X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=mp4.c;h=fc8c41b4af919358350812cae68033611c5d33c4;hb=d440a71683940a58747de6dc32643db452d9cf54;hp=89d90c7366431ecaa6a7ee64f306be3c09228833;hpb=6663ff04ae902bdea92b35b3b8dbdccd459d9099;p=paraslash.git

diff --git a/mp4.c b/mp4.c
index 89d90c73..fc8c41b4 100644
--- a/mp4.c
+++ b/mp4.c
@@ -8,14 +8,15 @@
 #include <regex.h>
 
 #include "para.h"
+#include "error.h"
 #include "portable_io.h"
 #include "string.h"
 #include "mp4.h"
 
 struct mp4_track {
-	bool is_audio;
-	uint16_t channelCount;
-	uint16_t sampleRate;
+	/* mp4a */
+	uint16_t channel_count;
+	uint16_t sample_rate;
 
 	/* stsz */
 	uint32_t stsz_sample_size;
@@ -25,19 +26,18 @@ struct mp4_track {
 	/* stts */
 	uint32_t stts_entry_count;
 	uint32_t *stts_sample_count;
-	uint32_t *stts_sample_delta;
 
 	/* stsc */
 	uint32_t stsc_entry_count;
 	uint32_t *stsc_first_chunk;
 	uint32_t *stsc_samples_per_chunk;
-	uint32_t *stsc_sample_desc_index;
 
 	/* stsc */
 	uint32_t stco_entry_count;
 	uint32_t *stco_chunk_offset;
 
-	uint32_t timeScale;
+	/* mdhd */
+	uint32_t time_scale;
 	uint64_t duration;
 };
 
@@ -49,6 +49,13 @@ struct mp4 {
 
 	uint64_t moov_offset;
 	uint64_t moov_size;
+	uint64_t meta_offset;
+	uint32_t meta_size;
+	uint64_t ilst_offset;
+	uint32_t ilst_size;
+	uint64_t udta_offset;
+	uint32_t udta_size;
+
 	uint8_t last_atom;
 	uint64_t file_size;
 
@@ -56,6 +63,8 @@ struct mp4 {
 	int32_t total_tracks;
 	/* track data */
 	struct mp4_track *track[MAX_TRACKS];
+	/* the first audio track found */
+	struct mp4_track *audio_track;
 
 	/* metadata */
 	struct mp4_metadata meta;
@@ -130,248 +139,49 @@ static uint8_t read_int8(struct mp4 *f, uint8_t *result)
 	return ret;
 }
 
