[Live-devel] Streaming H264 elementary stream vs file

[Simon Brown]

On Sep 8, 2020, at 12:52 AM, Simon Brown <sbrown at microvideo.co.uk> wrote:
>>> If I take our transport stream and convert it to raw H264 using 
>>> FFmpeg with this command line:
>>>
>>>   ffmpeg -i udp://:61110 -c:v copy -an -f h264 test.264
>>>
>>> and then ask testOnDemandRTSPServer to play it by asking for 
>>> rtsp://192.168.1.13/h264ESVideoTest
>>>
>>> it plays fine.
>>>
>>> However, if I change the ffmpeg command to pipe out the raw 264 
>>> data, and then the RTSP server to accept stdin as the file for 
>>> h264ESVideoTest I get a single frame displayed and nothing more. Is 
>>> there any reason for this?
>> Well, I’m sure there’s a reason for it; I just don’t know what that 
>> reason is :-)
>>
>> I assume that you’ve already successfully tested:
>>     your-modified-testOnDemandRTSPServer < test.264
>>
> Thanks - I asked for that.  Yes, I have successfully tested that. It 
> plays fine.  One thing that puzzled me though, is that if I ask for 
> the stream again it can start again at the beginning?
> I guess my understanding of pipes is poor, because I'd have thought 
> that if it's taken the file in, it can't read it a second time.
> I'll try and record the stream with openRTSP in both instances and see 
> what the difference is.
>
Some further testing yields slightly confusing results:

1) receive test.264 file with openRTSP, play out again on different 
testOnDemand server and it plays fine.

2) receive live stream with openRTSP - it stops after 30 seconds or so 
without me asking it to.  If I play it out again using 
testOnDemandRTSPServer then it plays in VLC, but at half the speed.

3) if I play that live file with ffplay however it plays it at normal speed.

4) if I now try and play the rtsp stream from the original source with 
ffplay it says it "could not find codec parameters for stream 0 (Video: 
264, none): unspecified size.

Regards,

Simon

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