hvirtual/quicktime/ima4.c

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#include "funcprotos.h"
#include "ima4.h"
#include "quicktime.h"

typedef struct
{
/* During decoding the work_buffer contains the most recently read chunk. */
/* During encoding the work_buffer contains interlaced overflow samples  */
/* from the last chunk written. */
        int16_t *work_buffer;
        unsigned char *read_buffer;    /* Temporary buffer for drive reads. */

/* Starting information for all channels during encoding. */
        int *last_samples, *last_indexes;
        long chunk; /* Number of chunk in work buffer */
        int buffer_channel; /* Channel of work buffer */

/* Number of samples in largest chunk read. */
/* Number of samples plus overflow in largest chunk write, interlaced. */
        long work_size;     
        long work_overflow; /* Number of overflow samples from the last chunk written. */
        long read_size;     /* Size of read buffer. */
} quicktime_ima4_codec_t;

static int ima4_step[89] = 
{
    7, 8, 9, 10, 11, 12, 13, 14, 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, 1707, 1878, 2066,
    2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
    5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
    15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
};

static int ima4_index[16] = 
{
    -1, -1, -1, -1, 2, 4, 6, 8,
    -1, -1, -1, -1, 2, 4, 6, 8
};

/* Known by divine revelation */

#define BLOCK_SIZE 0x22
#define SAMPLES_PER_BLOCK 0x40

/* ================================== private for ima4 */


void ima4_decode_sample(int *predictor, int *nibble, int *index, int *step)
{
        int difference, sign;

/* Get new index value */
        *index += ima4_index[*nibble];

        if(*index < 0) *index = 0; 
        else 
        if(*index > 88) *index = 88;

/* Get sign and magnitude from *nibble */
        sign = *nibble & 8;
        *nibble = *nibble & 7;

/* Get difference */
        difference = *step >> 3;
        if(*nibble & 4) difference += *step;
        if(*nibble & 2) difference += *step >> 1;
        if(*nibble & 1) difference += *step >> 2;

/* Predict value */
        if(sign) 
        *predictor -= difference;
        else 
        *predictor += difference;

        if(*predictor > 32767) *predictor = 32767;
        else
        if(*predictor < -32768) *predictor = -32768;

/* Update the step value */
        *step = ima4_step[*index];
}

void ima4_decode_block(quicktime_audio_map_t *atrack, int16_t *output, unsigned char *input)
{
        int predictor;
        int index;
        int step;
        int i, nibble, nibble_count, block_size;
        unsigned char *block_ptr;
        unsigned char *input_end = input + BLOCK_SIZE;
        quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)atrack->codec)->priv;

/* Get the chunk header */
        predictor = *input++ << 8;
        predictor |= *input++;

        index = predictor & 0x7f;
        if(index > 88) index = 88;

        predictor &= 0xff80;
        if(predictor & 0x8000) predictor -= 0x10000;
        step = ima4_step[index];

/* Read the input buffer sequentially, one nibble at a time */
        nibble_count = 0;
        while(input < input_end)
        {
                nibble = nibble_count ? (*input++  >> 4) & 0x0f : *input & 0x0f;

                ima4_decode_sample(&predictor, &nibble, &index, &step);
                *output++ = predictor;

                nibble_count ^= 1;
        }
}


void ima4_encode_sample(int *last_sample, int *last_index, int *nibble, int next_sample)
{
        int difference, new_difference, mask, step;

        difference = next_sample - *last_sample;
        *nibble = 0;
        step = ima4_step[*last_index];
        new_difference = step >> 3;

        if(difference < 0)
        {
                *nibble = 8;
                difference = -difference;
        }

        mask = 4;
        while(mask)
        {
                if(difference >= step)
                {
                        *nibble |= mask;
                        difference -= step;
                        new_difference += step;
                }

                step >>= 1;
                mask >>= 1;
        }

        if(*nibble & 8)
                *last_sample -= new_difference;
        else
                *last_sample += new_difference;

        if(*last_sample > 32767) *last_sample = 32767;
        else
        if(*last_sample < -32767) *last_sample = -32767;

        *last_index += ima4_index[*nibble];

        if(*last_index < 0) *last_index = 0;
        else
        if(*last_index > 88) *last_index= 88;
}

void ima4_encode_block(quicktime_audio_map_t *atrack, unsigned char *output, int16_t *input, int step, int channel)
{
        quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)atrack->codec)->priv;
        int i, nibble_count = 0, nibble, header;