-static bool atom_compare(int8_t a1, int8_t b1, int8_t c1, int8_t d1,
-		int8_t a2, int8_t b2, int8_t c2, int8_t d2)
-{
-	return a1 == a2 && b1 == b2 && c1 == c2 && d1 == d2;
-}
-
-enum atoms {
-	/* atoms with subatoms */
-	ATOM_MOOV = 1,
-	ATOM_TRAK = 2,
-	ATOM_EDTS = 3,
-	ATOM_MDIA = 4,
-	ATOM_MINF = 5,
-	ATOM_STBL = 6,
-	ATOM_UDTA = 7,
-	ATOM_ILST = 8, /* iTunes Metadata list */
-	ATOM_TITLE = 9,
-	ATOM_ARTIST = 10,
-	ATOM_WRITER = 11,
-	ATOM_ALBUM = 12,
-	ATOM_DATE = 13,
-	ATOM_TOOL = 14,
-	ATOM_COMMENT = 15,
-	ATOM_GENRE1 = 16,
-	ATOM_TRACK = 17,
-	ATOM_DISC = 18,
-	ATOM_COMPILATION = 19,
-	ATOM_GENRE2 = 20,
-	ATOM_TEMPO = 21,
-	ATOM_COVER = 22,
-	ATOM_DRMS = 23,
-	ATOM_SINF = 24,
-	ATOM_SCHI = 25,
-
-	SUBATOMIC = 128,
-
-	/* atoms without subatoms */
-	ATOM_FTYP = 129,
-	ATOM_MDAT = 130,
-	ATOM_MVHD = 131,
-	ATOM_TKHD = 132,
-	ATOM_TREF = 133,
-	ATOM_MDHD = 134, /* track header */
-	ATOM_VMHD = 135,
-	ATOM_SMHD = 136,
-	ATOM_HMHD = 137,
-	ATOM_STSD = 138, /* sample description box */
-	ATOM_STTS = 139, /* time to sample box */
-	ATOM_STSZ = 140, /* sample size box */
-	ATOM_STZ2 = 141,
-	ATOM_STCO = 142, /* chunk offset box */
-	ATOM_STSC = 143, /* sample to chunk box */
-	ATOM_MP4A = 144,
-	ATOM_MP4V = 145,
-	ATOM_MP4S = 146,
-	ATOM_ESDS = 147,
-	ATOM_META = 148, /* iTunes Metadata box */
-	ATOM_NAME = 149, /* iTunes Metadata name box */
-	ATOM_DATA = 150, /* iTunes Metadata data box */
-	ATOM_CTTS = 151,
-	ATOM_FRMA = 152,
-	ATOM_IVIV = 153,
-	ATOM_PRIV = 154,
-	ATOM_USER = 155,
-	ATOM_KEY = 156,
-	ATOM_ALBUM_ARTIST = 157,
-	ATOM_CONTENTGROUP = 158,
-	ATOM_LYRICS = 159,
-	ATOM_DESCRIPTION = 160,
-	ATOM_NETWORK = 161,
-	ATOM_SHOW = 162,
-	ATOM_EPISODENAME = 163,
-	ATOM_SORTTITLE = 164,
-	ATOM_SORTALBUM = 165,
-	ATOM_SORTARTIST = 166,
-	ATOM_SORTALBUMARTIST = 167,
-	ATOM_SORTWRITER = 168,
-	ATOM_SORTSHOW = 169,
-	ATOM_SEASON = 170,
-	ATOM_EPISODE = 171,
-	ATOM_PODCAST = 172,
-
-	ATOM_UNKNOWN = 255
-};
-
-#define ATOM_FREE ATOM_UNKNOWN
-#define ATOM_SKIP ATOM_UNKNOWN
-
-#define COPYRIGHT_SYMBOL ((int8_t)0xA9)
-
-static uint8_t atom_name_to_type(int8_t a, int8_t b, int8_t c, int8_t d)
-{
-	if (a == 'm') {
-		if (atom_compare(a, b, c, d, 'm', 'o', 'o', 'v'))
-			return ATOM_MOOV;
-		else if (atom_compare(a, b, c, d, 'm', 'i', 'n', 'f'))
-			return ATOM_MINF;
-		else if (atom_compare(a, b, c, d, 'm', 'd', 'i', 'a'))
-			return ATOM_MDIA;
-		else if (atom_compare(a, b, c, d, 'm', 'd', 'a', 't'))
-			return ATOM_MDAT;
-		else if (atom_compare(a, b, c, d, 'm', 'd', 'h', 'd'))
-			return ATOM_MDHD;
-		else if (atom_compare(a, b, c, d, 'm', 'v', 'h', 'd'))
-			return ATOM_MVHD;
-		else if (atom_compare(a, b, c, d, 'm', 'p', '4', 'a'))
-			return ATOM_MP4A;
-		else if (atom_compare(a, b, c, d, 'm', 'p', '4', 'v'))
-			return ATOM_MP4V;
-		else if (atom_compare(a, b, c, d, 'm', 'p', '4', 's'))
-			return ATOM_MP4S;
-		else if (atom_compare(a, b, c, d, 'm', 'e', 't', 'a'))
-			return ATOM_META;
-	} else if (a == 't') {
-		if (atom_compare(a, b, c, d, 't', 'r', 'a', 'k'))
-			return ATOM_TRAK;
-		else if (atom_compare(a, b, c, d, 't', 'k', 'h', 'd'))
-			return ATOM_TKHD;
-		else if (atom_compare(a, b, c, d, 't', 'r', 'e', 'f'))
-			return ATOM_TREF;
-		else if (atom_compare(a, b, c, d, 't', 'r', 'k', 'n'))
-			return ATOM_TRACK;
-		else if (atom_compare(a, b, c, d, 't', 'm', 'p', 'o'))
-			return ATOM_TEMPO;
-		else if (atom_compare(a, b, c, d, 't', 'v', 'n', 'n'))
-			return ATOM_NETWORK;
-		else if (atom_compare(a, b, c, d, 't', 'v', 's', 'h'))
-			return ATOM_SHOW;
-		else if (atom_compare(a, b, c, d, 't', 'v', 'e', 'n'))
-			return ATOM_EPISODENAME;
-		else if (atom_compare(a, b, c, d, 't', 'v', 's', 'n'))
-			return ATOM_SEASON;
-		else if (atom_compare(a, b, c, d, 't', 'v', 'e', 's'))
-			return ATOM_EPISODE;
-	} else if (a == 's') {
-		if (atom_compare(a, b, c, d, 's', 't', 'b', 'l'))
-			return ATOM_STBL;
-		else if (atom_compare(a, b, c, d, 's', 'm', 'h', 'd'))
-			return ATOM_SMHD;
-		else if (atom_compare(a, b, c, d, 's', 't', 's', 'd'))
-			return ATOM_STSD;
-		else if (atom_compare(a, b, c, d, 's', 't', 't', 's'))
-			return ATOM_STTS;
-		else if (atom_compare(a, b, c, d, 's', 't', 'c', 'o'))
-			return ATOM_STCO;
-		else if (atom_compare(a, b, c, d, 's', 't', 's', 'c'))
-			return ATOM_STSC;
-		else if (atom_compare(a, b, c, d, 's', 't', 's', 'z'))
-			return ATOM_STSZ;
-		else if (atom_compare(a, b, c, d, 's', 't', 'z', '2'))
-			return ATOM_STZ2;
-		else if (atom_compare(a, b, c, d, 's', 'k', 'i', 'p'))
-			return ATOM_SKIP;
-		else if (atom_compare(a, b, c, d, 's', 'i', 'n', 'f'))
-			return ATOM_SINF;
-		else if (atom_compare(a, b, c, d, 's', 'c', 'h', 'i'))
-			return ATOM_SCHI;
-		else if (atom_compare(a, b, c, d, 's', 'o', 'n', 'm'))
-			return ATOM_SORTTITLE;
-		else if (atom_compare(a, b, c, d, 's', 'o', 'a', 'l'))
-			return ATOM_SORTALBUM;
-		else if (atom_compare(a, b, c, d, 's', 'o', 'a', 'r'))
-			return ATOM_SORTARTIST;
-		else if (atom_compare(a, b, c, d, 's', 'o', 'a', 'a'))
-			return ATOM_SORTALBUMARTIST;
-		else if (atom_compare(a, b, c, d, 's', 'o', 'c', 'o'))
-			return ATOM_SORTWRITER;
-		else if (atom_compare(a, b, c, d, 's', 'o', 's', 'n'))
-			return ATOM_SORTSHOW;
-	} else if (a == COPYRIGHT_SYMBOL) {
-		if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'n', 'a', 'm'))
-			return ATOM_TITLE;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'A', 'R', 'T'))
-			return ATOM_ARTIST;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'w', 'r', 't'))
-			return ATOM_WRITER;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'a', 'l', 'b'))
-			return ATOM_ALBUM;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'd', 'a', 'y'))
-			return ATOM_DATE;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 't', 'o', 'o'))
-			return ATOM_TOOL;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'c', 'm', 't'))
-			return ATOM_COMMENT;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'g', 'e', 'n'))
-			return ATOM_GENRE1;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'g', 'r', 'p'))
-			return ATOM_CONTENTGROUP;
-		else if (atom_compare(a, b, c, d, COPYRIGHT_SYMBOL, 'l', 'y', 'r'))
-			return ATOM_LYRICS;
-	}
-
-	if (atom_compare(a, b, c, d, 'e', 'd', 't', 's'))
-		return ATOM_EDTS;
-	else if (atom_compare(a, b, c, d, 'e', 's', 'd', 's'))
-		return ATOM_ESDS;
-	else if (atom_compare(a, b, c, d, 'f', 't', 'y', 'p'))
-		return ATOM_FTYP;
-	else if (atom_compare(a, b, c, d, 'f', 'r', 'e', 'e'))
-		return ATOM_FREE;
-	else if (atom_compare(a, b, c, d, 'h', 'm', 'h', 'd'))
-		return ATOM_HMHD;
-	else if (atom_compare(a, b, c, d, 'v', 'm', 'h', 'd'))
-		return ATOM_VMHD;
-	else if (atom_compare(a, b, c, d, 'u', 'd', 't', 'a'))
-		return ATOM_UDTA;
-	else if (atom_compare(a, b, c, d, 'i', 'l', 's', 't'))
-		return ATOM_ILST;
-	else if (atom_compare(a, b, c, d, 'n', 'a', 'm', 'e'))
-		return ATOM_NAME;
-	else if (atom_compare(a, b, c, d, 'd', 'a', 't', 'a'))
-		return ATOM_DATA;
-	else if (atom_compare(a, b, c, d, 'd', 'i', 's', 'k'))
-		return ATOM_DISC;
-	else if (atom_compare(a, b, c, d, 'g', 'n', 'r', 'e'))
-		return ATOM_GENRE2;
-	else if (atom_compare(a, b, c, d, 'c', 'o', 'v', 'r'))
-		return ATOM_COVER;
-	else if (atom_compare(a, b, c, d, 'c', 'p', 'i', 'l'))
-		return ATOM_COMPILATION;
-	else if (atom_compare(a, b, c, d, 'c', 't', 't', 's'))
-		return ATOM_CTTS;
-	else if (atom_compare(a, b, c, d, 'd', 'r', 'm', 's'))
-		return ATOM_DRMS;
-	else if (atom_compare(a, b, c, d, 'f', 'r', 'm', 'a'))
-		return ATOM_FRMA;
-	else if (atom_compare(a, b, c, d, 'p', 'r', 'i', 'v'))
-		return ATOM_PRIV;
-	else if (atom_compare(a, b, c, d, 'i', 'v', 'i', 'v'))
-		return ATOM_IVIV;
-	else if (atom_compare(a, b, c, d, 'u', 's', 'e', 'r'))
-		return ATOM_USER;
-	else if (atom_compare(a, b, c, d, 'k', 'e', 'y', ' '))
-		return ATOM_KEY;
-	else if (atom_compare(a, b, c, d, 'a', 'A', 'R', 'T'))
-		return ATOM_ALBUM_ARTIST;
-	else if (atom_compare(a, b, c, d, 'd', 'e', 's', 'c'))
-		return ATOM_DESCRIPTION;
-	else if (atom_compare(a, b, c, d, 'p', 'c', 's', 't'))
-		return ATOM_PODCAST;
-	else
-		return ATOM_UNKNOWN;
+#define ATOM_ITEMS \
+	ATOM_ITEM(MOOV, 'm', 'o', 'o', 'v') \
+	ATOM_ITEM(TRAK, 't', 'r', 'a', 'k') \
+	ATOM_ITEM(MDIA, 'm', 'd', 'i', 'a') \
+	ATOM_ITEM(MINF, 'm', 'i', 'n', 'f') \
+	ATOM_ITEM(STBL, 's', 't', 'b', 'l') \
+	ATOM_ITEM(UDTA, 'u', 'd', 't', 'a') \
+	ATOM_ITEM(ILST, 'i', 'l', 's', 't') /* iTunes Metadata list */ \
+	ATOM_ITEM(ARTIST, 0xa9, 'A', 'R', 'T') \
+	ATOM_ITEM(TITLE, 0xa9, 'n', 'a', 'm') \
+	ATOM_ITEM(ALBUM, 0xa9, 'a', 'l', 'b') \
+	ATOM_ITEM(DATE, 0xa9, 'd', 'a', 'y') \
+	ATOM_ITEM(COMMENT, 0xa9, 'c', 'm', 't') \
+	ATOM_ITEM(MDHD, 'm', 'd', 'h', 'd') /* track header */ \
+	ATOM_ITEM(STSD, 's', 't', 's', 'd') /* sample description box */ \
+	ATOM_ITEM(STTS, 's', 't', 't', 's') /* time to sample box */ \
+	ATOM_ITEM(STSZ, 's', 't', 's', 'z') /* sample size box */ \
+	ATOM_ITEM(STCO, 's', 't', 'c', 'o') /* chunk offset box */ \
+	ATOM_ITEM(STSC, 's', 't', 's', 'c') /* sample to chunk box */ \
+	ATOM_ITEM(MP4A, 'm', 'p', '4', 'a') \
+	ATOM_ITEM(META, 'm', 'e', 't', 'a') /* iTunes Metadata box */ \
+	ATOM_ITEM(DATA, 'd', 'a', 't', 'a') /* iTunes Metadata data box */ \
+
+#define ATOM_ITEM(_name, a, b, c, d) ATOM_ ## _name,
+enum atom {ATOM_ITEMS};
+#undef ATOM_ITEM
+
+static uint8_t atom_name_to_type(uint8_t *p)
+{
+	#define ATOM_VALUE(a, b, c, d) ((a << 24) + (b << 16) + (c << 8) + d)
+	#define ATOM_ITEM(_name, a, b, c, d) \
+		{.name = # _name, .val = ATOM_VALUE(a, b, c, d)},
+	static const struct {
+		const char *name;
+		uint32_t val;
+	} atom_table[] = {ATOM_ITEMS};
+	#undef ATOM_ITEM
+	uint32_t val = read_u32_be(p);
+
+	for (uint8_t n = 0; n < ARRAY_SIZE(atom_table); n++)
+		if (val == atom_table[n].val)
+			return n;
+	return 255;
 }
 
