libavformat/id3v2enc.c - nest-android-app/ffmpeg - Git at Google

 /*
  * ID3v2 header writer
  *
  * 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 <stdint.h>
 #include <string.h>

 #include "libavutil/avstring.h"
 #include "libavutil/dict.h"
 #include "libavutil/intreadwrite.h"
 #include "avformat.h"
 #include "avio.h"
 #include "avio_internal.h"
 #include "id3v2.h"

 static void id3v2_put_size(AVIOContext *pb, int size)
 {
     avio_w8(pb, size >> 21 & 0x7f);
     avio_w8(pb, size >> 14 & 0x7f);
     avio_w8(pb, size >> 7  & 0x7f);
     avio_w8(pb, size       & 0x7f);
 }

 static int string_is_ascii(const uint8_t *str)
 {
     while (*str && *str < 128) str++;
     return !*str;
 }

 static void id3v2_encode_string(AVIOContext *pb, const uint8_t *str,
                                enum ID3v2Encoding enc)
 {
     int (*put)(AVIOContext*, const char*);

     if (enc == ID3v2_ENCODING_UTF16BOM) {
         avio_wl16(pb, 0xFEFF);      /* BOM */
         put = avio_put_str16le;
     } else
         put = avio_put_str;

     put(pb, str);
 }

 /**
  * Write a text frame with one (normal frames) or two (TXXX frames) strings
  * according to encoding (only UTF-8 or UTF-16+BOM supported).
  * @return number of bytes written or a negative error code.
  */
 static int id3v2_put_ttag(ID3v2EncContext *id3, AVIOContext *avioc, const char *str1, const char *str2,
                           uint32_t tag, enum ID3v2Encoding enc)
 {
     int len;
     uint8_t *pb;
     AVIOContext *dyn_buf;
     if (avio_open_dyn_buf(&dyn_buf) < 0)
         return AVERROR(ENOMEM);

     /* check if the strings are ASCII-only and use UTF16 only if
      * they're not */
     if (enc == ID3v2_ENCODING_UTF16BOM && string_is_ascii(str1) &&
         (!str2 || string_is_ascii(str2)))
         enc = ID3v2_ENCODING_ISO8859;

     avio_w8(dyn_buf, enc);
     id3v2_encode_string(dyn_buf, str1, enc);
     if (str2)
         id3v2_encode_string(dyn_buf, str2, enc);
     len = avio_close_dyn_buf(dyn_buf, &pb);

     avio_wb32(avioc, tag);
     /* ID3v2.3 frame size is not synchsafe */
     if (id3->version == 3)
         avio_wb32(avioc, len);
     else
         id3v2_put_size(avioc, len);
     avio_wb16(avioc, 0);
     avio_write(avioc, pb, len);

     av_freep(&pb);
     return len + ID3v2_HEADER_SIZE;
 }

 static int id3v2_check_write_tag(ID3v2EncContext *id3, AVIOContext *pb, AVDictionaryEntry *t,
                                  const char table[][4], enum ID3v2Encoding enc)
 {
     uint32_t tag;
     int i;

     if (t->key[0] != 'T' || strlen(t->key) != 4)
         return -1;
     tag = AV_RB32(t->key);
     for (i = 0; *table[i]; i++)
         if (tag == AV_RB32(table[i]))
             return id3v2_put_ttag(id3, pb, t->value, NULL, tag, enc);
     return -1;
 }

 static void id3v2_3_metadata_split_date(AVDictionary **pm)
 {
     AVDictionaryEntry *mtag = NULL;
     AVDictionary *dst = NULL;
     const char *key, *value;
     char year[5] = {0}, day_month[5] = {0};
     int i;

     while ((mtag = av_dict_get(*pm, "", mtag, AV_DICT_IGNORE_SUFFIX))) {
         key = mtag->key;
         if (!av_strcasecmp(key, "date")) {
             /* split date tag using "YYYY-MM-DD" format into year and month/day segments */
             value = mtag->value;
             i = 0;
             while (value[i] >= '0' && value[i] <= '9') i++;
             if (value[i] == '\0' || value[i] == '-') {
                 av_strlcpy(year, value, sizeof(year));
                 av_dict_set(&dst, "TYER", year, 0);

