ref: df1c24a047ec75dcd05ea73ac6d76666bd22f75a
dir: /src/vox.c/
/************************************************************************ * SOX * * * * AUDIO FILE PROCESSING UTILITY * * * * Project : SOX * * File : vox.c * * Version : V12.17.4 * * * * Version History : V12.17.4 - Tony Seebregts * * 5 May 2004 * * 1. Original * * * * Description : SOX file format handler for Dialogic/Oki ADPCM VOX * * files. * * * * Notes : 1. Based on the vox/devox code samples at: * * * * http://www.cis.ksu.edu/~tim/vox * * * * 2. Coded from SOX skeleton code supplied with SOX source. * * * * 3. Tested under: * * - Windows 2000 SP3/Visual C++ V6.0 * * - Windows 2000 SP3/Digital Mars V7.51 * * * ************************************************************************/ /////////////////////////////////////////// // ORIGINAL SOX COPYRIGHT AND DISCLAIMER // /////////////////////////////////////////// /************************************************************************ * July 5, 1991 * * * * Copyright 1991 Lance Norskog And Sundry Contributors * * * * This source code is freely redistributable and may be used for any * * purpose. This copyright notice must be maintained. * * * * Lance Norskog And Sundry Contributors are not responsible for the * * consequences of using this software. * * * ************************************************************************/ /////////////////// // INCLUDE FILES // /////////////////// #include "st_i.h" ////////////// // TYPEDEFS // ////////////// typedef struct voxstuff { struct { short last; // ADPCM codec state short index; } state; struct { uint8_t byte; // write store uint8_t flag; } store; } *vox_t; /////////////// // CONSTANTS // /////////////// static short STEPSIZE[49] = { 16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 253, 279, 307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963, 1060,1166,1282,1411,1552 }; static short STEPADJUST[8] = { -1,-1,-1,-1,2,4,6,8 }; ///////////////////////// // FUNCTION PROTOTYPES // ///////////////////////// static uint8_t envox (short, vox_t); static short devox (uint8_t,vox_t); //////////////////// // IMPLEMENTATION // //////////////////// /****************************************************************************** * Function : st_voxstartread * Description: Initialises the file parameters and ADPCM codec state. * Parameters : ft - file info structure * Returns : int - ST_SUCCESS * ST_EOF * Exceptions : * Notes : 1. VOX file format is 4-bit OKI ADPCM that decodes to * to 12 bit signed linear PCM. * 2. Dialogic only supports 6kHz, 8kHz and 11 kHz sampling * rates but the codecs allows any user specified rate. ******************************************************************************/ int st_voxstartread (ft_t ft) { vox_t state = (vox_t) ft->priv; // ... setup file info ft->file.buf = (char *)malloc(ST_BUFSIZ); if (!ft->file.buf) { st_fail_errno (ft,ST_ENOMEM,"Unable to allocate internal buffer memory"); return(ST_EOF); } ft->file.size = ST_BUFSIZ; ft->file.count = 0; ft->file.pos = 0; ft->file.eof = 0; ft->info.size = ST_SIZE_WORD; ft->info.encoding = ST_ENCODING_SIGN2; ft->info.channels = 1; // ... initialise CODEC state state->state.last = 0; state->state.index = 0; state->store.byte = 0; state->store.flag = 0; return (ST_SUCCESS); } /****************************************************************************** * Function : st_voxread * Description: Fills an internal buffer from the VOX file, converts the * OKI ADPCM 4-bit samples to 12-bit signed PCM and then scales * the samples to full range 16 bit PCM. * Parameters : ft - file info structure * buffer - output buffer * length - size of output buffer * Returns : int - number of samples returned in buffer * Exceptions : * Notes : ******************************************************************************/ st_ssize_t st_voxread (ft_t ft,st_sample_t *buffer,st_ssize_t length) { vox_t state = (vox_t) ft->priv; int count = 0; int N; uint8_t byte; short word; // ... round length down to nearest even number N = length/2; N *=2; // ... loop until buffer full or EOF while (count < N) { // ... refill buffer if (ft->file.pos >= ft->file.count) { ft->file.count = st_readbuf (ft,ft->file.buf,1,ft->file.size); ft->file.pos = 0; if (ft->file.count == 0) break; } // ... decode two nibbles stored as a byte byte = ft->file.buf[ft->file.pos++]; word = devox ((uint8_t) ((byte >> 4) & 0x0F),state); *buffer++ = ST_SIGNED_WORD_TO_SAMPLE (word * 16); word = devox ((uint8_t) (byte & 0x0F),state); *buffer++ = ST_SIGNED_WORD_TO_SAMPLE (word * 16); count += 2; } return count; } /****************************************************************************** * Function : st_voxstopread * Description: Frees the internal buffer allocated in st_voxstartread. * Parameters : ft - file info structure * Returns : int - ST_SUCCESS * Exceptions : * Notes : ******************************************************************************/ int st_voxstopread (ft_t ft) { free (ft->file.buf); return (ST_SUCCESS); } /****************************************************************************** * Function : st_voxstartwrite * Description: Initialises the file parameters and ADPCM codec state. * Parameters : ft - file info structure * Returns : int - ST_SUCCESS * ST_EOF * Exceptions : * Notes : 1. VOX file format is 4-bit OKI ADPCM that decodes to * to 12 bit signed linear PCM. * 2. Dialogic only supports 6kHz, 8kHz and 11 kHz sampling * rates but the codecs allows any user specified rate. ******************************************************************************/ int st_voxstartwrite (ft_t ft) { vox_t state = (vox_t) ft->priv; // ... setup file info ft->file.buf = (char *)malloc(ST_BUFSIZ); if (!ft->file.buf) { st_fail_errno (ft,ST_ENOMEM,"Unable to allocate internal buffer memory"); return(ST_EOF); } ft->file.size = ST_BUFSIZ; ft->file.count = 0; ft->file.pos = 0; ft->file.eof = 0; ft->info.size = ST_SIZE_WORD; ft->info.encoding = ST_ENCODING_SIGN2; ft->info.channels = 1; // ... initialise CODEC state state->state.last = 0; state->state.index = 0; state->store.byte = 0; state->store.flag = 0; return (ST_SUCCESS); } /****************************************************************************** * Function : st_voxwrite * Description: Converts the supplied buffer to 12 bit linear PCM and encodes * to OKI ADPCM 4-bit samples (packed a two nibbles per byte). * Parameters : ft - file info structure * buffer - output buffer * length - size of output buffer * Returns : int - ST_SUCCESS * ST_EOF * Exceptions : * Notes : ******************************************************************************/ st_ssize_t st_voxwrite (ft_t ft,st_sample_t *buffer,st_ssize_t length) { vox_t state = (vox_t) ft->priv; int count = 0; uint8_t byte = state->store.byte; uint8_t flag = state->store.flag; short word; while (count < length) { word = ST_SAMPLE_TO_SIGNED_WORD (*buffer++); word /= 16; byte <<= 4; byte |= envox (word,state) & 0x0F; flag++; flag %= 2; if (flag == 0) { ft->file.buf[ft->file.count++] = byte; if (ft->file.count >= ft->file.size) { st_writebuf (ft,ft->file.buf,1,ft->file.count); ft->file.count = 0; } } count++; } // ... keep last byte across calls state->store.byte = byte; state->store.flag = flag; return (count); } /****************************************************************************** * Function : st_voxstopwrite * Description: Flushes any leftover samples and frees the internal buffer * allocated in st_voxstartwrite. * Parameters : ft - file info structure * Returns : int - ST_SUCCESS * Exceptions : * Notes : ******************************************************************************/ int st_voxstopwrite (ft_t ft) { vox_t state = (vox_t) ft->priv; uint8_t byte = state->store.byte; uint8_t flag = state->store.flag; // ... flush remaining samples if (flag != 0) { byte <<= 4; byte |= envox (0,state) & 0x0F; ft->file.buf[ft->file.count++] = byte; } if (ft->file.count > 0) st_writebuf (ft,ft->file.buf,1,ft->file.count); // ... free buffer free (ft->file.buf); return (ST_SUCCESS); } /****************************************************************************** * Function : envox * Description: Internal utility routine to encode 12 bit signed PCM to * OKI ADPCM code * Parameters : sample - 12 bit linear PCM sample * state - CODEC state * Returns : uint8_t - ADPCM nibble (in low order nibble) * Exceptions : * Notes : ******************************************************************************/ static uint8_t envox (short sample,vox_t state) { uint8_t code; short dn; short ss; ss = STEPSIZE[state->state.index]; code = 0x00; if ((dn = sample - state->state.last) < 0) { code = 0x08; dn = -dn; } if (dn >= ss) { code = code | 0x04; dn -= ss; } if (dn >= ss/2) { code = code | 0x02; dn -= ss/2; } if (dn >= ss/4) { code = code | 0x01; } // ... use decoder to set the estimate of last sample and adjust the step index state->state.last = devox (code,state); return (code); } /****************************************************************************** * Function : devox * Description: Internal utility routine to decode OKI ADPCM 4-bit samples to * 12-bit signed PCM. * Parameters : code - ADPCM code (nibble) * state - CODEC state * Returns : short - 12 bit signed PCM sample * Exceptions : * Notes : ******************************************************************************/ static short devox (uint8_t code,vox_t state) { short dn; short ss; short sample; ss = STEPSIZE[state->state.index]; dn = ss/8; if (code & 0x01) dn += ss/4; if (code & 0x02) dn += ss/2; if (code & 0x04) dn += ss; if (code & 0x08) dn = -dn; sample = state->state.last + dn; // ... clip to 12 bits if (sample > 2047) sample = 2047; if (sample < -2048) sample = -2048; // ... adjust step size state->state.last = sample; state->state.index += STEPADJUST[code & 0x07]; if (state->state.index < 0) state->state.index = 0; if (state->state.index > 48) state->state.index = 48; // ... done return (sample); }