/* Get a fake starting sample */
        header = codec->last_samples[channel];
/* Force rounding. */
        if(header < 0x7fc0) header += 0x40;
        if(header < 0) header += 0x10000;
        header &= 0xff80;
        *output++ = (header & 0xff00) >> 8;
        *output++ = (header & 0x80) + (codec->last_indexes[channel] & 0x7f);

        for(i = 0; i < SAMPLES_PER_BLOCK; i++)
        {
                ima4_encode_sample(&(codec->last_samples[channel]), 
                                                        &(codec->last_indexes[channel]), 
                                                        &nibble, 
                                                        *input);

                if(nibble_count)
                        *output++ |= (nibble << 4);
                else
                        *output = nibble;

                input += step;
                nibble_count ^= 1;
        }
}

/* Convert the number of samples in a chunk into the number of bytes in that */
/* chunk.  The number of samples in a chunk should end on a block boundary. */
long ima4_samples_to_bytes(long samples, int channels)
{
        long bytes = samples / SAMPLES_PER_BLOCK * BLOCK_SIZE * channels;
        return bytes;
}

/* Decode the chunk into the work buffer */
int ima4_decode_chunk(quicktime_t *file, int track, long chunk, int channel)
{
        int result = 0;
        int i, j;
        long chunk_samples, chunk_bytes;
        unsigned char *chunk_ptr, *block_ptr;
        quicktime_trak_t *trak = file->atracks[track].track;
        quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)file->atracks[track].codec)->priv;

/* Get the byte count to read. */
        chunk_samples = quicktime_chunk_samples(trak, chunk);
        chunk_bytes = ima4_samples_to_bytes(chunk_samples, file->atracks[track].channels);

/* Get the buffer to read into. */
        if(codec->work_buffer && codec->work_size < chunk_samples)
        {
                free(codec->work_buffer);
                codec->work_buffer = 0;
        }

        if(!codec->work_buffer)
        {
                codec->work_size = chunk_samples;
                codec->work_buffer = malloc(sizeof(int16_t) * codec->work_size);
        }

        if(codec->read_buffer && codec->read_size < chunk_bytes)
        {
                free(codec->read_buffer);
                codec->read_buffer = 0;
        }

        if(!codec->read_buffer)
        {
                codec->read_size = chunk_bytes;
                codec->read_buffer = malloc(codec->read_size);
        }

/* codec->work_size now holds the number of samples in the last chunk */
/* codec->read_size now holds number of bytes in the last read buffer */

/* Read the entire chunk regardless of where the desired sample range starts. */
        result = quicktime_read_chunk(file, codec->read_buffer, track, chunk, 0, chunk_bytes);

/* Now decode the chunk, one block at a time, until the total samples in the chunk */
/* is reached. */

        if(!result)
        {
                block_ptr = codec->read_buffer;
                for(i = 0; i < chunk_samples; i += SAMPLES_PER_BLOCK)
                {
                        for(j = 0; j < file->atracks[track].channels; j++)
                        {
                                if(j == channel)
                                        ima4_decode_block(&(file->atracks[track]), &(codec->work_buffer[i]), block_ptr);

                                block_ptr += BLOCK_SIZE;
                        }
                }
        }
        codec->buffer_channel = channel;
        codec->chunk = chunk;

        return result;
}


/* =================================== public for ima4 */

static int delete_codec(quicktime_audio_map_t *atrack)
{
        quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)atrack->codec)->priv;

        if(codec->work_buffer) free(codec->work_buffer);
        if(codec->read_buffer) free(codec->read_buffer);
        if(codec->last_samples) free(codec->last_samples);
        if(codec->last_indexes) free(codec->last_indexes);
        codec->last_samples = 0;
        codec->last_indexes = 0;
        codec->read_buffer = 0;
        codec->work_buffer = 0;
        codec->chunk = 0;
        codec->buffer_channel = 0; /* Channel of work buffer */
        codec->work_size = 0;          /* Size of work buffer */
        codec->read_size = 0;
        free(codec);
        return 0;
}

static int decode(quicktime_t *file, 
                                        int16_t *output_i, 
                                        float *output_f,
                                        long samples, 
                                        int track, 
                                        int channel)
{
        int result = 0;
        int64_t chunk, chunk_sample, chunk_bytes, chunk_samples;
        int64_t i, chunk_start, chunk_end;
        quicktime_trak_t *trak = file->atracks[track].track;
        quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)file->atracks[track].codec)->priv;

