[FFmpeg-devel] [PATCH] avformat/id3v2enc: write CTOC too

[James Almer]

On 6/4/2019 11:45 AM, Paul B Mahol wrote:
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
>  libavformat/id3v2enc.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/libavformat/id3v2enc.c b/libavformat/id3v2enc.c
> index ffe358f019..9b72614447 100644
> --- a/libavformat/id3v2enc.c
> +++ b/libavformat/id3v2enc.c
> @@ -255,6 +255,39 @@ static int write_metadata(AVIOContext *pb, AVDictionary **metadata,
>      return 0;
>  }
>  
> +static int write_ctoc(AVFormatContext *s, ID3v2EncContext *id3, int enc)
> +{
> +    uint8_t *dyn_buf = NULL;
> +    AVIOContext *dyn_bc = NULL;
> +    char name[123];
> +    int len, ret;
> +
> +    if ((ret = avio_open_dyn_buf(&dyn_bc)) < 0)
> +        goto fail;
> +
> +    id3->len += avio_put_str(dyn_bc, "toc");
> +    avio_wb16(dyn_bc, 0x03);
> +    avio_w8(dyn_bc, s->nb_chapters);
> +    for (int i = 0; i < s->nb_chapters; i++) {
> +        snprintf(name, 122, "ch%d", i);
> +        id3->len += avio_put_str(dyn_bc, name);
> +    }
> +    len = avio_close_dyn_buf(dyn_bc, &dyn_buf);
> +    id3->len += 16 + ID3v2_HEADER_SIZE;
> +
> +    avio_wb32(s->pb, MKBETAG('C', 'T', 'O', 'C'));
> +    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;
> +}
> +
>  static int write_chapter(AVFormatContext *s, ID3v2EncContext *id3, int id, int enc)
>  {
>      const AVRational time_base = {1, 1000};
> @@ -306,6 +339,9 @@ int ff_id3v2_write_metadata(AVFormatContext *s, ID3v2EncContext *id3)
>      if ((ret = write_metadata(s->pb, &s->metadata, id3, enc)) < 0)
>          return ret;
>  
> +    if ((ret = write_ctoc(s, id3, enc)) < 0)

Shouldn't you check that s->nb_chapters is > 0 before calling this? Or
within that function, alternatively.

Even if CTOC could be written with 0 chapters, it would be an
unnecessary bloat in the output file.

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