]->h >> 1))
yading@10:         return -1;
yading@10: 
yading@10:     // Enforce total height to be be multiple of 2
yading@10:     if (h->rects[0]->h & 1) {
yading@10:         put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR);
yading@10:         avpriv_align_put_bits(&pb);
yading@10:     }
yading@10: 
yading@10:     flush_put_bits(&pb);
yading@10: 
yading@10:     return hdr - buf + put_bits_count(&pb)/8;
yading@10: }
yading@10: 
yading@10: static av_cold int xsub_encoder_init(AVCodecContext *avctx)
yading@10: {
yading@10:     if (!avctx->codec_tag)
yading@10:         avctx->codec_tag = MKTAG('D','X','S','B');
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: AVCodec ff_xsub_encoder = {
yading@10:     .name       = "xsub",
yading@10:     .type       = AVMEDIA_TYPE_SUBTITLE,
yading@10:     .id         = AV_CODEC_ID_XSUB,
yading@10:     .init       = xsub_encoder_init,
yading@10:     .encode_sub = xsub_encode,
yading@10:     .long_name  = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"),
yading@10: };