[FFmpeg-devel] libavformat/rtsp.c: fix RTSP not setup the UDP stream in SDP

["zhilizhao(赵志立)"]

> On Jul 30, 2021, at 4:36 PM, Chiu, Yung-Hsiang <mirror.tw at gmail.com> wrote:
> 
> Thanks for your review.
> 
> I don't have any standards or formal documents mentioned the proto
> 'udp' in SDP should be uppercase.
> 
> The only document I google for the video server 'orbit2x' is shown below
> https://developer.samsung.com/smarttv/develop/legacy-platform-library/art00071/index.html#sdp-supported-feature
> Apologize for our buggy video server...
> 
> Could you give me some suggestions I should write down in the commit message?

Something like “Do case-insensitive check on raw data over UDP protocol”. Add description
about why this is needed in commit message and/or code comments. I’m not native
english speaker, sorry I can’t give a proper description.

> 
> "zhilizhao(赵志立)" <quinkblack at foxmail.com> 於 2021年7月30日 週五 下午2:57寫道：
> 
>> 
>> 
>> 
>>> On Jul 30, 2021, at 10:55 AM, Chiu, Yung-Hsiang <mirror.tw at gmail.com> wrote:
>>> 
>>> Hi,
>>> 
>>> Our RTSP video server reply two streams in SDP are UDP and RTP/AVP/UDP.
>>>>> m=video 0 UDP 33
>>>>> m=video 0 RTP/AVP/UDP 33
>>> 
>>> ffmpeg now setup twice with the same transport "RTP/AVP/UDP"
>>> 
>>> The first time is
>>>>> SETUP rtsp://192.168.1.100:554/MOV_000012353521.mpg RTSP/1.0
>>>>> Transport: RTP/AVP/UDP;unicast;client_port=26972-26973
>>> 
>>> And the second time is
>>>>> SETUP rtsp://192.168.1.100:554/MOV_000012353521.mpg RTSP/1.0
>>>>> Transport: RTP/AVP/UDP;unicast;client_port=26974-26975
>>> 
>>> After reviewing the rtsp.c, I found the bug is caused by the
>>> acceptable string in sdp_parse_line() is "udp" only.
>> 
>> From RFC 4566, the protocol should be specified as “udp”:
>> 
>> https://datatracker.ietf.org/doc/html/rfc4566#section-8.2.2
>> 
>> From IANA, “UDP” is not a registered protocol field of SDP:
>> https://www.iana.org/assignments/sdp-parameters/sdp-parameters.xhtml
>> 
>> Is there any reference that the field can be uppercase? I want figure out
>> whether it’s a bug of FFmpeg, or a bug of the server. I don’t object the
>> patch, but the patch commit message should reflect the difference between
>> ‘fix bug of FFmpeg’ vs ‘workaround buggy server'.
>> 
>>> 
>>> The transport with "udp" or "UDP" should be acceptable in sdp_parse_line().
>>> 
>>> The full rtsp negotiation is shown below.
>>> 
>>> OPTIONS rtsp://192.168.1.100:554/MOV_000012353521.mpg RTSP/1.0
>>> CSeq: 1
>>> User-Agent: Lavf58.35.101
>>> 
>>> RTSP/1.0 200 OK
>>> Server: Orbit2x
>>> CSeq: 1
>>> Public: OPTIONS, DESCRIBE, SETUP, TEARDOWN, PLAY, PAUSE, GET_PARAMETER
>>> 
>>> 
>>> DESCRIBE rtsp://192.168.1.100:554/MOV_000012353521.mpg RTSP/1.0
>>> Accept: application/sdp
>>> CSeq: 2
>>> User-Agent: Lavf58.35.101
>>> 
>>> 
>>> RTSP/1.0 200 OK
>>> Server: Orbit2x
>>> CSeq: 2
>>> Public: OPTIONS, DESCRIBE, SETUP, TEARDOWN, PLAY, PAUSE, GET_PARAMETER
>>> Content-Type: application/sdp
>>> Content-Length: 179
>>> 
>>> v=0
>>> o=- 60596 0 IN IP4 192.168.1.100
>>> s=RTSP Session
>>> t=0 0
>>> c=IN IP4 192.168.1.100
>>> b=AS:7984.000
>>> a=type:vod
>>> a=range:npt=0-5313
>>> m=video 0 UDP 33
>>> m=video 0 RTP/AVP/UDP 33
>>> 
>>> SETUP rtsp://192.168.1.100:554/MOV_000012353521.mpg RTSP/1.0
>>> Transport: RTP/AVP/UDP;unicast;client_port=26972-26973
>>> CSeq: 3
>>> User-Agent: Lavf58.35.101
>>> 
>>> RTSP/1.0 200 OK
>>> Server: Orbit2x
>>> CSeq: 3
>>> Session: 728680355;timeout=60
>>> Transport: RTP/AVP/UDP;unicast;destination=192.168.2.184;client_port=26972;source=192.168.1.100;server_port=10000-10001;ssrc=7b9507dd
>>> 
>>> SETUP rtsp://192.168.1.100:554/MOV_000012353521.mpg RTSP/1.0
>>> Transport: RTP/AVP/UDP;unicast;client_port=26974-26975
>>> CSeq: 4
>>> User-Agent: Lavf58.35.101
>>> Session: 728680355
>>> 
>>> RTSP/1.0 200 OK
>>> Server: Orbit2x
>>> CSeq: 4
>>> Session: 728680355;timeout=60
>>> Transport: RTP/AVP/UDP;unicast;destination=192.168.2.184;client_port=26974;source=192.168.1.100;server_port=10000-10001;ssrc=7b9507dd
>>> 
>>> PLAY rtsp://192.168.1.100:554/MOV_000012353521.mpg RTSP/1.0
>>> Range: npt=0.000-
>>> CSeq: 5
>>> User-Agent: Lavf58.35.101
>>> Session: 728680355
>>> 
>>> RTSP/1.0 200 OK
>>> Server: Orbit2x
>>> CSeq: 5
>>> Session: 728680355
>>> Scale: 1.00
>>> Range: npt=0-
>>> 
>>> <0001-libavformat-rtsp.c-fix-RTSP-not-setup-the-UDP-stream.patch>_______________________________________________
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>> 
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