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libavcodec/xsubenc.c

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00001 /*
00002  * DivX (XSUB) subtitle encoder
00003  * Copyright (c) 2005 DivX, Inc.
00004  * Copyright (c) 2009 Bjorn Axelsson
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 #include "avcodec.h"
00024 #include "bytestream.h"
00025 #include "put_bits.h"
00026 
00034 #define PADDING 0
00035 #define PADDING_COLOR 0
00036 
00042 static void put_xsub_rle(PutBitContext *pb, int len, int color)
00043 {
00044     if (len <= 255)
00045         put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len);
00046     else
00047         put_bits(pb, 14, 0);
00048     put_bits(pb, 2, color);
00049 }
00050 
00056 static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap,
00057                            int linesize, int w, int h)
00058 {
00059     int x0, x1, y, len, color = PADDING_COLOR;
00060 
00061     for (y = 0; y < h; y++) {
00062         x0 = 0;
00063         while (x0 < w) {
00064             // Make sure we have enough room for at least one run and padding
00065             if (pb->size_in_bits - put_bits_count(pb) < 7*8)
00066                 return -1;
00067 
00068             x1 = x0;
00069             color = bitmap[x1++] & 3;
00070             while (x1 < w && (bitmap[x1] & 3) == color)
00071                 x1++;
00072             len = x1 - x0;
00073             if (PADDING && x0 == 0) {
00074                 if (color == PADDING_COLOR) {
00075                     len += PADDING;
00076                     x0  -= PADDING;
00077                 } else
00078                     put_xsub_rle(pb, PADDING, PADDING_COLOR);
00079             }
00080 
00081             // Run can't be longer than 255, unless it is the rest of a row
00082             if (x1 == w && color == PADDING_COLOR) {
00083                 len += PADDING + (w&1);
00084             } else
00085                 len = FFMIN(len, 255);
00086             put_xsub_rle(pb, len, color);
00087 
00088             x0 += len;
00089         }
00090         if (color != PADDING_COLOR && (PADDING + (w&1)))
00091             put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR);
00092 
00093         align_put_bits(pb);
00094 
00095         bitmap += linesize;
00096     }
00097 
00098     return 0;
00099 }
00100 
00101 static int make_tc(uint64_t ms, int *tc)
00102 {
00103     static const int tc_divs[3] = { 1000, 60, 60 };
00104     int i;
00105     for (i=0; i<3; i++) {
00106         tc[i] = ms % tc_divs[i];
00107         ms /= tc_divs[i];
00108     }
00109     tc[3] = ms;
00110     return ms > 99;
00111 }
00112 
00113 static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,
00114                        int bufsize, void *data)
00115 {
00116     AVSubtitle *h = data;
00117     uint64_t startTime = h->pts / 1000; // FIXME: need better solution...
00118     uint64_t endTime = startTime + h->end_display_time - h->start_display_time;
00119     int start_tc[4], end_tc[4];
00120     uint8_t *hdr = buf + 27; // Point behind the timestamp
00121     uint8_t *rlelenptr;
00122     uint16_t width, height;
00123     int i;
00124     PutBitContext pb;
00125 
00126     if (bufsize < 27 + 7*2 + 4*3) {
00127         av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");
00128         return -1;
00129     }
00130 
00131     // TODO: support multiple rects
00132     if (h->num_rects > 1)
00133         av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);
00134 
00135     // TODO: render text-based subtitles into bitmaps
00136     if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) {
00137         av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");
00138         return -1;
00139     }
00140 
00141     // TODO: color reduction, similar to dvdsub encoder
00142     if (h->rects[0]->nb_colors > 4)
00143         av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);
00144 
00145     // TODO: Palette swapping if color zero is not transparent
00146     if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff)
00147         av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");
00148 
00149     if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {
00150         av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");
00151         return -1;
00152     }
00153 
00154     snprintf(buf, 28,
00155         "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",
00156         start_tc[3], start_tc[2], start_tc[1], start_tc[0],
00157         end_tc[3],   end_tc[2],   end_tc[1],   end_tc[0]);
00158 
00159     // Width and height must probably be multiples of 2.
00160     // 2 pixels required on either side of subtitle.
00161     // Possibly due to limitations of hardware renderers.
00162     // TODO: check if the bitmap is already padded
00163     width  = FFALIGN(h->rects[0]->w, 2) + PADDING * 2;
00164     height = FFALIGN(h->rects[0]->h, 2);
00165 
00166     bytestream_put_le16(&hdr, width);
00167     bytestream_put_le16(&hdr, height);
00168     bytestream_put_le16(&hdr, h->rects[0]->x);
00169     bytestream_put_le16(&hdr, h->rects[0]->y);
00170     bytestream_put_le16(&hdr, h->rects[0]->x + width);
00171     bytestream_put_le16(&hdr, h->rects[0]->y + height);
00172 
00173     rlelenptr = hdr; // Will store length of first field here later.
00174     hdr+=2;
00175 
00176     // Palette
00177     for (i=0; i<4; i++)
00178         bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]);
00179 
00180     // Bitmap
00181     // RLE buffer. Reserve 2 bytes for possible padding after the last row.
00182     init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2);
00183     if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0],
00184                         h->rects[0]->pict.linesize[0]*2,
00185                         h->rects[0]->w, (h->rects[0]->h + 1) >> 1))
00186         return -1;
00187     bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field
00188 
00189     if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0],
00190                         h->rects[0]->pict.linesize[0]*2,
00191                         h->rects[0]->w, h->rects[0]->h >> 1))
00192         return -1;
00193 
00194     // Enforce total height to be be multiple of 2
00195     if (h->rects[0]->h & 1) {
00196         put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR);
00197         align_put_bits(&pb);
00198     }
00199 
00200     flush_put_bits(&pb);
00201 
00202     return hdr - buf + put_bits_count(&pb)/8;
00203 }
00204 
00205 static av_cold int xsub_encoder_init(AVCodecContext *avctx)
00206 {
00207     if (!avctx->codec_tag)
00208         avctx->codec_tag = MKTAG('D','X','S','B');
00209 
00210     return 0;
00211 }
00212 
00213 AVCodec xsub_encoder = {
00214     "xsub",
00215     AVMEDIA_TYPE_SUBTITLE,
00216     CODEC_ID_XSUB,
00217     0,
00218     xsub_encoder_init,
00219     xsub_encode,
00220     NULL,
00221     .long_name = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"),
00222 };

Generated on Fri Sep 16 2011 17:17:47 for FFmpeg by  doxygen 1.7.1