x264enc not working with tee + video output sink

[Gregory Petrosyan]

On Mon, Aug 16, 2010 at 11:52 PM, Gregory Petrosyan
<[hidden email]> wrote:

> On Mon, Aug 16, 2010 at 11:35 PM, Gregory Petrosyan
> <[hidden email]> wrote:
>> I am having some problems with GStreamer. Basically, I have a
>> pipeline, which used to work (with Ubuntu 9.04 GStreamer packages).
>> Here it is:
>>
>> ...
>>
>> Basically, it captures video from a DV camera, stores raw DV data,
>> encodes it to H.264 on the fly and shows video preview window.
>
> Here are the minimal pipelines, which reproduce the problem:
>
> This works:
> gst-launch-0.10 -e dv1394src ! queue ! dvdemux ! ffdec_dvvideo ! queue
> ! ffmpegcolorspace ! x264enc ! mpegtsmux ! queue ! filesink
> location=test.avi
>
> And this:
> gst-launch-0.10 -e dv1394src ! queue ! dvdemux ! ffdec_dvvideo ! tee
> name=t ! queue ! ffmpegcolorspace ! x264enc ! mpegtsmux ! queue !
> filesink location=test.avi t. ! queue ! ffmpegcolorspace ! xvimagesink
> sync=false
>
> results in frozen preview window + zero-length test.avi file.

After a little investigation, it seems like a x264enc-pipeline becomes
frozen, if there's a preview window in it. So,

gst-launch-0.10 -e dv1394src ! queue ! dvdemux ! ffdec_dvvideo ! queue
! tee name=t ! queue ! ffmpegcolorspace ! x264enc ! mpegtsmux ! queue
! filesink location=test.avi

(pure encoding) works fine, but

gst-launch-0.10 -e dv1394src ! queue ! dvdemux ! ffdec_dvvideo ! queue
! tee name=t ! queue ! ffmpegcolorspace ! x264enc byte-stream=true !
queue ! filesink location=test.avi t. ! queue ! ffmpegcolorspace !
xvimagesink sync=false

is completely frozen (same with glimagesink). When I change x264enc +
mpegtsmux to e.g. ffenc_msmpeg4v2 + avimux, everything works fine.

P.S. You can replace dv1394src stuff in the pipelines with filesrc +
decodebin2, results are the same.

P.P.S. But, tee to double x264enc instead of x264enc + video preview
(gst-launch-0.10 -e dv1394src ! queue ! dvdemux ! ffdec_dvvideo !
queue ! tee name=t ! queue ! ffmpegcolorspace ! x264enc
byte-stream=true ! queue ! filesink location=test.avi t. ! queue !
ffmpegcolorspace ! x264enc byte-stream=true ! queue ! filesink
location=test2.avi) works fine.

I am completely puzzled.

                Gregory

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[yiliang]

Hi,

I am seeing the same problem on Ubuntu 10.10. Has there any fix for this already?

Thanks!
Yiliang

[senthil]

Hello,

The queue will block the supplier when there is no more space in it. Please refer
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-plugins/html/gstreamer-plugins-queue.html

Since x264enc may take more time to consume, setting leaky property (as suggested in the doc) on the queue before xvimagesink might help.

Senthil

[yiliang]

Hi Senthil,

Thanks for the reply.

I have done more tests after the post. After some simplification (remove tee and queue, etc), here is the pipeline that gives me the problem. It will be stuck a couple of seconds after start, then it will exit abnormally.

    gst-launch -e v4l2src device=/dev/video0 ! x264enc byte-stream=true ! qtmux ! filesink location=a.mov

If I change byte-stream=false, the pipeline will go on, but the movie file recorded can not be played.

If I change qtmux to ffmux_mp4, the recording can go on no matter I set byte-stream to true or false. The movie can be played, but the movie file has lots of artifacts.

Lastly, if I use avimux, the pipeline works fine, and the movie file recorded can be played smoothly. So after all the test, it seems to be more a problem related how the qtmux (or ffmux_mp4) interacts with other elements.

Also it seems to be a different problem from that reported in the original post, since I can use avimux with x264enc.

I may post a message with a different subject.

Thanks!
Yiliang

[Tim-Philipp Müller-2]

> I have done more tests after the post. After some simplification (remove tee
> and queue, etc), here is the pipeline that gives me the problem. It will be
> stuck a couple of seconds after start, then it will exit abnormally.

Exit abnormally? How? What's the error message? (presumably a
not-negotiated error, which is qtmux rejecting H.264 in bytestream
format)

>  gst-launch -e v4l2src device=/dev/video0 ! x264enc byte-stream=true !
>  qtmux ! filesink location=a.mov
>
> If I change byte-stream=false, the pipeline will go on, but the movie file
> recorded can not be played.

Works fine for me with git/latest pre-releases. Is gst-launch finishing
up the file properly? (ie. sending the EOS and waiting for the EOS)

Cheers
 -Tim



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