[FFmpeg-devel] [PATCH 2/3] avformat/avienc: add reserve_index_space option

[Michael Niedermayer]

On Fri, Jan 20, 2017 at 05:06:59PM +0100, Tobias Rapp wrote:
> On 20.01.2017 15:56, Tobias Rapp wrote:
> >On 19.01.2017 18:32, Michael Niedermayer wrote:
> >>On Wed, Jan 18, 2017 at 10:27:02AM +0100, Tobias Rapp wrote:
> >>>Allows the user to reserve space for the ODML master index. A sufficient
> >>>sized master index in the AVI header avoids storing follow-up master
> >>>indexes within the 'movi' data later.
> >>>
> >>>If the option is omitted or zero the index size is estimated from output
> >>>duration and bitrate. A worst-case bitrate for video streams is assumed
> >>>in case it is not available.
> >>>
> >>>Note: fate reference files changed because the video stream had zero
> >>>bitrate before and is guessed now.
> >>>
> >>>Signed-off-by: Tobias Rapp <t.rapp at noa-archive.com>
> >>>---
> >>> libavformat/avi.h                       |  1 -
> >>> libavformat/avienc.c                    | 77
> >>>++++++++++++++++++++++++++++++---
> >>> libavformat/version.h                   |  2 +-
> >>> tests/ref/fate/mpeg4-bsf-unpack-bframes |  2 +-
> >>> tests/ref/lavf-fate/avi_cram            |  2 +-
> >>> 5 files changed, 74 insertions(+), 10 deletions(-)
> >>
> >>this breaks segment:
> >>./ffmpeg -i lena.pnm -f segment test%d.avi
> >>
> >>possibly related to avi_init()
> >
> >Yes, I can reproduce the problem when going back to Git master and just
> >adding a dummy init (see attached diff). Not sure how to fix this, other
> >muxers also have an init but seem to work fine (mkv) ...
> 
> Apparently the codec_tag is cleared in seg_write_header() around line 811:
> 
> [...]
> if (!oc->oformat->codec_tag ||
>     av_codec_get_id (oc->oformat->codec_tag, ipar->codec_tag) ==
> opar->codec_id ||
>     av_codec_get_tag(oc->oformat->codec_tag, ipar->codec_id) <= 0) {
>     opar->codec_tag = ipar->codec_tag;
> } else {
>     opar->codec_tag = 0;
> }
> [...]
> 
> See http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavformat/segment.c;hb=HEAD#l811
> 
> If .init is unset, the header is written before the codec_tag is
> cleared. If .init is set, it is written after these lines.

the return code of your init function is wrong i think

also  this patch causes a 1 byte difference in the output of:
./ffmpeg -i ~/tickets/1116/AVI-RLE_MP3.avi -vcodec copy -an out2.avi

is that intended ?

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

I am the wisest man alive, for I know one thing, and that is that I know
nothing. -- Socrates
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: Digital signature
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20170120/6f3ab2e1/attachment.sig>