                 if (value[i] == '-' &&
                     value[i+1] >= '0' && value[i+1] <= '1' &&
                     value[i+2] >= '0' && value[i+2] <= '9' &&
                     value[i+3] == '-' &&
                     value[i+4] >= '0' && value[i+4] <= '3' &&
                     value[i+5] >= '0' && value[i+5] <= '9' &&
                     (value[i+6] == '\0' || value[i+6] == ' ')) {
                     snprintf(day_month, sizeof(day_month), "%.2s%.2s", value + i + 4, value + i + 1);
                     av_dict_set(&dst, "TDAT", day_month, 0);
                 }
             } else
                 av_dict_set(&dst, key, value, 0);
         } else
             av_dict_set(&dst, key, mtag->value, 0);
     }
     av_dict_free(pm);
     *pm = dst;
 }

 void ff_id3v2_start(ID3v2EncContext *id3, AVIOContext *pb, int id3v2_version,
                     const char *magic)
 {
     id3->version = id3v2_version;

     avio_wb32(pb, MKBETAG(magic[0], magic[1], magic[2], id3v2_version));
     avio_w8(pb, 0);
     avio_w8(pb, 0); /* flags */

     /* reserve space for size */
     id3->size_pos = avio_tell(pb);
     avio_wb32(pb, 0);
 }

 static int write_metadata(AVIOContext *pb, AVDictionary **metadata,
                           ID3v2EncContext *id3, int enc)
 {
     AVDictionaryEntry *t = NULL;
     int ret;

     ff_metadata_conv(metadata, ff_id3v2_34_metadata_conv, NULL);
     if (id3->version == 3)
         id3v2_3_metadata_split_date(metadata);
     else if (id3->version == 4)
         ff_metadata_conv(metadata, ff_id3v2_4_metadata_conv, NULL);

     while ((t = av_dict_get(*metadata, "", t, AV_DICT_IGNORE_SUFFIX))) {
         if ((ret = id3v2_check_write_tag(id3, pb, t, ff_id3v2_tags, enc)) > 0) {
             id3->len += ret;
             continue;
         }
         if ((ret = id3v2_check_write_tag(id3, pb, t, id3->version == 3 ?
                                          ff_id3v2_3_tags : ff_id3v2_4_tags, enc)) > 0) {
             id3->len += ret;
             continue;
         }

         /* unknown tag, write as TXXX frame */
         if ((ret = id3v2_put_ttag(id3, pb, t->key, t->value, MKBETAG('T', 'X', 'X', 'X'), enc)) < 0)
             return ret;
         id3->len += ret;
     }

     return 0;
 }

 static int write_chapter(AVFormatContext *s, ID3v2EncContext *id3, int id, int enc)
 {
     const AVRational time_base = {1, 1000};
     AVChapter *ch = s->chapters[id];
     uint8_t *dyn_buf = NULL;
     AVIOContext *dyn_bc = NULL;
     char name[123];
     int len, start, end, ret;

     if ((ret = avio_open_dyn_buf(&dyn_bc)) < 0)
         goto fail;

     start = av_rescale_q(ch->start, ch->time_base, time_base);
     end   = av_rescale_q(ch->end,   ch->time_base, time_base);

     snprintf(name, 122, "ch%d", id);
     id3->len += avio_put_str(dyn_bc, name);
     avio_wb32(dyn_bc, start);
     avio_wb32(dyn_bc, end);
     avio_wb32(dyn_bc, 0xFFFFFFFFu);
     avio_wb32(dyn_bc, 0xFFFFFFFFu);

     if ((ret = write_metadata(dyn_bc, &ch->metadata, id3, enc)) < 0)
         goto fail;

     len = avio_close_dyn_buf(dyn_bc, &dyn_buf);
     id3->len += 16 + ID3v2_HEADER_SIZE;

     avio_wb32(s->pb, MKBETAG('C', 'H', 'A', 'P'));
     avio_wb32(s->pb, len);
     avio_wb16(s->pb, 0);
     avio_write(s->pb, dyn_buf, len);

 fail:
     if (dyn_bc && !dyn_buf)
         avio_close_dyn_buf(dyn_bc, &dyn_buf);
     av_freep(&dyn_buf);

     return ret;
 }

 int ff_id3v2_write_metadata(AVFormatContext *s, ID3v2EncContext *id3)
 {
     int enc = id3->version == 3 ? ID3v2_ENCODING_UTF16BOM :
                                   ID3v2_ENCODING_UTF8;
     int i, ret;

     if ((ret = write_metadata(s->pb, &s->metadata, id3, enc)) < 0)
         return ret;

     for (i = 0; i < s->nb_chapters; i++) {
         if ((ret = write_chapter(s, id3, i, enc)) < 0)
             return ret;
     }

     return 0;
 }

 int ff_id3v2_write_apic(AVFormatContext *s, ID3v2EncContext *id3, AVPacket *pkt)
 {
     AVStream *st = s->streams[pkt->stream_index];
     AVDictionaryEntry *e;

