Run FFmpeg Conversion

The whole "Configure" half of the Framerate Converter pack (Trope Tools, TropeMedia) is about building a command. This is the node that pulls the trigger. Run FFmpeg Conversion takes a CMD_LIST - the structured command from Build Command - and executes it, then reports back what happened in a way you can actually act on.

It's the "Process" stage of the granular pipeline, and it's where a custom chain goes from theory to a file on disk.

Inputs

• command_list - required, the CMD_LIST output from Build Command. You could in principle hand it any well-formed command list, but in practice it's the one that was built for you.
• expected_duration - optional, default 0. It's accepted so you can pass along the predicted output duration from Calc Conversion, but in the current version it's informational - the node runs the command and reports the result either way.

What you get back

Three outputs:

• output_path (STRING) - the file the command wrote. The node knows this because it's always the last argument in the command list, which is a neat trick for a generic runner.
• ffmpeg_output (STRING) - FFmpeg's stderr captured for you. On success it's mostly encoder chatter; on failure it's your diagnosis, and the composite node surfaces the last 500 characters of it in the error message.
• success (BOOLEAN) - did it exit cleanly? Wire this into conditional logic if you want the graph to react differently on failure vs. success.

It also degrades gracefully: if FFmpeg isn't installed it returns success: false with a "ffmpeg not found" message rather than a raw Python crash, and there's a one-hour timeout so a stuck encode eventually tells you it gave up instead of hanging your queue forever.

Install

Standard pack install: ComfyUI Manager → Trope Tools - Framerate Converter, or git clone https://github.com/LaserDog80/ComfyUI-FramerateConverter into custom_nodes/ and restart. It needs the system ffmpeg binary installed (brew/apt/gyan.dev) - the pack warns at startup if it's missing.

The flagship Convert Framerate node wraps this internally and raises a clean error on failure, so most users will never meet this node directly. It's worth knowing about for one reason: if you're debugging a conversion and want to see exactly what FFmpeg said, this is the node that hands you the raw stderr. Reading ffmpeg_output on a failed run is how you learn whether it was a codec problem, a container problem, or a path problem - which is a lot more useful than a generic "something failed."