/* Get the first chunk with this routine and then increase the chunk number. */
        quicktime_chunk_of_sample(&chunk_sample, &chunk, trak, file->atracks[track].current_position);

/* Read chunks and extract ranges of samples until the output is full. */
        for(i = 0; i < samples && !result; )
        {
/* Get chunk we're on. */
                chunk_samples = quicktime_chunk_samples(trak, chunk);

                if(!codec->work_buffer ||
                        codec->chunk != chunk ||
                        codec->buffer_channel != channel)
                {
/* read a new chunk if necessary */
                        result = ima4_decode_chunk(file, track, chunk, channel);
                }

/* Get boundaries from the chunk */
                chunk_start = 0;
                if(chunk_sample < file->atracks[track].current_position)
                        chunk_start = file->atracks[track].current_position - chunk_sample;

                chunk_end = chunk_samples;
                if(chunk_sample + chunk_end > file->atracks[track].current_position + samples)
                        chunk_end = file->atracks[track].current_position + samples - chunk_sample;

/* Read from the chunk */
                if(output_i)
                {
/*printf("decode_ima4 1 chunk %ld %ld-%ld output %ld\n", chunk, chunk_start + chunk_sample, chunk_end + chunk_sample, i); */
                        while(chunk_start < chunk_end)
                        {
                                output_i[i++] = codec->work_buffer[chunk_start++];
                        }
/*printf("decode_ima4 2\n"); */
                }
                else
                if(output_f)
                {
                        while(chunk_start < chunk_end)
                        {
                                output_f[i++] = (float)codec->work_buffer[chunk_start++] / 32767;
                        }
                }

                chunk++;
                chunk_sample += chunk_samples;
        }

        return result;
}

static int encode(quicktime_t *file, 
                                                int16_t **input_i, 
                                                float **input_f, 
                                                int track, 
                                                long samples)
{
        int result = 0;
        int64_t i, j, step;
        int64_t chunk_bytes;
        int64_t overflow_start;
        int64_t offset;
        int64_t chunk_samples; /* Samples in the current chunk to be written */
        quicktime_audio_map_t *track_map = &(file->atracks[track]);
        quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)track_map->codec)->priv;
        quicktime_trak_t *trak = track_map->track;
        int16_t *input_ptr;
        unsigned char *output_ptr;
        quicktime_atom_t chunk_atom;

/* Get buffer sizes */
        if(codec->work_buffer && codec->work_size < (samples + codec->work_overflow + 1) * track_map->channels)
        {
/* Create new buffer */
                int64_t new_size = (samples + codec->work_overflow + 1) * track_map->channels;
                int16_t *new_buffer = malloc(sizeof(int16_t) * new_size);

/* Copy overflow */
                for(i = 0; i < codec->work_overflow * track_map->channels; i++)
                        new_buffer[i] = codec->work_buffer[i];

/* Swap pointers. */
                free(codec->work_buffer);
                codec->work_buffer = new_buffer;
                codec->work_size = new_size;
        }
        else
        if(!codec->work_buffer)
        {
/* No buffer in the first place. */
                codec->work_size = (samples + codec->work_overflow) * track_map->channels;
/* Make the allocation enough for at least the flush routine. */
                if(codec->work_size < SAMPLES_PER_BLOCK * track_map->channels)
                        codec->work_size = SAMPLES_PER_BLOCK * track_map->channels;
                codec->work_buffer = malloc(sizeof(int16_t) * codec->work_size);
        }

/* Get output size */
        chunk_bytes = ima4_samples_to_bytes(samples + codec->work_overflow, track_map->channels);
        if(codec->read_buffer && codec->read_size < chunk_bytes)
        {
                free(codec->read_buffer);
                codec->read_buffer = 0;
        }

        if(!codec->read_buffer)
        {
                codec->read_buffer = malloc(chunk_bytes);
                codec->read_size = chunk_bytes;
        }

        if(!codec->last_samples)
        {
                codec->last_samples = malloc(sizeof(int) * track_map->channels);
                for(i = 0; i < track_map->channels; i++)
                {
                        codec->last_samples[i] = 0;
                }
        }

        if(!codec->last_indexes)
        {
                codec->last_indexes = malloc(sizeof(int) * track_map->channels);
                for(i = 0; i < track_map->channels; i++)
                {
                        codec->last_indexes[i] = 0;
                }
        }