     AVIOContext *dyn_buf;
     uint8_t     *buf;
     const CodecMime *mime = ff_id3v2_mime_tags;
     const char  *mimetype = NULL, *desc = "";
     int enc = id3->version == 3 ? ID3v2_ENCODING_UTF16BOM :
                                   ID3v2_ENCODING_UTF8;
     int i, len, type = 0;

     /* get the mimetype*/
     while (mime->id != AV_CODEC_ID_NONE) {
         if (mime->id == st->codec->codec_id) {
             mimetype = mime->str;
             break;
         }
         mime++;
     }
     if (!mimetype) {
         av_log(s, AV_LOG_ERROR, "No mimetype is known for stream %d, cannot "
                "write an attached picture.\n", st->index);
         return AVERROR(EINVAL);
     }

     /* get the picture type */
     e = av_dict_get(st->metadata, "comment", NULL, 0);
     for (i = 0; e && i < FF_ARRAY_ELEMS(ff_id3v2_picture_types); i++) {
         if (!av_strcasecmp(e->value, ff_id3v2_picture_types[i])) {
             type = i;
             break;
         }
     }

     /* get the description */
     if ((e = av_dict_get(st->metadata, "title", NULL, 0)))
         desc = e->value;

     /* use UTF16 only for non-ASCII strings */
     if (enc == ID3v2_ENCODING_UTF16BOM && string_is_ascii(desc))
         enc = ID3v2_ENCODING_ISO8859;

     /* start writing */
     if (avio_open_dyn_buf(&dyn_buf) < 0)
         return AVERROR(ENOMEM);

     avio_w8(dyn_buf, enc);
     avio_put_str(dyn_buf, mimetype);
     avio_w8(dyn_buf, type);
     id3v2_encode_string(dyn_buf, desc, enc);
     avio_write(dyn_buf, pkt->data, pkt->size);
     len = avio_close_dyn_buf(dyn_buf, &buf);

     avio_wb32(s->pb, MKBETAG('A', 'P', 'I', 'C'));
     if (id3->version == 3)
         avio_wb32(s->pb, len);
     else
         id3v2_put_size(s->pb, len);
     avio_wb16(s->pb, 0);
     avio_write(s->pb, buf, len);
     av_freep(&buf);

     id3->len += len + ID3v2_HEADER_SIZE;

     return 0;
 }

 void ff_id3v2_finish(ID3v2EncContext *id3, AVIOContext *pb,
                      int padding_bytes)
 {
     int64_t cur_pos;

     if (padding_bytes < 0)
         padding_bytes = 10;

     /* The ID3v2.3 specification states that 28 bits are used to represent the
      * size of the whole tag.  Therefore the current size of the tag needs to be
      * subtracted from the upper limit of 2^28-1 to clip the value correctly. */
     /* The minimum of 10 is an arbitrary amount of padding at the end of the tag
      * to fix cover art display with some software such as iTunes, Traktor,
      * Serato, Torq. */
     padding_bytes = av_clip(padding_bytes, 10, 268435455 - id3->len);
     ffio_fill(pb, 0, padding_bytes);
     id3->len += padding_bytes;

     cur_pos = avio_tell(pb);
     avio_seek(pb, id3->size_pos, SEEK_SET);
     id3v2_put_size(pb, id3->len);
     avio_seek(pb, cur_pos, SEEK_SET);
 }

 int ff_id3v2_write_simple(struct AVFormatContext *s, int id3v2_version,
                           const char *magic)
 {
     ID3v2EncContext id3 = { 0 };
     int ret;

     ff_id3v2_start(&id3, s->pb, id3v2_version, magic);
     if ((ret = ff_id3v2_write_metadata(s, &id3)) < 0)
         return ret;
     ff_id3v2_finish(&id3, s->pb, s->metadata_header_padding);

     return 0;
 }
	/*
	* ID3v2 header writer
	*
	* 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 <stdint.h>
	#include <string.h>