 /* read atom header, atom size is returned with header included. */
@@ -380,7 +190,7 @@ static int atom_read_header(struct mp4 *f, uint8_t *atom_type,
 {
 	uint32_t size;
 	int ret;
-	int8_t atom_header[8];
+	uint8_t atom_header[8];
 
 	ret = read_data(f, atom_header, 8);
 	if (ret <= 0)
@@ -398,8 +208,7 @@ static int atom_read_header(struct mp4 *f, uint8_t *atom_type,
 		if (atom_size)
 			*atom_size = size;
 	}
-	*atom_type = atom_name_to_type(atom_header[4], atom_header[5],
-		atom_header[6], atom_header[7]);
+	*atom_type = atom_name_to_type(atom_header + 4);
 	return 1;
 }
 
@@ -408,27 +217,6 @@ static int64_t get_position(const struct mp4 *f)
 	return f->current_position;
 }
 
-static int need_parse_when_meta_only(uint8_t atom_type)
-{
-	switch (atom_type) {
-	case ATOM_EDTS:
-	case ATOM_DRMS:
-	case ATOM_SINF:
-	case ATOM_SCHI:
-	case ATOM_STTS:
-	case ATOM_STSZ:
-	case ATOM_STZ2:
-	case ATOM_STCO:
-	case ATOM_STSC:
-	case ATOM_FRMA:
-	case ATOM_IVIV:
-	case ATOM_PRIV:
-		return 0;
-	default:
-		return 1;
-	}
-}
-
 static int32_t set_position(struct mp4 *f, int64_t position)
 {
 	f->cb->seek(f->cb->user_data, position);
@@ -491,13 +279,11 @@ static int read_stts(struct mp4 *f)
 		return ret;
 	t->stts_sample_count = para_malloc(t->stts_entry_count
 		* sizeof(int32_t));
-	t->stts_sample_delta = para_malloc(t->stts_entry_count
-		* sizeof (int32_t));
 	for (i = 0; i < t->stts_entry_count; i++) {
 		ret = read_int32(f, &t->stts_sample_count[i]);
 		if (ret <= 0)
 			return ret;
-		ret = read_int32(f, &t->stts_sample_delta[i]);
+		ret = read_int32(f, NULL); /* sample delta */
 		if (ret <= 0)
 			return ret;
 	}
@@ -526,9 +312,6 @@ static int read_stsc(struct mp4 *f)
 	t->stsc_first_chunk = para_malloc(t->stsc_entry_count * sizeof(int32_t));
 	t->stsc_samples_per_chunk = para_malloc(t->stsc_entry_count
 		* sizeof (int32_t));
-	t->stsc_sample_desc_index = para_malloc(t->stsc_entry_count *
-		sizeof (int32_t));
-
 	for (i = 0; i < t->stsc_entry_count; i++) {
 		ret = read_int32(f, &t->stsc_first_chunk[i]);
 		if (ret <= 0)
@@ -536,7 +319,7 @@ static int read_stsc(struct mp4 *f)
 		ret = read_int32(f, &t->stsc_samples_per_chunk[i]);
 		if (ret <= 0)
 			return ret;
-		ret = read_int32(f, &t->stsc_sample_desc_index[i]);
+		ret = read_int32(f, NULL); /* sample desc index */
 		if (ret <= 0)
 			return ret;
 	}
@@ -576,8 +359,6 @@ static int read_mp4a(struct mp4 *f)
 {
 	int ret;
 	int32_t i;
-	uint8_t atom_type = 0;
-	uint8_t header_size = 0;
 	struct mp4_track *t;
 
 	if (f->total_tracks == 0)
@@ -598,7 +379,7 @@ static int read_mp4a(struct mp4 *f)
 	ret = read_int32(f, NULL); /* reserved */
 	if (ret <= 0)
 		return ret;
-	ret = read_int16(f, &t->channelCount);
+	ret = read_int16(f, &t->channel_count);
 	if (ret <= 0)
 		return ret;
 	ret = read_int16(f, NULL);
@@ -610,20 +391,13 @@ static int read_mp4a(struct mp4 *f)
 	ret = read_int16(f, NULL);
 	if (ret <= 0)
 		return ret;
-	ret = read_int16(f, &t->sampleRate);
-	if (ret <= 0)
-		return ret;
-	ret = read_int16(f, NULL);
-	if (ret <= 0)
-		return ret;
-	return atom_read_header(f, &atom_type, &header_size, NULL);
+	return read_int16(f, &t->sample_rate);
 }
 
 static int read_stsd(struct mp4 *f)
 {
 	int ret;
 	uint32_t i, entry_count;
-	uint8_t header_size = 0;
 	struct mp4_track *t;
 
 	if (f->total_tracks == 0)
@@ -642,51 +416,19 @@ static int read_stsd(struct mp4 *f)
 		uint64_t skip = get_position(f);
 		uint64_t size;
 		uint8_t atom_type = 0;
-		ret = atom_read_header(f, &atom_type, &header_size, &size);
+		ret = atom_read_header(f, &atom_type, NULL, &size);
 		if (ret <= 0)
 			return ret;
 		skip += size;
-		t->is_audio = atom_type == ATOM_MP4A;
-		if (t->is_audio)
+		if (!f->audio_track && atom_type == ATOM_MP4A) {
+			f->audio_track = t;
 			read_mp4a(f);
+		}
 		set_position(f, skip);
 	}
 	return 1;
 }
 
