How to Pause and Resume rav1e AV1 Encoding

This article explains the mechanisms available to pause and resume active video encoding jobs when using the rav1e (librav1e) AV1 encoder. Because rav1e is designed as a library and a command-line tool, managing an active job requires a combination of operating system process control, API-level loop management, or integration with external multi-pass chunking frameworks.

Operating System Process Control

The most direct way to pause and resume an active rav1e encoding job without losing progress is through operating system-level process signals. This method works for both the rav1e command-line interface (CLI) and applications linking to the librav1e library.

• Linux and macOS (POSIX): You can suspend the encoder process by sending a SIGSTOP signal, which halts execution and keeps the current state in memory. To resume, send a SIGCONT signal.
  • Pause: kill -TSTP <PID> or kill -STOP <PID>
  • Resume: kill -CONT <PID>
• Windows: You can pause the rav1e process using the Resource Monitor or Process Explorer. Right-click the rav1e.exe process and select “Suspend”. To resume, right-click the process and select “Resume”.

These methods preserve the exact state of the encoder in the system RAM, allowing for an instant pause and resume cycle.

API-Level Flow Control (librav1e)

For developers integrating librav1e into their own software, pausing and resuming is controlled via the application’s frame-feeding loop.

The librav1e API operates on a push-pull model using the following functions: * Context::send_frame() to input raw video frames. * Context::receive_packet() to retrieve encoded AV1 packets.

Because the encoding process is synchronous with these function calls, you can pause the encoding job simply by halting the thread that manages this loop. Since the encoder state is preserved within the Context struct in memory, resuming encoding is as simple as restarting the loop and resuming calls to send_frame() and receive_packet().

Persistent Pause and Resume via Segmented Encoding

Neither the rav1e CLI nor the librav1e API supports native session serialization (saving the entire encoder state to a file to resume after a system reboot or application crash).

To achieve persistent pause and resume capabilities across system restarts, you must use a segmented encoding workflow:

1. Scene Detection and Chunking: Split the source video into smaller segments (chunks) at keyframe intervals.
2. Sequential Encoding: Encode each chunk individually using rav1e.
3. State Tracking: Maintain a queue or a manifest file tracking which chunks have been successfully encoded.
4. Concatenation: Merge the finished AV1 segments into a single container without re-encoding.

If the encoding process is interrupted or manually stopped, the tool can read the manifest and resume encoding from the start of the last uncompleted chunk, preventing the need to restart the entire video encoding job from the beginning.

Popular third-party encoding frameworks like Av1an use this segmented approach to manage rav1e encoding jobs, providing robust crash-recovery and pause/resume functionality.