lavf: TED Talks JSON captions demuxer.

1 files changed, 365 insertions, 0 deletions

diff --git a/libavformat/tedcaptionsdec.c b/libavformat/tedcaptionsdec.c
new file mode 100644
index 0000000000..85bed0a9ac
--- /dev/null
+++ b/libavformat/tedcaptionsdec.c
@@ -0,0 +1,365 @@
+/*
+ * TED Talks captions format decoder
+ * Copyright (c) 2012 Nicolas George
+ *
+ * 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/bprint.h"
+#include "libavutil/log.h"
+#include "libavutil/opt.h"
+#include "avformat.h"
+#include "internal.h"
+#include "subtitles.h"
+
+typedef struct {
+    AVClass *class;
+    int64_t start_time;
+    FFDemuxSubtitlesQueue subs;
+} TEDCaptionsDemuxer;
+
+static const AVOption tedcaptions_options[] = {
+    { "start_time", "set the start time (offset) of the subtitles, in ms",
+      offsetof(TEDCaptionsDemuxer, start_time), FF_OPT_TYPE_INT64,
+      { .i64 = 15000 }, INT64_MIN, INT64_MAX,
+      AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM },
+    { NULL },
+};
+
+static const AVClass tedcaptions_demuxer_class = {
+    .class_name = "tedcaptions_demuxer",
+    .item_name  = av_default_item_name,
+    .option     = tedcaptions_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+#define BETWEEN(a, amin, amax) ((unsigned)((a) - (amin)) <= (amax) - (amin))
+
+#define HEX_DIGIT_TEST(c) (BETWEEN(c, '0', '9') || BETWEEN((c) | 32, 'a', 'z'))
+#define HEX_DIGIT_VAL(c) ((c) <= '9' ? (c) - '0' : ((c) | 32) - 'a' + 10)
+#define ERR_CODE(c) (c < 0 ? c : AVERROR_INVALIDDATA)
+
+static void av_bprint_utf8(AVBPrint *bp, unsigned c)
+{
+    int bytes, i;
+
+    if (c <= 0x7F) {
+        av_bprint_chars(bp, c, 1);
+        return;
+    }
+    bytes = (av_log2(c) - 2) / 5;
+    av_bprint_chars(bp, (c >> (bytes * 6)) | ((0xFF80 >> bytes) & 0xFF), 1);
+    for (i = bytes - 1; i >= 0; i--)
+        av_bprint_chars(bp, ((c >> (i * 6)) & 0x3F) | 0x80, 1);
+}
+
+static void next_byte(AVIOContext *pb, int *cur_byte)
+{
+    uint8_t b;
+    int ret = avio_read(pb, &b, 1);
+    *cur_byte = ret > 0 ? b : ret == 0 ? AVERROR_EOF : ret;
+}
+
+static void skip_spaces(AVIOContext *pb, int *cur_byte)
+{
+    while (*cur_byte == ' '  || *cur_byte == '\t' ||
+           *cur_byte == '\n' || *cur_byte == '\r')
+        next_byte(pb, cur_byte);
+}
+
+static int expect_byte(AVIOContext *pb, int *cur_byte, uint8_t c)
+{
+    skip_spaces(pb, cur_byte);
+    if (*cur_byte != c)
+        return ERR_CODE(*cur_byte);
+    next_byte(pb, cur_byte);
+    return 0;
+}
+
+static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full)
+{
+    int ret;
+
+    av_bprint_init(bp, 0, full ? -1 : 1);
+    ret = expect_byte(pb, cur_byte, '"');
+    if (ret < 0)
+        goto fail;
+    while (*cur_byte > 0 && *cur_byte != '"') {
+        if (*cur_byte == '\\') {
+            next_byte(pb, cur_byte);
+            if (*cur_byte < 0) {
+                ret = AVERROR_INVALIDDATA;
+                goto fail;
+            }
+            if ((*cur_byte | 32) == 'u') {
+                unsigned chr = 0, i;
+                for (i = 0; i < 4; i++) {
+                    next_byte(pb, cur_byte);
+                    if (!HEX_DIGIT_TEST(*cur_byte)) {
+                        ret = ERR_CODE(*cur_byte);
+                        goto fail;
+                    }
+                    chr = chr * 16 + HEX_DIGIT_VAL(*cur_byte);
+                }
+                av_bprint_utf8(bp, chr);
+            } else {
+                av_bprint_chars(bp, *cur_byte, 1);
+            }
+        } else {
+            av_bprint_chars(bp, *cur_byte, 1);
+        }
+        next_byte(pb, cur_byte);
+    }
+    ret = expect_byte(pb, cur_byte, '"');