-static int32_t tag_add_field(struct mp4_metadata *meta, const char *item,
-		const char *value, int32_t len)
-{
-	meta->tags = para_realloc(meta->tags,
-		(meta->count + 1) * sizeof(struct mp4_tag));
-	meta->tags[meta->count].item = para_strdup(item);
-	meta->tags[meta->count].len = len;
-	if (len >= 0) {
-		meta->tags[meta->count].value = para_malloc(len + 1);
-		memcpy(meta->tags[meta->count].value, value, len);
-		meta->tags[meta->count].value[len] = 0;
-	} else {
-		meta->tags[meta->count].value = para_strdup(value);
-	}
-	meta->count++;
-	return 1;
-}
-
-static int read_string(struct mp4 *f, uint32_t length, char **result)
-{
-	char *str = para_malloc(length + 1);
-	int ret = read_data(f, str, length);
-
-	if (ret <= 0) {
-		free(str);
-		*result = NULL;
-	} else {
-		str[length] = '\0';
-		*result = str;
-	}
-	return ret;
-}
-
 static const char *get_metadata_name(uint8_t atom_type)
 {
 	switch (atom_type) {
@@ -703,9 +445,10 @@ static int parse_tag(struct mp4 *f, uint8_t parent, int32_t size)
 {
 	int ret;
 	uint64_t subsize, sumsize;
-	char *data = NULL;
+	char *value = NULL;
 	uint32_t len = 0;
 	uint64_t destpos;
+	struct mp4_tag *tag;
 
 	for (
 		sumsize = 0;
@@ -716,30 +459,43 @@ static int parse_tag(struct mp4 *f, uint8_t parent, int32_t size)
 		uint8_t header_size = 0;
 		ret = atom_read_header(f, &atom_type, &header_size, &subsize);
 		if (ret <= 0)
-			return ret;
+			goto fail;
 		destpos = get_position(f) + subsize - header_size;
 		if (atom_type != ATOM_DATA)
 			continue;
 		ret = read_int8(f, NULL); /* version */
 		if (ret <= 0)
-			return ret;
+			goto fail;
 		ret = read_int24(f, NULL); /* flags */
 		if (ret <= 0)
-			return ret;
+			goto fail;
 		ret = read_int32(f, NULL); /* reserved */
 		if (ret <= 0)
-			return ret;
-		free(data);
-		ret = read_string(f, subsize - (header_size + 8), &data);
-		if (ret <= 0)
-			return ret;
+			goto fail;
+		ret = -ERRNO_TO_PARA_ERROR(EINVAL);
+		if (subsize < header_size + 8 || subsize > UINT_MAX)
+			goto fail;
 		len = subsize - (header_size + 8);
+		free(value);
+		value = para_malloc(len + 1);
+		ret = read_data(f, value, len);
+		if (ret <= 0)
+			goto fail;
+		value[len] = '\0';
 	}
-	if (!data)
-		return -1;
-	tag_add_field(&f->meta, get_metadata_name(parent), data, len);
-	free(data);
+	if (!value)
+		return -ERRNO_TO_PARA_ERROR(EINVAL);
+	f->meta.tags = para_realloc(f->meta.tags, (f->meta.count + 1)
+		* sizeof(struct mp4_tag));
+	tag = f->meta.tags + f->meta.count;
+	tag->item = para_strdup(get_metadata_name(parent));
+	tag->value = value;
+	tag->len = len;
+	f->meta.count++;
 	return 1;
+fail:
+	free(value);
+	return ret;
 }
 
 static int read_mdhd(struct mp4 *f)
@@ -762,7 +518,7 @@ static int read_mdhd(struct mp4 *f)
 		ret = read_int64(f, NULL); /* modification-time */
 		if (ret <= 0)
 			return ret;
-		ret = read_int32(f, &t->timeScale);
+		ret = read_int32(f, &t->time_scale);
 		if (ret <= 0)
 			return ret;
 		ret = read_int64(f, &t->duration);
@@ -777,7 +533,7 @@ static int read_mdhd(struct mp4 *f)
 		ret = read_int32(f, NULL); /* modification-time */
 		if (ret <= 0)
 			return ret;
-		ret = read_int32(f, &t->timeScale);
+		ret = read_int32(f, &t->time_scale);
 		if (ret <= 0)
 			return ret;
 		ret = read_int32(f, &temp);
@@ -814,7 +570,9 @@ static int32_t read_ilst(struct mp4 *f, int32_t size)
 		case ATOM_ALBUM:
 		case ATOM_COMMENT:
 		case ATOM_DATE:
-			parse_tag(f, atom_type, subsize - header_size);
+			ret = parse_tag(f, atom_type, subsize - header_size);
+			if (ret <= 0)
+				return ret;
 		}
 		set_position(f, destpos);
 		sumsize += subsize;
@@ -841,118 +599,133 @@ static int32_t read_meta(struct mp4 *f, uint64_t size)
 			return ret;
 		if (subsize <= header_size + 4)
 			return 1;
-		if (atom_type == ATOM_ILST)
-			read_ilst(f, subsize - (header_size + 4));
-		else
+		if (atom_type == ATOM_ILST) {
+			f->ilst_offset = get_position(f) - header_size;
+			f->ilst_size = subsize;
+			ret = read_ilst(f, subsize - (header_size + 4));
+			if (ret <= 0)
+				return ret;
+		} else
 			set_position(f, get_position(f) + subsize - header_size);
 		sumsize += subsize;
 	}
 	return 1;
 }
 
-static int atom_read(struct mp4 *f, uint64_t size, uint8_t atom_type)
+static bool need_atom(uint8_t atom_type, bool meta_only)
 {
-	uint64_t dest_position = get_position(f) + size - 8;
-	int ret = 1; /* return success for atoms we don't care about */
-
+	/* these are needed in any case */
 	switch (atom_type) {
-	case ATOM_STSZ: ret = read_stsz(f); break;
-	case ATOM_STTS: ret = read_stts(f); break;
-	case ATOM_STSC: ret = read_stsc(f); break;
-	case ATOM_STCO: ret = read_stco(f); break;
-	case ATOM_STSD: ret = read_stsd(f); break;
-	case ATOM_MDHD: ret = read_mdhd(f); break;
-	case ATOM_META: ret = read_meta(f, size); break;
+	case ATOM_STSD:
+	case ATOM_META:
+	case ATOM_TRAK:
+	case ATOM_MDIA:
+	case ATOM_MINF:
+	case ATOM_STBL:
+	case ATOM_UDTA:
+		return true;
 	}
-	set_position(f, dest_position);
-	return ret;
+	/* meta-only opens don't need anything else */
+	if (meta_only)
+		return false;
+	/* these are only required for regular opens */
+	switch (atom_type) {
+	case ATOM_STTS:
+	case ATOM_STSZ:
+	case ATOM_STCO:
+	case ATOM_STSC:
+	case ATOM_MDHD:
+		return true;
+	}
+	return false;
 }
 
 /* parse atoms that are sub atoms of other atoms */
-static int parse_sub_atoms(struct mp4 *f, uint64_t total_size, int meta_only)
+static int parse_sub_atoms(struct mp4 *f, uint64_t total_size, bool meta_only)
 {
 	int ret;
-	uint64_t size;
-	uint8_t atom_type = 0;
-	uint64_t counted_size = 0;
-	uint8_t header_size = 0;
+	uint64_t dest, size, end = get_position(f) + total_size;
 
