AVFormat: LRC demuxer and muxer

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

1 files changed, 152 insertions, 0 deletions

diff --git a/libavformat/lrcenc.c b/libavformat/lrcenc.c
new file mode 100644
index 0000000000..c1afc2ccac
--- /dev/null
+++ b/libavformat/lrcenc.c
@@ -0,0 +1,152 @@
+/*
+ * 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 "version.h"
+#include "libavutil/bprint.h"
+#include "libavutil/dict.h"
+#include "libavutil/log.h"
+#include "libavutil/macros.h"
+
+static int lrc_write_header(AVFormatContext *s)
+{
+    const AVDictionaryEntry *metadata_item;
+
+    if(s->nb_streams != 1 ||
+       s->streams[0]->codec->codec_type != AVMEDIA_TYPE_SUBTITLE) {
+        av_log(s, AV_LOG_ERROR,
+               "LRC supports only a single subtitle stream.\n");
+        return AVERROR(EINVAL);
+    }
+    if(s->streams[0]->codec->codec_id != AV_CODEC_ID_SUBRIP &&
+       s->streams[0]->codec->codec_id != AV_CODEC_ID_TEXT) {
+        av_log(s, AV_LOG_ERROR, "Unsupported subtitle codec: %s\n",
+               avcodec_get_name(s->streams[0]->codec->codec_id));
+        return AVERROR(EINVAL);
+    }
+    avpriv_set_pts_info(s->streams[0], 64, 1, 100);
+
+    ff_metadata_conv_ctx(s, ff_lrc_metadata_conv, NULL);
+    if(!(s->flags & AVFMT_FLAG_BITEXACT)) { // avoid breaking regression tests
+        /* LRC provides a metadata slot for specifying encoder version
+         * in addition to encoder name. We will store LIBAVFORMAT_VERSION
+         * to it.
+         */
+        av_dict_set(&s->metadata, "ve", AV_STRINGIFY(LIBAVFORMAT_VERSION), 0);
+    } else {
+        av_dict_set(&s->metadata, "ve", NULL, 0);
+    }
+    for(metadata_item = NULL;
+       (metadata_item = av_dict_get(s->metadata, "", metadata_item,
+                                    AV_DICT_IGNORE_SUFFIX)) != NULL;) {
+        char *delim;
+        if(!metadata_item->value[0]) {
+            continue;
+        }
+        while((delim = strchr(metadata_item->value, '\n')) != NULL) {
+            *delim = ' ';
+        }
+        while((delim = strchr(metadata_item->value, '\r')) != NULL) {
+            *delim = ' ';
+        }
+        avio_printf(s->pb, "[%s:%s]\n",
+                    metadata_item->key, metadata_item->value);
+    }
+    avio_printf(s->pb, "\n");
+    return 0;
+}
+
+static int lrc_write_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    if(pkt->pts != AV_NOPTS_VALUE) {
+        char *data = av_malloc(pkt->size + 1);
+        char *line;
+        char *delim;
+
+        if(!data) {
+            return AVERROR(ENOMEM);
+        }
+        memcpy(data, pkt->data, pkt->size);
+        data[pkt->size] = '\0';
+
+        for(delim = data + pkt->size - 1;
+            delim >= data && (delim[0] == '\n' || delim[0] == '\r'); delim--) {
+            delim[0] = '\0'; // Strip last empty lines
+        }
+        line = data;
+        while(line[0] == '\n' || line[0] == '\r') {
+            line++; // Skip first empty lines
+        }
+
+        while(line) {
+            delim = strchr(line, '\n');
+            if(delim) {
+                if(delim > line && delim[-1] == '\r') {
+                    delim[-1] = '\0';
+                }
+                delim[0] = '\0';
+                delim++;
+            }
+            if(line[0] == '[') {
+                av_log(s, AV_LOG_WARNING,
+                       "Subtitle starts with '[', may cause problems with LRC format.\n");
+            }
+
+            if(pkt->pts >= 0) {
+                avio_printf(s->pb, "[%02"PRId64":%02"PRId64".%02"PRId64"]",
+                            (pkt->pts / 6000),
+                            ((pkt->pts / 100) % 60),
+                            (pkt->pts % 100));
+            } else {
+                /* Offset feature of LRC can easily make pts negative,
+                 * we just output it directly and let the player drop it. */
+                avio_printf(s->pb, "[-%02"PRId64":%02"PRId64".%02"PRId64"]",
+                            (-pkt->pts) / 6000,
+                            ((-pkt->pts) / 100) % 60,
+                            (-pkt->pts) % 100);
+            }
+            avio_printf(s->pb, "%s\n", line);
+            line = delim;
+        }
+        av_free(data);
+    }
+    return 0;
+}
+
+AVOutputFormat ff_lrc_muxer = {
+    .name           = "lrc",
+    .long_name      = NULL_IF_CONFIG_SMALL("LRC lyrics"),
+    .extensions     = "lrc",
+    .priv_data_size = 0,
+    .write_header   = lrc_write_header,
+    .write_packet   = lrc_write_packet,
+    .flags          = AVFMT_VARIABLE_FPS | AVFMT_GLOBALHEADER |
+                      AVFMT_TS_NEGATIVE | AVFMT_TS_NONSTRICT,
+    .subtitle_codec = AV_CODEC_ID_SUBRIP
+};