avcodec/srtdec: factor out HTML parsing code

This code will be used in SAMI decoder in a later commit.

Signed-off-by: Clément Bœsch <u@pkh.me>

1 files changed, 176 insertions, 0 deletions

diff --git a/libavcodec/htmlsubtitles.c b/libavcodec/htmlsubtitles.c
new file mode 100644
index 0000000000..97be82daa0
--- /dev/null
+++ b/libavcodec/htmlsubtitles.c
@@ -0,0 +1,176 @@
+/*
+ * 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 "libavutil/common.h"
+#include "libavutil/parseutils.h"
+#include "avcodec.h"
+#include "htmlsubtitles.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 SrtStack {
+    char tag[128];
+    char param[PARAM_NUMBER][128];
+} SrtStack;
+
+static void rstrip_spaces_buf(AVBPrint *buf)
+{
+    while (buf->len > 0 && buf->str[buf->len - 1] == ' ')
+        buf->str[--buf->len] = 0;
+}
+
+void ff_htmlmarkup_to_ass(AVCodecContext *avctx, AVBPrint *dst, const char *in)
+{
+    char *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}");
+
+    for (; !end && *in; in++) {
+        switch (*in) {
+        case '\r':
+            break;
+        case '\n':
+            if (line_start) {
+                end = 1;
+                break;
+            }
+            rstrip_spaces_buf(dst);
+            av_bprintf(dst, "\\N");
+            line_start = 1;
+            break;
+        case ' ':
+            if (!line_start)
+                av_bprint_chars(dst, *in, 1);
+            break;
+        case '{':    /* skip all {\xxx} substrings except for {\an%d}
+                        and all microdvd like styles such as {Y:xxx} */
+            len = 0;
+            an += sscanf(in, "{\\an%*1u}%n", &len) >= 0 && len > 0;
+            if ((an != 1 && (len = 0, sscanf(in, "{\\%*[^}]}%n", &len) >= 0 && len > 0)) ||
+                (len = 0, sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n", &len) >= 0 && len > 0)) {
+                in += len - 1;
+            } else
+                av_bprint_chars(dst, *in, 1);
+            break;
+        case '<':
+            tag_close = in[1] == '/';
+            len = 0;
+            if (sscanf(in+tag_close+1, "%127[^>]>%n", buffer, &len) >= 1 && len > 0) {
+                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]) {
+                                            av_bprintf(dst, "%s", 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])
+                                    av_bprintf(dst, "%s", stack[sptr].param[i]);
+                        }
+                    } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
+                        av_bprintf(dst, "{\\%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;
+                        av_bprint_chars(dst, *in, 1);
+                    } else
+                        av_strlcpy(stack[sptr++].tag, buffer,
+                                   sizeof(stack[0].tag));
+                    break;
+                }
+            }
+        default:
+            av_bprint_chars(dst, *in, 1);
+            break;
+        }
+        if (*in != ' ' && *in != '\r' && *in != '\n')
+            line_start = 0;
+    }
+
+    while (dst->len >= 2 && !strncmp(&dst->str[dst->len - 2], "\\N", 2))
+        dst->len -= 2;
+    dst->str[dst->len] = 0;
+    rstrip_spaces_buf(dst);
+}