Re: [FFmpeg-devel] [PATCH 01/10] avformat/hls: fix repeated requests for media init section

["mypopy@gmail.com" <mypopy@gmail.com>]

On Tue, Apr 12, 2022 at 4:15 PM Zhao Zhili <quinkblack@foxmail.com> wrote:
>
> ---
>  libavformat/hls.c | 59 ++++++++++++++++++++++++++++++++---------------
>  1 file changed, 40 insertions(+), 19 deletions(-)
>
> diff --git a/libavformat/hls.c b/libavformat/hls.c
> index 83ff4cc607..67c9650e0b 100644
> --- a/libavformat/hls.c
> +++ b/libavformat/hls.c
> @@ -407,48 +407,65 @@ struct init_section_info {
>      char byterange[32];
>  };
>
> -static struct segment *new_init_section(struct playlist *pls,
> +/*
> + * Return a new init section if info is new, otherwise return an entry
> + * from pls->init_sections.
> + */
> +static struct segment *get_init_section(struct playlist *pls,
>                                          struct init_section_info *info,
> -                                        const char *url_base)
> +                                        const char *url_base,
> +                                        int *new_init)
>  {
> -    struct segment *sec;
> +    struct segment *sec_ptr = NULL;
> +    struct segment sec = {};
>      char tmp_str[MAX_URL_SIZE], *ptr = tmp_str;
>
> +    *new_init = 1;
>      if (!info->uri[0])
>          return NULL;
>
> -    sec = av_mallocz(sizeof(*sec));
> -    if (!sec)
> -        return NULL;
> -
>      if (!av_strncasecmp(info->uri, "data:", 5)) {
>          ptr = info->uri;
>      } else {
>          ff_make_absolute_url(tmp_str, sizeof(tmp_str), url_base, info->uri);
>          if (!tmp_str[0]) {
> -            av_free(sec);
>              return NULL;
>          }
>      }
> -    sec->url = av_strdup(ptr);
> -    if (!sec->url) {
> -        av_free(sec);
> -        return NULL;
> -    }
> +    // Don't dup until make sure it's a new initialization section
> +    sec.url = ptr;
>
>      if (info->byterange[0]) {
> -        sec->size = strtoll(info->byterange, NULL, 10);
> +        sec.size = strtoll(info->byterange, NULL, 10);
>          ptr = strchr(info->byterange, '@');
>          if (ptr)
> -            sec->url_offset = strtoll(ptr+1, NULL, 10);
> +            sec.url_offset = strtoll(ptr+1, NULL, 10);
>      } else {
>          /* the entire file is the init section */
> -        sec->size = -1;
> +        sec.size = -1;
>      }
>
> -    dynarray_add(&pls->init_sections, &pls->n_init_sections, sec);
> +    for (int i = 0; i < pls->n_init_sections; i++) {
> +        sec_ptr = pls->init_sections[i];
> +        if (!strcmp(sec_ptr->url, sec.url) &&
> +            sec_ptr->size == sec.size &&
> +            sec_ptr->url_offset == sec.url_offset) {
> +            *new_init = 0;
> +            return sec_ptr;
> +        }
> +    }
> +
> +    sec_ptr = av_malloc(sizeof(*sec_ptr));
> +    if (!sec_ptr) return NULL;
> +    *sec_ptr = sec;
> +    sec_ptr->url = av_strdup(ptr);
> +    if (!sec_ptr->url) {
> +        av_free(sec_ptr);
> +        return NULL;
> +    }
> +    dynarray_add(&pls->init_sections, &pls->n_init_sections, sec_ptr);
>
> -    return sec;
> +    return sec_ptr;
>  }
>
>  static void handle_init_section_args(struct init_section_info *info, const char *key,
> @@ -851,13 +868,17 @@ static int parse_playlist(HLSContext *c, const char *url,
>              else if (!strcmp(ptr, "VOD"))
>                  pls->type = PLS_TYPE_VOD;
>          } else if (av_strstart(line, "#EXT-X-MAP:", &ptr)) {
> +            int new_init = 1;
>              struct init_section_info info = {{0}};
>              ret = ensure_playlist(c, &pls, url);
>              if (ret < 0)
>                  goto fail;
>              ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_init_section_args,
>                                 &info);
> -            cur_init_section = new_init_section(pls, &info, url);
> +            cur_init_section = get_init_section(pls, &info, url, &new_init);
> +            /* Skip if it's the same init section */
> +            if (!new_init)
> +                continue;
>              if (!cur_init_section) {
>                  ret = AVERROR(ENOMEM);
>                  goto fail;
> --
> 2.31.1
Can these patches handle multiple instances of the media init sections?
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