How do I force a framerate for an input container eg stream (MJPEG)

Overview

I am using pyav to grab an MJPEG Stream from an IP-Camera, the camera is set to 60FPS when using H264, the framerate is correct at 60FPS when using MJPEG (over HTTP) the framerates are at 25FPS.

I was not able to find a way to force 60FPS i tried to set time_base with setting an Fraction(1, 60) without an success, also when i try to set options like {"r": "60"} has no effect. Because FFMPEG does not know about the framerate it makes a guess or fallback i think to 25FPS

Expected behavior

A way to force a framerate

Actual behavior

Container properties after setting time_base Fraction(1, 60) base_rate: 25 guessed_rate: 25 time_base: 1/60

Investigation

Try to set params like time_base on stream and codec_context without an succcess. Passing params to stream or contatiner without an success

Research

I have done the following:

• Checked the PyAV documentation
• Searched on Google
• Searched on Stack Overflow
• Looked through old GitHub issues
• Asked on PyAV Gitter
• ... and waited 72 hours for a response.