GSTreamer Improvements

[joaoantoniocardoso]

Consider this pipeline instead:

pipeline = " ! ".join([
    f"appsrc name=src do-timestamp=true",
    f"queue",
    f"h264parse",
    f"video/x-h264,stream-format=avc,alignment=au", # Don't impose a framerate here, and mp4 mux requires avc/au
    # f"h264timestamper", # Not needed because we are reconstructing PTS+DTS in our application
    f"queue",
    f"watchdog timeout={timeout_ms}", # Detect if it gets stuck
    f"mp4mux faststart=true",
    f"filesink sync=false location={output_filename}",
])