| 1 | /* |
| 2 | * DivX (XSUB) subtitle encoder |
| 3 | * Copyright (c) 2005 DivX, Inc. |
| 4 | * Copyright (c) 2009 Bjorn Axelsson |
| 5 | * |
| 6 | * This file is part of FFmpeg. |
| 7 | * |
| 8 | * FFmpeg is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * FFmpeg is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with FFmpeg; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | #include "avcodec.h" |
| 24 | #include "bytestream.h" |
| 25 | #include "put_bits.h" |
| 26 | |
| 27 | /** |
| 28 | * Number of pixels to pad left and right. |
| 29 | * |
| 30 | * The official encoder pads the subtitles with two pixels on either side, |
| 31 | * but until we find out why, we won't do it (we will pad to have width |
| 32 | * divisible by 2 though). |
| 33 | */ |
| 34 | #define PADDING 0 |
| 35 | #define PADDING_COLOR 0 |
| 36 | |
| 37 | /** |
| 38 | * Encode a single color run. At most 16 bits will be used. |
| 39 | * @param len length of the run, values > 255 mean "until end of line", may not be < 0. |
| 40 | * @param color color to encode, only the lowest two bits are used and all others must be 0. |
| 41 | */ |
| 42 | static void put_xsub_rle(PutBitContext *pb, int len, int color) |
| 43 | { |
| 44 | if (len <= 255) |
| 45 | put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len); |
| 46 | else |
| 47 | put_bits(pb, 14, 0); |
| 48 | put_bits(pb, 2, color); |
| 49 | } |
| 50 | |
| 51 | /** |
| 52 | * Encode a 4-color bitmap with XSUB rle. |
| 53 | * |
| 54 | * The encoded bitmap may be wider than the source bitmap due to padding. |
| 55 | */ |
| 56 | static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap, |
| 57 | int linesize, int w, int h) |
| 58 | { |
| 59 | int x0, x1, y, len, color = PADDING_COLOR; |
| 60 | |
| 61 | for (y = 0; y < h; y++) { |
| 62 | x0 = 0; |
| 63 | while (x0 < w) { |
| 64 | // Make sure we have enough room for at least one run and padding |
| 65 | if (pb->size_in_bits - put_bits_count(pb) < 7*8) |
| 66 | return -1; |
| 67 | |
| 68 | x1 = x0; |
| 69 | color = bitmap[x1++] & 3; |
| 70 | while (x1 < w && (bitmap[x1] & 3) == color) |
| 71 | x1++; |
| 72 | len = x1 - x0; |
| 73 | if (PADDING && x0 == 0) { |
| 74 | if (color == PADDING_COLOR) { |
| 75 | len += PADDING; |
| 76 | x0 -= PADDING; |
| 77 | } else |
| 78 | put_xsub_rle(pb, PADDING, PADDING_COLOR); |
| 79 | } |
| 80 | |
| 81 | // Run can't be longer than 255, unless it is the rest of a row |
| 82 | if (x1 == w && color == PADDING_COLOR) { |
| 83 | len += PADDING + (w&1); |
| 84 | } else |
| 85 | len = FFMIN(len, 255); |
| 86 | put_xsub_rle(pb, len, color); |
| 87 | |
| 88 | x0 += len; |
| 89 | } |
| 90 | if (color != PADDING_COLOR && (PADDING + (w&1))) |
| 91 | put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR); |
| 92 | |
| 93 | avpriv_align_put_bits(pb); |
| 94 | |
| 95 | bitmap += linesize; |
| 96 | } |
| 97 | |
| 98 | return 0; |
| 99 | } |
| 100 | |
| 101 | static int make_tc(uint64_t ms, int *tc) |
| 102 | { |
| 103 | static const int tc_divs[3] = { 1000, 60, 60 }; |
| 104 | int i; |
| 105 | for (i=0; i<3; i++) { |
| 106 | tc[i] = ms % tc_divs[i]; |
| 107 | ms /= tc_divs[i]; |
| 108 | } |
| 109 | tc[3] = ms; |
| 110 | return ms > 99; |
| 111 | } |
| 112 | |
| 113 | static int xsub_encode(AVCodecContext *avctx, unsigned char *buf, |
| 114 | int bufsize, const AVSubtitle *h) |
| 115 | { |
| 116 | uint64_t startTime = h->pts / 1000; // FIXME: need better solution... |
| 117 | uint64_t endTime = startTime + h->end_display_time - h->start_display_time; |
| 118 | int start_tc[4], end_tc[4]; |
| 119 | uint8_t *hdr = buf + 27; // Point behind the timestamp |
| 120 | uint8_t *rlelenptr; |
| 121 | uint16_t width, height; |
| 122 | int i; |
| 123 | PutBitContext pb; |
| 124 | |
| 125 | if (bufsize < 27 + 7*2 + 4*3) { |
