HammerHead is an old drum machine for Windows. One of its features allows you to import new drum sounds using a file format called HUB. clawhammer.rb allows you to extract the sounds out of a HUB file into individual *.wav files. This allows you to use the sounds in modern programs like Logic or GarageBand.
The HUB file format was reverse-engineered using FileInspector.
ruby clawhammer.rb [path of HUB file]
For example:
ruby clawhammer.rb groove.hub
This will create six output files:
groove-1.wav
groove-2.wav
groove-3.wav
groove-4.wav
groove-5.wav
groove-6.wav
Clawhammer uses the WaveFile gem to create the output wave files. Therefore, you'll need to have this gem installed on your machine. To do so, run the following command:
gem install wavefile
The HUB format is very simple. A HUB file contains 6 records, which represent each of the sounds stored in the file. Each record contains a header, followed by actual sample data.
| Header for Sound #1 |
| Sound #1 Sample Data |
| Header for Sound #2 |
| Sound #2 Sample Data |
| ... |
| Header for Sound #6 |
| Sound #6 Sample Data |
Each header is 36 bytes, and has the following format:
| Bytes | Description | Data Format |
|---|---|---|
| 0: | Length of the HUB title, in bytes. | Integer. Signed or unsigned doesn't matter, since the maximum valid value is 30. |
| 1-30: | HUB title. If HUB title is less than 30 characters, the extra bytes will be garbage. The title will be identical for each header. | 1-byte ASCII characters |
| 31-34: | Length of the sound's sample data, in bytes. | Unsigned, little-endian |
| 35: | Flag for whether sound should be stretched to fill a full measure when played in HammerHead. (For example, a drum loop). Ignored by Clawhammer. | 0x01 for true, 0x00 for false |
The sample data payload follows the header. The length of the sample data is indicated in bytes 31-34 of the header.
The sample data in each record only includes raw sample data, i.e. what you would find in the data chunk body of a *.wav file. It doesn't include any of the other chunks specified by the *.wav format such as a fmt chunk - it doesn't need one because HammerHead assumes that samples are 16-bit, 1 channel (mono), with a sample rate of 44100. (For more on the *.wav format, visit http://wavefilegem.com/how_wave_files_work.html).