avformat: add Scenarist Closed Captions demuxer

Fixes #4767.

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 183 insertions, 0 deletions

diff --git a/libavformat/sccdec.c b/libavformat/sccdec.c
new file mode 100644
index 0000000000..a4ce5572a4
--- /dev/null
+++ b/libavformat/sccdec.c
@@ -0,0 +1,183 @@
+/*
+ * SCC subtitle demuxer
+ * Copyright (c) 2017 Paul B Mahol
+ *
+ * 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 "avformat.h"
+#include "internal.h"
+#include "subtitles.h"
+#include "libavutil/bprint.h"
+#include "libavutil/intreadwrite.h"
+
+typedef struct SCCContext {
+    FFDemuxSubtitlesQueue q;
+} SCCContext;
+
+static int scc_probe(AVProbeData *p)
+{
+    char buf[128];
+    FFTextReader tr;
+
+    ff_text_init_buf(&tr, p->buf, p->buf_size);
+
+    while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n')
+        ff_text_r8(&tr);
+
+    if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0)
+        return 0;
+
+    if (!memcmp(buf, "Scenarist_SCC V1.0", 18))
+        return AVPROBE_SCORE_MAX;
+
+    return 0;
+}
+
+static int convert(uint8_t x)
+{
+    if (x >= 'a')
+        x -= 87;
+    else if (x >= 'A')
+        x -= 55;
+    else
+        x -= '0';
+    return x;
+}
+
+static int scc_read_header(AVFormatContext *s)
+{
+    SCCContext *scc = s->priv_data;
+    AVStream *st = avformat_new_stream(s, NULL);
+    char line[4096], line2[4096];
+    int count = 0, ret = 0;
+    ptrdiff_t len2, len;
+    uint8_t out[4096];
+    FFTextReader tr;
+
+    ff_text_init_avio(s, &tr, s->pb);
+
+    if (!st)
+        return AVERROR(ENOMEM);
+    avpriv_set_pts_info(st, 64, 1, 1000);
+    st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
+    st->codecpar->codec_id   = AV_CODEC_ID_EIA_608;
+
+    while (!ff_text_eof(&tr)) {
+        const int64_t pos = ff_text_pos(&tr);
+        char *saveptr = NULL, *lline;
+        int hh1, mm1, ss1, fs1, i;
+        int hh2, mm2, ss2, fs2;
+        int64_t ts_start, ts_end;
+        AVPacket *sub;
+
+        if (count == 0) {
+            while (!ff_text_eof(&tr)) {
+                len = ff_subtitles_read_line(&tr, line, sizeof(line));
+                if (len > 13)
+                    break;
+            }
+        }
+
+        if (!strncmp(line, "Scenarist_SCC V1.0", 18))
+            continue;
+        if (sscanf(line, "%d:%d:%d:%d", &hh1, &mm1, &ss1, &fs1) != 4 &&
+            sscanf(line, "%d:%d:%d;%d", &hh1, &mm1, &ss1, &fs1) != 4)
+            continue;
+
+        ts_start = (hh1 * 3600LL + mm1 * 60LL + ss1) * 1000LL + fs1 * 33;
+
+        while (!ff_text_eof(&tr)) {
+            len2 = ff_subtitles_read_line(&tr, line2, sizeof(line2));
+            if (len2 > 13)
+                break;
+        }
+        if (sscanf(line2, "%d:%d:%d:%d", &hh2, &mm2, &ss2, &fs2) != 4 &&
+            sscanf(line2, "%d:%d:%d;%d", &hh2, &mm2, &ss2, &fs2) != 4)
+            continue;
+
+        ts_end = (hh2 * 3600LL + mm2 * 60LL + ss2) * 1000LL + fs2 * 33;
+        count++;
+
+        lline = (char *)&line;
+        lline += 12;
+
+        for (i = 0; i < 4095; i += 3) {
+            char *ptr = av_strtok(lline, " ", &saveptr);
+            char c1, c2, c3, c4;
+
+            if (!ptr)
+                break;
+
+            if (sscanf(ptr, "%c%c%c%c", &c1, &c2, &c3, &c4) != 4)
+                break;
+
+            lline = NULL;
+            out[i+0] = 0xfc;
+            out[i+1] = convert(c2) | (convert(c1) << 4);
+            out[i+2] = convert(c4) | (convert(c3) << 4);
+        }
+        out[i] = 0;
+
+        sub = ff_subtitles_queue_insert(&scc->q, out, i, 0);
+        if (!sub)
+            return AVERROR(ENOMEM);
+
+        sub->pos = pos;
+        sub->pts = ts_start;
+        sub->duration = FFMAX(1200, ts_end - ts_start);
+        memmove(line, line2, sizeof(line));
+        FFSWAP(ptrdiff_t, len, len2);
+    }
+
+    ff_subtitles_queue_finalize(s, &scc->q);
+
+    return ret;
+}
+
+static int scc_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    SCCContext *scc = s->priv_data;
+    return ff_subtitles_queue_read_packet(&scc->q, pkt);
+}
+
+static int scc_read_seek(AVFormatContext *s, int stream_index,
+                         int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
+{
+    SCCContext *scc = s->priv_data;
+    return ff_subtitles_queue_seek(&scc->q, s, stream_index,
+                                   min_ts, ts, max_ts, flags);
+}
+
+static int scc_read_close(AVFormatContext *s)
+{
+    SCCContext *scc = s->priv_data;
+    ff_subtitles_queue_clean(&scc->q);
+    return 0;
+}
+
+AVInputFormat ff_scc_demuxer = {
+    .name           = "scc",
+    .long_name      = NULL_IF_CONFIG_SMALL("Scenarist Closed Captions"),
+    .priv_data_size = sizeof(SCCContext),
+    .read_probe     = scc_probe,
+    .read_header    = scc_read_header,
+    .read_packet    = scc_read_packet,
+    .read_seek2     = scc_read_seek,
+    .read_close     = scc_read_close,
+    .extensions     = "scc",
+};