[libav-api] Cannot open stream

Joshua Kordani jkordani at lsa2.com
Thu Jun 12 17:54:20 CEST 2014


Additionally, the rtpmap line in the sdp file comes AFTER the fmtp line, 
this causes wireshark to be confused, and according to the comments in 
libavformat/rtsp.c, may not be handled by the library, as the dynamic 
handler may not have the knowledge that the fmtp string is associated 
with an h264 stream, so the sprops-param line may just be discarded.

Joshua Kordani
LSA Autonomy

On 6/12/14 10:24 AM, Joshua Kordani wrote:
> It also should be noted that in the sdp, the server is indicating that 
> it will only be providing single nal packets "packetization-mode=0" 
> but instead provides an rtp stream with fragmented nals.  In this 
> case, packetization-mode should be non-zero.  I don't know if this is 
> confusing the library at all (I doubt it) but I figured I'd say 
> something.
>
> Joshua Kordani
> LSA Autonomy
>
> On 6/12/14 2:07 AM, Manuel Torres wrote:
>> SPS and PPS are not present. I can see IDRs with a frequency of 
>> 60-100ms.
>> Any thoughts?
>>
>>
>> On Thu, Jun 12, 2014 at 7:50 AM, Manuel Torres <
>> manuel.torres.fernandez at gmail.com> wrote:
>>
>>> This is what avplay displays when opening the stream:
>>> http://pastebin.com/K6jmtGps
>>>
>>> My code can open the BigBuckBunny stream.
>>>
>>> I will now check the Wireshark capture and let you know.
>>>
>>>
>>>
>>> On Wed, Jun 11, 2014 at 7:34 PM, Joshua Kordani <jkordani at lsa2.com> 
>>> wrote:
>>>
>>>> and alternatively, what happens when you point your code at the 
>>>> following
>>>> rtsp url?
>>>> rtsp://184.72.239.149/vod/mp4:BigBuckBunny_115k.mov
>>>>
>>>> Joshua Kordani
>>>> LSA Autonomy
>>>>
>>>> On 6/11/14 11:49 AM, Manuel Torres wrote:
>>>>
>>>>> Done. I captured just a few seconds to keep the file size low. 
>>>>> Here is
>>>>> the
>>>>> download link:
>>>>>
>>>>> https://www.wetransfer.com/downloads/8d6c64606d347f395c6a0dfd870241
>>>>> 9b20140611154702/5f67e064c7ebf8c694577589d69c1d5420140611154702/c7dee4 
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Jun 11, 2014 at 5:32 PM, Joshua Kordani <jkordani at lsa2.com>
>>>>> wrote:
>>>>>
>>>>>   Can you make a short wireshark capture that includes the rtsp as 
>>>>> well as
>>>>>> the rtp traffic going from this camera, for, say, 30 seconds?  Do 
>>>>>> this
>>>>>> using your program to start the feed.
>>>>>>
>>>>>> Joshua Kordani
>>>>>> LSA Autonomy
>>>>>>
>>>>>>
>>>>>> On 6/11/14 11:21 AM, Manuel Torres wrote:
>>>>>>
>>>>>>   No. It is an external source of which I have no control and I 
>>>>>> cannot
>>>>>>> figure
>>>>>>> out what is diferent in it from the rest if the sources I can 
>>>>>>> open with
>>>>>>> both avplay and my code. It puzzles me even more that VLC and 
>>>>>>> MPlayer
>>>>>>> do
>>>>>>> open the stream.
>>>>>>>
>>>>>>> Enviado desde dispositivo móvil.
>>>>>>> Sent from mobile device.
>>>>>>> On Jun 11, 2014 5:15 PM, "Joshua Kordani" <jkordani at lsa2.com> 
>>>>>>> wrote:
>>>>>>>
>>>>>>>    Are you creating this stream yourself?
>>>>>>>
>>>>>>>> Joshua Kordani
>>>>>>>> LSA Autonomy
>>>>>>>>
>>>>>>>> On 6/11/14 11:08 AM, Manuel Torres wrote:
>>>>>>>>
>>>>>>>>    If by "resource" you mean the URL, the answer is no, avplay 
>>>>>>>> does not
>>>>>>>>
>>>>>>>>> display the video. The traces in my first e-mail are also 
>>>>>>>>> displayed
>>>>>>>>> by
>>>>>>>>> avplay, that is, no size and no color space.
>>>>>>>>>
>>>>>>>>> Enviado desde dispositivo móvil.
>>>>>>>>> Sent from mobile device.
>>>>>>>>> On Jun 11, 2014 4:10 PM, "Luca Barbato" <lu_zero at gentoo.org> 
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>     On 11/06/14 09:41, Manuel Torres wrote:
>>>>>>>>>
>>>>>>>>>   First of all, thank you Luca and Joshua for taking the time 
>>>>>>>>> to help
>>>>>>>>>> me
>>>>>>>>>>
>>>>>>>>>>>    and
>>>>>>>>>>>
>>>>>>>>>>    thank you very much Joshua for that awesome explanation. I 
>>>>>>>>>> see
>>>>>>>>>> that
>>>>>>>>>>
>>>>>>>>>>> there
>>>>>>>>>>> is a lot to learn.
>>>>>>>>>>>
>>>>>>>>>>> Back on topic:
>>>>>>>>>>> I checked the format context and the codec context and I only
>>>>>>>>>>> found an
>>>>>>>>>>> empty (NULL) "extradata" field in the codec context. I also 
>>>>>>>>>>> checked
>>>>>>>>>>> some
>>>>>>>>>>> other fields in both structures where I thought the data 
>>>>>>>>>>> could be
>>>>>>>>>>> but
>>>>>>>>>>>
>>>>>>>>>>>    found
>>>>>>>>>>>
>>>>>>>>>>    nothing. Am I looking in the right place?
>>>>>>>>>>
>>>>>>>>>>>     Looks quite strange, if you just do avplay rtsp://resource
>>>>>>>>>>>
>>>>>>>>>>>   does it play?
>>>>>>>>>> lu
>>>>>>>>>>
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