[FFmpeg-devel] [FFmpeg-cvslog] avformat/hls: add http_persistent option

[Aman Gupta]

On Mon, Dec 25, 2017 at 6:29 PM wm4 <nfxjfg at googlemail.com> wrote:

> On Tue, 26 Dec 2017 02:14:11 +0000
> Aman Gupta <ffmpeg at tmm1.net> wrote:
>
> > On Mon, Dec 25, 2017 at 1:03 PM Michael Niedermayer
> <michael at niedermayer.cc>
> > wrote:
> >
> > > On Mon, Dec 25, 2017 at 06:08:11PM +0000, Aman Gupta wrote:
> > > > On Mon, Dec 25, 2017 at 9:58 AM Michael Niedermayer
> > > <michael at niedermayer.cc>
> > > > wrote:
> > > >
> > > > > On Fri, Dec 22, 2017 at 11:00:34PM +0000, Aman Gupta wrote:
> > > > > > ffmpeg | branch: master | Aman Gupta <aman at tmm1.net> | Wed Oct
> 4
> > > > > 14:52:52 2017 -0700| [b7d6c0cd48dac7869b9e6803e2d47d05a4fa373b] |
> > > > > committer: Aman Gupta
> > > > > >
> > > > > > avformat/hls: add http_persistent option
> > > > > >
> > > > > > This teaches the HLS demuxer to use the HTTP protocols
> > > > > > multiple_requests=1 option, to take advantage of "Connection:
> > > > > > Keep-Alive" when downloading playlists and segments from the HLS
> > > server.
> > > > > >
> > > > > > With the new option, you can avoid TCP connection and TLS
> negotiation
> > > > > > overhead, which is particularly beneficial when streaming via a
> > > > > > high-latency internet connection.
> > > > > >
> > > > > > Similar to the http_persistent option recently implemented in
> > > hlsenc.c
> > > > > >
> > > > > > Signed-off-by: Aman Gupta <aman at tmm1.net>
> > > > > > Signed-off-by: Anssi Hannula <anssi.hannula at iki.fi>
> > > > > >
> > > > > > >
> > > > >
> > >
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b7d6c0cd48dac7869b9e6803e2d47d05a4fa373b
> > > > > > ---
> > > > > >
> > > > > >  doc/demuxers.texi |  4 ++++
> > > > > >  libavformat/hls.c | 72
> > > > > +++++++++++++++++++++++++++++++++++++++++++++++++++----
> > > > > >  2 files changed, 72 insertions(+), 4 deletions(-)
> > > > >
> > > > > This causes ffmpeg to infinite loop with simplehttpd.py
> > > >
> > > >
> > > > Is that the same as SimpleHTTPServer.py?
> > > >
> > > > Sounds like it doesn't support persistent connections, but also isn't
> > > > returning "Connection: close" in the response.
> > > >
> > > > I can investigate if you tell me where to find that httpd server.
> > >
> > > Iam not sure where i got it from or its original source but it matches
> the
> > > source here:
> > >
> > >
> > >
> https://www.linuxjournal.com/content/tech-tip-really-simple-http-server-python
> >
> >
> > Thanks.
> >
> > I was able to reproduce the issue. It appears to be because the simple
> http
> > server is quite too simple, and can only handle one request at a time.
> The
> > http_multiple option tries to make a second request before the first is
> > completed, causing a deadlock.
> >
> > I guess we could disable http_multiple by default...
> >
> > Aman
> >
> > <
> https://www.linuxjournal.com/content/tech-tip-really-simple-http-server-python
> >
>
> So I hear this causes some infinite loop. Could this be made adaptive?


I guess we could detect if the server is http/1.1 with the first request
and only make multiple connections if it is.

Technically multiple connections should work with http/1.0 servers though.
It's just this specific http server which can only handle one connection at
a time.

The "infinite loop" is because there is no timeout on the request socket,
and the server never accepts the http request to send a response (because
another connection is still active).


>
> What does the HTTP spec say about this, and what do other HTTP
> implementations do here?



The spec says nothing about multiple concurrent connections.

Aman


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