[FFmpeg-devel] [PATCH 1/3] lavf/subtitles: add some SMIL helpers.

[Nicolas George]

Le decadi 30 prairial, an CCXX, Clément Bœsch a écrit :
> This is needed for SAMI and RealText demuxers.
> ---
>  libavformat/subtitles.c |   35 +++++++++++++++++++++++++++++++++++
>  libavformat/subtitles.h |   13 +++++++++++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/libavformat/subtitles.c b/libavformat/subtitles.c
> index 5e3cdee..39e18f8 100644
> --- a/libavformat/subtitles.c
> +++ b/libavformat/subtitles.c
> @@ -20,6 +20,7 @@
>  
>  #include "avformat.h"
>  #include "subtitles.h"
> +#include "libavutil/avstring.h"
>  
>  FFDemuxSubEntry *ff_subtitles_queue_insert_event(FFDemuxSubtitlesQueue *q,
>                                                   const uint8_t *event, int len,
> @@ -105,3 +106,37 @@ void ff_subtitles_queue_free(FFDemuxSubtitlesQueue *q)
>      av_freep(&q->subs);
>      q->nsub = q->allocated_size = 0;
>  }
> +
> +int ff_smil_extract_next_chunk(AVIOContext *pb, AVBPrint *buf, char *c)
> +{
> +    int i = 0;
> +    char end_chr;
> +
> +    if (!*c) // cached char?
> +        *c = avio_r8(pb);
> +    if (!*c)
> +        return 0;
> +
> +    end_chr = *c == '<' ? '>' : '<';
> +    do {
> +        av_bprint_chars(buf, *c, 1);
> +        *c = avio_r8(pb);
> +        i++;
> +    } while (*c != end_chr && *c);
> +    if (end_chr == '>') {
> +        av_bprint_chars(buf, '>', 1);
> +        *c = 0;
> +    }
> +    return i;
> +}
> +
> +char *ff_smil_get_attr_ptr(const char *s, const char *tag)
> +{
> +    char *p = av_stristr(s, tag);
> +    if (p) {
> +        p += strlen(tag);
> +        if (*p == '=') p++;
> +        if (*p == '"') p++;
> +    }
> +    return p;
> +}

Unless I am mistaken, ff_smil_get_attr_ptr(s, "x") will find the "index"
too.

> diff --git a/libavformat/subtitles.h b/libavformat/subtitles.h
> index c098131..be875cd 100644
> --- a/libavformat/subtitles.h
> +++ b/libavformat/subtitles.h
> @@ -23,6 +23,7 @@
>  
>  #include <stdint.h>
>  #include "avformat.h"
> +#include "libavutil/bprint.h"
>  
>  typedef struct {
>      uint8_t *event;         ///< allocated subtitle line, zero terminated
> @@ -67,4 +68,16 @@ int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q,
>   */
>  void ff_subtitles_queue_free(FFDemuxSubtitlesQueue *q);
>  
> +/**
> + * SMIL helper to load next chunk ("<...>" or untagged content) in buf
> + *
> + * @param c cached character, to avoid a backward seek
> + */
> +int ff_smil_extract_next_chunk(AVIOContext *pb, AVBPrint *buf, char *c);
> +
> +/**
> + * SMIL helper to point on the value of a given tag
> + */

I find that comment rather obscure. Especially since it looks like you are
scanning for what is called, in HTML, an attribute and not a tag.

> +char *ff_smil_get_attr_ptr(const char *s, const char *tag);
> +
>  #endif /* AVFORMAT_SUBTITLES_H */

Regards,

-- 
  Nicolas George
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