	#include "libavutil/avstring.h"
	#include "libavutil/dict.h"
	#include "libavutil/intreadwrite.h"
	#include "avformat.h"
	#include "avio.h"
	#include "avio_internal.h"
	#include "id3v2.h"

	static void id3v2_put_size(AVIOContext *pb, int size)
	{
	avio_w8(pb, size >> 21 & 0x7f);
	avio_w8(pb, size >> 14 & 0x7f);
	avio_w8(pb, size >> 7 & 0x7f);
	avio_w8(pb, size & 0x7f);
	}

	static int string_is_ascii(const uint8_t *str)
	{
	while (str && str < 128) str++;
	return !*str;
	}

	static void id3v2_encode_string(AVIOContext pb, const uint8_t str,
	enum ID3v2Encoding enc)
	{
	int (put)(AVIOContext, const char*);

	if (enc == ID3v2_ENCODING_UTF16BOM) {
	avio_wl16(pb, 0xFEFF); /* BOM */
	put = avio_put_str16le;
	} else
	put = avio_put_str;

	put(pb, str);
	}

	/**
	* Write a text frame with one (normal frames) or two (TXXX frames) strings
	* according to encoding (only UTF-8 or UTF-16+BOM supported).
	* @return number of bytes written or a negative error code.
	*/
	static int id3v2_put_ttag(ID3v2EncContext id3, AVIOContext avioc, const char str1, const char str2,
	uint32_t tag, enum ID3v2Encoding enc)
	{
	int len;
	uint8_t *pb;
	AVIOContext *dyn_buf;
	if (avio_open_dyn_buf(&dyn_buf) < 0)
	return AVERROR(ENOMEM);

	/* check if the strings are ASCII-only and use UTF16 only if
	* they're not */
	if (enc == ID3v2_ENCODING_UTF16BOM && string_is_ascii(str1) &&
	(!str2 \|\| string_is_ascii(str2)))
	enc = ID3v2_ENCODING_ISO8859;

	avio_w8(dyn_buf, enc);
	id3v2_encode_string(dyn_buf, str1, enc);
	if (str2)
	id3v2_encode_string(dyn_buf, str2, enc);
	len = avio_close_dyn_buf(dyn_buf, &pb);

	avio_wb32(avioc, tag);
	/* ID3v2.3 frame size is not synchsafe */
	if (id3->version == 3)
	avio_wb32(avioc, len);
	else
	id3v2_put_size(avioc, len);
	avio_wb16(avioc, 0);
	avio_write(avioc, pb, len);

	av_freep(&pb);
	return len + ID3v2_HEADER_SIZE;
	}

	static int id3v2_check_write_tag(ID3v2EncContext id3, AVIOContext pb, AVDictionaryEntry *t,
	const char table[][4], enum ID3v2Encoding enc)
	{
	uint32_t tag;
	int i;

	if (t->key[0] != 'T' \|\| strlen(t->key) != 4)
	return -1;
	tag = AV_RB32(t->key);
	for (i = 0; *table[i]; i++)
	if (tag == AV_RB32(table[i]))
	return id3v2_put_ttag(id3, pb, t->value, NULL, tag, enc);
	return -1;
	}

	static void id3v2_3_metadata_split_date(AVDictionary **pm)
	{
	AVDictionaryEntry *mtag = NULL;
	AVDictionary *dst = NULL;
	const char key, value;
	char year[5] = {0}, day_month[5] = {0};
	int i;

	while ((mtag = av_dict_get(*pm, "", mtag, AV_DICT_IGNORE_SUFFIX))) {
	key = mtag->key;
	if (!av_strcasecmp(key, "date")) {
	/* split date tag using "YYYY-MM-DD" format into year and month/day segments */
	value = mtag->value;
	i = 0;
	while (value[i] >= '0' && value[i] <= '9') i++;
	if (value[i] == '\0' \|\| value[i] == '-') {
	av_strlcpy(year, value, sizeof(year));
	av_dict_set(&dst, "TYER", year, 0);

