Supported File Types & Sizes for Mozikoshi-san (Transcription Service)
June 7, 2025



Supported Files for Mojiokoshi-san
The supported file types for Mojiokoshi-san are listed below. Uploading anything else will result in an error.
*Multiple file uploads are not supported. Please upload one file at a time.
Uploading files that exceed the supported file format or time limits will cause an upload error that prevents completion.
You can enable uploads by reducing the file size, converting the file, or splitting the file.
[Image Files]
File size: Less than 10MB
Supported file formats: .jpg, .jpeg, .png, .webp
*If the text is sideways or upside down, transcription may not be possible, so please correct the orientation.
[Document Files]
File size: Less than 50MB
Supported file format: .pdf
[Audio Files]
Audio duration: Within 90 minutes
File size: Less than 1GB
Supported file formats: .mp3, .wav, .wma, .mp4, .aifc, .flac, .aac, .aiff, .aifc
[Video Files]
Audio duration: Within 90 minutes
File size: Less than 1GB
Supported file formats: .mp4, .mov, .avi, .flv, .mkv, .webm, .wmv, .3gp
What Happens If You Upload Unsupported Files
If you try to upload a file that is not supported, errors such as the upload not completing will occur.
Example: MP4 file, file size 2GB, audio duration 3 hours
Unsupported files cannot be transcribed no matter how many times you try to upload them.
Furthermore, unexpected operations might consume transcription time even if transcription is not possible.
Please be aware of this.
How to Transcribe Unsupported Files
When you want to transcribe a 3-hour audio file...
In such cases, the best approach is to:
- Split the file to match the supported duration
- Convert to a supported file format
By splitting or changing the file format, the file size will naturally decrease.
Example: Change an M4A file (video) to an MP3 file (audio only)
Example: Split a 3-hour MP3 file into three 1-hour files
*When splitting by time, splitting at 90 minutes can increase transcription time or file size, so it's recommended to split into approximately 1-hour segments if possible.
1. How to Split Files to Match Supported Durations
To split files according to the supported duration, please use external services.
The sites introduced here are just examples; please search for and use a service that fits your needs.
Splitting MP3 Files
Splitting MP3 files is easy with online sites or installable free software.
MP3 Cutter is a convenient and easy-to-use online tool.
*When splitting by time, splitting at 90 minutes can increase transcription time or file size, so it's recommended to split into segments of 1 hour or less if possible.
2. Convert to a Compatible File Format

If you need to convert files, an online site like Online Audio Converter is convenient and easy to use.
3. Upload to Mojiokoshi3
Once you've split your audio file or converted it to a compatible format, upload it to Mojiokoshi3.
Select the language and speech recognition model,
Then click the "Transcribe" button.
By splitting the audio file, you will no longer encounter the "upload won't finish" error.
4. Transcription Complete
After clicking the transcribe button, the transcription will be completed shortly.
By splitting the file according to the remaining time, we were able to transcribe everything without any issues!
Please give it a try.
■ AI transcription service "Mr. Transscription"
"Mr. Transcription" is an online transcription tool that can be used from zero initial cost and 1,000 yen per month (* free version available).
- Supports more than 20 file formats such as audio, video, and images
- Can be used from both PC and smartphone
- Supports technical terms such as medical care, IT, and long-term care
- Supports creation of subtitle files and speaker separation
- Supports transcription in approximately 100 languages including English, Chinese, Japanese, Korean, German, French, Italian, etc.
To use it, just upload the audio file from the site. Transcription text is available in seconds to tens of minutes.
You can use it for free if you transcribe it for up to 10 minutes, so please try it once.
Email: mojiokoshi3.com@gmail.com
Transcription for audio / video / image transcription. It is a transcription service that anyone can use for free without installation.
- What is Mr. Transcription?
- Transcript images, sounds, and videos with Mr. Transcription
- Free registration
- Rate plan
- manual