Recording Video

[Ian Davidson]

Please can you advise me.

I am attempting to record audio/video which I expect to last up to 1½
hours.  If I try to do that as one single file, storing as AVI, I get a
file which is over 2GB and that causes problems.  Therefore, I like to
record 3 shorter videos - and in the past I have manually stopped the
recording at a 'convenient point' and started a new recording - keeping
each recording to a maximum of 40 minutes.

An alternative approach would be to record for a certain time and then
automatically stop and start a new recording.  This would mean that the
recording break would probably come when someone was speaking, so there
would be a little 'hiccup'.  I wrote the script below to see how much of
a gap there was between successive recordings (the camera was pointing
at a digital clock showing seconds).  The videos did not turn out quite
as I expected.


#!/bin/bash
fileNamePart="${HOME}/video"
v4l2-ctl -i 1
counter=0
while [ $counter -lt 3 ]; do
     let counter=counter+1
     fullFileName="${fileNamePart}-${counter}.avi"
     gst-launch-1.0 -e v4l2src norm=PAL num-buffers=100 !
'video/x-raw,format=(string)I420,width=352,height=288,framerate=(fraction)25/1'
! queue ! mux. alsasrc num-buffers=440 ! audioconvert !
'audio/x-raw,rate=44100,channels=2' ! queue ! mux. avimux name=mux !
filesink location="$fullFileName"
done

It would appear that video-1 was fine.  Video-2 then started and there
was a slight break in the audio from the end of video-1. However, the
video content of video-2 has a 4 second gap in the middle of the clip.

I assume that the 2 sources v4l2src and alsasrc are each set to produce
the nominated number of buffers - and that's what they are going to do.  
The fact that one source has produced an EOS (I assume) does not stop
the other.

Would I be correct in assuming that, if I wrote a C program, rather than
using gst-launch, I would be able close both sources down at a time that
suited me?  And also that I cannot do it using gst-launch?

Thanks

Ian

By the way, thanks to those who have already got me this far.
--
--
Ian Davidson
--
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[Peter Rennert]

Your problem might be slightly more complex than my setup, because you
have to deal with sound as well, but have a look on this blog post [1].

This works for me. However, I am loosing one frame each time I switch
the file location. Reason why this happens is described in [2] and has
to do with the fact that I am dealing with encoded data only.
Unfortunately, noone gave me an answer to this question.

In your case, if you disconnect the pipeline straight after a queue
after your video source and replace the entire

! queue ! mux. alsasrc num-buffers=440 ! audioconvert !
'audio/x-raw,rate=44100,channels=2' ! queue ! mux. avimux name=mux !
filesink

with a new one, you might be even able avoid any problems I faced.

Btw, you do not have to write in C. C++, Python and even Java would be
alternatives.

[1]
http://groakat.wordpress.com/2012/12/05/gstreamer-stream-h264-webcam-data-to-series-of-files/
[2]
http://lists.freedesktop.org/archives/gstreamer-devel/2012-December/038199.html




On 12/14/2012 06:13 PM, Ian Davidson wrote:

> Please can you advise me.
>
> I am attempting to record audio/video which I expect to last up to 1½
> hours.  If I try to do that as one single file, storing as AVI, I get
> a file which is over 2GB and that causes problems. Therefore, I like
> to record 3 shorter videos - and in the past I have manually stopped
> the recording at a 'convenient point' and started a new recording -
> keeping each recording to a maximum of 40 minutes.
>
> An alternative approach would be to record for a certain time and then
> automatically stop and start a new recording.  This would mean that
> the recording break would probably come when someone was speaking, so
> there would be a little 'hiccup'.  I wrote the script below to see how
> much of a gap there was between successive recordings (the camera was
> pointing at a digital clock showing seconds).  The videos did not turn
> out quite as I expected.
>
>
> #!/bin/bash
> fileNamePart="${HOME}/video"
> v4l2-ctl -i 1
> counter=0
> while [ $counter -lt 3 ]; do
>     let counter=counter+1
>     fullFileName="${fileNamePart}-${counter}.avi"
>     gst-launch-1.0 -e v4l2src norm=PAL num-buffers=100 !
> 'video/x-raw,format=(string)I420,width=352,height=288,framerate=(fraction)25/1'
> ! queue ! mux. alsasrc num-buffers=440 ! audioconvert !
> 'audio/x-raw,rate=44100,channels=2' ! queue ! mux. avimux name=mux !
> filesink location="$fullFileName"
> done
>
> It would appear that video-1 was fine.  Video-2 then started and there
> was a slight break in the audio from the end of video-1. However, the
> video content of video-2 has a 4 second gap in the middle of the clip.
>
> I assume that the 2 sources v4l2src and alsasrc are each set to
> produce the nominated number of buffers - and that's what they are
> going to do.  The fact that one source has produced an EOS (I assume)
> does not stop the other.
>
> Would I be correct in assuming that, if I wrote a C program, rather
> than using gst-launch, I would be able close both sources down at a
> time that suited me?  And also that I cannot do it using gst-launch?
>
> Thanks
>
> Ian
>
> By the way, thanks to those who have already got me this far.

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[Jesper Larsen]

Take a look at the multifilesink element.
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-good-plugins/html/gst-plugins-good-plugins-multifilesink.html

You might be able to use it in a gst-launch line using the properties
- max-file-size
- next-file

Jesper

On Fri, Dec 14, 2012 at 7:13 PM, Ian Davidson <[hidden email]> wrote:

Please can you advise me.

