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-rw-r--r--libavcodec/movtextdec.c116
1 files changed, 116 insertions, 0 deletions
diff --git a/libavcodec/movtextdec.c b/libavcodec/movtextdec.c
new file mode 100644
index 0000000000..05ff53afb4
--- /dev/null
+++ b/libavcodec/movtextdec.c
@@ -0,0 +1,116 @@
+/*
+ * 3GPP TS 26.245 Timed Text decoder
+ * Copyright (c) 2012 Philip Langdale <philipl@overt.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 "avcodec.h"
+#include "ass.h"
+#include "libavutil/avstring.h"
+#include "libavutil/common.h"
+#include "libavutil/bprint.h"
+#include "libavutil/intreadwrite.h"
+
+static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end)
+{
+ while (text < text_end) {
+ switch (*text) {
+ case '\r':
+ break;
+ case '\n':
+ av_bprintf(buf, "\\N");
+ break;
+ default:
+ av_bprint_chars(buf, *text, 1);
+ break;
+ }
+ text++;
+ }
+
+ av_bprintf(buf, "\r\n");
+ return 0;
+}
+
+static int mov_text_init(AVCodecContext *avctx) {
+ /*
+ * TODO: Handle the default text style.
+ * NB: Most players ignore styles completely, with the result that
+ * it's very common to find files where the default style is broken
+ * and respecting it results in a worse experience than ignoring it.
+ */
+ return ff_ass_subtitle_header_default(avctx);
+}
+
+static int mov_text_decode_frame(AVCodecContext *avctx,
+ void *data, int *got_sub_ptr, AVPacket *avpkt)
+{
+ AVSubtitle *sub = data;
+ int ts_start, ts_end;
+ AVBPrint buf;
+ const char *ptr = avpkt->data;
+ const char *end;
+
+ if (!ptr || avpkt->size < 2)
+ return AVERROR_INVALIDDATA;
+
+ /*
+ * A packet of size two with value zero is an empty subtitle
+ * used to mark the end of the previous non-empty subtitle.
+ * We can just drop them here as we have duration information
+ * already. If the value is non-zero, then it's technically a
+ * bad packet.
+ */
+ if (avpkt->size == 2)
+ return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;
+
+ /*
+ * The first two bytes of the packet are the length of the text string
+ * In complex cases, there are style descriptors appended to the string
+ * so we can't just assume the packet size is the string size.
+ */
+ end = ptr + FFMIN(2 + AV_RB16(ptr), avpkt->size);
+ ptr += 2;
+
+ ts_start = av_rescale_q(avpkt->pts,
+ avctx->time_base,
+ (AVRational){1,100});
+ ts_end = av_rescale_q(avpkt->pts + avpkt->duration,
+ avctx->time_base,
+ (AVRational){1,100});
+
+ // Note that the spec recommends lines be no longer than 2048 characters.
+ av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
+ text_to_ass(&buf, ptr, end);
+
+ if (!av_bprint_is_complete(&buf))
+ return AVERROR(ENOMEM);
+
+ ff_ass_add_rect(sub, buf.str, ts_start, ts_end-ts_start, 0);
+ *got_sub_ptr = sub->num_rects > 0;
+ av_bprint_finalize(&buf, NULL);
+ return avpkt->size;
+}
+
+AVCodec ff_movtext_decoder = {
+ .name = "mov_text",
+ .long_name = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"),
+ .type = AVMEDIA_TYPE_SUBTITLE,
+ .id = AV_CODEC_ID_MOV_TEXT,
+ .init = mov_text_init,
+ .decode = mov_text_decode_frame,
+};