AVFormat: LRC demuxer and muxer

Reviewed-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 248 insertions, 0 deletions

diff --git a/libavformat/lrcdec.c b/libavformat/lrcdec.c
new file mode 100644
index 0000000000..3b02e3492a
--- /dev/null
+++ b/libavformat/lrcdec.c
@@ -0,0 +1,248 @@
+/*
+ * LRC lyrics file format decoder
+ * Copyright (c) 2014 StarBrilliant <m13253@hotmail.com>
+ *
+ * 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 <inttypes.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "avformat.h"
+#include "internal.h"
+#include "lrc.h"
+#include "metadata.h"
+#include "subtitles.h"
+#include "libavutil/bprint.h"
+#include "libavutil/dict.h"
+
+typedef struct LRCContext {
+    FFDemuxSubtitlesQueue q;
+    int64_t ts_offset; // offset metadata item
+} LRCContext;
+
+static int64_t find_header(const char *p)
+{
+    int64_t offset = 0;
+    while(p[offset] == ' ' || p[offset] == '\t') {
+        offset++;
+    }
+    if(p[offset] == '[' && p[offset + 1] >= 'a' && p[offset + 1] <= 'z') {
+        return offset;
+    } else {
+        return -1;
+    }
+}
+
+static int64_t count_ts(const char *p)
+{
+    int64_t offset = 0;
+    int in_brackets = 0;
+
+    for(;;) {
+        if(p[offset] == ' ' || p[offset] == '\t') {
+            offset++;
+        } else if(p[offset] == '[') {
+            offset++;
+            in_brackets++;
+        } else if (p[offset] == ']' && in_brackets) {
+            offset++;
+            in_brackets--;
+        } else if(in_brackets &&
+                 (p[offset] == ':' || p[offset] == '.' || p[offset] == '-' ||
+                 (p[offset] >= '0' && p[offset] <= '9'))) {
+            offset++;
+        } else {
+            break;
+        }
+    }
+    return offset;
+}
+
+static int64_t read_ts(const char *p, int64_t *start)
+{
+    int64_t offset = 0;
+    uint64_t mm, ss, cs;
+
+    while(p[offset] == ' ' || p[offset] == '\t') {
+        offset++;
+    }
+    if(p[offset] != '[') {
+        return 0;
+    }
+    if(sscanf(p, "[-%"SCNu64":%"SCNu64".%"SCNu64"]", &mm, &ss, &cs) == 3) {
+        /* Just in case negative pts, players may drop it but we won't. */
+        *start = -(int64_t) (mm*60000 + ss*1000 + cs*10);
+    } else if(sscanf(p, "[%"SCNu64":%"SCNu64".%"SCNu64"]", &mm, &ss, &cs) == 3) {
+        *start = mm*60000 + ss*1000 + cs*10;
+    } else {
+        return 0;
+    }
+    do {
+        offset++;
+    } while(p[offset] && p[offset-1] != ']');
+    return offset;
+}
+
+static int64_t read_line(AVBPrint *buf, AVIOContext *pb)
+{
+    int64_t pos = avio_tell(pb);
+
+    av_bprint_clear(buf);
+    while(!url_feof(pb)) {
+        int c = avio_r8(pb);
+        if(c != '\r') {
+            av_bprint_chars(buf, c, 1);
+        }
+        if(c == '\n') {
+            break;
+        }
+    }
+    return pos;
+}
+
+static int lrc_probe(AVProbeData *p)
+{
+    int64_t offset = 0;
+    int64_t mm;
+    uint64_t ss, cs;
+    const AVMetadataConv *metadata_item;
+
+    if(!memcmp(p->buf, "\xef\xbb\xbf", 3)) { // Skip UTF-8 BOM header
+        offset += 3;
+    }
+    while(p->buf[offset] == '\n' || p->buf[offset] == '\r') {
+        offset++;
+    }
+    if(p->buf[offset] != '[') {
+        return 0;
+    }
+    offset++;
+    // Common metadata item but not exist in ff_lrc_metadata_conv
+    if(!memcmp(p->buf + offset, "offset:", 7)) {
+        return 40;
+    }
+    if(sscanf(p->buf + offset, "%"SCNd64":%"SCNu64".%"SCNu64"]",
+              &mm, &ss, &cs) == 3) {
+        return 50;
+    }
+    // Metadata items exist in ff_lrc_metadata_conv
+    for(metadata_item = ff_lrc_metadata_conv;
