[FFmpeg-devel] [PATCH] avformat/flacdec: support fast-seek

[Michael Niedermayer]

On Fri, Sep 25, 2015 at 11:58:31AM +0800, Ching-Yi Chan wrote:
> Thanks for checking.
> 
> I also check the AVFMT_FLAG_FAST_SEEK flag with parsing headers,
> to fill the seektable into index entries only if AVFMT_FLAG_FAST_SEEK flag
> is on.
> 
> If the AVFMT_FLAG_FAST_SEEK flag is not enabled, it will seek in original
> way.

i think we misunderstand us somehow

your code does not work for me
seeking to  1.894167 results in a seek to
pts: 0.000000 pos:   8256

seeking to  1.470835 results in a seek to
pts: 0.809796 pos:  27366

you notice that moving the target to a later point moves the result
to a earlier one.

please see below for further comments

[...]

> +#define SEEKPOINT_SIZE 18
> +
> +static void ff_reset_index_position(int64_t metadata_head_size, AVStream *st)

the ff_ prefix is for non static functions


[...9

> @@ -249,12 +277,30 @@ static av_unused int64_t flac_read_timestamp(AVFormatContext *s, int stream_inde
>      return pts;
>  }
>  
> +static int flac_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
> +    if (!(s->flags&AVFMT_FLAG_FAST_SEEK)) {
> +        return -1;
> +    }
> +
> +    int index = av_index_search_timestamp(s->streams[0], timestamp, flags);

libavformat/flacdec.c:285:5: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
libavformat/flacdec.c:289:5: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]

please make sure your patch adds no compiler warnings


> +    if(index<0 || index >= s->streams[0]->nb_index_entries)
> +        return -1;
> +
> +    AVIndexEntry e = s->streams[0]->index_entries[index];

> +    int ret = avio_seek(s->pb, e.pos, SEEK_SET);

this is wrong and must use int64_t otherwise the following >= 0 check
can be wrong

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Democracy is the form of government in which you can choose your dictator
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