ACT
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- Samples: http://samples.mplayerhq.hu/A-codecs/act/
- Working decoder: http://www.netac.com/Download/C635/C635%20Driver&Tools.zip
ACT files are created by Chinese-made portable MP3 players when recording from the internal microphone.
ACT files uses the G729A speech compression codec. There are 3 different ways to record to this format from a player.
- Fine Rec
- Long Rec
- Long Vox, in this mode the player will record when voice activated.
These 3 formats map to 2 bitstream formats, the Fine and Long bitstream formats.
| Name | Sample rate | Frame size | Frames per chunk | Chunk size | Padding bytes |
|---|---|---|---|---|---|
| Fine | 8000 | 10 | 51 | 510 | 2 |
| Long | 4400 | 22 | 23 | 506 | 6 |
ACT File Format
Files are always aligned to 512 bytes boundary and contains 512 byte header and chunks of the same size. Each chunk consists of fixed number of frames and padding bytes.