I tested the 2x sped-up file provided by you for transcription and I can confirm that the API bills only for the duration of the sped-up file(rounded to the nearest second).
Here are the details of the original file:
- File Type: MP3
- Duration: 60.10 seconds
- Sample Rate: 48000 Hz
- Channels: 1 (Mono)
- Bit Rate: 128.069 kbps
The sped-up file has the following:
- File Type: MP3
- Duration: 30.05 seconds
- Sample Rate: 48000 Hz
- Channels: 1 (Mono)
- Bit Rate: 64.088 kbps
The 2x sped-up file provided by you was the only one I transcribed today and here’s the screenshot of usage:
Hence if you upload the 2x sped-up file, you’ll only be billed for half the duration.