/* Arm the input buffer after the last overflow */
        step = track_map->channels;
        for(j = 0; j < track_map->channels; j++)
        {
                input_ptr = codec->work_buffer + codec->work_overflow * track_map->channels + j;

                if(input_i)
                {
                        for(i = 0; i < samples; i++)
                        {
                                *input_ptr = input_i[j][i];
                                input_ptr += step;
                        }
                }
                else
                if(input_f)
                {
                        for(i = 0; i < samples; i++)
                        {
                                *input_ptr = (int16_t)(input_f[j][i] * 32767);
                                input_ptr += step;
                        }
                }
        }

/* Encode from the input buffer to the read_buffer up to a multiple of  */
/* blocks. */
        input_ptr = codec->work_buffer;
        output_ptr = codec->read_buffer;

        for(i = 0; 
                i + SAMPLES_PER_BLOCK <= samples + codec->work_overflow; 
                i += SAMPLES_PER_BLOCK)
        {
                for(j = 0; j < track_map->channels; j++)
                {
                        ima4_encode_block(track_map, output_ptr, input_ptr + j, track_map->channels, j);

                        output_ptr += BLOCK_SIZE;
                }
                input_ptr += SAMPLES_PER_BLOCK * track_map->channels;
        }

/* Write to disk */
        chunk_samples = (int64_t)((samples + codec->work_overflow) / SAMPLES_PER_BLOCK) * SAMPLES_PER_BLOCK;

/*printf("quicktime_encode_ima4 1 %ld\n", chunk_samples); */
/* The block division may result in 0 samples getting encoded. */
/* Don't write 0 samples. */
        if(chunk_samples)
        {
                quicktime_write_chunk_header(file, trak, &chunk_atom);
                result = quicktime_write_data(file, codec->read_buffer, chunk_bytes);
                quicktime_write_chunk_footer(file, 
                        trak,
                        track_map->current_chunk,
                        &chunk_atom, 
                        chunk_samples);

                if(result) 
                        result = 0; 
                else 
                        result = 1; /* defeat fwrite's return */

                track_map->current_chunk++;
        }

/* Move the last overflow to the front */
        overflow_start = i;
        input_ptr = codec->work_buffer;
        for(i = overflow_start * track_map->channels ; 
                i < (samples + codec->work_overflow) * track_map->channels; 
                i++)
        {
                *input_ptr++ = codec->work_buffer[i];
        }
        codec->work_overflow = samples + codec->work_overflow - overflow_start;

        return result;
}

void flush(quicktime_t *file, int track)
{
        quicktime_audio_map_t *track_map = &(file->atracks[track]);
        quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)track_map->codec)->priv;
        int result = 0;
        int i;

/*printf("quicktime_flush_ima4 %ld\n", codec->work_overflow); */
        if(codec->work_overflow)
        {
/* Zero out enough to get a block */
                i = codec->work_overflow * track_map->channels;
                while(i < SAMPLES_PER_BLOCK * track_map->channels)
                {
                        codec->work_buffer[i++] = 0;
                }
                codec->work_overflow = i / track_map->channels + 1;
/* Write the work_overflow only. */
                result = encode(file, 0, 0, track, 0);
        }
}

void quicktime_init_codec_ima4(quicktime_audio_map_t *atrack)
{
        quicktime_codec_t *codec_base = (quicktime_codec_t*)atrack->codec;
        quicktime_ima4_codec_t *codec;

/* Init public items */
        codec_base->priv = calloc(1, sizeof(quicktime_ima4_codec_t));
        codec_base->delete_acodec = delete_codec;
        codec_base->decode_video = 0;
        codec_base->encode_video = 0;
        codec_base->decode_audio = decode;
        codec_base->encode_audio = encode;
        codec_base->flush = flush;
        codec_base->fourcc = QUICKTIME_IMA4;
        codec_base->title = "IMA 4";
        codec_base->desc = "IMA 4";
        codec_base->wav_id = 0x11;

/* Init private items */
        codec = codec_base->priv;
}

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