Comfy-Org/ComfyUI · error · ValueError

SaveAudioMP3: input audio is None (source video may have no

Error message

SaveAudioMP3: input audio is None (source video may have no audio track).

What it means

SaveAudioMP3.execute raises when audio is None — the MP3 export variant of SaveAudio with the identical None-input guard. The encoder (via UI.AudioSaveHelper) needs a waveform and sample rate, so a None audio object aborts execution.

Source

Thrown at comfy_extras/nodes_audio.py:211

            search_aliases=["export mp3"],
            display_name="Save Audio (MP3) (DEPRECATED)",
            category="audio",
            essentials_category="Audio",
            inputs=[
                IO.Audio.Input("audio"),
                IO.String.Input("filename_prefix", default="audio/ComfyUI"),
                IO.Combo.Input("quality", options=["V0", "128k", "320k"], default="V0"),
            ],
            hidden=[IO.Hidden.prompt, IO.Hidden.extra_pnginfo],
            is_deprecated=True,
            is_output_node=True,
            outputs=[IO.Audio.Output("audio")]
        )

    @classmethod
    def execute(cls, audio, filename_prefix="ComfyUI", format="mp3", quality="128k") -> IO.NodeOutput:
        if audio is None:
            raise ValueError("SaveAudioMP3: input audio is None (source video may have no audio track).")
        return IO.NodeOutput(
            audio,
            ui=UI.AudioSaveHelper.get_save_audio_ui(
                audio, filename_prefix=filename_prefix, cls=cls, format=format, quality=quality
            )
        )


class SaveAudioOpus(IO.ComfyNode):
    @classmethod
    def define_schema(cls):
        return IO.Schema(
            node_id="SaveAudioOpus",
            search_aliases=["export opus"],
            display_name="Save Audio (Opus) (DEPRECATED)",
            category="audio",
            inputs=[
                IO.Audio.Input("audio"),

View on GitHub (pinned to 1c6d8d45b3)

Solutions

Confirm the upstream source has audio; use ffprobe if unsure
Feed the node from LoadAudio or a generator node instead of a silent video's audio tap
Skip the MP3 branch when audio is None via a switch node

Defensive patterns

Strategy: type-guard

Validate before calling

if audio is None:
    return  # skip MP3 export

Type guard

def is_audio(v) -> bool:
    return isinstance(v, dict) and 'waveform' in v and 'sample_rate' in v

Prevention

Check for None audio before export nodes
Use ffprobe to prefilter silent files in batch jobs
Prefer the non-deprecated save nodes going forward

When it happens

Trigger: MP3 export node receiving the audio output of a video loader whose video lacked an audio track, or any unconnected/None optional audio input.

Common situations: Converting video audio to MP3 in batch pipelines where some inputs are silent; deprecated SaveAudioMP3 usage after refactors changed upstream node outputs.

Related errors

AI-assisted analysis of Comfy-Org/ComfyUI@1c6d8d45b3 (2026-08-14). Data as JSON: /api/errors/49e02d6663d4a8bb. Report an issue: GitHub.