+    if (ret < 0)
+        goto fail;
+    if (full && !av_bprint_is_complete(bp)) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+    return 0;
+
+fail:
+    av_bprint_finalize(bp, NULL);
+    return ret;
+}
+
+static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp)
+{
+    int ret;
+
+    ret = parse_string(pb, cur_byte, bp, 0);
+    if (ret < 0)
+        return ret;
+    ret = expect_byte(pb, cur_byte, ':');
+    if (ret < 0)
+        return ret;
+    return 0;
+}
+
+static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result)
+{
+    const char *text[] = { "false", "true" }, *p;
+    int i;
+
+    skip_spaces(pb, cur_byte);
+    for (i = 0; i < 2; i++) {
+        p = text[i];
+        if (*cur_byte != *p)
+            continue;
+        for (; *p; p++, next_byte(pb, cur_byte))
+            if (*cur_byte != *p)
+                return AVERROR_INVALIDDATA;
+        if (BETWEEN(*cur_byte | 32, 'a', 'z'))
+            return AVERROR_INVALIDDATA;
+        *result = i;
+        return 0;
+    }
+    return AVERROR_INVALIDDATA;
+}
+
+static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result)
+{
+    int64_t val = 0;
+
+    skip_spaces(pb, cur_byte);
+    if ((unsigned)*cur_byte - '0' > 9)
+        return AVERROR_INVALIDDATA;
+    while (BETWEEN(*cur_byte, '0', '9')) {
+        val = val * 10 + (*cur_byte - '0');
+        next_byte(pb, cur_byte);
+    }
+    *result = val;
+    return 0;
+}
+
+static int parse_file(AVIOContext *pb, FFDemuxSubtitlesQueue *subs)
+{
+    int ret, cur_byte, start_of_par;
+    AVBPrint label, content;
+    int64_t pos, start, duration;
+    AVPacket *pkt;
+
+    next_byte(pb, &cur_byte);
+    ret = expect_byte(pb, &cur_byte, '{');
+    if (ret < 0)
+        return AVERROR_INVALIDDATA;
+    ret = parse_label(pb, &cur_byte, &label);
+    if (ret < 0 || strcmp(label.str, "captions"))
+        return AVERROR_INVALIDDATA;
+    ret = expect_byte(pb, &cur_byte, '[');
+    if (ret < 0)
+        return AVERROR_INVALIDDATA;
+    while (1) {
+        content.size = 0;
+        start = duration = AV_NOPTS_VALUE;
+        ret = expect_byte(pb, &cur_byte, '{');
+        if (ret < 0)
+            return ret;
+        pos = avio_tell(pb) - 1;
+        while (1) {
+            ret = parse_label(pb, &cur_byte, &label);
+            if (ret < 0)
+                return ret;
+            if (!strcmp(label.str, "startOfParagraph")) {
+                ret = parse_boolean(pb, &cur_byte, &start_of_par);
+                if (ret < 0)
+                    return ret;
+            } else if (!strcmp(label.str, "content")) {
+                ret = parse_string(pb, &cur_byte, &content, 1);
+                if (ret < 0)
+                    return ret;
+            } else if (!strcmp(label.str, "startTime")) {
+                ret = parse_int(pb, &cur_byte, &start);
+                if (ret < 0)
+                    return ret;
+            } else if (!strcmp(label.str, "duration")) {
+                ret = parse_int(pb, &cur_byte, &duration);
+                if (ret < 0)
+                    return ret;
+            } else {
+                return AVERROR_INVALIDDATA;
+            }
+            skip_spaces(pb, &cur_byte);
+            if (cur_byte != ',')
+                break;
+            next_byte(pb, &cur_byte);
+        }
+        ret = expect_byte(pb, &cur_byte, '}');
+        if (ret < 0)
+            return ret;
+
+        if (!content.size || start == AV_NOPTS_VALUE ||
+            duration == AV_NOPTS_VALUE)
+            return AVERROR_INVALIDDATA;
+        pkt = ff_subtitles_queue_insert(subs, content.str, content.len, 0);
