<!DOCTYPE html> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body> I am developing a C++ video inspection program that creates MP4/H264/MP3 files and needs to play them back with the video stream processed by various gstreamer elements and audio separately. In general this has been working fine when just video was being recorded/played back, but I am just adding audio to the mix. Some MP4 files will contain only a video stream and some will contain both video and audio streams. I need some way to handle the playback of these MP4 files that may or may not have MP3 audio streams. As a simple idea if I use something like (The real C++ code constructs the gstreamer piple line and tees the video stream to various gstreamer sub pipelines): <pre>gst-launch-1.0 -v filesrc location=temp.mp4 ! qtdemux name=demux</pre> <pre> demux.video_0 ! queue ! h264parse ! openh264dec ! glimagesink</pre> <pre> demux.audio_0 ! queue ! decodebin ! audioconvert ! pulsesink</pre> This plays back the video and audio streams fine (not sure how well synchronised?) from an MP4 with video and audio streams, but hangs if the MP4 only has a video stream. So I think I need to: 1. Maybe there is some gstreamer element or attribute that can ignore the audio stream if not present somehow ? 2. Check if the MP4 file has an audio stream before creating the gstreamer pipeline in C++. 3. Create the basic C++ pipleline in C++ and interrogate pads or something somehow and add the "demux.audio_0 ! queue ! decodebin ! audioconvert ! pulsesink" sub pipeline if it is seen an audio stream is present. Any ideas on the simplest/most CPU efficient way of doing this with gstreamer ? </body> </html>