[FFmpeg-devel] [PATCH v3] avformat/rtpdec_rfc4175: Fix incorrect copy_offset calculation

[Kieran Kunhya]

On Mon, 5 Aug 2019 at 17:10, Michael Niedermayer <michael at niedermayer.cc>
wrote:

> On Thu, Jun 27, 2019 at 06:06:22AM +0000, Jacob Siddall wrote:
> > The previous calculation code did not account for the fact that the
> > copy_offset for the start of the frame array is at index 0, yet the
> > scan line number from the rfc4175 RTP header starts at 1.
> > This caused 2 issues to appear:
> > - The first scan line was being copied into the array where the second
> >   scan line should be. This caused the resulting video to have a green
> >   line at the top of it.
> > - Since the packet containing the last scan line would fail the
> >   calculation, the packet with the RTP marker would not be processed
> >   which caused a log message saying "Missed previous RTP marker" to be
> >   outputted for each frame.
> >
> > Signed-off-by: Jacob Siddall <kobe at live.com.au>
> > ---
> > Changes in v2:
> >   - Don't handle packet if the line number is less than 1
> >
> > Section 12 in the VSF technical recommendation TR-03 specifies that the
> > video scan line numbers should start at 1.
> >
> http://www.videoservicesforum.org/download/technical_recommendations/VSF_TR-03_2015-11-12.pdf
>
>
SMPTE 2110-20 says line numbers start at 0. (Yes there are 3 different
"standards" for handling the line number because of the geniuses in the
broadcast industry).

Kieran