| 126 | av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n"); |
| 127 | return -1; |
| 128 | } |
| 129 | |
| 130 | // TODO: support multiple rects |
| 131 | if (h->num_rects != 1) |
| 132 | av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects); |
| 133 | |
| 134 | // TODO: render text-based subtitles into bitmaps |
| 135 | if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) { |
| 136 | av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n"); |
| 137 | return -1; |
| 138 | } |
| 139 | |
| 140 | // TODO: color reduction, similar to dvdsub encoder |
| 141 | if (h->rects[0]->nb_colors > 4) |
| 142 | av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors); |
| 143 | |
| 144 | // TODO: Palette swapping if color zero is not transparent |
| 145 | if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff000000) |
| 146 | av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n"); |
| 147 | |
| 148 | if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) { |
| 149 | av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n"); |
| 150 | return -1; |
| 151 | } |
| 152 | |
| 153 | snprintf(buf, 28, |
| 154 | "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]", |
| 155 | start_tc[3], start_tc[2], start_tc[1], start_tc[0], |
| 156 | end_tc[3], end_tc[2], end_tc[1], end_tc[0]); |
| 157 | |
| 158 | // Width and height must probably be multiples of 2. |
| 159 | // 2 pixels required on either side of subtitle. |
| 160 | // Possibly due to limitations of hardware renderers. |
| 161 | // TODO: check if the bitmap is already padded |
| 162 | width = FFALIGN(h->rects[0]->w, 2) + PADDING * 2; |
| 163 | height = FFALIGN(h->rects[0]->h, 2); |
| 164 | |
| 165 | bytestream_put_le16(&hdr, width); |
| 166 | bytestream_put_le16(&hdr, height); |
| 167 | bytestream_put_le16(&hdr, h->rects[0]->x); |
| 168 | bytestream_put_le16(&hdr, h->rects[0]->y); |
| 169 | bytestream_put_le16(&hdr, h->rects[0]->x + width -1); |
| 170 | bytestream_put_le16(&hdr, h->rects[0]->y + height -1); |
| 171 | |
| 172 | rlelenptr = hdr; // Will store length of first field here later. |
| 173 | hdr+=2; |
| 174 | |
| 175 | // Palette |
| 176 | for (i=0; i<4; i++) |
| 177 | bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]); |
| 178 | |
| 179 | // Bitmap |
| 180 | // RLE buffer. Reserve 2 bytes for possible padding after the last row. |
| 181 | init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2); |
| 182 | if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0], |
| 183 | h->rects[0]->pict.linesize[0]*2, |
| 184 | h->rects[0]->w, (h->rects[0]->h + 1) >> 1)) |
| 185 | return -1; |
| 186 | bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field |
| 187 | |
| 188 | if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0], |
| 189 | h->rects[0]->pict.linesize[0]*2, |
| 190 | h->rects[0]->w, h->rects[0]->h >> 1)) |
| 191 | return -1; |
| 192 | |
| 193 | // Enforce total height to be a multiple of 2 |
| 194 | if (h->rects[0]->h & 1) { |
| 195 | put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR); |
| 196 | avpriv_align_put_bits(&pb); |
| 197 | } |
| 198 | |
| 199 | flush_put_bits(&pb); |
| 200 | |
| 201 | return hdr - buf + put_bits_count(&pb)/8; |
| 202 | } |
| 203 | |
| 204 | static av_cold int xsub_encoder_init(AVCodecContext *avctx) |
| 205 | { |
| 206 | if (!avctx->codec_tag) |
| 207 | avctx->codec_tag = MKTAG('D','X','S','B'); |
| 208 | |
| 209 | avctx->bits_per_coded_sample = 4; |
| 210 | |
| 211 | return 0; |
| 212 | } |
| 213 | |
| 214 | AVCodec ff_xsub_encoder = { |
| 215 | .name = "xsub", |
| 216 | .long_name = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"), |
| 217 | .type = AVMEDIA_TYPE_SUBTITLE, |
| 218 | .id = AV_CODEC_ID_XSUB, |
| 219 | .init = xsub_encoder_init, |
| 220 | .encode_sub = xsub_encode, |
| 221 | }; |