[FFmpeg-devel] [PATCH 2/2] avformat/mxfenc: do not write index tables with the same InstanceUID

[Marton Balint]

On Wed, 16 Mar 2022, Tomas Härdin wrote:

> ons 2022-03-16 klockan 20:38 +0100 skrev Marton Balint:
>> 
>> 
>> On Wed, 16 Mar 2022, Tomas Härdin wrote:
>> 
>> > mån 2022-03-14 klockan 21:44 +0100 skrev Marton Balint:
>> > > 
>> > > 
>> > > On Mon, 14 Mar 2022, Tomas Härdin wrote:
>> > > 
>> > > > mån 2022-03-14 klockan 20:54 +0100 skrev Marton Balint:
>> > > > > 
>> > > > > 
>> > > > > On Mon, 14 Mar 2022, Tomas Härdin wrote:
>> > > > > 
>> > > > > > mån 2022-03-14 klockan 19:49 +0100 skrev Marton Balint:
>> > > > > > > Only index tables repeating previous index tables should
>> > > > > > > use
>> > > > > > > the
>> > > > > > > same
>> > > > > > > InstaceUID. Use the index start position when generating
>> > > > > > > the
>> > > > > > > InstanceUID to fix
>> > > > > > > this.
>> > > > > > > 
>> > > > > > > Signed-off-by: Marton Balint <cus at passwd.hu>
>> > > > > > > ---
>> > > > > > >  libavformat/mxfenc.c | 2 +-
>> > > > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
>> > > > > > > 
>> > > > > > > diff --git a/libavformat/mxfenc.c b/libavformat/mxfenc.c
>> > > > > > > index ba8e7babfb..5b972eadaa 100644
>> > > > > > > --- a/libavformat/mxfenc.c
>> > > > > > > +++ b/libavformat/mxfenc.c
>> > > > > > > @@ -1757,7 +1757,7 @@ static void
>> > > > > > > mxf_write_index_table_segment(AVFormatContext *s)
>> > > > > > >  
>> > > > > > >      // instance id
>> > > > > > >      mxf_write_local_tag(s, 16, 0x3C0A);
>> > > > > > > -    mxf_write_uuid(pb, IndexTableSegment, 0);
>> > > > > > > +    mxf_write_uuid(pb, IndexTableSegment, mxf-
>> > > > > > > > last_indexed_edit_unit);
>> > > > > > 
>> > > > > > Two things: yes, it is good that this fixes the same
>> > > > > > InstanceUID
>> > > > > > being
>> > > > > > reused. But more importantly, we should not be writing
>> > > > > > files
>> > > > > > with
>> > > > > > over
>> > > > > > 65536 partitions!
>> > > > > 
>> > > > > last_indexed_edit_unit is frame based not partition based, so
>> > > > > it
>> > > > > can 
>> > > > > overflow 65536 realtively easily, that is why I submitted
>> > > > > patch
>> > > > > 1.
>> > > > 
>> > > > Right. But we could use the partition number instead.
>> > > 
>> > > Well, we could use mxf->body_partitions_count but it is not
>> > > trivial
>> > > to see 
>> > > that it will work for all cases.
>> > 
>> > I don't see why not. But upping to 32-bit is easy anyways.
>> 
>> I tried, but body partition count is the same for the last body
>> partition 
>> and for the footer partition, both having different index tables...
>> 
>> So I still find it more starightforward to use index start position 
>> instead of some magic to find out the proper partition count, is it
>> fine 
>> with you?
>
> I mean it shouldn't matter so long as its unique. So sure

Ok, applied the series then.

Thanks,
Marton