/* * DivX (XSUB) subtitle encoder * Copyright (c) 2005 DivX, Inc. * Copyright (c) 2009 Bjorn Axelsson * * This file is part of FFmpeg. * * FFmpeg 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 2.1 of the License, or (at your option) any later version. * * FFmpeg 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 FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "avcodec.h" #include "bytestream.h" #include "put_bits.h" /** * Number of pixels to pad left and right. * * The official encoder pads the subtitles with two pixels on either side, * but until we find out why, we won't do it (we will pad to have width * divisible by 2 though). */ #define PADDING 0 #define PADDING_COLOR 0 /** * Encode a single color run. At most 16 bits will be used. * @param len length of the run, values > 255 mean "until end of line", may not be < 0. * @param color color to encode, only the lowest two bits are used and all others must be 0. */ static void put_xsub_rle(PutBitContext *pb, int len, int color) { if (len <= 255) put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len); else put_bits(pb, 14, 0); put_bits(pb, 2, color); } /** * Encode a 4-color bitmap with XSUB rle. * * The encoded bitmap may be wider than the source bitmap due to padding. */ static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap, int linesize, int w, int h) { int x0, x1, y, len, color = PADDING_COLOR; for (y = 0; y < h; y++) { x0 = 0; while (x0 < w) { // Make sure we have enough room for at least one run and padding if (pb->size_in_bits - put_bits_count(pb) < 7*8) return -1; x1 = x0; color = bitmap[x1++] & 3; while (x1 < w && (bitmap[x1] & 3) == color) x1++; len = x1 - x0; if (PADDING && x0 == 0) { if (color == PADDING_COLOR) { len += PADDING; x0 -= PADDING; } else put_xsub_rle(pb, PADDING, PADDING_COLOR); } // Run can't be longer than 255, unless it is the rest of a row if (x1 == w && color == PADDING_COLOR) { len += PADDING + (w&1); } else len = FFMIN(len, 255); put_xsub_rle(pb, len, color); x0 += len; } if (color != PADDING_COLOR && (PADDING + (w&1))) put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR); avpriv_align_put_bits(pb); bitmap += linesize; } return 0; } static int make_tc(uint64_t ms, int *tc) { static const int tc_divs[3] = { 1000, 60, 60 }; int i; for (i=0; i<3; i++) { tc[i] = ms % tc_divs[i]; ms /= tc_divs[i]; } tc[3] = ms; return ms > 99; } static int xsub_encode(AVCodecContext *avctx, unsigned char *buf, int bufsize, const AVSubtitle *h) { uint64_t startTime = h->pts / 1000; // FIXME: need better solution... uint64_t endTime = startTime + h->end_display_time - h->start_display_time; int start_tc[4], end_tc[4]; uint8_t *hdr = buf + 27; // Point behind the timestamp uint8_t *rlelenptr; uint16_t width, height; int i; PutBitContext pb; if (bufsize < 27 + 7*2 + 4*3) { av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n"); return -1; } // TODO: support multiple rects if (h->num_rects != 1) av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects); // TODO: render text-based subtitles into bitmaps if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) { av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n"); return -1; } // TODO: color reduction, similar to dvdsub encoder if (h->rects[0]->nb_colors > 4) av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors); // TODO: Palette swapping if color zero is not transparent if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff) av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n"); if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) { av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n"); return -1; } snprintf(buf, 28, "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]", start_tc[3], start_tc[2], start_tc[1], start_tc[0], end_tc[3], end_tc[2], end_tc[1], end_tc[0]); // Width and height must probably be multiples of 2. // 2 pixels required on either side of subtitle. // Possibly due to limitations of hardware renderers. // TODO: check if the bitmap is already padded width = FFALIGN(h->rects[0]->w, 2) + PADDING * 2; height = FFALIGN(h->rects[0]->h, 2); bytestream_put_le16(&hdr, width); bytestream_put_le16(&hdr, height); bytestream_put_le16(&hdr, h->rects[0]->x); bytestream_put_le16(&hdr, h->rects[0]->y); bytestream_put_le16(&hdr, h->rects[0]->x + width -1); bytestream_put_le16(&hdr, h->rects[0]->y + height -1); rlelenptr = hdr; // Will store length of first field here later. hdr+=2; // Palette for (i=0; i<4; i++) bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]); // Bitmap // RLE buffer. Reserve 2 bytes for possible padding after the last row. init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2); if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0], h->rects[0]->pict.linesize[0]*2, h->rects[0]->w, (h->rects[0]->h + 1) >> 1)) return -1; bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0], h->rects[0]->pict.linesize[0]*2, h->rects[0]->w, h->rects[0]->h >> 1)) return -1; // Enforce total height to be a multiple of 2 if (h->rects[0]->h & 1) { put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR); avpriv_align_put_bits(&pb); } flush_put_bits(&pb); return hdr - buf + put_bits_count(&pb)/8; } static av_cold int xsub_encoder_init(AVCodecContext *avctx) { if (!avctx->codec_tag) avctx->codec_tag = MKTAG('D','X','S','B'); return 0; } AVCodec ff_xsub_encoder = { .name = "xsub", .long_name = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"), .type = AVMEDIA_TYPE_SUBTITLE, .id = AV_CODEC_ID_XSUB, .init = xsub_encoder_init, .encode_sub = xsub_encode, };