Audio only playback with playbin

[hjuvi]

Hi,

Thanks a lot for this option.

It took me some time to find the related documentation:
https://gstreamer.freedesktop.org/documentation/playback/playsink.html?gi-language=c#GstPlayFlags

It does improve the behaviour with a problematic video, it doesn't seem to freeze anymore.
I don't know exactly what's happening "under the hood", compared with fakevideosink. Maybe the video is discarded at an earlier stage in the pipeline, I don't know...
In the end, it seems to be a better option, and I guess that I'll switch to this solution, after having done some more tests with other videos.

Thanks a lot for the support!
I'm still interested in the "under the hood" difference details (if this can be explained in simple terms)

Cédric


6 janvier 2023 13:24 "Jan Schmidt via gstreamer-devel" <gstreamer-devel at lists.freedesktop.org> a
écrit:

> Hi,
> 
> On 3/1/23 20:36, hjuvi via gstreamer-devel wrote:
> 
>> Hello,
>> 
>> I'm writing a terminal-based audio player application based on GStreamer (currently testing with
>> version 1.20.4).
>> 
>> This is really intended to be an audio player only, but I'd like to be able to play the audio part
>> of an audio/video file.
>> For this purpose, I'm using a fake sink for the video, to avoid having a popup window with the
>> video.
> 
> If you set the flags property on playbin to 'soft-volume+audio' it won't try and display the video
> part at all. You can use the gst_util_set_object_arg() method to set the flags using the string.
> 
> Cheers,
> 
> Jan.
> 
>> My player works perfectly for pure audio files, but I have some problems with audio/video files. It
>> plays correctly if I just let it play, but:
>> - It seems that I don't receive the EOS message (only 'about-to-finish').
>> - If I try to seek, it works for a moment, but then it ends up getting lost, with strange
>> behaviours (position not updated, audio freeze or acceleration), and most of the time it freezes
>> completely (the main loop is blocked).
>> 
>> I'm seeking with (GST_SEEK_FLAG_FLUSH | GST_SEEK_FLAG_KEY_UNIT) flags.
>> 
>> My questions are:
>> 1) Is the playbin appropriate for this purpose? I find it very convenient, so I hope it is not
>> necessary to build the pipeline for audio only.
>> 2) Is the fake sink (fakesink or fakevideosink) the right solution to disable video? (I used
>> fakevideosink because the behaviour was even worse with fakesink).
>> 3) Does the fake sink just disable the output, or does it saves the video decoding (which would be
>> useless)?
>> 4) Am I using the right flags to seek? (GST_SEEK_FLAG_FLUSH | GST_SEEK_FLAG_KEY_UNIT)
>> 5) If there is no obvious error in what I've done, would you suggest any method to debug this?
>> (additional traces...)
>> 
>> In case it might help to understand, the source code is here:
>> https://forge.tedomum.net/hjuvi/ondine
>> And all the calls to GStreamer are done in this particular file:
>> https://forge.tedomum.net/hjuvi/ondine/-/blob/main/src/ondine_player.c
>> 
>> Thanks a lot for your help.
>> 
>> --
>> Cédric