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The ffmpeg module provides three variants of ffmpeg execution, each with different levels of control and monitoring capabilities.

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ffmpeg_slim

Run ffmpeg with cancellation support only (no output monitoring). This is the lightest-weight variant — it spawns ffmpeg, waits for it to complete, and returns the exit result. Use ffmpeg if you need to stream stdout/stderr, or ffmpeg_graceful for graceful shutdown. 
pub async fn ffmpeg_slim<Prepare>(
    cancellation_token: CancellationToken,
    prepare: Prepare,
) -> Result<CommandExit, FfmpegError>
where
    Prepare: FnOnce(&mut Command),

​
Parameters

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cancellation_token
CancellationToken
required
A token to cancel the ffmpeg process. When cancelled, the process is killed immediately.
​
prepare
FnOnce(&mut Command)
required
A closure that configures the ffmpeg command before execution. Use this to add arguments, set environment variables, etc.

​
Returns

Returns Result<CommandExit, FfmpegError>:
  • Ok(CommandExit) - Contains the exit code, stdout, and stderr from the ffmpeg process
  • Err(FfmpegError::NotFound) - The ffmpeg binary could not be found in PATH or via LIBFFMPEG_FFMPEG_PATH

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Example

use libffmpeg::ffmpeg::ffmpeg_slim;
use tokio_util::sync::CancellationToken;

let token = CancellationToken::new();
let result = ffmpeg_slim(token, |cmd| {
    cmd.arg("-i")
        .arg("input.mp4")
        .arg("-c:v")
        .arg("libx264")
        .arg("output.mp4");
}).await?;

​
ffmpeg

Run ffmpeg with output monitoring via a CommandMonitorServer. Stdout and stderr lines are streamed through the monitor, allowing real-time progress parsing or logging. On cancellation the process is killed immediately — use ffmpeg_graceful if you need stdin-based quit with a SIGKILL fallback. 
pub async fn ffmpeg<Prepare>(
    cancellation_token: CancellationToken,
    server: &CommandMonitorServer,
    prepare: Prepare,
) -> Result<CommandExit, FfmpegError>
where
    Prepare: FnOnce(&mut Command),

​
Parameters

​
cancellation_token
CancellationToken
required
A token to cancel the ffmpeg process. When cancelled, the process is killed immediately.
​
server
&CommandMonitorServer
required
A server that monitors stdout/stderr output from the ffmpeg process. Use this to track progress or parse output in real-time.
​
prepare
FnOnce(&mut Command)
required
A closure that configures the ffmpeg command before execution.

​
Returns

Returns Result<CommandExit, FfmpegError>:
  • Ok(CommandExit) - Contains the exit code, stdout, and stderr from the ffmpeg process
  • Err(FfmpegError::NotFound) - The ffmpeg binary could not be found

​
Example

use libffmpeg::ffmpeg::ffmpeg;
use libcmd::CommandMonitorServer;
use tokio_util::sync::CancellationToken;

let token = CancellationToken::new();
let server = CommandMonitorServer::new();

let result = ffmpeg(token, &server, |cmd| {
    cmd.arg("-i")
        .arg("input.mp4")
        .arg("-progress")
        .arg("pipe:1")
        .arg("output.mp4");
}).await?;

​
ffmpeg_graceful

Run ffmpeg with output monitoring and graceful shutdown. On cancellation, sends q to ffmpeg’s stdin (its built-in quit command), giving the process up to 5 seconds to exit cleanly before falling back to SIGKILL. This allows ffmpeg to finalize the output file properly. 
pub async fn ffmpeg_graceful<Prepare>(
    cancellation_token: CancellationToken,
    client: &CommandMonitorClient,
    server: &CommandMonitorServer,
    prepare: Prepare,
) -> Result<CommandExit, FfmpegError>
where
    Prepare: FnOnce(&mut Command),

​
Parameters

​
cancellation_token
CancellationToken
required
A token to cancel the ffmpeg process. When cancelled, the function sends “q” to stdin and waits up to 5 seconds before force-killing.
​
client
&CommandMonitorClient
required
A client used to send the “q” command to ffmpeg’s stdin during graceful shutdown.
​
server
&CommandMonitorServer
required
A server that monitors stdout/stderr output from the ffmpeg process.
​
prepare
FnOnce(&mut Command)
required
A closure that configures the ffmpeg command before execution.

​
Returns

Returns Result<CommandExit, FfmpegError>:
  • Ok(CommandExit) - Contains the exit code, stdout, and stderr from the ffmpeg process
  • Err(FfmpegError::NotFound) - The ffmpeg binary could not be found

​
Graceful Shutdown Flow

  1. If the process exits naturally before cancellation, do nothing and return early
  2. User requests cancellation via the cancellation_token
  3. Send “q” to ffmpeg’s stdin
  4. Wait up to 5 seconds for the process to exit gracefully
  5. If the process doesn’t exit after 5 seconds, send SIGKILL

​
Example

use libffmpeg::ffmpeg::ffmpeg_graceful;
use libcmd::{CommandMonitorClient, CommandMonitorServer};
use tokio_util::sync::CancellationToken;

let token = CancellationToken::new();
let server = CommandMonitorServer::new();
let client = CommandMonitorClient::new();

let result = ffmpeg_graceful(token, &client, &server, |cmd| {
    cmd.arg("-i")
        .arg("input.mp4")
        .arg("-c:v")
        .arg("libx264")
        .arg("output.mp4");
}).await?;

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