SAMI demuxer and decoder.

1 files changed, 158 insertions, 0 deletions

diff --git a/libavcodec/samidec.c b/libavcodec/samidec.c
new file mode 100644
index 0000000..1852959
--- /dev/null
+++ b/libavcodec/samidec.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2012 Clément Bœsch
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * SAMI subtitle decoder
+ * @see http://msdn.microsoft.com/en-us/library/ms971327.aspx
+ */
+
+#include "ass.h"
+#include "libavutil/avstring.h"
+#include "libavutil/bprint.h"
+
+typedef struct {
+    AVBPrint source;
+    AVBPrint content;
+    AVBPrint full;
+} SAMIContext;
+
+static int sami_paragraph_to_ass(AVCodecContext *avctx, const char *src)
+{
+    SAMIContext *sami = avctx->priv_data;
+    int ret = 0;
+    char *tag = NULL;
+    char *dupsrc = av_strdup(src);
+    char *p = dupsrc;
+
+    av_bprint_clear(&sami->content);
+    for (;;) {
+        char *saveptr = NULL;
+        int prev_chr_is_space = 0;
+        AVBPrint *dst = &sami->content;
+
+        /* parse & extract paragraph tag */
+        p = av_stristr(p, "<P");
+        if (!p)
+            break;
+        if (p[2] != '>' && !isspace(p[2])) { // avoid confusion with tags such as <PRE>
+            p++;
+            continue;
+        }
+        if (dst->len) // add a separator with the previous paragraph if there was one
+            av_bprintf(dst, "\\N");
+        tag = av_strtok(p, ">", &saveptr);
+        if (!tag || !saveptr)
+            break;
+        p = saveptr;
+
+        /* check if the current paragraph is the "source" (speaker name) */
+        if (av_stristr(tag, "ID=Source") || av_stristr(tag, "ID=\"Source\"")) {
+            dst = &sami->source;
+            av_bprint_clear(dst);
+        }
+
+        /* if empty event -> skip subtitle */
+        while (isspace(*p))
+            p++;
+        if (!strncmp(p, "&nbsp;", 6)) {
+            ret = -1;
+            goto end;
+        }
+
+        /* extract the text, stripping most of the tags */
+        while (*p) {
+            if (*p == '<') {
+                if (!av_strncasecmp(p, "<P", 2) && (p[2] == '>' || isspace(p[2])))
+                    break;
+                if (!av_strncasecmp(p, "<BR", 3))
+                    av_bprintf(dst, "\\N");
+                p++;
+                while (*p && *p != '>')
+                    p++;
+                if (!*p)
+                    break;
+                if (*p == '>')
+                    p++;
+            }
+            if (!isspace(*p))
+                av_bprint_chars(dst, *p, 1);
+            else if (!prev_chr_is_space)
+                av_bprint_chars(dst, ' ', 1);
+            prev_chr_is_space = isspace(*p);
+            p++;
+        }
+    }
+
+    av_bprint_clear(&sami->full);
+    if (sami->source.len)
+        av_bprintf(&sami->full, "{\\i1}%s{\\i0}\\N", sami->source.str);
+    av_bprintf(&sami->full, "%s\r\n", sami->content.str);
+
+end:
+    av_free(dupsrc);
+    return ret;
+}
+
+static int sami_decode_frame(AVCodecContext *avctx,
+                             void *data, int *got_sub_ptr, AVPacket *avpkt)
+{
+    AVSubtitle *sub = data;
+    const char *ptr = avpkt->data;
+    SAMIContext *sami = avctx->priv_data;
+
+    if (ptr && avpkt->size > 0 && !sami_paragraph_to_ass(avctx, ptr)) {
+        int ts_start     = av_rescale_q(avpkt->pts, avctx->time_base, (AVRational){1,100});
+        int ts_duration  = avpkt->duration != -1 ?
+                           av_rescale_q(avpkt->duration, avctx->time_base, (AVRational){1,100}) : -1;
+        ff_ass_add_rect(sub, sami->full.str, ts_start, ts_duration, 0);
+    }
+    *got_sub_ptr = sub->num_rects > 0;
+    return avpkt->size;
+}
+
+static av_cold int sami_init(AVCodecContext *avctx)
+{
+    SAMIContext *sami = avctx->priv_data;
+    av_bprint_init(&sami->source,  0, 2048);
+    av_bprint_init(&sami->content, 0, 2048);
+    av_bprint_init(&sami->full,    0, 2048);
+    return ff_ass_subtitle_header_default(avctx);
+}
+
+static av_cold int sami_close(AVCodecContext *avctx)
+{
+    SAMIContext *sami = avctx->priv_data;
+    av_bprint_finalize(&sami->source,  NULL);
+    av_bprint_finalize(&sami->content, NULL);
+    av_bprint_finalize(&sami->full,    NULL);
+    return 0;
+}
+
+AVCodec ff_sami_decoder = {
+    .name           = "sami",
+    .long_name      = NULL_IF_CONFIG_SMALL("SAMI subtitle"),
+    .type           = AVMEDIA_TYPE_SUBTITLE,
+    .id             = CODEC_ID_SAMI,
+    .priv_data_size = sizeof(SAMIContext),
+    .init           = sami_init,
+    .close          = sami_close,
+    .decode         = sami_decode_frame,
+};