Question about decodebin and prerolling
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Question about decodebin and prerolling
 
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Hi,
I just tried: gst-launch-1.0 decodebin uri=dvb://BBC%20NEWS ! x264enc ! mp4mux ! filesink location=news.mp4 but it failed due to not being able to PREROLL. playbin can handle uri=dvb://BBC%20NEWS, but it seems decodebin cannot. Hopefully I am missing something fairly obvious. -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
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Re: Question about decodebin and prerolling
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Re: Question about decodebin and prerolling
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On Thu, 2018-12-20 at 09:10 +0000, Tim-Philipp Müller wrote:
> On Thu, 2018-12-20 at 08:41 +0000, Russel Winder wrote: > > Hi, > > > I just tried: > > > > gst-launch-1.0 decodebin uri=dvb://BBC%20NEWS ! x264enc ! mp4mux ! > > filesink location=news.mp4 > > > > but it failed due to not being able to PREROLL. > > > > playbin can handle uri=dvb://BBC%20NEWS, but it seems decodebin > > cannot. Hopefully I am missing something fairly obvious. > > Hard to say what the problem is without more info but I would guess > that it's between decodebin and the encoder. Try adding a videoconvert > element. Also note that you will want to pass -e to gst-launch so your > file is finalised properly when you exit later. sure what to put in these initial "requests for help". If there is something specific that would help you give advice, I am entirely happy to provide. I tried: gst-launch-1.0 -e decodebin uri=dvb://BBC%20NEWS ! videoconvert ! x264enc ! mp4mux ! filesink location=news.mp4 Setting pipeline to PAUSED ... Pipeline is PREROLLING ... ^Chandling interrupt. Interrupt: Stopping pipeline ... ERROR: pipeline doesn't want to preroll. Setting pipeline to NULL ... Freeing pipeline ... but got the same result. gst-launch-1.0 playbin uri=dvb://BBC%20NEWS puts up a window and plays the BBC News channel. So all the DVB stuff is present and correct. It just seems that there is something playbin is doing that decodebin isn't that causes the pipeline not to need prerolling: Setting pipeline to PAUSED ... Pipeline is live and does not need PREROLL ... Setting pipeline to PLAYING ... New clock: GstSystemClock Redistribute latency... Redistribute latency... Redistribute latency... ERROR: from element /GstPlayBin:playbin0/GstPlaySink:playsink/GstBin:vbin/GstXvImageSink:xvimagesink0: Output window was closed Additional debug info: xvimagesink.c(555): gst_xv_image_sink_handle_xevents (): /GstPlayBin:playbin0/GstPlaySink:playsink/GstBin:vbin/GstXvImageSink:xvimagesink0 Execution ended after 0:00:03.559091765 Setting pipeline to PAUSED ... Setting pipeline to READY ... Setting pipeline to NULL ... Freeing pipeline ... -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
AW: Question about decodebin and prerolling
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Re: AW: Question about decodebin and prerolling
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On Thu, 2018-12-20 at 15:23 +0100, Bernhard Graaf wrote:
> Hello Russel, > > May you send us the output from gst-launch-1.0 playbin -v > uri=dvb://BBC%20NEWS. > > Seams something handled different from playbin-side. Well that was informative! :-) I did as suggested and immediately discovered that the playbin is using uridecodebin not decodebin, so I tried: gst-launch-1.0 uridecodebin uri=dvb://BBC%20NEWS ! x264enc ! mp4mux ! filesink location=news.mp4 and it worked. Well when I say worked, I got video but no audio. Huge step forward, but not a complete solution as yet. -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
AW: AW: Question about decodebin and prerolling
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AW: AW: Question about decodebin and prerolling
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Re: AW: AW: Question about decodebin and prerolling
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In reply to this post by BGraaf
On Thu, 2018-12-20 at 16:47 +0100, Bernhard Graaf wrote:
> You need to decode audio as well, something like: > gst-launch-1.0 uridecodebin uri=dvb://BBC%20NEWS name=d ! queue ! x264enc ! > mp4mux name=m ! filesink location=news.mp4 d. ! queue ! audioencoder ! m. I am a real beginner at this sorry, playbin has done it all for me to date! There doesn't seem to be a 'audioencoder' element. -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
AW: AW: AW: Question about decodebin and prerolling
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Re: AW: AW: Question about decodebin and prerolling
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In reply to this post by BGraaf
On Thu, 2018-12-20 at 16:53 +0100, Bernhard Graaf wrote:
> And don't forget the -e, otherwise the file may be corrupted. Indeed. Of course the problem is how to translate the gst-launch-1.0 graph into Rust code. -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: AW: AW: AW: Question about decodebin and prerolling
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In reply to this post by BGraaf
On Thu, 2018-12-20 at 18:41 +0100, Bernhard Graaf wrote:
> Audioencoder is only a synonymous for what encoder you want to use (mpgeg, > ac3, and so on). > I had been hoping it was a smart element working according to the format of input, otherwise you have to know ahead of time what formats are in use. As it happens the test file has a52 format, and the MPEG-4 file should have AAC (I believe, this is not a fact!) Whilst there is an a52dec element, the faac element is not in the bad plugin as reported at https://gstreamer.freedesktop.org/documentation/plugins.html -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
AW: AW: AW: AW: Question about decodebin and prerolling
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Re: Question about decodebin and prerolling
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Bernhard,
Thanks for that bit of info. Armed with that and all the previous stuff, I have now got a Rust program that records DVB to MPEG4 files. Couple that with a small Rust program to schedule recording events using at, I think I have exactly what the user asked for. :-) Thanks for you help, it aided me find out what I needed to know. -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: Question about decodebin and prerolling
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As a postscript to the whole playbin/decodebin/uridecodebin thing, I
discovered that: 1. playbin creates a dvbsrc to handle DVB. 2. uridecodebin creates a dvbbasebin to handle DVB. 3. dvbsrc and dvbbasebin have subtly different properties for controlling DVB. 4. uridecodebin (using dvbbasebin), queue, x264enc, avenc_ac3, mp4mux, and filesink seem to work nicely in Rust to make a DVB → MP4 recorder. 5. decodebin.rs and encodebin.rs in the GStreamer_Rs examples were very helpful. If anyone has an opportunity (and desire :-) ) to take a look at: https://github.com/Me-TV/Me-TV/blob/master/src/bin/me-tv-record.rs and send me any constructive critique points (positive or negative), I'd be very grateful. -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
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