AVFormat: LRC demuxer and muxer

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

Changelog

@@ -32,6 +32,7 @@ version <next>:
 - hqx filter (hq2x, hq3x, hq4x)
 - flanger filter
 - Image format auto-detection
+- LRC demuxer and muxer
 
 
 version 2.2:

doc/general.texi

@@ -310,6 +310,7 @@ library:
     @tab Used by Linux Media Labs MPEG-4 PCI boards
 @item LOAS                      @tab   @tab X
     @tab contains LATM multiplexed AAC audio
+@item LRC                       @tab X @tab X
 @item LVF                       @tab   @tab X
 @item LXF                       @tab   @tab X
     @tab VR native stream format, used by Leitch/Harris' video servers.

libavformat/Makefile

@@ -211,6 +211,8 @@ OBJS-$(CONFIG_LATM_DEMUXER)              += rawdec.o
 OBJS-$(CONFIG_LATM_MUXER)                += latmenc.o rawenc.o
 OBJS-$(CONFIG_LMLM4_DEMUXER)             += lmlm4.o
 OBJS-$(CONFIG_LOAS_DEMUXER)              += loasdec.o rawdec.o
+OBJS-$(CONFIG_LRC_DEMUXER)               += lrcdec.o lrc.o subtitles.o
+OBJS-$(CONFIG_LRC_MUXER)                 += lrcenc.o lrc.o
 OBJS-$(CONFIG_LVF_DEMUXER)               += lvfdec.o
 OBJS-$(CONFIG_LXF_DEMUXER)               += lxfdec.o
 OBJS-$(CONFIG_M4V_DEMUXER)               += m4vdec.o rawdec.o

libavformat/allformats.c

@@ -163,6 +163,7 @@ void av_register_all(void)
     REGISTER_MUXDEMUX(LATM,             latm);
     REGISTER_DEMUXER (LMLM4,            lmlm4);
     REGISTER_DEMUXER (LOAS,             loas);
+    REGISTER_MUXDEMUX(LRC,              lrc);
     REGISTER_DEMUXER (LVF,              lvf);
     REGISTER_DEMUXER (LXF,              lxf);
     REGISTER_MUXDEMUX(M4V,              m4v);

libavformat/lrc.c

+/*
+ * 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 "metadata.h"
+#include "lrc.h"
+
+const AVMetadataConv ff_lrc_metadata_conv[] = {
+    {"ti", "title"},
+    {"al", "album"},
+    {"ar", "artist"},
+    {"au", "author"},
+    {"by", "creator"},
+    {"re", "encoder"},
+    {"ve", "encoder_version"},
+    {0, 0}
+};

libavformat/lrc.h

+/*
+ * 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
+ */
+
+#ifndef AVFORMAT_LRC_H
+#define AVFORMAT_LRC_H
+
+#include "metadata.h"
+
+extern const AVMetadataConv ff_lrc_metadata_conv[];
+
+#endif

libavformat/lrcdec.c

+/*
+ * 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
+};

libavformat/lrcenc.c

+/*
+ * 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
+};