[FFmpeg-soc] shrink rtsp sdp buffer

[Ronald S. Bultje]

Hi,

On Thu, May 27, 2010 at 2:58 AM, Martin Storsjö <martin at martin.st> 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.

We should just revert this patch:

http://github.com/yuvi/ffmpeg/commit/6ed54534d4f930cb430539f9b9f0f3caa192ebcb

(sorry, websvn doesn't work so can't give a direct link.)

Ronald