-	while (counted_size < total_size) {
+	for (dest = get_position(f); dest < end; set_position(f, dest)) {
+		uint8_t header_size, atom_type;
 		ret = atom_read_header(f, &atom_type, &header_size, &size);
 		if (ret <= 0)
 			return ret;
 		if (size == 0)
 			return -1;
-		counted_size += size;
+		dest = get_position(f) + size - header_size;
 		if (atom_type == ATOM_TRAK) {
 			if (f->total_tracks >= MAX_TRACKS)
 				return -1;
 			f->total_tracks++;
 			f->track[f->total_tracks - 1] = para_calloc(
 				sizeof(struct mp4_track));
+		} else if (atom_type == ATOM_UDTA) {
+			f->udta_offset = get_position(f) - header_size;
+			f->udta_size = size;
 		}
-		/* parse subatoms */
-		if (meta_only && !need_parse_when_meta_only(atom_type)) {
-			set_position(f, get_position(f) + size - header_size);
-		} else if (atom_type < SUBATOMIC) {
+		if (!need_atom(atom_type, meta_only))
+			continue;
+		switch (atom_type) {
+		case ATOM_STSZ: ret = read_stsz(f); break;
+		case ATOM_STTS: ret = read_stts(f); break;
+		case ATOM_STSC: ret = read_stsc(f); break;
+		case ATOM_STCO: ret = read_stco(f); break;
+		case ATOM_STSD: ret = read_stsd(f); break;
+		case ATOM_MDHD: ret = read_mdhd(f); break;
+		case ATOM_META:
+			f->meta_offset = get_position(f) - header_size;
+			f->meta_size = size;
+			ret = read_meta(f, size);
+			break;
+		default:
 			ret = parse_sub_atoms(f, size - header_size, meta_only);
-			if (ret <= 0)
-				return ret;
-		} else {
-			ret = atom_read(f, size, atom_type);
-			if (ret <= 0)
-				return ret;
 		}
+		if (ret <= 0)
+			return ret;
 	}
 	return 1;
 }
 
-/* parse root atoms */
-static int parse_atoms(struct mp4 *f, int meta_only)
+static int open_file(const struct mp4_callback *cb, bool meta_only, struct mp4 **result)
 {
 	int ret;
 	uint64_t size;
-	uint8_t atom_type = 0;
-	uint8_t header_size = 0;
-
-	f->file_size = 0;
+	uint8_t atom_type, header_size;
+	struct mp4 *f = para_calloc(sizeof(*f));
 
+	f->cb = cb;
 	while ((ret = atom_read_header(f, &atom_type, &header_size, &size)) > 0) {
 		f->file_size += size;
 		f->last_atom = atom_type;
-
-		if (atom_type == ATOM_MOOV && size > header_size) {
-			f->moov_offset = get_position(f) - header_size;
-			f->moov_size = size;
-		}
-
-		/* parse subatoms */
-		if (meta_only && !need_parse_when_meta_only(atom_type)) {
-			set_position(f, get_position(f) + size - header_size);
-		} else if (atom_type < SUBATOMIC) {
-			ret = parse_sub_atoms(f, size - header_size, meta_only);
-			if (ret <= 0)
-				return ret;
-		} else {
-			/* skip this atom */
+		if (atom_type != ATOM_MOOV || size <= header_size) { /* skip */
 			set_position(f, get_position(f) + size - header_size);
+			continue;
 		}
+		f->moov_offset = get_position(f) - header_size;
+		f->moov_size = size;
+		ret = parse_sub_atoms(f, size - header_size, meta_only);
+		if (ret <= 0)
+			break;
+	}
+	if (ret < 0) {
+		ret = -E_MP4_OPEN;
+		goto fail;
 	}
+	ret = -E_MP4_TRACK;
+	if (!f->audio_track)
+		goto fail;
+	*result = f;
+	return 1;
+fail:
+	*result = NULL;
+	free(f);
 	return ret;
 }
 
-struct mp4 *mp4_open_read(const struct mp4_callback *cb)
+int mp4_open_read(const struct mp4_callback *cb, struct mp4 **result)
 {
-	int ret;
-	struct mp4 *f = para_calloc(sizeof(struct mp4));
-
-	f->cb = cb;
-	ret = parse_atoms(f, 0);
-	if (ret < 0) {
-		free(f);
-		return NULL;
-	}
-	return f;
+	return open_file(cb, false, result);
 }
 
 void mp4_close(struct mp4 *f)
@@ -963,10 +736,8 @@ void mp4_close(struct mp4 *f)
 		if (f->track[i]) {
 			free(f->track[i]->stsz_table);
 			free(f->track[i]->stts_sample_count);
-			free(f->track[i]->stts_sample_delta);
 			free(f->track[i]->stsc_first_chunk);
 			free(f->track[i]->stsc_samples_per_chunk);
-			free(f->track[i]->stsc_sample_desc_index);
 			free(f->track[i]->stco_chunk_offset);
 			free(f->track[i]);
 		}
@@ -979,173 +750,110 @@ void mp4_close(struct mp4 *f)
 	free(f);
 }
 
-static int32_t chunk_of_sample(const struct mp4 *f, int32_t track,
-		int32_t sample, int32_t *chunk_sample, int32_t *chunk)
+static int32_t chunk_of_sample(const struct mp4 *f, int32_t sample,
+		int32_t *chunk)
 {
-	int32_t total_entries = 0;
-	int32_t chunk2entry;
-	int32_t chunk1, chunk2, chunk1samples, range_samples, total = 0;
-
-	*chunk_sample = 0;
-	*chunk = 1;
-	if (f->track[track] == NULL) {
-		return -1;
-	}
-
-	total_entries = f->track[track]->stsc_entry_count;
+	const struct mp4_track *t = f->audio_track;
+	uint32_t *fc = t->stsc_first_chunk, *spc = t->stsc_samples_per_chunk;
+	int32_t chunk1, chunk1samples, n, total, i;
 
-	chunk1 = 1;
-	chunk1samples = 0;
-	chunk2entry = 0;
-
-	do {
-		chunk2 = f->track[track]->stsc_first_chunk[chunk2entry];
-		*chunk = chunk2 - chunk1;
-		range_samples = *chunk * chunk1samples;
-
-		if (sample < total + range_samples)
+	for (i = 1, total = 0; i < t->stsc_entry_count; i++, total += n) {
+		n = (fc[i] - fc[i - 1]) * spc[i - 1]; /* number of samples */
+		if (sample < total + n)
 			break;
-
-		chunk1samples = f->track[track]->stsc_samples_per_chunk[chunk2entry];
-		chunk1 = chunk2;
-
-		if (chunk2entry < total_entries) {
-			chunk2entry++;
-			total += range_samples;
-		}
-	} while (chunk2entry < total_entries);
-
-	if (chunk1samples)
+	}
+	chunk1 = fc[i - 1];
+	chunk1samples = spc[i - 1];
+	if (chunk1samples != 0)
 		*chunk = (sample - total) / chunk1samples + chunk1;
 	else
 		*chunk = 1;
-
-	*chunk_sample = total + (*chunk - chunk1) * chunk1samples;
-
-	return 0;
-}
-
-static int32_t chunk_to_offset(const struct mp4 *f, int32_t track,
-		int32_t chunk)
-{
-	const struct mp4_track *p_track = f->track[track];
-
-	if (p_track->stco_entry_count && (chunk > p_track->stco_entry_count)) {
-		return p_track->stco_chunk_offset[p_track->stco_entry_count -
-						  1];
-	} else if (p_track->stco_entry_count) {
-		return p_track->stco_chunk_offset[chunk - 1];
-	} else {
-		return 8;
-	}
-
-	return 0;
-}
-
-static int32_t sample_range_size(const struct mp4 *f, int32_t track,
-		int32_t chunk_sample, int32_t sample)
-{
-	int32_t i, total;
-	const struct mp4_track *t = f->track[track];
-
-	if (t->stsz_sample_size)
-		return (sample - chunk_sample) * t->stsz_sample_size;
-	if (sample >= t->stsz_sample_count)
-		return 0; /* error */
-	for (i = chunk_sample, total = 0; i < sample; i++)
-		total += t->stsz_table[i];
-	return total;
+	return total + (*chunk - chunk1) * chunk1samples;
 }
 
 /**
- * Return the number of milliseconds of the given track.
+ * Return the number of milliseconds of the audio track.
  *
  * \param f As returned by \ref mp4_open_read(), must not be NULL.
- * \param track Between zero and the value returned by \ref mp4_get_total_tracks().
- *
- * The function returns zero if the audio file is of zero length or contains a
- * corrupt track header.
  */
-uint64_t mp4_get_duration(const struct mp4 *f, int32_t track)
+uint64_t mp4_get_duration(const struct mp4 *f)
 {
-	const struct mp4_track *t = f->track[track];
+	const struct mp4_track *t = f->audio_track;
 
