Android .m4a audio files fail with OpenAI Transcription node

Questions
1

Describe the problem/error/question

Hi everyone,

I’m using n8n Cloud and I’ve been testing the OpenAI Transcription (Whisper) node with .m4a audio files.

Here’s what I’ve found:

  • iOS Voice Memo .m4a files transcribe successfully using the OpenAI node :white_check_mark:

  • Android Voice Recorder .m4a files always fail with this error :cross_mark:

  • Android Voice Recorder .m4a files transcribe successfully using the gemini :white_check_mark:

how can i transcribe m4a files or m4a to mp3 without ffmpeg on n8n cloud

What is the error message (if any)?

Invalid file format. Supported formats: [‘flac’, ‘m4a’, ‘mp3’, ‘mp4’, ‘mpeg’, ‘mpga’, ‘oga’, ‘ogg’, ‘wav’, ‘webm’]

1 Like
2

same error.

with file all fine, i`d easy open it in adobe audition.

whats problem???

3

not solve yet

@n8n

If your question has not been solved, please let us know in a new reply on your original topic and we’ll get back on it.

4

Did you manage to solve it? How did you solve it?

5

On cloud version, you have to use an external service that you can convert the file.

On self-hosted ffmpeg does the job.

Explanation:

Both iOS and Android use the AAC (Advanced Audio Coding) codec inside their .m4a files, but they often use different profiles and bitrates:

  • ​iOS Voice Memo (.m4a): Typically uses AAC-LC (Low Complexity) with standard settings that are highly compatible and widely supported. Whisper supports this.

  • ​Android Voice Recorder (.m4a): Can use various profiles like AAC-HE (High Efficiency) or AAC-HEv2 at very low bitrates, or a slightly non-standard implementation of AAC.

So, I tried with an android 7 and the file works, tried with android 11 I get your error…

So, the compatibility between Google (aka android) and Openai(that likes more the IOS)…

iOS Voice Memo AAC-LC (Low Complexity) Highly compatible, standard, simple profile. OpenAI’s parser reads the moov box, sees a perfect, common definition for AAC-LC, and successfully decodes the stream.

Android Recorder AAC-HE / AAC-Main (High Efficiency / Main Profile) Optimized for lower bitrates, often with complex tricks like SBR (Spectral Band Replication) (Source 2.1). OpenAI’s parser reads the moov box, sees a definition for HE or Main AAC that is slightly non-standard or unfamiliar to its strict internal audio library.

6

i coudlnt yet, Looking at the answer below, it seems impossible without third party library