From: Andre Noll <maan@systemlinux.org>
Date: Thu, 26 Dec 2013 20:22:12 +0000 (+0000)
Subject: The mp3 tagger.
X-Git-Tag: v0.5.6~100^2~2
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=30e8f0c610f0f3279475197e70e3be62af5cfcc9

The mp3 tagger.

This commit adds support for adding and modifying the ID3 tags of mp3
files. Both ID3 version 1 and version 2 are supported. If no tags
were found, a version 2 tag is added, otherwise only the existing
tags are modified.

The documentation is updated to mention that libid3tag is required
for the new feature.
---

diff --git a/error.h b/error.h
index 697b545a..90a2fc9e 100644
--- a/error.h
+++ b/error.h
@@ -408,7 +408,10 @@ extern const char **para_errlist[];
 	PARA_ERROR(MP3_INFO, "could not read mp3 info"), \
 	PARA_ERROR(HEADER_FREQ, "invalid header frequency"), \
 	PARA_ERROR(HEADER_BITRATE, "invalid header bitrate"), \
-
+	PARA_ERROR(ID3_DETACH, "could not detach id3 frame"), \
+	PARA_ERROR(ID3_ATTACH, "could not atttach id3 frame"), \
+	PARA_ERROR(ID3_SETENCODING, "could not set id3 text encoding field"), \
+	PARA_ERROR(ID3_SETSTRING, "could not set id3 string field"), \
 
 #define AAC_AFH_ERRORS \
 	PARA_ERROR(STSZ, "did not find stcz atom"), \
diff --git a/mp3_afh.c b/mp3_afh.c
index ccd28dad..484172ab 100644
--- a/mp3_afh.c
+++ b/mp3_afh.c
@@ -22,6 +22,7 @@
 #include "error.h"
 #include "afh.h"
 #include "string.h"
+#include "fd.h"
 
 /*
  * MIN_CONSEC_GOOD_FRAMES defines how many consecutive valid MP3 frames we need
@@ -183,6 +184,201 @@ static int mp3_get_id3(unsigned char *map, size_t numbytes, __a_unused int fd,
 	return ret;
 }
 
