[FFmpeg-devel] [PATCH] RTP/Vorbis payload implementation (GSoC qual task)

Colin McQuillan m.niloc
Mon Apr 13 16:20:43 CEST 2009

2009/4/13 Ronald S. Bultje <rsbultje at gmail.com>:
> Hi,
> On Mon, Apr 13, 2009 at 9:45 AM, Colin McQuillan <m.niloc at googlemail.com> wrote:
>> ffmpeg-large-fmtp-params.patch is the first patch. This allows large
>> FMTP parameter values as used by Vorbis.
> [..]
> - ? ?char value[4096];
> + ? ?int value_alloc = FFMIN(INT_MAX,strlen(p));
> + ? ?char *value = av_malloc(value_alloc);
> How large, in practice? We generally prefer fixed values over these
> virtually random numbers... I mean, by itself p is constricted to
> <8092 already anyway (by virtue of that being the max SDP size), so
> basically shouldn't increasing value to 8192 work?
> Ronald

RFC 5215 says:

"Raw Vorbis packets are currently unbounded in length; application
profiles will likely define a practical limit.  Typical Vorbis packet
sizes range from very small (2-3 bytes) to quite large (8-12
kilobytes).  The reference implementation [LIBVORBIS] typically
produces packets less than ~800 bytes, except for the setup header
packets, which are ~4-12 kilobytes."

That 12KB gets base64 encoded for SDP making 16KB. I could make this
fixed and increase the SDP limit.

Colin McQuillan

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