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

Michael Niedermayer michael at niedermayer.cc
Fri Jun 28 19:28:56 EEST 2019

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
> Changes in v3:
>   - Changed the commit hash abbreviation in the patch file diff to be 10
>     characters in length rather than 7. This was causing the patch file
>     to fail when it was applied. 
>  libavformat/rtpdec_rfc4175.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

The patch looks reasonable to me but i dont really know rfc4175
Ideally someone who knows rfc4175 should make the final decission to apply it
maybe whoever applies it can also bump the micro version so user apps have
a way to detect this line shifting change


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The bravest are surely those who have the clearest vision
of what is before them, glory and danger alike, and yet
notwithstanding go out to meet it. -- Thucydides
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20190628/7e3d0088/attachment.sig>

More information about the ffmpeg-devel mailing list