-	if (t->timeScale == 0)
+	if (t->time_scale == 0)
 		return 0;
-	return t->duration * 1000 / t->timeScale;
-}
-
-int32_t mp4_get_total_tracks(const struct mp4 *f)
-{
-	return f->total_tracks;
+	return t->duration * 1000 / t->time_scale;
 }
 
-/**
- * Check whether the given track number corresponds to an audio track.
- *
- * \param f See \ref mp4_get_duration().
- * \param track See \ref mp4_get_duration().
- *
- * Besides audio tracks, an mp4 file may contain video and system tracks. For
- * those the function returns false.
- */
-bool mp4_is_audio_track(const struct mp4 *f, int32_t track)
-{
-	return f->track[track]->is_audio;
-}
-
-void mp4_set_sample_position(struct mp4 *f, int32_t track, int32_t sample)
+int mp4_set_sample_position(struct mp4 *f, int32_t sample)
 {
+	const struct mp4_track *t = f->audio_track;
 	int32_t offset, chunk, chunk_sample;
+	uint32_t n, srs; /* sample range size */
 
-	chunk_of_sample(f, track, sample, &chunk_sample, &chunk);
-	offset = chunk_to_offset(f, track, chunk)
-		+ sample_range_size(f, track, chunk_sample, sample);
-	set_position(f, offset);
+	if (sample >= t->stsz_sample_count)
+		return -ERRNO_TO_PARA_ERROR(EINVAL);
+	chunk_sample = chunk_of_sample(f, sample, &chunk);
+	if (t->stsz_sample_size > 0)
+		srs = (sample - chunk_sample) * t->stsz_sample_size;
+	else {
+		for (srs = 0, n = chunk_sample; n < sample; n++)
+			srs += t->stsz_table[n];
+	}
+	if (t->stco_entry_count > 0 && chunk > t->stco_entry_count)
+		offset = t->stco_chunk_offset[t->stco_entry_count - 1];
+	else if (t->stco_entry_count > 0)
+		offset = t->stco_chunk_offset[chunk - 1];
+	else
+		offset = 8;
+	set_position(f, offset + srs);
+	return 1;
 }
 
-int32_t mp4_get_sample_size(const struct mp4 *f, int track, int sample)
+int32_t mp4_get_sample_size(const struct mp4 *f, int sample)
 {
-	const struct mp4_track *t = f->track[track];
+	const struct mp4_track *t = f->audio_track;
 
 	if (t->stsz_sample_size != 0)
 		return t->stsz_sample_size;
 	return t->stsz_table[sample];
 }
 
-uint32_t mp4_get_sample_rate(const struct mp4 *f, int32_t track)
+uint32_t mp4_get_sample_rate(const struct mp4 *f)
 {
-	return f->track[track]->sampleRate;
+	return f->audio_track->sample_rate;
 }
 
-uint32_t mp4_get_channel_count(const struct mp4 *f, int32_t track)
+uint32_t mp4_get_channel_count(const struct mp4 *f)
 {
-	return f->track[track]->channelCount;
+	return f->audio_track->channel_count;
 }
 
-int32_t mp4_num_samples(const struct mp4 *f, int32_t track)
+int32_t mp4_num_samples(const struct mp4 *f)
 {
+	const struct mp4_track *t = f->audio_track;
 	int32_t i;
 	int32_t total = 0;
 
-	for (i = 0; i < f->track[track]->stts_entry_count; i++) {
-		total += f->track[track]->stts_sample_count[i];
-	}
+	for (i = 0; i < t->stts_entry_count; i++)
+		total += t->stts_sample_count[i];
 	return total;
 }
 
-struct mp4 *mp4_open_meta(const struct mp4_callback *cb)
+int mp4_open_meta(const struct mp4_callback *cb, struct mp4 **result)
 {
-	int ret;
-	struct mp4 *f = para_calloc(sizeof(struct mp4));
+	struct mp4 *f;
+	int ret = open_file(cb, true, &f);
 
-	f->cb = cb;
-	ret = parse_atoms(f, 1);
-	if (ret < 0) {
-		free(f);
-		return NULL;
+	if (ret < 0)
+		return ret;
+	if (f->udta_size == 0 || f->meta_size == 0 || f->ilst_size == 0) {
+		mp4_close(f);
+		*result = NULL;
+		return -E_MP4_MISSING_ATOM;
 	}
-	return f;
+	*result = f;
+	return 1;
 }
 
 /**
@@ -1161,271 +869,38 @@ struct mp4_metadata *mp4_get_meta(struct mp4 *f)
 	return &f->meta;
 }
 