+        if (!pkt)
+            return AVERROR(ENOMEM);
+        pkt->pos      = pos;
+        pkt->pts      = start;
+        pkt->duration = duration;
+        av_bprint_finalize(&content, NULL);
+
+        skip_spaces(pb, &cur_byte);
+        if (cur_byte != ',')
+            break;
+        next_byte(pb, &cur_byte);
+    }
+    ret = expect_byte(pb, &cur_byte, ']');
+    if (ret < 0)
+        return ret;
+    ret = expect_byte(pb, &cur_byte, '}');
+    if (ret < 0)
+        return ret;
+    skip_spaces(pb, &cur_byte);
+    if (cur_byte != AVERROR_EOF)
+        return ERR_CODE(cur_byte);
+    return 0;
+}
+
+static av_cold int tedcaptions_read_header(AVFormatContext *avf)
+{
+    TEDCaptionsDemuxer *tc = avf->priv_data;
+    AVStream *st;
+    int ret, i;
+    AVPacket *last;
+
+    ret = parse_file(avf->pb, &tc->subs);
+    if (ret < 0) {
+        if (ret == AVERROR_INVALIDDATA)
+            av_log(avf, AV_LOG_ERROR, "Syntax error near offset %"PRId64".\n",
+                   avio_tell(avf->pb));
+        ff_subtitles_queue_clean(&tc->subs);
+        return ret;
+    }
+    ff_subtitles_queue_finalize(&tc->subs);
+    for (i = 0; i < tc->subs.nb_subs; i++)
+        tc->subs.subs[i].pts += tc->start_time;
+
+    last = &tc->subs.subs[tc->subs.nb_subs - 1];
+    st = avformat_new_stream(avf, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+    st->codec->codec_type     = AVMEDIA_TYPE_SUBTITLE;
+    st->codec->codec_id       = CODEC_ID_TEXT;
+    avpriv_set_pts_info(st, 64, 1, 1000);
+    st->probe_packets = 0;
+    st->start_time    = 0;
+    st->duration      = last->pts + last->duration;
+    st->cur_dts       = 0;
+
+    return 0;
+}
+
+static int tedcaptions_read_packet(AVFormatContext *avf, AVPacket *packet)
+{
+    TEDCaptionsDemuxer *tc = avf->priv_data;
+
+    return ff_subtitles_queue_read_packet(&tc->subs, packet);
+}
+
+static int tedcaptions_read_close(AVFormatContext *avf)
+{
+    TEDCaptionsDemuxer *tc = avf->priv_data;
+
+    ff_subtitles_queue_clean(&tc->subs);
+    return 0;
+}
+
+static av_cold int tedcaptions_read_probe(AVProbeData *p)
+{
+    static const char *const tags[] = {
+        "\"captions\"", "\"duration\"", "\"content\"",
+        "\"startOfParagraph\"", "\"startTime\"",
+    };
+    unsigned i, count = 0;
+    const char *t;
+
+    if (p->buf[strspn(p->buf, " \t\r\n")] != '{')
+        return 0;
+    for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) {
+        if (!(t = strstr(p->buf, tags[i])))
+            continue;
+        t += strlen(tags[i]);
+        t += strspn(t, " \t\r\n");
+        if (*t == ':')
+            count++;
+    }
+    return count == FF_ARRAY_ELEMS(tags) ? AVPROBE_SCORE_MAX :
+           count                         ? AVPROBE_SCORE_MAX / 2 : 0;
+}
+
+static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index,
+                                 int64_t min_ts, int64_t ts, int64_t max_ts,
+                                 int flags)
+{
+    TEDCaptionsDemuxer *tc = avf->priv_data;
+    return ff_subtitles_queue_seek(&tc->subs, avf, stream_index,
+                                   min_ts, ts, max_ts, flags);
+}
+
+AVInputFormat ff_tedcaptions_demuxer = {
+    .name           = "tedcaptions",
+    .long_name      = NULL_IF_CONFIG_SMALL("TED Talks captions"),
+    .priv_data_size = sizeof(TEDCaptionsDemuxer),
+    .priv_class     = &tedcaptions_demuxer_class,
+    .read_header    = tedcaptions_read_header,
+    .read_packet    = tedcaptions_read_packet,
+    .read_close     = tedcaptions_read_close,
+    .read_probe     = tedcaptions_read_probe,
+    .read_seek2     = tedcaptions_read_seek,
+};