I am currently writing a python script to extract samples from old Roland 12 bit sample disks and save them as 16 bit wav files.
The samples are layouted as follows 0 [S0 bit 11..4] [S0 bit 3..0|S1 bit 3..0] [S1 bit 11..4] 3 [S2 bit 11..4] [S2 bit 3..0|S3 bit 3..0] [S3 bit 11..4] In other words sample0=(data[0]<<4)|(data[1]>>4) sample1=(data[2]<<4)|(data[1] & 0x0f) I use this code for the conversion (using the struct module) import struct from array import array def getWaveData(diskBuffer): offset=0 words=array('H') for i in range(len(diskBuffer)/3): h0=struct.unpack_from('>h',diskBuffer,offset) h1=struct.unpack_from('<h',diskBuffer,offset+1) words.append(h0[0] & 0xfff0) words.append(h1[0] & 0xfff0) offset+=3 return words I unpack the samples in an array of unsigned shorts for I later can use the byteswap() method if the code is running on a big endian machine. What options using pure python do I have to make the conversion faster? I thought of unpacking more bytes at once e.g. using a format '>hxhxhxhx' for 4 even samples and '<xhxhxhxh' for 4 odd samples vice versa. Can I map the '& 0xfff0' to the whole array? -- https://mail.python.org/mailman/listinfo/python-list