-static int find_atom(struct mp4 *f, uint64_t base, uint32_t size,
-	const char *name)
-{
-	uint32_t remaining = size;
-	uint64_t atom_offset = base;
-
-	for (;;) {
-		int ret;
-		char atom_name[4];
-		uint32_t atom_size;
-
-		set_position(f, atom_offset);
-
-		if (remaining < 8)
-			return -1;
-		ret = read_int32(f, &atom_size);
-		if (ret <= 0)
-			return ret;
-		if (atom_size > remaining || atom_size < 8)
-			return -1;
-		ret = read_data(f, atom_name, 4);
-		if (ret <= 0)
-			return ret;
-		if (!memcmp(atom_name, name, 4)) {
-			set_position(f, atom_offset);
-			return 1;
-		}
-		remaining -= atom_size;
-		atom_offset += atom_size;
-	}
-}
-
-/*
- * Try to find atom <name> with atom <name_inside> in it. Besides -1/0/1 for
- * error, EOF and success, this function may return 2 to indicate that the
- * desired atoms were not found.
- */
-static int find_atom_v2(struct mp4 *f, uint64_t base, uint32_t size,
-		const char *name, uint32_t extraheaders, const char *name_inside)
-{
-	uint64_t first_base = (uint64_t) (-1);
-
-	for (;;) {
-		uint64_t mybase;
-		uint32_t mysize;
-		int ret = find_atom(f, base, size, name);
-
-		if (ret <= 0)
-			return ret;
-		mybase = get_position(f);
-		ret = read_int32(f, &mysize);
-		if (ret <= 0)
-			return ret;
-		if (first_base == (uint64_t) (-1))
-			first_base = mybase;
-
-		if (mysize < 8 + extraheaders)
-			break;
-
-		if (find_atom (f, mybase + (8 + extraheaders),
-				mysize - (8 + extraheaders), name_inside)) {
-			set_position(f, mybase);
-			return 1;
-		}
-		base += mysize;
-		if (size <= mysize)
-			break;
-		size -= mysize;
-	}
-	if (first_base != (uint64_t)(-1)) {
-		set_position(f, first_base);
-		return 1;
-	}
-	/* wanted atom inside not found */
-	return 2;
-}
-
-struct membuffer {
-	void *data;
-	unsigned written;
-	unsigned allocated;
-};
-
-static struct membuffer *membuffer_create(void)
-{
-	struct membuffer *buf = para_calloc(sizeof(*buf));
-
-	buf->allocated = 256;
-	buf->data = para_malloc(buf->allocated);
-	return buf;
-}
-
-static void membuffer_write(struct membuffer *buf, const void *ptr,
-		unsigned bytes)
-{
-	unsigned dest_size = buf->written + bytes;
-
-	if (dest_size > buf->allocated) {
-		do {
-			buf->allocated <<= 1;
-		} while (dest_size > buf->allocated);
-		buf->data = para_realloc(buf->data, buf->allocated);
-	}
-
-	if (ptr)
-		memcpy((char *) buf->data + buf->written, ptr, bytes);
-	buf->written += bytes;
-}
-
-static void membuffer_write_atom_name(struct membuffer *buf, const char *data)
-{
-	membuffer_write(buf, data, 4);
-}
-
-static void membuffer_write_int32(struct membuffer *buf, uint32_t data)
-{
-	uint8_t temp[4];
-	write_u32_be(temp, data);
-	membuffer_write(buf, temp, 4);
-}
-
-static void membuffer_write_std_tag(struct membuffer *buf, const char *name,
-		const char *value)
-{
-	uint32_t len = strlen(value);
-	membuffer_write_int32(buf, 8 /* atom header */
-		+ 8 /* data atom header */
-		+ 8 /* flags + reserved */
-		+ len);
-	membuffer_write_atom_name(buf, name);
-	membuffer_write_int32(buf, 8 /* data atom header */
-		+ 8 /* flags + reserved */
-		+ len);
-	membuffer_write_atom_name(buf, "data");
-	membuffer_write_int32(buf, 1);	/* flags */
-	membuffer_write_int32(buf, 0);	/* reserved */
-	membuffer_write(buf, value, len);
-}
-
-static unsigned membuffer_get_size(const struct membuffer *buf)
-{
-	return buf->written;
-}
-
-static void *membuffer_detach(struct membuffer *buf)
-{
-	void *ret = para_realloc(buf->data, buf->written);
-	free(buf);
-	return ret;
-}
-
-struct stdmeta_entry {
-	const char *atom;
-	const char *name;
-};
-
-static const char *find_standard_meta(const char *name)
-{
-	const struct stdmeta_entry stdmetas[] = {
-		{"\xA9" "nam", "title"},
-		{"\xA9" "ART", "artist"},
-		{"\xA9" "alb", "album"},
-		{"\xA9" "day", "date"},
-		{"\xA9" "cmt", "comment"},
-	};
-
-	for (unsigned n = 0; n < ARRAY_SIZE(stdmetas); n++)
-		if (!strcasecmp(name, stdmetas[n].name))
-			return stdmetas[n].atom;
-	return NULL;
-}
-
-static uint32_t create_ilst(const struct mp4_metadata *meta, void **out_buffer,
-		uint32_t * out_size)
-{
-	struct membuffer *buf = membuffer_create();
-	unsigned metaptr;
-
-	for (metaptr = 0; metaptr < meta->count; metaptr++) {
-		struct mp4_tag *tag = meta->tags + metaptr;
-		const char *std_meta_atom = find_standard_meta(tag->item);
-		if (std_meta_atom)
-			membuffer_write_std_tag(buf, std_meta_atom, tag->value);
+/** Total length of an on-disk metadata tag. */
+#define TAG_LEN(_len) (24 + (_len))
+static void create_ilst(const struct mp4_metadata *meta, uint8_t *out)
+{
+	for (unsigned n = 0; n < meta->count; n++) {
+		struct mp4_tag *tag = meta->tags + n;
+		unsigned len = strlen(tag->value);
+		const char *atom_name;
+
+		if (!strcasecmp(tag->item, "title"))
+			atom_name = "\xA9" "nam";
+		else if (!strcasecmp(tag->item, "artist"))
+			atom_name = "\xA9" "ART";
+		else if (!strcasecmp(tag->item, "album"))
+			atom_name = "\xA9" "alb";
+		else if (!strcasecmp(tag->item, "date"))
+			atom_name = "\xA9" "day";
+		else if (!strcasecmp(tag->item, "comment"))
+			atom_name = "\xA9" "cmt";
 		else
-			PARA_ERROR_LOG("invalid tag item: %s\n", tag->item);
-	}
-	*out_size = membuffer_get_size(buf);
-	*out_buffer = membuffer_detach(buf);
-	return 1;
-}
-
-static void membuffer_write_atom(struct membuffer *buf, const char *name, unsigned size,
-			  const void *data)
-{
-	membuffer_write_int32(buf, size + 8);
-	membuffer_write_atom_name(buf, name);
-	membuffer_write(buf, data, size);
-}
-
-static void *membuffer_get_ptr(const struct membuffer *buf)
-{
-	return buf->data;
-}
-
-static bool membuffer_transfer_from_file(struct membuffer *buf, struct mp4 *src,
-		unsigned bytes)
-{
-	unsigned oldsize = membuffer_get_size(buf);
-	char *bufptr;
-
-	membuffer_write(buf, 0, bytes);
-	bufptr = membuffer_get_ptr(buf);
-	if (read_data(src, bufptr + oldsize, bytes) != 1) {
-		free(buf->data);
-		free(buf);
-		return false;
+			assert(false);
+		write_u32_be(out, TAG_LEN(len));
+		memcpy(out + 4, atom_name, 4);
+		write_u32_be(out + 8, 8 /* data atom header */
+			+ 8 /* flags + reserved */
+			+ len);
+		memcpy(out + 12, "data", 4);
+		write_u32_be(out + 16, 1); /* flags */
+		write_u32_be(out + 20, 0); /* reserved */
+		memcpy(out + 24, tag->value, len);
+		out += TAG_LEN(len);
 	}
-	return true;
-}
-
-static uint32_t create_meta(const struct mp4_metadata *meta, void **out_buffer,
-		uint32_t * out_size)
-{
-	struct membuffer *buf;
-	uint32_t ilst_size;
-	void *ilst_buffer;
-
-	if (!create_ilst(meta, &ilst_buffer, &ilst_size))
-		return 0;
-
-	buf = membuffer_create();
-
-	membuffer_write_int32(buf, 0);
-	membuffer_write_atom(buf, "ilst", ilst_size, ilst_buffer);
-	free(ilst_buffer);
-
-	*out_size = membuffer_get_size(buf);
-	*out_buffer = membuffer_detach(buf);
-	return 1;
-}
-
-static uint32_t create_udta(const struct mp4_metadata *meta, void **out_buffer,
-uint32_t * out_size)
-{
-	struct membuffer *buf;
-	uint32_t meta_size;
-	void *meta_buffer;
-
-	if (!create_meta(meta, &meta_buffer, &meta_size))
-		return 0;
-
-	buf = membuffer_create();
-
-	membuffer_write_atom(buf, "meta", meta_size, meta_buffer);
-
-	free(meta_buffer);
-
-	*out_size = membuffer_get_size(buf);
-	*out_buffer = membuffer_detach(buf);
-	return 1;
-}
-
-static uint32_t fix_byte_order_32(uint32_t src)
-{
-	return read_u32_be(&src);
 }
 
 static void *modify_moov(struct mp4 *f, uint32_t *out_size)
@@ -1433,164 +908,89 @@ static void *modify_moov(struct mp4 *f, uint32_t *out_size)
 	int ret;
 	uint64_t total_base = f->moov_offset + 8;
 	uint32_t total_size = (uint32_t) (f->moov_size - 8);
-	uint64_t udta_offset, meta_offset, ilst_offset;
-	uint32_t udta_size, meta_size, ilst_size;
-	uint32_t new_ilst_size;
-	void *new_ilst_buffer, *out_buffer;
+	uint32_t new_ilst_size = 0;
+	void *out_buffer;
 	uint8_t *p_out;
 	int32_t size_delta;
 	uint32_t tmp;
 
