add SubRip decoder

Originally committed as revision 26119 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 240 insertions, 0 deletions

diff --git a/libavcodec/srtdec.c b/libavcodec/srtdec.c
new file mode 100644
index 0000000000..42eae322d1
--- /dev/null
+++ b/libavcodec/srtdec.c
@@ -0,0 +1,240 @@
+/*
+ * SubRip subtitle decoder
+ * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
+ *
+ * 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 "libavutil/avstring.h"
+#include "libavcore/parseutils.h"
+#include "avcodec.h"
+#include "ass.h"
+
+static int html_color_parse(AVCodecContext *avctx, const char *str)
+{
+    uint8_t rgba[4];
+    if (av_parse_color(rgba, str, strcspn(str, "\" >"), avctx) < 0)
+        return -1;
+    return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
+}
+
+enum {
+    PARAM_UNKNOWN = -1,
+    PARAM_SIZE,
+    PARAM_COLOR,
+    PARAM_FACE,
+    PARAM_NUMBER
+};
+
+typedef struct {
+    char tag[128];
+    char param[PARAM_NUMBER][128];
+} SrtStack;
+
+static const char *srt_to_ass(AVCodecContext *avctx, char *out, char *out_end,
+                              const char *in, int x1, int y1, int x2, int y2)
+{
+    char c, *param, buffer[128], tmp[128];
+    int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
+    SrtStack stack[16];
+
+    stack[0].tag[0] = 0;
+    strcpy(stack[0].param[PARAM_SIZE],  "{\\fs}");
+    strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
+    strcpy(stack[0].param[PARAM_FACE],  "{\\fn}");
+
+    if (x1 >= 0 && y1 >= 0) {
+        if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
+            out += snprintf(out, out_end-out,
+                            "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
+        else
+            out += snprintf(out, out_end-out, "{\\an1}{\\pos(%d,%d)}", x1, y1);
+    }
+
+    for (; *in && out < out_end && !end; in++) {
+        switch (*in) {
+        case '\r':
+            break;
+        case '\n':
+            if (line_start) {
+                end = 1;
+                break;
+            }
+            while (out[-1] == ' ')
+                out--;
+            out += snprintf(out, out_end-out, "\\N");
+            line_start = 1;
+            break;
+        case ' ':
+            if (!line_start)
+                *out++ = *in;
+            break;
+        case '{':    /* skip all {\xxx} substrings except for {\an%d}
+                        and all microdvd like styles such as {Y:xxx} */
+            an += sscanf(in, "{\\an%*1u}%c", &c) == 1;
+            if ((an != 1 && sscanf(in, "{\\%*[^}]}%n%c", &len, &c) > 0) ||
+                sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n%c", &len, &c) > 0) {
+                in += len - 1;
+            } else
+                *out++ = *in;
+            break;
+        case '<':
+            tag_close = in[1] == '/';
+            if (sscanf(in+tag_close+1, "%128[^>]>%n%c", buffer, &len,&c) >= 2) {
+                if ((param = strchr(buffer, ' ')))
+                    *param++ = 0;
+                if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
+                    ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
+                    int i, j, unknown = 0;
+                    in += len + tag_close;
+                    if (!tag_close)
+                        memset(stack+sptr, 0, sizeof(*stack));
+                    if (!strcmp(buffer, "font")) {
+                        if (tag_close) {
+                            for (i=PARAM_NUMBER-1; i>=0; i--)
+                                if (stack[sptr-1].param[i][0])
+                                    for (j=sptr-2; j>=0; j--)
+                                        if (stack[j].param[i][0]) {
+                                            out += snprintf(out, out_end-out,
+                                                            stack[j].param[i]);
+                                            break;
+                                        }
+                        } else {
+                            while (param) {
+                                if (!strncmp(param, "size=", 5)) {
+                                    unsigned font_size;
+                                    param += 5 + (param[5] == '"');
+                                    if (sscanf(param, "%u", &font_size) == 1) {
+                                        snprintf(stack[sptr].param[PARAM_SIZE],
+                                             sizeof(stack[0].param[PARAM_SIZE]),
+                                             "{\\fs%u}", font_size);
+                                    }
