[FFmpeg-devel] [avfomat/rtp: source ips lost when specified as URL options] Patch for ffmpeg using rtp protocol where sources option is not retained

[Jun Li]

On Tue, Feb 25, 2020 at 5:01 AM Ross Nicholson <phunkyfish at gmail.com> wrote:

> Hey Jun Li,
>
> I noticed you have submitted some patches which work around the same code
> area's that I submitted for. Your patches look quite tidy and well thought
> out so I was wondering if you could look at this patch and see if I'm going
> about it in the right way.
>
> I'm not sure this area of ffmpeg currently has a maintainer currently so
> the patches may be difficult to progress.
>
> Ross
>
> On Tue, 11 Feb 2020 at 22:42, Ross Nicholson <phunkyfish at gmail.com> wrote:
>
>> The patch was created as a workaround to an issue from in kodi
>> (apologies, it's a rather long thread):
>> https://forum.kodi.tv/showthread.php?tid=350901&pid=2923550#pid2923550
>>
>> As an example, here is a URL: rtp://87.141.215.251@232.0.10.234:10000
>>
>> Taking this URL we should be able to either reformat it to: rtp://
>> 232.0.10.234:10000?sources=87.141.215.251 or pass the sources as an
>> av_dict to avfomat_open_input.
>>
>> Neither option works however. Instead the above workaround was created
>> but it's not really the right way to fix this. Would be great to get some
>> guidance on the right place to fix this in the right way.
>>
>> Thanks in advance.
>>
>> On Tue, 11 Feb 2020 at 22:30, phunkyfish <phunkyfish at gmail.com> wrote:
>>
>>> ---
>>>  libavformat/rtsp.c | 26 ++++++++++++++++++++++++--
>>>  1 file changed, 24 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
>>> index 859defa592..f922055134 100644
>>> --- a/libavformat/rtsp.c
>>> +++ b/libavformat/rtsp.c
>>> @@ -2334,7 +2334,9 @@ static int sdp_read_header(AVFormatContext *s)
>>>      RTSPStream *rtsp_st;
>>>      int size, i, err;
>>>      char *content;
>>> +    const char *p, *sp="", *sources="", *sp2, *sources2;
>>>      char url[1024];
>>> +    char sources_buf[1024];
>>>
>>>      if (!ff_network_init())
>>>          return AVERROR(EIO);
>>> @@ -2360,6 +2362,16 @@ static int sdp_read_header(AVFormatContext *s)
>>>      av_freep(&content);
>>>      if (err) goto fail;
>>>
>>> +    /* Search for sources= tag in original URL for rtp protocol only */
>>> +    if (strncmp(s->url, "rtp://", 6) == 0) {
>>> +        p = strchr(s->url, '?');
>>> +        if (p && av_find_info_tag(sources_buf, sizeof(sources_buf),
>>> "sources", p)) {
>>> +            /* av_log(s, AV_LOG_VERBOSE, "sdp_read_header found sources
>>> %s\n", sources_buf);  */
>>> +            sp = sources_buf;
>>> +            sources = "&sources=";
>>> +        }
>>> +    }
>>> +
>>>      /* open each RTP stream */
>>>      for (i = 0; i < rt->nb_rtsp_streams; i++) {
>>>          char namebuf[50];
>>> @@ -2377,12 +2389,22 @@ static int sdp_read_header(AVFormatContext *s)
>>>                  av_dict_free(&opts);
>>>                  goto fail;
>>>              }
>>> +
>>> +            /* Prepare to add sources to the url to be opened.
>>> +               Otherwise the join to the source specific muliticast
>>> will be missing */
>>> +            sources2 = sources;
>>> +            sp2 = sp;
>>> +            /* ignore sources from original URL, when sources are
>>> already set in rtsp_st */
>>> +            if (rtsp_st->nb_include_source_addrs > 0)
>>> +                sources2 = sp2 = "";
>>> +
>>>              ff_url_join(url, sizeof(url), "rtp", NULL,
>>>                          namebuf, rtsp_st->sdp_port,
>>> -
>>> "?localport=%d&ttl=%d&connect=%d&write_to_source=%d",
>>> +
>>> "?localport=%d&ttl=%d&connect=%d&write_to_source=%d%s%s",
>>>                          rtsp_st->sdp_port, rtsp_st->sdp_ttl,
>>>                          rt->rtsp_flags & RTSP_FLAG_FILTER_SRC ? 1 : 0,
>>> -                        rt->rtsp_flags & RTSP_FLAG_RTCP_TO_SOURCE ? 1 :
>>> 0);
>>> +                        rt->rtsp_flags & RTSP_FLAG_RTCP_TO_SOURCE ? 1 :
>>> 0,
>>> +                        sources2, sp2);
>>>
>>>              append_source_addrs(url, sizeof(url), "sources",
>>>                                  rtsp_st->nb_include_source_addrs,
>>> --
>>> 2.20.1 (Apple Git-117)
>>>
>>>
Hi Ross,
I am not sure I understand your requirement clearly, an alternative way is
to save the url in sdp(maybe in rtp_read_header?) and read it out in
sdp_read_header. But I am not sure which field can carry this info (maybe
uri attribute ?).

Since you already have the code change, why now send it as a formal patch
so that FFmpeg maintainers/experts can have a review ?

-Jun