[Live-devel] openRTSP: Empty output file

[Julian Pitney]

Hi Ross,

I've acquired video on the Pi using "cat /dev/video0 > test.264" and
attempted two things with the resulting test.264 file. First, I used it as
the source for testH264VideoStreamer (same results as before, empty output
file from openRTSP). Second, I tried to wrap it into an MP4 using
Handbrake, but Handbrake did not recognize the file format. From these
tests, I've concluded that the Pi camera pipeline does not output h264
directly.

The next thing I tried was obtaining a source file using "raspivid -o
test.h264" and repeating the same two tests mentioned above. Using this new
file as the source for testH264VideoStreamer yielded the same result (empty
output from openRTSP), however, wrapping this h264 file into an MP4 using
Handbrake succeeded and produced a "watchable" MP4. Based on reading the
raspivid documentation and having successfully used Handbrake to turn the
raspivid output from h264 -> MP4, I believe that raspivid is producing a
valid h264 file.

Piping the output of raspivid into testH264VideoStreamer is a viable
solution for me, provided I can determine why openRTSP is producing an
empty output file given this input. I'm wondering if you know of any reason
an h264 file would be recognized/compatible with Handbrake, but not
recognized by the live555 code. My thoughts are that there must be
different ways of encoding something as h264 and that raspivid is doing
this in a way that causes openRTSP not to recognize the stream (Perhaps
incompatible headers or inline headers?). I know very little about h264 so
I'm going to start by doing some tutorials. If anything jumps out at you as
a potential source of error, please let me know.


Thanks again,
Julian

On Tue, May 16, 2017 at 12:39 PM, Ross Finlayson <finlayson at live555.com>
wrote:

> > I'm attempting to use testH264VideoStreamer to stream the output of my
> RPi's camera to a LAN, and to receive/open the stream with openRTSP. I've
> done this successfully using a raw h264 file as the source for
> testH264VideoStreamer, however when I attempt to use the output of the Pi's
> camera as the source (By modifying testH264VideoStreamer to read from
> /dev/video0 or stdin, as suggested in the FAQ), openRTSP connects to the
> stream successfully and appears to be playing the stream, but the output
> file is always empty.
> >
> > I read the FAQ and saw that the usual culprit for this is a firewall
> blocking UDP packets.
>
> Julian,
>
> If you are able to run “testH264VideoStreamer” streaming from a raw H.264
> source file, and successfully receive the data using “openRTSP”, then a
> firewall would not be the problem causing to you to not receive data when
> you switch to running “testH264VideoStreamer” streaming from stdin.
>
> (Note that “testH264VideoStreamer” streams using IP multicast, which means
> that it usually does not stream beyond a single LAN.  However, because you
> already received the data (when streaming from a raw H.264 source file),
> that is not an issue.)
>
> If the only thing that you changed was the input source for your H.264
> data, then the problem must be that input source.  You can test this by
> running
>         cat /dev/video0 > test.264
> for a few seconds, then typing <control>-c
> Do you get a valid (non-empty) H.264 video file?  Are you able to
> successfully use *this* file as a source for streaming from
> “testH264VideoStreamer” (as you did before)?
>
>
> Ross Finlayson
> Live Networks, Inc.
> http://www.live555.com/
>
>
> _______________________________________________
> live-devel mailing list
> live-devel at lists.live555.com
> http://lists.live555.com/mailman/listinfo/live-devel
>
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