How to wait for x264enc to encode buffered frames on end-of-stream

[Alex Lynch]

I have a Python GStreamer application that uses appsrc to record mp4 files.

The issue is that despite specifying tune=zerolatency for x264enc, there is latency, and the output video is truncated when an eos is sent to the pipeline. Depending on the machine, the latency is substantial, resulting in a much shorter than expected output file.

If I change the pipeline to save the video as an AVI file, it is not truncated. Unfortunately, the resulting file is approximately 2 GB per minute versus 12 MB per minute with H.264.

Here is the x264enc pipeline:

appsrc name=appsrc format=time is-live=true caps=video/x-raw,format=(string)BGR appsrc. ! videoconvert ! x264enc tune=zerolatency ! qtmux ! filesink location=out.mp4

When the application is finished, it sends end-of-stream messages to the appsrc and pipeline:

if self._appsrc.emit("end-of-stream") == Gst.FlowReturn.OK:
    self._sink_pipeline.send_event(Gst.Event.new_eos())

Is there a way for my application to wait while x264enc processes its buffer? A message, perhaps? I don't care how long it takes to finish. What's important is that all frames pushed to the appsrc are written to the output video file.

Thanks,

Alex.

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[pisymbol .]

On Tue, Aug 20, 2019 at 11:28 AM Alex Lynch <[hidden email]> wrote:

I have a Python GStreamer application that uses appsrc to record mp4 files.

The issue is that despite specifying tune=zerolatency for x264enc, there is latency, and the output video is truncated when an eos is sent to the pipeline. Depending on the machine, the latency is substantial, resulting in a much shorter than expected output file.

If I change the pipeline to save the video as an AVI file, it is not truncated. Unfortunately, the resulting file is approximately 2 GB per minute versus 12 MB per minute with H.264.

Here is the x264enc pipeline:

appsrc name=appsrc format=time is-live=true caps=video/x-raw,format=(string)BGR appsrc. ! videoconvert ! x264enc tune=zerolatency ! qtmux ! filesink location=out.mp4

When the application is finished, it sends end-of-stream messages to the appsrc and pipeline:

if self._appsrc.emit("end-of-stream") == Gst.FlowReturn.OK:
    self._sink_pipeline.send_event(Gst.Event.new_eos())

Is there a way for my application to wait while x264enc processes its buffer? A message, perhaps? I don't care how long it takes to finish. What's important is that all frames pushed to the appsrc are written to the output video file.

Alex, I assume you are waiting on the EOS message the bus emits after the full pipeline emits the EOS. That should allow the x264enc to flush all outstanding buffers.

I made a similar mistake in that I wasn't caching the EOS message on the bus which caused me truncation too because I wasn't giving time for all the elements to flush (this seems like.a flush after EOS issue more so than latency).

-aps

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[Vinod Kesti]

Alex Lynch

Event to flow through all the way till sink and sink fill finally post it on
the bus. You can wait for EOS message on the bus.





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