[FFmpeg-trac] #2343(avformat:new): Stream is blocked by 20 seconds or more when reading an mjpeg stream at low resolutions

FFmpeg trac at avcodec.org
Sun Mar 10 23:11:07 CET 2013

#2343: Stream is blocked by 20 seconds or more when reading an mjpeg stream at low
             Reporter:  virtuald     |                    Owner:
                 Type:  enhancement  |                   Status:  new
             Priority:  wish         |                Component:  avformat
              Version:  git-master   |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |

Comment (by DonMoir):

 I found with IP cameras, there can be a long delay on open. Generally
 speaking, each IP camera has it's own best way of opening and sometimes
 multiple ways of opening for same camera. There are some generic types
 like: rtsp:// http:// These URL's are good enough for basic playback but
 allow no additional control like pan,tilt,zoom (PTZ) and can introduce an
 unwanted delay. I am finding it necessary to provide a special open call
 for IP cameras. For testing I am setting max_analyze_duration to 0. In the
 case of the camera I am testing with, I know it's mjpeg, how to control
 PTZ, etc. So it boils down to 'knowing' the camera. There have been some
 attempts to formalize but its not complete. The IP camera interfaces are
 all over the place.

 I have a long way to go on the above, but one thing for sure is I don't
 want delayed video for a real time LAN based camera. For testing, I ignore
 all timing and display the frames as fast as they arrive. The timing
 itself is not to much of an issue, but the initial delay can throw things
 way off in terms of seeing real time video. Like if I wave my hand in
 front of the camera I want to see it as soon as possible and not 5 to 10
 seconds later.

 A generic open in this case is just not going to work well.

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2343#comment:2>
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