compose: a relative --out is joined to the run dir; the failure is a bare 'ffmpeg could not assemble'

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Closed bug report

John Lauer · 25d ago ·closed by John Lauer

What happens

cd <project>/aiflow
adom-aiflow --run run-1mm --ai-thread <t> compose --out run-1mm/final.mp4
ERROR: ffmpeg could not assemble the video and its narration
Hint: Input of `compose` (skill aiflow-process-video): read .../aiflow-process-video/SKILL.md, section "Compose".

Every segment and both concat lists were fine (19 video and 19 audio parts, all with valid durations). Running the same command without --out composed the 78 s video into run-1mm/final.mp4 at once.

Cause

In 0.2.6 and 0.2.7, Cmd::Compose resolves a relative --out against the run directory, not the working directory:

let outp = if Path::new(out).is_absolute() { PathBuf::from(out) } else { dir.join(out) };

So --out run-1mm/final.mp4 became run-1mm/run-1mm/final.mp4, whose folder does not exist, and ffmpeg's final mux failed. The error hides that: ffmpeg runs with -v error but its stderr is not shown, and the message names neither the output path nor the reason.

Suggested fix

Resolve a relative --out against the working directory, like every other path flag, or say in --help that it is relative to the run (today it says only [default: final.mp4]).
Create the output's parent directory, or refuse up front with the resolved path.
On an ffmpeg failure, print the resolved output path and ffmpeg's last stderr lines, with a hint naming the fix.

Found by a Claude Opus 5.5 thread on 2026-10-20.

1 Reply

John Lauer · 25d ago

Fixed in adom-aiflow 0.2.8.

Default output: with no --out, the video is still final.mp4 in the run directory.
A relative --out now resolves against the working directory, like every other path flag. compose --help says so.
The output folder is created if it does not exist, or compose refuses up front and names the resolved path.
Every ffmpeg call in compose captures stderr. The assemble error names the resolved output path and quotes ffmpeg's last lines, so a bad path or codec problem is visible at once.
One code path: compose had a second copy of the assembly code (compose_run), which now calls the shared one.

Upgrade: adom-wiki pkg install adom/adom-aiflow, then adom-aiflow --version says 0.2.8.

John Lauer closed this · 25d ago