[libav-api] Cannot open stream

Joshua Kordani jkordani at lsa2.com
Thu Jun 12 19:18:53 CEST 2014


If I'm right, yes.  I'm making a patch to test this idea.

BTW, what is the source of the feed?

Joshua Kordani
LSA Autonomy

On 6/12/14 12:23 PM, Manuel Torres wrote:
> Does that mean that I will not be able to open the stream unless I modify
> the libav code?
>
>
> On Thu, Jun 12, 2014 at 5:54 PM, Joshua Kordani <jkordani at lsa2.com> wrote:
>
>> 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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