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avformat/id3v2: honor the tag version in CHAP frame sizes

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ID3v2.3 stores a frame size as a plain 32-bit integer. ID3v2.4 stores it
as a synchsafe integer. write_chapter() always wrote the plain form, and
read_chapter() always read it that way. Once an embedded text frame
reached 128 bytes, the size no longer fitted and the chapter was dropped.

Write the CHAP header with the same version rule as other frames. Read an
embedded frame with that rule, and keep the chapter when a subframe size
does not fit.

Fixes: https://code.ffmpeg.org/FFmpeg/FFmpeg/issues/25357
Signed-off-by: Jun Zhao <barryjzhao@tencent.com>
This commit is contained in:
Jun Zhao
2026-10-23 07:06:02 +08:00
parent 179d083493
commit e828b52165
2 changed files with 42 additions and 26 deletions
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42
libavformat/id3v2.c
View File

@@ -487,7 +487,7 @@ static void list_append(ID3v2ExtraMeta *new_elem, ExtraMetaList *list)
* Parse GEOB tag into a ID3v2ExtraMetaGEOB struct.
*/
static void read_geobtag(AVFormatContext *s, AVIOContext *pb, int taglen,
const char *tag, ExtraMetaList *extra_meta, int isv34)
const char *tag, ExtraMetaList *extra_meta, int version)
{
ID3v2ExtraMetaGEOB *geob_data = NULL;
ID3v2ExtraMeta *new_extra = NULL;
@@ -618,7 +618,7 @@ static void rstrip_spaces(char *buf)
}
static void read_apic(AVFormatContext *s, AVIOContext *pb, int taglen,
const char *tag, ExtraMetaList *extra_meta, int isv34)
const char *tag, ExtraMetaList *extra_meta, int version)
{
int enc, pic_type;
char mimetype[64] = {0};
@@ -628,7 +628,7 @@ static void read_apic(AVFormatContext *s, AVIOContext *pb, int taglen,
ID3v2ExtraMeta *new_extra = NULL;
int64_t end = avio_tell(pb) + taglen;
if (taglen <= 4 || (!isv34 && taglen <= 6))
if (taglen <= 4 || (version == 2 && taglen <= 6))
goto fail;
new_extra = av_mallocz(sizeof(*new_extra));
@@ -641,7 +641,7 @@ static void read_apic(AVFormatContext *s, AVIOContext *pb, int taglen,
taglen--;
/* mimetype */
if (isv34) {
if (version != 2) {
int ret = avio_get_str(pb, taglen, mimetype, sizeof(mimetype));
if (ret < 0 || ret >= taglen)
goto fail;
@@ -714,9 +714,8 @@ static void free_chapter(void *obj)
}
static void read_chapter(AVFormatContext *s, AVIOContext *pb, int len,
const char *ttag, ExtraMetaList *extra_meta, int isv34)
const char *ttag, ExtraMetaList *extra_meta, int version)
{
int taglen;
char tag[5];
ID3v2ExtraMeta *new_extra = NULL;
ID3v2ExtraMetaCHAP *chap = NULL;
@@ -739,19 +738,30 @@ static void read_chapter(AVFormatContext *s, AVIOContext *pb, int len,
len -= 16;
while (len > 10) {
unsigned tlen;
if (avio_read(pb, tag, 4) < 4)
goto fail;
break;
tag[4] = 0;
taglen = avio_rb32(pb);
/* Embedded frames use the same header as the surrounding tag.
* 2.2 has no CHAP. 2.3 sizes are plain; 2.4 sizes are synchsafe. */
if (version == 4)
tlen = get_size(pb, 4);
else
tlen = avio_rb32(pb);
avio_skip(pb, 2);
len -= 10;
if (taglen < 0 || taglen > len)
goto fail;
if (tlen > (unsigned)len) {
av_log(s, AV_LOG_WARNING,
"Invalid ID3v2 chapter subframe %.4s size %u, keeping the chapter\n",
tag, tlen);
break;
}
if (tag[0] == 'T')
read_ttag(s, pb, taglen, &chap->meta, tag);
read_ttag(s, pb, tlen, &chap->meta, tag);
else
avio_skip(pb, taglen);
len -= taglen;
avio_skip(pb, tlen);
len -= tlen;
}
ff_metadata_conv(&chap->meta, NULL, ff_id3v2_34_metadata_conv);
@@ -775,7 +785,7 @@ static void free_priv(void *obj)
}
static void read_priv(AVFormatContext *s, AVIOContext *pb, int taglen,
const char *tag, ExtraMetaList *extra_meta, int isv34)
const char *tag, ExtraMetaList *extra_meta, int version)
{
ID3v2ExtraMeta *meta;
ID3v2ExtraMetaPRIV *priv;
@@ -813,7 +823,7 @@ typedef struct ID3v2EMFunc {
const char *tag4;
void (*read)(AVFormatContext *s, AVIOContext *pb, int taglen,
const char *tag, ExtraMetaList *extra_meta,
int isv34);
int version);
void (*free)(void *obj);
} ID3v2EMFunc;
@@ -1092,7 +1102,7 @@ static void id3v2_parse(AVIOContext *pb, AVDictionary **metadata,
read_lang_descr_tag(s, pbx, "comment", tlen, metadata);
else
/* parse special meta tag */
extra_func->read(s, pbx, tlen, tag, extra_meta, isv34);
extra_func->read(s, pbx, tlen, tag, extra_meta, version);
} else if (!tag[0]) {
if (tag[1])
av_log(s, AV_LOG_WARNING, "invalid frame id, assuming padding\n");

26
libavformat/id3v2enc.c
View File

@@ -60,6 +60,18 @@ static void id3v2_encode_string(AVIOContext *pb, const uint8_t *str,
put(pb, str);
}
/* ID3v2.3 frame size is not synchsafe; 2.4 is. */
static void id3v2_put_frame_header(ID3v2EncContext *id3, AVIOContext *pb,
uint32_t tag, int len, int flags)
{
avio_wb32(pb, tag);
if (id3->version == 3)
avio_wb32(pb, len);
else
id3v2_put_size(pb, len);
avio_wb16(pb, flags);
}
static int id3v2_put_frame(ID3v2EncContext *id3, AVIOContext *avioc, AVIOContext *dyn_buf,
const uint32_t tag, const uint8_t flags)
{
@@ -67,13 +79,7 @@ static int id3v2_put_frame(ID3v2EncContext *id3, AVIOContext *avioc, AVIOContext
uint8_t *pb;
len = avio_get_dyn_buf(dyn_buf, &pb);
avio_wb32(avioc, tag);
/* ID3v2.3 frame size is not sync-safe */
if (id3->version == 3)
avio_wb32(avioc, len);
else
id3v2_put_size(avioc, len);
avio_wb16(avioc, flags);
id3v2_put_frame_header(id3, avioc, tag, len, flags);
avio_write(avioc, pb, len);
id3->len += len + ID3v2_HEADER_SIZE;
@@ -463,9 +469,9 @@ static int write_chapter(AVFormatContext *s, AVIOContext *pb,
len = avio_get_dyn_buf(dyn_bc, &dyn_buf);
id3->len += 16 + ID3v2_HEADER_SIZE;
avio_wb32(pb, MKBETAG('C', 'H', 'A', 'P'));
avio_wb32(pb, len);
avio_wb16(pb, 0);
/* Nested frames already updated id3->len, so this header is written
* directly instead of through id3v2_put_frame(). */
id3v2_put_frame_header(id3, pb, MKBETAG('C', 'H', 'A', 'P'), len, 0);
avio_write(pb, dyn_buf, len);
fail: