[FFmpeg-trac] #1224(undetermined:new): dvb-t to rtmp crash.

FFmpeg trac at avcodec.org
Sat Apr 21 18:36:12 CEST 2012

#1224: dvb-t to rtmp crash.
             Reporter:  eregi        |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0

Comment (by Cigaes):

 I am afraid that solves it: the only difference between these commands is
 the speed of the encoding process: the first is very slow ({{{veryslow}}})
 is a dead giveaway) and the second is very fast ({{{ultrafast}}} is a
 clue; the very small resolution helps too).

 My conclusion is that the problem is that when the encoding command is too
 slow, the kernel buffer overflows and causes a read error. Now that I know
 that, I can reproduce the problem, and I see, using strace, that read on
 the device fails with EOVERFLOW (shame on the MPEG-TS demuxer not to
 report it).

 You need to tweak your encoding parameters so that encoding is
 significantly faster than realtime. You can do the tweaking with a large
 enough dump, you just have to look at the {{{fps}}} field in the status
 line: it must stay way above 30.

 Possible ways: use {{{-vcodec libx264}}} and {{{-preset ultrafast}}};
 reduce the resolution.

 Depending on your needs and means, upgrading the hardware may or may not
 be an option.

 Good luck.

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1224#comment:31>
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