+        metadata_item->native; metadata_item++) {
+        size_t metadata_item_len = strlen(metadata_item->native);
+        if(p->buf[offset + metadata_item_len] == ':' &&
+           !memcmp(p->buf + offset, metadata_item->native, metadata_item_len)) {
+            return 40;
+        }
+    }
+    return 5; // Give it 5 scores since it starts with a bracket
+}
+
+static int lrc_read_header(AVFormatContext *s)
+{
+    LRCContext *lrc = s->priv_data;
+    AVBPrint line;
+    AVStream *st;
+
+    st = avformat_new_stream(s, NULL);
+    if(!st) {
+        return AVERROR(ENOMEM);
+    }
+    avpriv_set_pts_info(st, 64, 1, 1000);
+    lrc->ts_offset = 0;
+    st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
+    st->codec->codec_id   = AV_CODEC_ID_TEXT;
+    av_bprint_init(&line, 0, AV_BPRINT_SIZE_UNLIMITED);
+
+    while(!url_feof(s->pb)) {
+        int64_t pos = read_line(&line, s->pb);
+        int64_t header_offset = find_header(line.str);
+        if(header_offset >= 0) {
+            char *comma_offset = strchr(line.str, ':');
+            if(comma_offset) {
+                char *right_bracket_offset = strchr(line.str, ']');
+                if(!right_bracket_offset) {
+                    continue;
+                }
+
+                *right_bracket_offset = *comma_offset = '\0';
+                if(strcmp(line.str + 1, "offset") ||
+                   sscanf(comma_offset + 1, "%"SCNd64, &lrc->ts_offset) != 1) {
+                    av_dict_set(&s->metadata, line.str + 1, comma_offset + 1, 0);
+                }
+                *comma_offset = ':';
+                *right_bracket_offset = ']';
+            }
+
+        } else {
+            AVPacket *sub;
+            int64_t ts_start = AV_NOPTS_VALUE;
+            int64_t ts_stroffset = 0;
+            int64_t ts_stroffset_incr = 0;
+            int64_t ts_strlength = count_ts(line.str);
+
+            while((ts_stroffset_incr = read_ts(line.str + ts_stroffset,
+                                               &ts_start)) != 0) {
+                ts_stroffset += ts_stroffset_incr;
+                sub = ff_subtitles_queue_insert(&lrc->q, line.str + ts_strlength,
+                                                line.len - ts_strlength, 0);
+                if(!sub) {
+                    return AVERROR(ENOMEM);
+                }
+                sub->pos = pos;
+                sub->pts = ts_start - lrc->ts_offset;
+                sub->duration = -1;
+            }
+        }
+    }
+    ff_subtitles_queue_finalize(&lrc->q);
+    ff_metadata_conv_ctx(s, NULL, ff_lrc_metadata_conv);
+    return 0;
+}
+
+static int lrc_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    LRCContext *lrc = s->priv_data;
+    return ff_subtitles_queue_read_packet(&lrc->q, pkt);
+}
+
+static int lrc_read_seek(AVFormatContext *s, int stream_index,
+                         int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
+{
+    LRCContext *lrc = s->priv_data;
+    return ff_subtitles_queue_seek(&lrc->q, s, stream_index,
+                                   min_ts, ts, max_ts, flags);
+}
+
+static int lrc_read_close(AVFormatContext *s)
+{
+    LRCContext *lrc = s->priv_data;
+    ff_subtitles_queue_clean(&lrc->q);
+    return 0;
+}
+
+AVInputFormat ff_lrc_demuxer = {
+    .name           = "lrc",
+    .long_name      = NULL_IF_CONFIG_SMALL("LRC lyrics"),
+    .priv_data_size = sizeof (LRCContext),
+    .read_probe     = lrc_probe,
+    .read_header    = lrc_read_header,
+    .read_packet    = lrc_read_packet,
+    .read_close     = lrc_read_close,
+    .read_seek2     = lrc_read_seek
+};