+/* These helpers are not mentioned in the libid3tag header file. */
+void id3_field_init(union id3_field *field, enum id3_field_type type);
+void id3_field_finish(union id3_field *field);
+
+/*
+ * Frames of type ID3_FRAME_COMMENT contain three fields of type language,
+ * string, and fullstring. The third field contains the actual comment.
+ */
+static int set_comment_fields(struct id3_frame *fr, id3_ucs4_t *ucs4_val)
+{
+	int ret;
+	union id3_field *field;
+
+	field = id3_frame_field(fr, 1);
+	id3_field_init(field, ID3_FIELD_TYPE_LANGUAGE);
+
+	field = id3_frame_field(fr, 2);
+	id3_field_init(field, ID3_FIELD_TYPE_STRING);
+
+	field = id3_frame_field(fr, 3);
+	id3_field_init(field, ID3_FIELD_TYPE_STRINGFULL);
+	ret = id3_field_setfullstring(field, ucs4_val);
+	if (ret < 0)
+		return -E_ID3_SETSTRING;
+	return 1;
+}
+
+/*
+ * UCS-4 stands for Universal Character Set where each character uses exactly
+ * 32 bits. It is also known as UTF-32, see ISO 10646.
+ *
+ * We have to use UCS-4 as an intermediate representation because the functions
+ * of libid3tag which set the tag content expect an array of UCS-4 characters.
+ * Fortunately, libid3tag contains conversion functions from and to UTF-8.
+ */
+static int replace_tag(char const *id, const char *val, struct id3_tag *id3_t,
+		int options)
+{
+	int ret;
+	struct id3_frame *fr;
+	union id3_field *field;
+	id3_ucs4_t *ucs4_val;
+
+	/* First, detach all frames that match the given id. */
+	while ((fr = id3_tag_findframe(id3_t, id, 0))) {
+		PARA_INFO_LOG("deleting %s frame\n", id);
+		ret = id3_tag_detachframe(id3_t, fr);
+		if (ret < 0)
+			return -E_ID3_DETACH;
+		id3_frame_delete(fr);
+	}
+	if (!val || !*val)
+		return 0;
+	fr = id3_frame_new(id);
+	PARA_DEBUG_LOG("frame desc: %s, %d fields\n", fr->description, fr->nfields);
+
+	/* Frame 0 contains the encoding. We always use UTF-8. */
+	field = id3_frame_field(fr, 0);
+	id3_field_init(field, ID3_FIELD_TYPE_TEXTENCODING);
+	ret = id3_field_settextencoding(field, ID3_FIELD_TEXTENCODING_UTF_8);
+	if (ret < 0)
+		return -E_ID3_SETENCODING;
+	/* create UCS-4 representation */
+	ucs4_val = id3_utf8_ucs4duplicate((const id3_utf8_t *)val);
+
+	if (strcmp(id, ID3_FRAME_COMMENT) == 0)
+		ret = set_comment_fields(fr, ucs4_val);
+	else {
+		/* Non-comment frames contain the value in field 1. */
+		field = id3_frame_field(fr, 1);
+		if (options & ID3_TAG_OPTION_ID3V1) {
+			id3_ucs4_t *ptr[] = {ucs4_val, NULL};
+			id3_field_init(field, ID3_FIELD_TYPE_STRINGLIST);
+			ret = id3_field_setstrings(field, 1, ptr);
+		} else {
+			id3_field_init(field, ID3_FIELD_TYPE_STRINGFULL);
+			ret = id3_field_setfullstring(field, ucs4_val);
+		}
+	}
+	free(ucs4_val);
+	if (ret < 0)
+		return -E_ID3_SETSTRING;
+
+	PARA_INFO_LOG("attaching %s frame, value: %s\n", id, val);
+	ret = id3_tag_attachframe(id3_t, fr);
+	if (ret < 0)
+		return -E_ID3_ATTACH;
+	return 1;
+}
+
+static int replace_tags(struct id3_tag *id3_t, struct taginfo *tags)
+{
+	int ret, options = id3_tag_options(id3_t, 0, 0);
+
+	ret = replace_tag(ID3_FRAME_ARTIST, tags->artist, id3_t, options);
+	if (ret < 0)
+		return ret;
+	ret = replace_tag(ID3_FRAME_TITLE, tags->title, id3_t, options);
+	if (ret < 0)
+		return ret;
+	ret = replace_tag(ID3_FRAME_ALBUM, tags->album, id3_t, options);
+	if (ret < 0)
+		return ret;
+	ret = replace_tag(ID3_FRAME_YEAR, tags->year, id3_t, options);
+	if (ret < 0)
+		return ret;
+	ret = replace_tag(ID3_FRAME_COMMENT, tags->comment, id3_t, options);
+	if (ret < 0)
+		return ret;
+	return 1;
+}
+
+/* id3_tag_delete() does not seem to work due to refcount issues. */
+static void free_tag(struct id3_tag *id3_t)
+{
+	int i, j;
+	for (i = 0; i < id3_t->nframes; i++) {
+		struct id3_frame *fr = id3_t->frames[i];
+		for (j = 0; j < fr->nfields; j++) {
+			union id3_field *field = &fr->fields[j];
+			id3_field_finish(field);
+		}
+		free(fr);
+	}
+	free(id3_t->frames);
+	free(id3_t);
+}
+
+static int mp3_rewrite_tags(const char *map, size_t mapsize,
+		struct taginfo *tags, int fd, __a_unused const char *filename)
+{
+	int ret;
+	id3_length_t old_v2size, new_v2size;
+	id3_byte_t v1_buffer[128], *v2_buffer;
+	size_t data_sz;
+	struct id3_tag *v1_tag = NULL, *v2_tag = NULL;
+
+	if (mapsize >= 128) {
+		v1_tag = id3_tag_parse((const id3_byte_t *)map + mapsize - 128,
+			128);
+		if (v1_tag) {
+			PARA_NOTICE_LOG("replacing id3v1 tag\n");
+			ret = replace_tags(v1_tag, tags);
+			if (ret < 0)
+				goto out;
+			id3_tag_render(v1_tag, v1_buffer);
+		}
+	}
+	old_v2size = 0;
+	v2_tag = id3_tag_parse((const id3_byte_t *)map, mapsize);
+	if (v2_tag) {
+		PARA_NOTICE_LOG("replacing id3v2 tag\n");
+		old_v2size = v2_tag->paddedsize;
+	} else if (!v1_tag) {
+		PARA_NOTICE_LOG("no id3 tags found, adding id3v2 tag\n");
+		v2_tag = id3_tag_new();
+		assert(v2_tag);
+	}
+	if (v2_tag) {
+		/*
+		 * Turn off all options to avoid creating an extended header.
+		 * id321 does not understand it.
+		 */
+		id3_tag_options(v2_tag, ~0U, 0);
+		ret = replace_tags(v2_tag, tags);
+		if (ret < 0)
+			goto out;
+		new_v2size = id3_tag_render(v2_tag, NULL);
+		v2_buffer = para_malloc(new_v2size);
+		id3_tag_render(v2_tag, v2_buffer);
+		PARA_INFO_LOG("writing v2 tag (%lu bytes)\n", new_v2size);
+		ret = write_all(fd, (char *)v2_buffer, new_v2size);
+		free(v2_buffer);
+		if (ret < 0)
+			goto out;
+	}
+	data_sz = mapsize - old_v2size;
+	if (v1_tag && data_sz >= 128)
+		data_sz -= 128;
+	PARA_INFO_LOG("writing data part (%zu bytes)\n", data_sz);
+	ret = write_all(fd, map + old_v2size, data_sz);
+	if (ret < 0)
+		goto out;
+	if (v1_tag) {
+		PARA_INFO_LOG("writing v1 tag\n");
+		ret = write_all(fd, (char *)v1_buffer, 128);
+	}
+out:
+	if (v1_tag)
+		free_tag(v1_tag);
+	if (v2_tag)
+		free_tag(v2_tag);
+	return ret;
+}
+
 #else /* HAVE_ID3TAG */
 
 /*
@@ -499,4 +695,7 @@ void mp3_init(struct audio_format_handler *afh)
 {
 	afh->get_file_info = mp3_get_file_info;
 	afh->suffixes = mp3_suffixes;
+#ifdef HAVE_LIBID3TAG
+	afh->rewrite_tags = mp3_rewrite_tags;
+#endif /* HAVE_LIBID3TAG */
 }
diff --git a/web/manual.m4 b/web/manual.m4
index b7e05978..e5ff1ab1 100644
--- a/web/manual.m4
+++ b/web/manual.m4
@@ -259,7 +259,8 @@ Optional:
 	- XREFERENCE(http://www.underbit.com/products/mad/,
 	libid3tag). For version-2 ID3 tag support, you'll need
 	the libid3tag development package libid3tag0-dev. Without
-	libid3tag, only version one tags are recognized.
+	libid3tag, only version-1 tags are recognized. The mp3 tagger
+	also needs this library for modifying (id3v1 and id3v2) tags.
 
 	- XREFERENCE(http://www.xiph.org/downloads/, ogg vorbis).
 	For ogg vorbis streams you'll need libogg, libvorbis,