[FFmpeg-devel] [PATCH] add hds demuxer

[Rostislav Pehlivanov]

On 1 November 2016 at 02:00, Steven Liu <lingjiujianke at gmail.com> wrote:

> 2016-11-01 3:16 GMT+08:00 Jan Ekstrom <jeebjp at gmail.com>:
>
> > On Mon, Oct 31, 2016 at 5:30 PM, Nicolas George <george at nsup.org> wrote:
> > > Le nonidi 9 brumaire, an CCXXV, Steven Liu a écrit :
> > >>      I saw ffmpeg have no HDS and DASH demuxer, and all of them's
> > format is
> > >> use xml, maybe this parser is a very useful parser, what about the
> basic
> > >> xml :-D
> > >
> > > The Timed Text Markup Language, a subtitle format used by Youtube and
> > > possibly a few others, is based on XML too.
> > >
> > > I have started working on a simple XML parser, but Michael quickly
> found
> > > a bug in my attempt to remove the recursiveness in libavfilter, and I
> > > consider it to be the highest priority. Therefore, I stopped shortly
> > > after implementing the framework API and input buffer handling.
> > >
> >
> > Hi,
> >
> > As someone who thought about doing some work on formats that require
> > an XML parser, while I do appreciate that you are making a "simple"
> > XML parser, I am not sure if this is the best way forward. XML and
> > thus by continuation libraries that handle XML are indeed
> > abominations, but I am definitely not sure if we should be NIH'ing XML
> > parsing. For example, namespaces are already utilized in DASH/CENC.
> > Maybe we should just pick one XML parsing library that seems to be the
> > least bad of all bad alternatives, and then standardize FFmpeg on it?
> > Be it libxml2, libexpat or anything else?
> >
> > Best regards,
> > Jan
> >
>
> Hi Jan Ekstrom,
>     I cannot sure if i misunderstand you, but i think FFmpeg need a basic
> XML parser,
> because the FFmpeg have the muxer of DASH/HDS and so on but have no
> demuxer, and not only FFmpeg have the muxer to the DASH/ HDS and so on.
> There have many tools can muxing the format.
> So the XML format is not unify , so need a basic XML parser to paring the
> simple XML format at first.
> of course, use the third part libxml2 or libexpat is a way to parse the
> XML, but i think FFmpeg need a parser by itself, not depend on third part
> and use --enable-xxxx, --disable-xxxx to decide the DASH/HDS demuxer enable
> or not perhaps not a better way.
>
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >
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>

I think JEEB is right here as well, XML parsing needs to be done by a
separate library because of how bad the format is. Mostly all distributions
come with some form of XML parsing library already installed so it's not
really a dependency which would require the user to install anything
additional. Having to use --enable-lib<xml parsing library> is a small
price to pay to not have to maintain a buggy and insecure XML parsing code
in the repo.