perturbation of an audio/video decoding execution trace with gstreamer

[Christiane.Kamdem-Kengne at imag.fr]

Hi everyone,

I am a new coming in gstreamer community and i have a pipeline to  
decode and trace a .mp4 file.

gst-launch  
--gst-debug=filesrc:7,queue:7,audioconvert:7,audioresample:7,qtdemux:7,faad:7,ffmpeg:7,audioresample:7,audioconvert:7,autoaudiosink:7,autovideosink:7,  filesrc location=...! qtdemux name=demuxer demuxer. ! queue ! faad ! audioconvert ! audioresample ! autoaudiosink demuxer. ! queue ! ffdec_h264 ! ffmpegcolorspace ! autovideosink >  
file1

I inserted the "identity" component to disturb the decoding, and  
effectively, i saw images which became very slow and sound disappeared.
I used this command:

debug=filesrc:7,queue:7,audioconvert:7,audioresample:7,qtdemux:7,faad:7,ffmpeg:7,audioresample:7,audioconvert:7,autoaudiosink:7,autovideosink:7,  filesrc location=...! qtdemux name=demuxer demuxer. ! queue ! faad ! audioconvert ! audioresample ! autoaudiosink demuxer. ! queue ! identity sleep-time=1000000 ! ffdec_h264 ! ffmpegcolorspace ! autovideosink >  
file2

The first time i did this execution, two new functions appeared in file2,
(i)  gst_ffmpegdec_chain:'skipping...',
(ii) gst_ffmpegdec_video_frame:'Dropping..'
  I assumed that the meaning is that some data were dropped or something else

However, since many days, i use the same pipelines, with the same  
video to decode; i obtain the same bad visualization, but any new  
function in file 2 :(
the only difference is the number of occurrence of this function:

gst_ffmpegdec_update_qos:'update  558 times in one case
---
gst_ffmpegdec_update_qos:'update  4 times in the other case

I don't know why i am unable to produce again a disturbed trace with  
'skipping..' and 'dropping..'

My questions are:
1- have you any idea about these functions?
2- Do you know any other component useful to disturb a A/V decoding  
processing?
I tried also "identity error-after=N"

Thank you for your help