Re: [FFmpeg-devel] [PATCH 3/3] lavf/id3v2dec: support multiple values and TIPL frames

[Ridley Combs <rcombs@rcombs.me>]

> On Aug 24, 2022, at 19:16, Soft Works <softworkz@hotmail.com> wrote:
> 
> 
> 
>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org <mailto:ffmpeg-devel-bounces@ffmpeg.org>> On Behalf Of
>> rcombs
>> Sent: Thursday, August 25, 2022 1:52 AM
>> To: ffmpeg-devel@ffmpeg.org <mailto:ffmpeg-devel@ffmpeg.org>
>> Subject: [FFmpeg-devel] [PATCH 3/3] lavf/id3v2dec: support multiple
>> values and TIPL frames
>> 
>> Fixes https://trac.ffmpeg.org/ticket/6949
>> 
>> Ordinary text frames in ID3v2 are allowed to have multiple
>> (null-separated) values. This technically isn't allowed in TXXX,
>> but it's used in practice by Picard, and supporting it is harmless.
>> 
>> TIPL/IPL (Involved People List) and TMCL (Musician Credits List) work
>> similarly to TXXX, but alternate key-value-key-value.
>> ---
>> libavformat/id3v2.c | 49 ++++++++++++++++++++++++++-----------------
>> --
>> 1 file changed, 28 insertions(+), 21 deletions(-)
>> 
>> diff --git a/libavformat/id3v2.c b/libavformat/id3v2.c
>> index 191a305ffb..335a1436b2 100644
>> --- a/libavformat/id3v2.c
>> +++ b/libavformat/id3v2.c
>> @@ -321,8 +321,12 @@ static void read_ttag(AVFormatContext *s,
>> AVIOContext *pb, int taglen,
>>                       AVDictionary **metadata, const char *key)
>> {
>>     uint8_t *dst;
>> -    int encoding, dict_flags = AV_DICT_DONT_OVERWRITE |
>> AV_DICT_DONT_STRDUP_VAL;
>> +    uint8_t *dst_key = NULL;
>> +    int encoding, dict_flags = AV_DICT_MULTIKEY |
>> AV_DICT_DONT_STRDUP_VAL | AV_DICT_DEDUP;
>>     unsigned genre;
>> +    int count = 0;
>> +    int is_tipl = !(strcmp(key, "TIPL") && strcmp(key, "TMCL") &&
>> +                    strcmp(key, "IPL"));
>> 
>>     if (taglen < 1)
>>         return;
>> @@ -330,30 +334,33 @@ static void read_ttag(AVFormatContext *s,
>> AVIOContext *pb, int taglen,
>>     encoding = avio_r8(pb);
>>     taglen--; /* account for encoding type byte */
>> 
>> -    if (decode_str(s, pb, encoding, &dst, &taglen) < 0) {
>> -        av_log(s, AV_LOG_ERROR, "Error reading frame %s, skipped\n",
>> key);
>> -        return;
>> -    }
>> -
>> -    if (!(strcmp(key, "TCON") && strcmp(key, "TCO"))
>> &&
>> -        (sscanf(dst, "(%d)", &genre) == 1 || sscanf(dst, "%d",
>> &genre) == 1) &&
>> -        genre <= ID3v1_GENRE_MAX) {
>> -        av_freep(&dst);
>> -        dst = av_strdup(ff_id3v1_genre_str[genre]);
>> -    } else if (!(strcmp(key, "TXXX") && strcmp(key, "TXX"))) {
>> -        /* dst now contains the key, need to get value */
>> -        key = dst;
>> +    while (taglen > 1) {
> 
> int n = 0;
> 
>>         if (decode_str(s, pb, encoding, &dst, &taglen) < 0) {
>>             av_log(s, AV_LOG_ERROR, "Error reading frame %s,
>> skipped\n", key);
>> -            av_freep(&key);
>>             return;
>>         }
>> -        dict_flags |= AV_DICT_DONT_STRDUP_KEY;
>> -    } else if (!*dst)
>> -        av_freep(&dst);
>> 
>> -    if (dst)
>> -        av_dict_set(metadata, key, dst, dict_flags);
>> +        count++;
>> +
>> +        if (!(strcmp(key, "TCON") && strcmp(key, "TCO"))
>> &&
>> +            (sscanf(dst, "(%d)", &genre) == 1 || sscanf(dst, "%d",
>> &genre) == 1) &&
> 
> (sscanf(dst, "(%d)", &genre) == 1 || (sscanf(dst, "%d%n", &genre, &n) == 1 && n == strlen(dst))) &&
> 
> avoids parsing genre strings starting with numbers (like '2step')
> as genre id.

Sounds reasonable, but this isn't new code (it's just reindented); please send this as its own patch.

> 
> 
> Thanks for resubmitting,
> softworkz
> 
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