	if (value[i] == '-' &&
	value[i+1] >= '0' && value[i+1] <= '1' &&
	value[i+2] >= '0' && value[i+2] <= '9' &&
	value[i+3] == '-' &&
	value[i+4] >= '0' && value[i+4] <= '3' &&
	value[i+5] >= '0' && value[i+5] <= '9' &&
	(value[i+6] == '\0' \|\| value[i+6] == ' ')) {
	snprintf(day_month, sizeof(day_month), "%.2s%.2s", value + i + 4, value + i + 1);
	av_dict_set(&dst, "TDAT", day_month, 0);
	}
	} else
	av_dict_set(&dst, key, value, 0);
	} else
	av_dict_set(&dst, key, mtag->value, 0);
	}
	av_dict_free(pm);
	*pm = dst;
	}

	void ff_id3v2_start(ID3v2EncContext id3, AVIOContext pb, int id3v2_version,
	const char *magic)
	{
	id3->version = id3v2_version;

	avio_wb32(pb, MKBETAG(magic[0], magic[1], magic[2], id3v2_version));
	avio_w8(pb, 0);
	avio_w8(pb, 0); /* flags */

	/* reserve space for size */
	id3->size_pos = avio_tell(pb);
	avio_wb32(pb, 0);
	}

	static int write_metadata(AVIOContext pb, AVDictionary *metadata,
	ID3v2EncContext *id3, int enc)
	{
	AVDictionaryEntry *t = NULL;
	int ret;

	ff_metadata_conv(metadata, ff_id3v2_34_metadata_conv, NULL);
	if (id3->version == 3)
	id3v2_3_metadata_split_date(metadata);
	else if (id3->version == 4)
	ff_metadata_conv(metadata, ff_id3v2_4_metadata_conv, NULL);

	while ((t = av_dict_get(*metadata, "", t, AV_DICT_IGNORE_SUFFIX))) {
	if ((ret = id3v2_check_write_tag(id3, pb, t, ff_id3v2_tags, enc)) > 0) {
	id3->len += ret;
	continue;
	}
	if ((ret = id3v2_check_write_tag(id3, pb, t, id3->version == 3 ?
	ff_id3v2_3_tags : ff_id3v2_4_tags, enc)) > 0) {
	id3->len += ret;
	continue;
	}

	/* unknown tag, write as TXXX frame */
	if ((ret = id3v2_put_ttag(id3, pb, t->key, t->value, MKBETAG('T', 'X', 'X', 'X'), enc)) < 0)
	return ret;
	id3->len += ret;
	}

	return 0;
	}

	static int write_chapter(AVFormatContext s, ID3v2EncContext id3, int id, int enc)
	{
	const AVRational time_base = {1, 1000};
	AVChapter *ch = s->chapters[id];
	uint8_t *dyn_buf = NULL;
	AVIOContext *dyn_bc = NULL;
	char name[123];
	int len, start, end, ret;

	if ((ret = avio_open_dyn_buf(&dyn_bc)) < 0)
	goto fail;

	start = av_rescale_q(ch->start, ch->time_base, time_base);
	end = av_rescale_q(ch->end, ch->time_base, time_base);

	snprintf(name, 122, "ch%d", id);
	id3->len += avio_put_str(dyn_bc, name);
	avio_wb32(dyn_bc, start);
	avio_wb32(dyn_bc, end);
	avio_wb32(dyn_bc, 0xFFFFFFFFu);
	avio_wb32(dyn_bc, 0xFFFFFFFFu);

	if ((ret = write_metadata(dyn_bc, &ch->metadata, id3, enc)) < 0)
	goto fail;

	len = avio_close_dyn_buf(dyn_bc, &dyn_buf);
	id3->len += 16 + ID3v2_HEADER_SIZE;

	avio_wb32(s->pb, MKBETAG('C', 'H', 'A', 'P'));
	avio_wb32(s->pb, len);
	avio_wb16(s->pb, 0);
	avio_write(s->pb, dyn_buf, len);

	fail:
	if (dyn_bc && !dyn_buf)
	avio_close_dyn_buf(dyn_bc, &dyn_buf);
	av_freep(&dyn_buf);

	return ret;
	}

	int ff_id3v2_write_metadata(AVFormatContext s, ID3v2EncContext id3)
	{
	int enc = id3->version == 3 ? ID3v2_ENCODING_UTF16BOM :
	ID3v2_ENCODING_UTF8;
	int i, ret;

	if ((ret = write_metadata(s->pb, &s->metadata, id3, enc)) < 0)
	return ret;

	for (i = 0; i < s->nb_chapters; i++) {
	if ((ret = write_chapter(s, id3, i, enc)) < 0)
	return ret;
	}

	return 0;
	}

	int ff_id3v2_write_apic(AVFormatContext s, ID3v2EncContext id3, AVPacket *pkt)
	{
	AVStream *st = s->streams[pkt->stream_index];
	AVDictionaryEntry *e;

