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

[Soft Works <softworkz@hotmail.com>]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> rcombs
> Sent: Thursday, August 25, 2022 1:52 AM
> To: 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.


Thanks for resubmitting,
softworkz

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