[FFmpeg-devel] [PATCH][RFC] nsv seeking

[Jai Menon]

On 3/20/09, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Mon, Mar 16, 2009 at 12:15:27PM +0530, Jai Menon wrote:
>  > Hi,
>  >
>  > Attached patch adds seeking support for NSV files. I'm not sure if its
>  > completely correct, hence the RFC ;). It works fine here and is an
>  > improvement compared to the current situation.
>  > Comments?
>  >
>  > As a side note, the whole file could use a cleanup ;)
>
>
> [...]
>  > @@ -347,12 +348,22 @@
>  >      PRINT(("NSV got infos; filepos %"PRId64"\n", url_ftell(pb)));
>  >
>  >      if (table_entries_used > 0) {
>  > +        int i;
>  >          nsv->index_entries = table_entries_used;
>  >          if((unsigned)table_entries >= UINT_MAX / sizeof(uint32_t))
>  >              return -1;
>  > -        nsv->nsvf_index_data = av_malloc(table_entries * sizeof(uint32_t));
>  > -#warning "FIXME: Byteswap buffer as needed"
>  > -        get_buffer(pb, (unsigned char *)nsv->nsvf_index_data, table_entries * sizeof(uint32_t));
>  > +        nsv->nsvf_index_data = av_malloc(table_entries_used * sizeof(uint32_t));
>
>  integer overflow leading to heap buffer overflow

modified

>  > @@ -453,6 +465,16 @@
>  >              av_set_pts_info(st, 64, framerate.den, framerate.num);
>  >              st->start_time = 0;
>  >              st->duration = av_rescale(nsv->duration, framerate.num, 1000*framerate.den);
>  > +
>  > +            for(i=0;i<nsv->index_entries;i++) {
>  > +                if(nsv->extended_index_data) {
>  > +                    av_add_index_entry(st, nsv->nsvf_index_data[i], nsv->extended_index_data[i],
>  > +                                       0, 0, AVINDEX_KEYFRAME);
>  > +                } else {
>  > +                    int64_t ts = av_rescale((i/nsv->index_entries)*nsv->duration, framerate.num, 1000*framerate.den);
>  > +                    av_add_index_entry(st, nsv->nsvf_index_data[i], ts, 0, 0, AVINDEX_KEYFRAME);
>  > +                }
>  > +            }
>  >          }
>  >          if (atag != T_NONE) {
>  >  #ifndef DISABLE_AUDIO
>
>  is there a reason for the temp table? i mean cant they be droped
>  in av_add_index_entry() directly?

the toc is read while file header and metadata is read so there are no
streams at this point of time. or am missing something?

>  > @@ -598,6 +620,11 @@
>  >          pkt->stream_index = st[NSV_ST_VIDEO]->index;//NSV_ST_VIDEO;
>  >          pkt->dts = nst->frame_offset;
>  >          pkt->flags |= nsv->state == NSV_HAS_READ_NSVS ? PKT_FLAG_KEY : 0; /* keyframe only likely on a sync frame */
>  > +
>  > +        if(!nsv->nsvf_index_data) {
>  > +            av_add_index_entry(st[NSV_ST_VIDEO], url_ftell(pb) - vsize, nst->frame_offset,
>  > +                               0, 0, nsv->state == NSV_HAS_READ_NSVS ? AVINDEX_KEYFRAME : 0);
>  > +        }
>  >  /*
>  >          for (i = 0; i < MIN(8, vsize); i++)
>  >              PRINT(("NSV video: [%d] = %02x\n", i, pkt->data[i]));
>
>  > @@ -683,15 +710,25 @@
>  >
>  >  static int nsv_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
>  >  {
>  > -#if 0
>
>  ideally this should use the new seeking api

when it does end up in svn, i'll rtfs and look at this again :)
updated patch attached.

-- 
Regards,

Jai
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