	AVIOContext *dyn_buf;
	uint8_t *buf;
	const CodecMime *mime = ff_id3v2_mime_tags;
	const char mimetype = NULL, desc = "";
	int enc = id3->version == 3 ? ID3v2_ENCODING_UTF16BOM :
	ID3v2_ENCODING_UTF8;
	int i, len, type = 0;

	/* get the mimetype*/
	while (mime->id != AV_CODEC_ID_NONE) {
	if (mime->id == st->codec->codec_id) {
	mimetype = mime->str;
	break;
	}
	mime++;
	}
	if (!mimetype) {
	av_log(s, AV_LOG_ERROR, "No mimetype is known for stream %d, cannot "
	"write an attached picture.\n", st->index);
	return AVERROR(EINVAL);
	}

	/* get the picture type */
	e = av_dict_get(st->metadata, "comment", NULL, 0);
	for (i = 0; e && i < FF_ARRAY_ELEMS(ff_id3v2_picture_types); i++) {
	if (!av_strcasecmp(e->value, ff_id3v2_picture_types[i])) {
	type = i;
	break;
	}
	}

	/* get the description */
	if ((e = av_dict_get(st->metadata, "title", NULL, 0)))
	desc = e->value;

	/* use UTF16 only for non-ASCII strings */
	if (enc == ID3v2_ENCODING_UTF16BOM && string_is_ascii(desc))
	enc = ID3v2_ENCODING_ISO8859;

	/* start writing */
	if (avio_open_dyn_buf(&dyn_buf) < 0)
	return AVERROR(ENOMEM);

	avio_w8(dyn_buf, enc);
	avio_put_str(dyn_buf, mimetype);
	avio_w8(dyn_buf, type);
	id3v2_encode_string(dyn_buf, desc, enc);
	avio_write(dyn_buf, pkt->data, pkt->size);
	len = avio_close_dyn_buf(dyn_buf, &buf);

	avio_wb32(s->pb, MKBETAG('A', 'P', 'I', 'C'));
	if (id3->version == 3)
	avio_wb32(s->pb, len);
	else
	id3v2_put_size(s->pb, len);
	avio_wb16(s->pb, 0);
	avio_write(s->pb, buf, len);
	av_freep(&buf);

	id3->len += len + ID3v2_HEADER_SIZE;

	return 0;
	}

	void ff_id3v2_finish(ID3v2EncContext id3, AVIOContext pb,
	int padding_bytes)
	{
	int64_t cur_pos;

	if (padding_bytes < 0)
	padding_bytes = 10;

	/* The ID3v2.3 specification states that 28 bits are used to represent the
	* size of the whole tag. Therefore the current size of the tag needs to be
	* subtracted from the upper limit of 2^28-1 to clip the value correctly. */
	/* The minimum of 10 is an arbitrary amount of padding at the end of the tag
	* to fix cover art display with some software such as iTunes, Traktor,
	* Serato, Torq. */
	padding_bytes = av_clip(padding_bytes, 10, 268435455 - id3->len);
	ffio_fill(pb, 0, padding_bytes);
	id3->len += padding_bytes;

	cur_pos = avio_tell(pb);
	avio_seek(pb, id3->size_pos, SEEK_SET);
	id3v2_put_size(pb, id3->len);
	avio_seek(pb, cur_pos, SEEK_SET);
	}

	int ff_id3v2_write_simple(struct AVFormatContext *s, int id3v2_version,
	const char *magic)
	{
	ID3v2EncContext id3 = { 0 };
	int ret;

	ff_id3v2_start(&id3, s->pb, id3v2_version, magic);
	if ((ret = ff_id3v2_write_metadata(s, &id3)) < 0)
	return ret;
	ff_id3v2_finish(&id3, s->pb, s->metadata_header_padding);

	return 0;
	}