[FFmpeg-devel] [PATCH 2/8] avformat/movenc: Avoid calling strlen multiple times

[James Almer]

On 8/23/2021 10:16 AM, Andreas Rheinhardt wrote:
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>   libavformat/movenc.c | 22 +++++++++++++---------
>   1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> index 18410c70fa..acf9d63c52 100644
> --- a/libavformat/movenc.c
> +++ b/libavformat/movenc.c
> @@ -2766,6 +2766,7 @@ static int mov_write_hdlr_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
>       MOVMuxContext *mov = s->priv_data;
>       const char *hdlr, *descr = NULL, *hdlr_type = NULL;
>       int64_t pos = avio_tell(pb);
> +    size_t descr_len;
>   
>       hdlr      = "dhlr";
>       hdlr_type = "url ";
> @@ -2829,9 +2830,10 @@ static int mov_write_hdlr_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
>       avio_wb32(pb, 0); /* reserved */
>       avio_wb32(pb, 0); /* reserved */
>       avio_wb32(pb, 0); /* reserved */
> +    descr_len = strlen(descr);
>       if (!track || track->mode == MODE_MOV)
> -        avio_w8(pb, strlen(descr)); /* pascal string */
> -    avio_write(pb, descr, strlen(descr)); /* handler description */
> +        avio_w8(pb, descr_len); /* pascal string */
> +    avio_write(pb, descr, descr_len); /* handler description */
>       if (track && track->mode != MODE_MOV)
>           avio_w8(pb, 0); /* c string */
>       return update_size(pb, pos);
> @@ -3502,21 +3504,22 @@ static int mov_write_itunes_hdlr_tag(AVIOContext *pb, MOVMuxContext *mov,
>   /* helper function to write a data tag with the specified string as data */
>   static int mov_write_string_data_tag(AVIOContext *pb, const char *data, int lang, int long_style)
>   {
> +    size_t data_len = strlen(data);
>       if (long_style) {
> -        int size = 16 + strlen(data);
> +        int size = 16 + data_len;
>           avio_wb32(pb, size); /* size */
>           ffio_wfourcc(pb, "data");
>           avio_wb32(pb, 1);
>           avio_wb32(pb, 0);
> -        avio_write(pb, data, strlen(data));
> +        avio_write(pb, data, data_len);
>           return size;
>       } else {
> +        avio_wb16(pb, data_len); /* string length */
>           if (!lang)
>               lang = ff_mov_iso639_to_lang("und", 1);
> -        avio_wb16(pb, strlen(data)); /* string length */
>           avio_wb16(pb, lang);
> -        avio_write(pb, data, strlen(data));
> -        return strlen(data) + 4;
> +        avio_write(pb, data, data_len);
> +        return data_len + 4;
>       }
>   }
>   
> @@ -3792,9 +3795,10 @@ static int mov_write_mdta_keys_tag(AVIOContext *pb, MOVMuxContext *mov,
>       avio_wb32(pb, 0); /* entry count */
>   
>       while (t = av_dict_get(s->metadata, "", t, AV_DICT_IGNORE_SUFFIX)) {
> -        avio_wb32(pb, strlen(t->key) + 8);
> +        size_t key_len = strlen(t->key);
> +        avio_wb32(pb, key_len + 8);
>           ffio_wfourcc(pb, "mdta");
> -        avio_write(pb, t->key, strlen(t->key));
> +        avio_write(pb, t->key, key_len);
>           count += 1;
>       }
>       curpos = avio_tell(pb);

nit: could just use avio_printf(pb, "%s", string) for all these instead.