/*
* huffman_encode_file huffman encodes in to out.
*/
int
huffman_encode_file(FILE *in, FILE *out)
{
SymbolFrequencies sf;
SymbolEncoder *se;
huffman_node *root = NULL;
int rc;
unsigned int symbol_count;
/* Get the frequency of each symbol in the input file. */
symbol_count = get_symbol_frequencies(&sf, in);
/* Build an optimal table from the symbolCount. */
se = calculate_huffman_codes(&sf);
root = sf[0];
/* Scan the file again and, using the table
previously built, encode it into the output file. */
rewind(in);
rc = write_code_table(out, se, symbol_count);
if(rc == 0)
rc = do_file_encode(in, out, se);
/* Free the Huffman tree. */
free_huffman_tree(root);
free_encoder(se);
return rc;
}
int huffman_encode_memory(const unsigned char *bufin,
unsigned int bufinlen,
unsigned char **pbufout,
unsigned int *pbufoutlen)
{
SymbolFrequencies sf;
SymbolEncoder *se;
huffman_node *root = NULL;
int rc;
unsigned int symbol_count;
buf_cache cache;
/* Ensure the arguments are valid. */
if(!pbufout || !pbufoutlen)
return 1;
if(init_cache(&cache, CACHE_SIZE, pbufout, pbufoutlen))
return 1;
/* Get the frequency of each symbol in the input memory. */
symbol_count = get_symbol_frequencies_from_memory(&sf, bufin, bufinlen);
/* Build an optimal table from the symbolCount. */
se = calculate_huffman_codes(&sf);
root = sf[0];
/* Scan the memory again and, using the table
previously built, encode it into the output memory. */
rc = write_code_table_to_memory(&cache, se, symbol_count);
if(rc == 0)
rc = do_memory_encode(&cache, bufin, bufinlen, se);
/* Flush the cache. */
flush_cache(&cache);
/* Free the Huffman tree. */
free_huffman_tree(root);
free_encoder(se);
free_cache(&cache);
return rc;
}
/* 把 in 压缩成 out */
int huffman_encode_file(FILE *in, FILE *out)
{
symfreq sf;
symcode *sc;
node *root = NULL;
int rc;
unsigned int syms;
/* 获取输入文件中符号出现频率 */
syms = get_symfreq(&sf, in);
/* 生成编码表 */
sc = calc_code(&sf);
root = sf[0];
/* 再次扫描文件，使用之前生成的编码表来编码 */
rewind(in);
rc = write_code_table(out, sc, syms);
if (rc == 0)
rc = do_file_encode(in, out, sc);
/* 释放空间 */
free_tree(root);
free_encoder(sc);
return rc;
}
PyObject*
encoders_encode_alac(PyObject *dummy, PyObject *args, PyObject *keywds)
{
static char *kwlist[] = {"file",
"pcmreader",
"block_size",
"initial_history",
"history_multiplier",
"maximum_k",
"minimum_interlacing_leftweight",
"maximum_interlacing_leftweight",
NULL};
PyObject *file_obj;
FILE *output_file;
BitstreamWriter *output = NULL;
pcmreader* pcmreader;
struct alac_context encoder;
array_ia* channels = array_ia_new();
unsigned frame_file_offset;
PyObject *log_output;
init_encoder(&encoder);
encoder.options.minimum_interlacing_leftweight = 0;
encoder.options.maximum_interlacing_leftweight = 4;
/*extract a file object, PCMReader-compatible object and encoding options*/
if (!PyArg_ParseTupleAndKeywords(
args, keywds, "OO&iiii|ii",
kwlist,
&file_obj,
pcmreader_converter,
&pcmreader,
&(encoder.options.block_size),
&(encoder.options.initial_history),
&(encoder.options.history_multiplier),
&(encoder.options.maximum_k),
&(encoder.options.minimum_interlacing_leftweight),
&(encoder.options.maximum_interlacing_leftweight)))
return NULL;
encoder.bits_per_sample = pcmreader->bits_per_sample;
/*determine if the PCMReader is compatible with ALAC*/
if ((pcmreader->bits_per_sample != 16) &&
(pcmreader->bits_per_sample != 24)) {
PyErr_SetString(PyExc_ValueError, "bits per sample must be 16 or 24");
goto error;
}
/*convert file object to bitstream writer*/
if ((output_file = PyFile_AsFile(file_obj)) == NULL) {
PyErr_SetString(PyExc_TypeError,
"file must by a concrete file object");
goto error;
} else {
output = bw_open(output_file, BS_BIG_ENDIAN);
bw_add_callback(output,
byte_counter,
&(encoder.mdat_byte_size));
}
#else
int
ALACEncoder_encode_alac(char *filename,
FILE *input,
int block_size,
int initial_history,
int history_multiplier,
int maximum_k)
{
FILE *output_file;
BitstreamWriter *output = NULL;
pcmreader *pcmreader;
struct alac_context encoder;
array_ia* channels = array_ia_new();
unsigned frame_file_offset;
init_encoder(&encoder);
encoder.options.block_size = block_size;
encoder.options.initial_history = initial_history;
encoder.options.history_multiplier = history_multiplier;
encoder.options.maximum_k = maximum_k;
encoder.options.minimum_interlacing_leftweight = 0;
encoder.options.maximum_interlacing_leftweight = 4;
output_file = fopen(filename, "wb");
/*assume CD quality for now*/
pcmreader = open_pcmreader(input, 44100, 2, 0x3, 16, 0, 1);
encoder.bits_per_sample = pcmreader->bits_per_sample;
/*convert file object to bitstream writer*/
output = bw_open(output_file, BS_BIG_ENDIAN);
bw_add_callback(output,
byte_counter,
&(encoder.mdat_byte_size));
#endif
/*write placeholder mdat header*/
output->write(output, 32, 0);
output->write_bytes(output, (uint8_t*)"mdat", 4);
/*write frames from pcm_reader until empty*/
if (pcmreader->read(pcmreader, encoder.options.block_size, channels))
goto error;
while (channels->_[0]->len > 0) {
#ifndef STANDALONE
Py_BEGIN_ALLOW_THREADS
#endif
/*log the number of PCM frames in each ALAC frameset*/
encoder.frame_log->_[LOG_SAMPLE_SIZE]->append(
encoder.frame_log->_[LOG_SAMPLE_SIZE],
channels->_[0]->len);
frame_file_offset = encoder.mdat_byte_size;
/*log each frameset's starting offset in the mdat atom*/
encoder.frame_log->_[LOG_FILE_OFFSET]->append(
encoder.frame_log->_[LOG_FILE_OFFSET],
frame_file_offset);
write_frameset(output, &encoder, channels);
/*log each frame's total size in bytes*/
encoder.frame_log->_[LOG_BYTE_SIZE]->append(
encoder.frame_log->_[LOG_BYTE_SIZE],
encoder.mdat_byte_size - frame_file_offset);
#ifndef STANDALONE
Py_END_ALLOW_THREADS
#endif
if (pcmreader->read(pcmreader, encoder.options.block_size, channels))
goto error;
}
/*return to header and rewrite it with the actual value*/
bw_pop_callback(output, NULL);
fseek(output_file, 0, 0);
output->write(output, 32, encoder.mdat_byte_size);
/*close and free allocated files/buffers,
which varies depending on whether we're running standlone or not*/
#ifndef STANDALONE
log_output = alac_log_output(&encoder);
pcmreader->del(pcmreader);
output->free(output);
free_encoder(&encoder);
channels->del(channels);
return log_output;
error:
pcmreader->del(pcmreader);
output->free(output);
free_encoder(&encoder);
channels->del(channels);
return NULL;
}