I am attempting to record audio/video which I expect to last up to 1½ hours.  If I try to do that as one single file, storing as AVI, I get a file which is over 2GB and that causes problems.  Therefore, I like to record 3 shorter videos - and in the past I have manually stopped the recording at a 'convenient point' and started a new recording - keeping each recording to a maximum of 40 minutes.

An alternative approach would be to record for a certain time and then automatically stop and start a new recording.  This would mean that the recording break would probably come when someone was speaking, so there would be a little 'hiccup'.  I wrote the script below to see how much of a gap there was between successive recordings (the camera was pointing at a digital clock showing seconds).  The videos did not turn out quite as I expected.


#!/bin/bash
fileNamePart="${HOME}/video"
v4l2-ctl -i 1
counter=0
while [ $counter -lt 3 ]; do
    let counter=counter+1
    fullFileName="${fileNamePart}-${counter}.avi"
    gst-launch-1.0 -e v4l2src norm=PAL num-buffers=100 ! 'video/x-raw,format=(string)I420,width=352,height=288,framerate=(fraction)25/1' ! queue ! mux. alsasrc num-buffers=440 ! audioconvert ! 'audio/x-raw,rate=44100,channels=2' ! queue ! mux. avimux name=mux ! filesink location="$fullFileName"
done

It would appear that video-1 was fine.  Video-2 then started and there was a slight break in the audio from the end of video-1. However, the video content of video-2 has a 4 second gap in the middle of the clip.

I assume that the 2 sources v4l2src and alsasrc are each set to produce the nominated number of buffers - and that's what they are going to do.  The fact that one source has produced an EOS (I assume) does not stop the other.

Would I be correct in assuming that, if I wrote a C program, rather than using gst-launch, I would be able close both sources down at a time that suited me?  And also that I cannot do it using gst-launch?

Thanks

Ian

By the way, thanks to those who have already got me this far.
--
--
Ian Davidson
--
Facts used in this message may or may not reflect an underlying objective reality. Facts are supplied for personal use only.
Recipients quoting supplied information do so at their own risk. Facts supplied may vary in whole or part from widely accepted standards.
While painstakingly researched, facts may or may not be indicative of actually occurring events or natural phenomena.
The author accepts no responsibility for personal loss or injury resulting from memorisation and subsequent use.
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[Tim-Philipp Müller-2]

On Mon, 2012-12-17 at 08:16 +0100, Jesper Larsen wrote:
> Take a look at the multifilesink element.
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-good-plugins/html/gst-plugins-good-plugins-multifilesink.html
>
> You might be able to use it in a gst-launch line using the properties
> - max-file-size
> - next-file

Unfortunately that's not going to work so easily with non-streaming
formats like AVI, because you need headers at the beginning of the file
etc., and the AVI muxer won't write new ones when you switch to the next
file. This works better with e.g. ogg or mpeg-{ps,ts}.

Cheers
 -Tim

> On Fri, Dec 14, 2012 at 7:13 PM, Ian Davidson
> <[hidden email]> wrote:
>         Please can you advise me.
>        
>         I am attempting to record audio/video which I expect to last
>         up to 1½ hours.  If I try to do that as one single file,
>         storing as AVI, I get a file which is over 2GB and that causes
>         problems.  Therefore, I like to record 3 shorter videos - and
>         in the past I have manually stopped the recording at a
>         'convenient point' and started a new recording - keeping each
>         recording to a maximum of 40 minutes.
>        
>         An alternative approach would be to record for a certain time
>         and then automatically stop and start a new recording.  This
>         would mean that the recording break would probably come when
>         someone was speaking, so there would be a little 'hiccup'.  I
>         wrote the script below to see how much of a gap there was
>         between successive recordings (the camera was pointing at a
>         digital clock showing seconds).  The videos did not turn out
>         quite as I expected.
>        
>        
>         #!/bin/bash
>         fileNamePart="${HOME}/video"
>         v4l2-ctl -i 1
>         counter=0
>         while [ $counter -lt 3 ]; do
>             let counter=counter+1
>             fullFileName="${fileNamePart}-${counter}.avi"
>             gst-launch-1.0 -e v4l2src norm=PAL num-buffers=100 !
>         'video/x-raw,format=(string)I420,width=352,height=288,framerate=(fraction)25/1' ! queue ! mux. alsasrc num-buffers=440 ! audioconvert ! 'audio/x-raw,rate=44100,channels=2' ! queue ! mux. avimux name=mux ! filesink location="$fullFileName"
>         done
>        
>         It would appear that video-1 was fine.  Video-2 then started
>         and there was a slight break in the audio from the end of
>         video-1. However, the video content of video-2 has a 4 second
>         gap in the middle of the clip.
>        
>         I assume that the 2 sources v4l2src and alsasrc are each set
>         to produce the nominated number of buffers - and that's what
>         they are going to do.  The fact that one source has produced
>         an EOS (I assume) does not stop the other.
>        
>         Would I be correct in assuming that, if I wrote a C program,
>         rather than using gst-launch, I would be able close both
>         sources down at a time that suited me?  And also that I cannot
>         do it using gst-launch?
>        
>         Thanks
>        
>         Ian
>        
>         By the way, thanks to those who have already got me this far.
>         _______________________________________________
>         gstreamer-devel mailing list
>         [hidden email]
>         http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
>

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