[FFmpeg-devel] Segmentation fault in libquvi.c

[wm4]

On Wed, 8 Apr 2015 15:37:03 +0200
Gilles Chanteperdrix <gilles.chanteperdrix at xenomai.org> wrote:

> On Wed, Apr 08, 2015 at 02:40:52PM +0200, Michael Niedermayer wrote:
> > On Wed, Apr 08, 2015 at 10:55:45AM +0200, Gilles Chanteperdrix wrote:
> > > Hi, 
> > > 
> > > I just triend libquvi, and get a segmentation fault in the
> > > libquvi_read_header function, because ff_copy_whitelists is called
> > > before qc->fmtctx is allocated by avformat_open_input. I added a
> > > call to avformat_alloc_context() before ff_copy_whitelists and the
> > > libquvi demuxer works.
> > >
> > > However, I wonder how to fix this properly: the error handling
> > > labels look backward, so that I am not sure where to free the
> > > allocated context in case of error.
> > 
> > applied this, yes its correct
> 
> Ok, there are other details missing, the stream does not get a
> duration, start_time and bitrate. This can easily be fixed, but as
> wm4 said libquvi seems an abandoned project.
> 
> Would there be any interest in a solution based on youtube-dl? It
> seems to be the standard, these days. I just ran a few tests:
> 
> youtube -qs 'url' returns 0 or 1 depending on whether the url can be
> parsed by the tool
> 
> youtube -e 'url' prints the stream title
> 
> and youtube -f 'url' prints the video url.
> 
> To use this portably, we can use system() and redirect the
> output to a temporary file, and read the title or URL from the file.
> Or is popen available on all platforms where ffmpeg runs?
> 
> Is it a clean enough solution? If yes, I can submit the patch adding
> this solution. From what I could see, all solutions to parse youtube
> (including quvi) are based on scripts anyway.
> 

Calling external processes from within libavformat doesn't sound like
the right thing to do. You can do it perfectly fine in a higher level,
of course (I'm doing this too).