[Ffmpeg-devel] [RFC] av_seek_frame behaviour

[Michael Niedermayer]

Hi

On Mon, Apr 23, 2007 at 01:28:45PM +0200, Baptiste Coudurier wrote:
[...]
> > also av_seek_frame_generic() just 
> > reads the file linearly from the last position to the point to which the
> > user wants to seek so even with huge files a little forward/backward
> > seeking should be ok
> 
> Humm:
> 
>     if(index < 0 || index==st->nb_index_entries-1){
>         int i;
>         AVPacket pkt;
> 
>         if(st->index_entries && st->nb_index_entries){
>             ie= &st->index_entries[st->nb_index_entries-1];
>             url_fseek(&s->pb, ie->pos, SEEK_SET);
>             av_update_cur_dts(s, st, ie->timestamp);
>         }else
>             url_fseek(&s->pb, 0, SEEK_SET);
> 
> In fact av_seek_frame_generic seek back to the beginning of file if no
> index is there, maybe it is not wanted ? Or see below.
> 
> > that is unless the demuxer doesnt use av_add_index_entry() properly
> 
> Ok, so demuxer should use av_add_index_entry ? 

if it wants to use the avindex to seek either directly or through a function
like av_seek_frame_generic() ...


> Im not against that, it
> just needs to check all demuxers.
> 
> > also iam not opposed to add some flags so that the user can indicate
> > the amount of accuracy/speed she wants but first we actually need
> > to have multiple working seek variants before a API to access them
> > makes sense ...
> 
> Agree. I began to check some seek functions:
> 
> TS seems to use av_seek_frame_binary internally and returning -1 which
> will make av_seek_frame to call av_seek_frame_binary again. Twice try in
> case of failure.

:(

[...]

> FLV seems to work removing seek function and letting av_seek_frame
> calling av_seek_frame_generic.

ok, feel free to remove it (if the seek regression tests related to
flv dont change)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I count him braver who overcomes his desires than him who conquers his
enemies for the hardest victory is over self. -- Aristotle
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