+                                } else if (!strncmp(param, "color=", 6)) {
+                                    param += 6 + (param[6] == '"');
+                                    snprintf(stack[sptr].param[PARAM_COLOR],
+                                         sizeof(stack[0].param[PARAM_COLOR]),
+                                         "{\\c&H%X&}",
+                                         html_color_parse(avctx, param));
+                                } else if (!strncmp(param, "face=", 5)) {
+                                    param += 5 + (param[5] == '"');
+                                    len = strcspn(param,
+                                                  param[-1] == '"' ? "\"" :" ");
+                                    av_strlcpy(tmp, param,
+                                               FFMIN(sizeof(tmp), len+1));
+                                    param += len;
+                                    snprintf(stack[sptr].param[PARAM_FACE],
+                                             sizeof(stack[0].param[PARAM_FACE]),
+                                             "{\\fn%s}", tmp);
+                                }
+                                if ((param = strchr(param, ' ')))
+                                    param++;
+                            }
+                            for (i=0; i<PARAM_NUMBER; i++)
+                                if (stack[sptr].param[i][0])
+                                    out += snprintf(out, out_end-out,
+                                                    stack[sptr].param[i]);
+                        }
+                    } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
+                        out += snprintf(out, out_end-out,
+                                        "{\\%c%d}", buffer[0], !tag_close);
+                    } else {
+                        unknown = 1;
+                        snprintf(tmp, sizeof(tmp), "</%s>", buffer);
+                    }
+                    if (tag_close) {
+                        sptr--;
+                    } else if (unknown && !strstr(in, tmp)) {
+                        in -= len + tag_close;
+                        *out++ = *in;
+                    } else
+                        av_strlcpy(stack[sptr++].tag, buffer,
+                                   sizeof(stack[0].tag));
+                    break;
+                }
+            }
+        default:
+            *out++ = *in;
+            break;
+        }
+        if (*in != ' ' && *in != '\r' && *in != '\n')
+            line_start = 0;
+    }
+
+    out = FFMIN(out, out_end-3);
+    while (!strncmp(out-2, "\\N", 2))
+        out -= 2;
+    while (out[-1] == ' ')
+        out--;
+    out += snprintf(out, out_end-out, "\r\n");
+    return in;
+}
+
+static const char *read_ts(const char *buf, int *ts_start, int *ts_end,
+                           int *x1, int *y1, int *x2, int *y2)
+{
+    int i, hs, ms, ss, he, me, se;
+
+    for (i=0; i<2; i++) {
+        /* try to read timestamps in either the first or second line */
+        int c = sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
+                       "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
+                       &hs, &ms, &ss, ts_start, &he, &me, &se, ts_end,
+                       x1, x2, y1, y2);
+        buf += strcspn(buf, "\n") + 1;
+        if (c >= 8) {
+            *ts_start = 100*(ss + 60*(ms + 60*hs)) + *ts_start/10;
+            *ts_end   = 100*(se + 60*(me + 60*he)) + *ts_end  /10;
+            return buf;
+        }
+    }
+    return NULL;
+}
+
+static int srt_decode_frame(AVCodecContext *avctx,
+                            void *data, int *got_sub_ptr, AVPacket *avpkt)
+{
+    AVSubtitle *sub = data;
+    int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
+    char buffer[2048];
+    const char *ptr = avpkt->data;
+
+    if (avpkt->size <= 0)
+        return avpkt->size;
+
+    ff_ass_init(sub);
+
+    while (*ptr) {
+        ptr = read_ts(ptr, &ts_start, &ts_end, &x1, &y1, &x2, &y2);
+        if (!ptr)
+            break;
+        ptr = srt_to_ass(avctx, buffer, buffer+sizeof(buffer), ptr,
+                         x1, y1, x2, y2);
+        ff_ass_add_rect(sub, buffer, ts_start, ts_end, 0);
+    }
+
+    *got_sub_ptr = sub->num_rects > 0;
+    return avpkt->size;
+}
+
+AVCodec srt_decoder = {
+    .name         = "srt",
+    .long_name    = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
+    .type         = AVMEDIA_TYPE_SUBTITLE,
+    .id           = CODEC_ID_SRT,
+    .init         = ff_ass_subtitle_header_default,
+    .decode       = srt_decode_frame,
+};