[FFmpeg-soc] shrink rtsp sdp buffer

[Martin Storsjö]

On Thu, 27 May 2010, Martin Storsjö wrote:

> On Wed, 26 May 2010, Josh Allmann wrote:
> 
> > The following reverts changes made in r18508 and shrinks the sdp
> > buffer in rtsp.c. I only do this because 16k on the stack is a lot.
> > 
> > This cleans up the last remnants of Vorbis in rtsp.c -- its sdp/fmtp
> > processing is now done in rtpdec_xiph.c, so this codepath is not
> > touched by Vorbis over RTP anymore except in the case of an error in
> > parsing sdp/fmtp. Even then, it should still fall-through rather
> > cleanly.
> 
> Did you test it?
> 
> > Index: libavformat/rtsp.c
> > ===================================================================
> > --- libavformat/rtsp.c	(revision 23344)
> > +++ libavformat/rtsp.c	(working copy)
> > @@ -271,9 +271,7 @@
> >  static void sdp_parse_fmtp(AVStream *st, const char *p)
> >  {
> >      char attr[256];
> > -    /* Vorbis setup headers can be up to 12KB and are sent base64
> > -     * encoded, giving a 12KB * (4/3) = 16KB FMTP line. */
> > -    char value[16384];
> > +    char value[4096];
> >      int i;
> >      RTSPStream *rtsp_st = st->priv_data;
> >      AVCodecContext *codec = st->codec;
> 
> This should be ok.
> 
> > @@ -537,10 +535,8 @@
> >       * contain long SDP lines containing complete ASF Headers (several
> >       * kB) or arrays of MDPR (RM stream descriptor) headers plus
> >       * "rulebooks" describing their properties. Therefore, the SDP line
> > -     * buffer is large.
> > -     *
> > -     * The Vorbis FMTP line can be up to 16KB - see sdp_parse_fmtp. */
> > -    char buf[16384], *q;
> > +     * buffer is large. */
> > +    char buf[8192], *q;
> >      SDPParseState sdp_parse_state, *s1 = &sdp_parse_state;
> >  
> >      memset(s1, 0, sizeof(SDPParseState));
> 
> You can't shrink this one, since this codepath still is run for all cases, 
> even if the RTP depacketizer handles the parsing of fmtp lines itself. 
> sdp_parse() calls sdp_parse_line(), which then either calls 
> rtsp_st->dynamic_handler->parse_sdp_a_line() or sdp_parse_fmtp(). But the 
> comment referring to sdp_parse_fmtp for vorbis should perhaps be updated.

Ping?

// Martin