[FFmpeg-devel] [PATCH] ffmpeg_opt: set correct priv_data for feed stream

[Michael Niedermayer]

On Fri, Nov 07, 2014 at 09:12:03AM +0100, Lukasz Marek wrote:
> On 6 November 2014 22:55, Michael Niedermayer <michaelni at gmx.at> wrote:
> 
> > On Thu, Nov 06, 2014 at 09:27:45PM +0100, Lukasz Marek wrote:
> > > On 06.11.2014 01:32, Michael Niedermayer wrote:
> > > >On Thu, Nov 06, 2014 at 12:59:45AM +0100, Lukasz Marek wrote:
> > > >>new_output_stream creates a codec context with arbitraty picked codec.
> > > >>Later data is updated, but priv_data are left alone.
> > > >>There is a bit chance there is a mismatch between codecs.
> > > >>
> > > >>Signed-off-by: Lukasz Marek <lukasz.m.luki2 at gmail.com>
> > > >>---
> > > >>  ffmpeg_opt.c         | 16 ++++++++++++++++
> > > >>  libavformat/ffmdec.c |  6 ++++--
> > > >>  2 files changed, 20 insertions(+), 2 deletions(-)
> > > >
> > > >with this fate-lavf-ffm crashes
> > > >
> > > >==10836== Invalid write of size 8
> > > >==10836==    at 0x935442: decode_init (mpegaudiodec_template.c:419)
> > > >==10836==    by 0xA69226: avcodec_open2 (utils.c:1614)
> > > >==10836==    by 0x64CC5F: avformat_find_stream_info (utils.c:3053)
> > > >==10836==    by 0x41C2D7: open_input_file (ffmpeg_opt.c:886)
> > > >==10836==    by 0x42427A: open_files (ffmpeg_opt.c:2699)
> > > >==10836==    by 0x4243F8: ffmpeg_parse_options (ffmpeg_opt.c:2736)
> > > >==10836==    by 0x43762E: main (ffmpeg.c:3861)
> > > >==10836==  Address 0x10f072b0 is not stack'd, malloc'd or (recently)
> > free'd
> > > >==10836==
> > > >==10836== Invalid write of size 8
> > > >==10836==    at 0xDC67D0: avpriv_float_dsp_init (float_dsp.c:120)
> > > >==10836==    by 0x93546B: decode_init (mpegaudiodec_template.c:421)
> > > >==10836==    by 0xA69226: avcodec_open2 (utils.c:1614)
> > > >==10836==    by 0x64CC5F: avformat_find_stream_info (utils.c:3053)
> > > >==10836==    by 0x41C2D7: open_input_file (ffmpeg_opt.c:886)
> > > >==10836==    by 0x42427A: open_files (ffmpeg_opt.c:2699)
> > > >==10836==    by 0x4243F8: ffmpeg_parse_options (ffmpeg_opt.c:2736)
> > > >==10836==    by 0x43762E: main (ffmpeg.c:3861)
> > > >==10836==  Address 0x10f072e8 is not stack'd, malloc'd or (recently)
> > free'd
> > > >and pages more
> > >
> > > I tried to debug it, but there is too much code to read to handle
> > > one very specific case and I'm not sure there is other, better
> > > solution.
> >
> > > Probably, I haven't check, clear solution would be to clear
> > > priv_data in read_ffserver_streams right after copy_context, and set
> > > it to NULL, but I will need private data soon to support it in
> > > ffserver.
> >
> > Maybe iam missing something but why does the ffm demuxer attempt to
> > setup a encoder instead of exporting the "recommanded" encoder
> > settings as name-value pairs (possibly in metadata) and ffmpeg then
> > sets up the encoder streams based on that instead of copying
> > contexts
> >
> 
> Probably you are not mistaken.
> After sending I had second thoughts, probably it would be better to do one
> of the followings:
> - add option to muxer instead to control context should be read/write from
> file (now is always written)
> - export parsing function that is major part of read_header so ffmpeg can
> pass its own context and params will be read. This has disadvantage that
> ffmpeg would need ffm's private header. Already present in ffserver though.
> - your solution
> 
> 
> > Trying to set the encoder contexts up in a demuxer (which normally
> > would interface to decoders not encoders) seems odd to me
> > Though of course this is how it was designed before the patch already
> >
> 
> Yes, but maybe its time to clean hack and not to add new one. In new patch
> I just clear possibly incorrect priv_data.
> I will come back to during the weekend when I want to finish private
> options handling in ffserver

>  ffmpeg_opt.c |    4 ++++
>  1 file changed, 4 insertions(+)
> e5b2af2c3acface30f9c71a326ffb7d907353b6b  0001-ffmpeg_opt-free-incorrect-priv_data-for-feed-stream.patch
> From 9d3188dd3fadfad47ef4cbe2073604d4cd7ebdc2 Mon Sep 17 00:00:00 2001
> From: Lukasz Marek <lukasz.m.luki2 at gmail.com>
> Date: Fri, 7 Nov 2014 09:05:41 +0100
> Subject: [PATCH] ffmpeg_opt: free incorrect priv_data for feed stream
> 
> new_output_stream creates a codec context with arbitraty picked codec.
> Later data is updated, but priv_data are left alone.
> There is a bit chance there is a mismatch between codecs.
> 
> Signed-off-by: Lukasz Marek <lukasz.m.luki2 at gmail.com>

applied

thanks

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

During times of universal deceit, telling the truth becomes a
revolutionary act. -- George Orwell
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