How to play mpeg4 dump (in a fifo)

[Nezer Zaidenberg]

Hi Nicola,

Thanks, but I have read somewhere that I am better off using pad-block or
appsrc/sink (as you mentioned) since I want to connect two pipelines in the
same process.
(as a side note, I used gdp[de]pay successfully to implement what I wanted).

I have considered using the pad-block - but it is too complicated and it is
underdocumented. For instance jokosher used pad-block not knowing that it
needs buffers to have the signal flushed and they only found it out by a
mail in the mailing list.

Also, I don't want to stop the whole pipeline to finalize every one-minute
recording - when I try to send an eos to a regular recording, it usually
takes a couple of seconds for it to finalize - and I don't want the user to
experience this video freeze.

I would like your opinion about something else (sorry if I am being too
bold) - appsink and appsrc are very general (good) ideas.
But what I am really looking for is a way to create a global queue - and
have one pipeline filling it and another (or others) emptying it.
What I imagine (actually what I plan to implement) is a "queuesink" that
just queues the buffers it gets in a global queue, and a "queuesrc" that
takes a global queue and drains it.
This would also fit well with all the other pipeline communication ways
like shm{sink,src}, tcp{client,server}{sink,src}, udp{src,sink}, and even
file{src,sink} that use a pipe.

Now appsink and appsrc involve a lot of hacking to achieve this (attaching
signal handlers and removing them when a pipeline is destroyed in a
synchronized way) relatively, just to have simple handlers that only save
the buffers in a queue - a concept which plays a central role in gstreamer
already - and thus has a strong stable implementation already.

I feel that this simple idea will not gain much by using the full power of
the app{sink,src}, and would rather use an element that does this job
itself.

Is there any element today in gstreamer that does this?
If not, and if I implement such an element, do you have any advice/remarks?

Thanks,
  Tomer

On Mon, Nov 28, 2011 at 4:23 PM, Mailing List SVR
<lists at svrinformatica.it>wrote:

>  Il 28/11/2011 12:34, Nezer Zaidenberg ha scritto:
>
> Hi All,
>
>  I have a live source (webcam) that I want to record continuously without
> losing any video - but also be able to playback everything up to the last
> minute. I am trying to dump the video to a fifo and then record it from the
> fifo one minute at a time.
>
>  The problem is that it seems there is a problem with the timestamps. It
> looks like gstreamer expects a clock to be supplied by the filesrc but that
> doesn't happen.
> Specifically when I try to play the pipe instead of record it, I get
> choppy video and a warning is emitted about the timestamps.
>
>  Does anyone know how I could record an mpeg stream from a fifo?
>
>  For reference, here are the pipelines:
> source pipe:
> gst-launch rtspsrc location="<webcam>" ! rtpmp4vdepay ! filesink
> location=pipe
>
>  record pipe:
> gst-launch filesrc location=pipe ! 'video/mpeg, mpegversion=4,
> systemstream=false, width=320, height=240. framerate=(fraction)30/1,
> codec_data=...' ! matroskamux ! filesink location="1.mkv"
>
>  play pipe:
> gst-launch filesrc location=pipe ! 'video/mpeg, mpegversion=4,
> systemstream=false, width=320, height=240. framerate=(fraction)30/1,
> codec_data=...' ! ffdec_mpeg4 ! ffmpegcolorspace ! autovideosink
>
>
> try to add do-timestamp=true to the filesrc element (or sync=false to the
> videosink), however gstreamer allow to record and play with only 1
> pipeline, no need for this hack:
>
>
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-plugins/html/gstreamer-plugins-tee.html
>
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gstreamer-app.html
>
> Nicola
>
>
>  Thanks,
>   Tomer & Nezer
>
>
>
>
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