-	ret = find_atom_v2(f, total_base, total_size, "udta", 0, "meta");
-	if (ret <= 0)
-		return NULL;
-	if (ret == 2) {
-		struct membuffer *buf;
-		void *new_udta_buffer;
-		uint32_t new_udta_size;
-		if (!create_udta(&f->meta, &new_udta_buffer, &new_udta_size))
-			return NULL;
-
-		buf = membuffer_create();
-		set_position(f, total_base);
-		if (!membuffer_transfer_from_file(buf, f, total_size)) {
-			free(new_udta_buffer);
-			return NULL;
-		}
-		membuffer_write_atom(buf, "udta", new_udta_size,
-			new_udta_buffer);
-
-		free(new_udta_buffer);
-
-		*out_size = membuffer_get_size(buf);
-		return membuffer_detach(buf);
-	}
-	udta_offset = get_position(f);
-	ret = read_int32(f, &udta_size);
-	if (ret <= 0)
-		return NULL;
-	ret = find_atom_v2(f, udta_offset + 8, udta_size - 8, "meta", 4, "ilst");
-	if (ret <= 0)
-		return NULL;
-	if (ret == 2) {
-		struct membuffer *buf;
-		void *new_meta_buffer;
-		uint32_t new_meta_size;
-
-		if (!create_meta(&f->meta, &new_meta_buffer, &new_meta_size))
-			return NULL;
-
-		buf = membuffer_create();
-		set_position(f, total_base);
-		if (!membuffer_transfer_from_file(buf, f,
-				udta_offset - total_base)) {
-			free(new_meta_buffer);
-			return NULL;
-		}
-
-		membuffer_write_int32(buf, udta_size + 8 + new_meta_size);
-		membuffer_write_atom_name(buf, "udta");
-		if (!membuffer_transfer_from_file(buf, f, udta_size)) {
-			free(new_meta_buffer);
-			return NULL;
-		}
-		membuffer_write_atom(buf, "meta", new_meta_size,
-			new_meta_buffer);
-		free(new_meta_buffer);
-
-		*out_size = membuffer_get_size(buf);
-		return membuffer_detach(buf);
-	}
-	meta_offset = get_position(f);
-	ret = read_int32(f, &meta_size);
-	if (ret <= 0)
-		return NULL;
- 	/* shouldn't happen, find_atom_v2 above takes care of it */
-	if (!find_atom(f, meta_offset + 12, meta_size - 12, "ilst"))
-		return NULL;
-	ilst_offset = get_position(f);
-	ret = read_int32(f, &ilst_size);
-	if (ret <= 0)
-		return NULL;
-	if (!create_ilst(&f->meta, &new_ilst_buffer, &new_ilst_size))
-		return NULL;
-	size_delta = new_ilst_size - (ilst_size - 8);
+	for (unsigned n = 0; n < f->meta.count; n++)
+		new_ilst_size += TAG_LEN(strlen(f->meta.tags[n].value));
+	size_delta = new_ilst_size - (f->ilst_size - 8);
 	*out_size = total_size + size_delta;
 	out_buffer = para_malloc(*out_size);
 	p_out = out_buffer;
 	set_position(f, total_base);
-	ret = read_data(f, p_out, udta_offset - total_base);
+	ret = read_data(f, p_out, f->udta_offset - total_base);
 	if (ret <= 0)
 		return NULL;
-	p_out += (uint32_t) (udta_offset - total_base);
+	p_out += f->udta_offset - total_base;
 	ret = read_int32(f, &tmp);
 	if (ret <= 0)
 		return NULL;
-	*(uint32_t *)p_out = fix_byte_order_32(tmp + size_delta);
+	write_u32_be(p_out, tmp + size_delta);
 	p_out += 4;
 	ret = read_data(f, p_out, 4);
 	if (ret <= 0)
 		return NULL;
 	p_out += 4;
-	ret = read_data(f, p_out, meta_offset - udta_offset - 8);
+	ret = read_data(f, p_out, f->meta_offset - f->udta_offset - 8);
 	if (ret <= 0)
 		return NULL;
-	p_out += (uint32_t) (meta_offset - udta_offset - 8);
+	p_out += f->meta_offset - f->udta_offset - 8;
 	ret = read_int32(f, &tmp);
 	if (ret <= 0)
 		return NULL;
-	*(uint32_t *)p_out = fix_byte_order_32(tmp + size_delta);
+	write_u32_be(p_out, tmp + size_delta);
 	p_out += 4;
 	ret = read_data(f, p_out, 4);
 	if (ret <= 0)
 		return NULL;
 	p_out += 4;
-	ret = read_data(f, p_out, ilst_offset - meta_offset - 8);
+	ret = read_data(f, p_out, f->ilst_offset - f->meta_offset - 8);
 	if (ret <= 0)
 		return NULL;
-	p_out += (uint32_t) (ilst_offset - meta_offset - 8);
+	p_out += f->ilst_offset - f->meta_offset - 8;
 	ret = read_int32(f, &tmp);
 	if (ret <= 0)
 		return NULL;
-	*(uint32_t *)p_out = fix_byte_order_32(tmp + size_delta);
+	write_u32_be(p_out, tmp + size_delta);
 	p_out += 4;
 	ret = read_data(f, p_out, 4);
 	if (ret <= 0)
 		return NULL;
 	p_out += 4;
-	memcpy(p_out, new_ilst_buffer, new_ilst_size);
+	create_ilst(&f->meta, p_out);
 	p_out += new_ilst_size;
-	set_position(f, ilst_offset + ilst_size);
-	ret = read_data(f, p_out, total_size
-		- (ilst_offset - total_base) - ilst_size);
+	set_position(f, f->ilst_offset + f->ilst_size);
+	ret = read_data(f, p_out, total_size - (f->ilst_offset - total_base)
+		- f->ilst_size);
 	if (ret <= 0)
 		return NULL;
-	free(new_ilst_buffer);
 	return out_buffer;
 }
 
-static int32_t write_data(struct mp4 *f, void *data, uint32_t size)
-{
-	int32_t result = 1;
-
-	result = f->cb->write(f->cb->user_data, data, size);
-
-	f->current_position += size;
-
-	return result;
-}
-
-static int32_t write_int32(struct mp4 *f, uint32_t data)
+static int write_data(struct mp4 *f, void *data, size_t size)
 {
-	int8_t temp[4];
-	write_u32_be(temp, data);
-	return write_data(f, temp, sizeof(temp));
+	while (size > 0) {
+		ssize_t ret = f->cb->write(f->cb->user_data, data, size);
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+			return -ERRNO_TO_PARA_ERROR(errno);
+		}
+		f->current_position += ret;
+		size -= ret;
+	}
+	return 1;
 }
 
-int32_t mp4_meta_update(struct mp4 *f)
+int mp4_meta_update(struct mp4 *f)
 {
 	void *new_moov_data;
 	uint32_t new_moov_size;
+	uint8_t buf[8] = "----moov";
+	int ret;
 
 	set_position(f, 0);
 	new_moov_data = modify_moov(f, &new_moov_size);
@@ -1598,27 +998,26 @@ int32_t mp4_meta_update(struct mp4 *f)
 		mp4_close(f);
 		return 0;
 	}
-	/* copy moov atom to end of the file */
 	if (f->last_atom != ATOM_MOOV) {
-		char *free_data = "free";
-
-		/* rename old moov to free */
 		set_position(f, f->moov_offset + 4);
-		write_data(f, free_data, 4);
-
-		set_position(f, f->file_size);
-		write_int32(f, new_moov_size + 8);
-		write_data(f, "moov", 4);
-		write_data(f, new_moov_data, new_moov_size);
-	} else {
+		ret = write_data(f, "free", 4); /* rename old moov to free */
+		if (ret < 0)
+			goto free_moov;
+		set_position(f, f->file_size); /* write new moov atom at EOF */
+	} else /* overwrite old moov atom */
 		set_position(f, f->moov_offset);
-		write_int32(f, new_moov_size + 8);
-		write_data(f, "moov", 4);
-		write_data(f, new_moov_data, new_moov_size);
-	}
-	free(new_moov_data);
+	write_u32_be(buf, new_moov_size + 8);
+	ret = write_data(f, buf, sizeof(buf));
+	if (ret < 0)
+		goto free_moov;
+	ret = write_data(f, new_moov_data, new_moov_size);
+	if (ret < 0)
+		goto free_moov;
 	f->cb->truncate(f->cb->user_data);
-	return 1;
+	ret = 1;
+free_moov:
+	free(new_moov_data);
+	return ret;
 }
 
 static char *meta_find_by_name(const struct mp4 *f, const char *item)