What Is It?
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]
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
About the HUB Format
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:
|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).