[fdkaac.git] / src / wav_reader.c

/* 
 * Copyright (C) 2013 nu774
 * For conditions of distribution and use, see copyright notice in COPYING
 */
#if HAVE_CONFIG_H
#  include "config.h"
#endif

#if HAVE_STDINT_H
#  include <stdint.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include "wav_reader.h"
#include "m4af_endian.h"

#define RIFF_FOURCC(a,b,c,d) ((a)|((b)<<8)|((c)<<16)|((d)<<24))

#define TRY_IO(expr) \
    do { \
        if (expr) \
            goto FAIL; \
    } while (0)

#define ASSERT_FORMAT(ctx, expr) \
    do { \
        if (!expr) { \
            if (!ctx->last_error) \
                ctx->last_error = WAV_INVALID_FORMAT; \
            goto FAIL;\
        } \
    } while (0)

struct wav_reader_t {
    pcm_sample_description_t sample_format;
    int64_t length;
    int64_t position;
    int ignore_length;
    int last_error;
    wav_io_context_t io;
    void *io_cookie;
};

static const uint8_t WAV_GUID_PCM[] = {
    1, 0, 0, 0, 0, 0, 0x10, 0, 0x80, 0, 0, 0xaa, 0, 0x38, 0x9b, 0x71
};
static const uint8_t WAV_GUID_FLOAT[] = {
    3, 0, 0, 0, 0, 0, 0x10, 0, 0x80, 0, 0, 0xaa, 0, 0x38, 0x9b, 0x71
};

const pcm_sample_description_t *wav_get_format(wav_reader_t *reader)
{
    return &reader->sample_format;
}

int64_t wav_get_length(wav_reader_t *reader)
{
    return reader->length;
}

int64_t wav_get_position(wav_reader_t *reader)
{
    return reader->position;
}

void wav_teardown(wav_reader_t **reader)
{
    free(*reader);
    *reader = 0;
}

static
int riff_read(wav_reader_t *reader, void *buffer, uint32_t size)
{
    int rc;
    uint32_t count = 0;

    if (reader->last_error)
        return -1;
    do {
        rc = reader->io.read(reader->io_cookie, buffer, size - count);
        if (rc > 0)
            count += rc;
        else if (rc < 0)
            reader->last_error = WAV_IO_ERROR;
    } while (rc > 0 && count < size);
    return count > 0 ? count : rc;
}

static
int riff_skip(wav_reader_t *reader, int64_t count)
{
    char buff[8192];
    int rc;

    if (reader->last_error)
        return -1;
    if (count == 0)
        return 0;
    if (reader->io.seek &&
        reader->io.seek(reader->io_cookie, count, SEEK_CUR) >= 0)
        return 0;

    do {
        if ((rc = riff_read(reader, buff, count > 8192 ? 8192 : count)) > 0)
            count -= rc;
    } while (rc > 0 && count > 0);

    if (count > 0)
        reader->last_error = WAV_IO_ERROR;
    return reader->last_error ? -1 : 0;
}

static
int riff_seek(wav_reader_t *reader, int64_t off, int whence)
{
    int rc;
    if (reader->last_error)
        return -1;
    if (!reader->io.seek)
        goto FAIL;
    if ((rc = reader->io.seek(reader->io_cookie, off, whence)) < 0)
        goto FAIL;
    return 0;
FAIL:
    reader->last_error = WAV_IO_ERROR;
    return -1;
}

static
int64_t riff_tell(wav_reader_t *reader)
{
    int64_t off;

    if (reader->last_error || !reader->io.tell)
        return -1;
    off = reader->io.tell(reader->io_cookie);
    if (off < 0) {
        reader->last_error = WAV_IO_ERROR;
        return -1;
    }
    return off;
}

static
int riff_read16(wav_reader_t *reader, uint16_t *value)
{
    TRY_IO(riff_read(reader, value, 2) != 2);
    *value = m4af_ltoh16(*value);
    return 0;
FAIL:
    return -1;
}

static
int riff_read32(wav_reader_t *reader, uint32_t *value)
{
    TRY_IO(riff_read(reader, value, 4) != 4);
    *value = m4af_ltoh32(*value);
    return 0;
FAIL:
    return -1;
}

static
int riff_read64(wav_reader_t *reader, uint64_t *value)
{
    TRY_IO(riff_read(reader, value, 8) != 8);
    *value = m4af_ltoh64(*value);
    return 0;
FAIL:
    return -1;
}

static
int riff_scan(wav_reader_t *reader, const char *fmt, ...)
{
    int c, count = 0;
    va_list ap;

    va_start(ap, fmt);
    while ((c = *fmt++)) {
        switch (c) {
        case 'S':
            TRY_IO(riff_read16(reader, va_arg(ap, uint16_t*)));
            ++count;
            break;
        case 'L':
            TRY_IO(riff_read32(reader, va_arg(ap, uint32_t*)));
            ++count;
            break;
        case 'Q':
            TRY_IO(riff_read64(reader, va_arg(ap, uint64_t*)));
            ++count;
            break;
        }
    }
FAIL:
    va_end(ap);
    return count;
}

static
uint32_t riff_next_chunk(wav_reader_t *reader, uint32_t *chunk_size)
{
    uint32_t fcc;
    if (riff_scan(reader, "LL", &fcc, chunk_size) == 2)
        return fcc;
    return 0;
}

int wav_read_frames(wav_reader_t *reader, void *buffer, unsigned nframes)
{
    int rc;
    unsigned nbytes;

    if (!reader->ignore_length && nframes > reader->length - reader->position)
        nframes = reader->length - reader->position;
    nbytes = nframes * reader->sample_format.bytes_per_frame;
    if (nbytes) {
        if ((rc = riff_read(reader, buffer, nbytes)) < 0)
            return -1;
        nframes = rc / reader->sample_format.bytes_per_frame;
        reader->position += nframes;
    }
    return nframes;
}

static
int riff_ds64(wav_reader_t *reader, int64_t *length)
{
    uint32_t fcc, chunk_size, table_size;
    uint64_t riff_size, sample_count;

    fcc = riff_next_chunk(reader, &chunk_size);
    ASSERT_FORMAT(reader,
                  fcc == RIFF_FOURCC('d','s','6','4') && chunk_size >= 28);
    TRY_IO(riff_scan(reader, "QQQL",
                     &riff_size, length, &sample_count, &table_size) != 4);
    if (table_size == 0)
        return 0;
    reader->last_error = WAV_UNSUPPORTED_FORMAT;
FAIL:
    return -1;
}

static
int wav_fmt(wav_reader_t *reader, uint32_t size)
{
    uint16_t wFormatTag, nChannels, nBlockAlign, wBitsPerSample, cbSize;
    uint32_t nSamplesPerSec, nAvgBytesPerSec, dwChannelMask = 0;
    uint16_t wValidBitsPerSample;
    uint8_t guid[16];
    int is_float = 0;

    ASSERT_FORMAT(reader, size >= 16);
    TRY_IO(riff_scan(reader, "SSLLSS", &wFormatTag, &nChannels,
                     &nSamplesPerSec, &nAvgBytesPerSec, &nBlockAlign,
                     &wBitsPerSample) != 6);
    wValidBitsPerSample = wBitsPerSample;

    if (wFormatTag != 1 && wFormatTag != 3 && wFormatTag != 0xfffe) {
        reader->last_error = WAV_UNSUPPORTED_FORMAT;
        goto FAIL;
    }
    ASSERT_FORMAT(reader,
                  nChannels && nSamplesPerSec && nAvgBytesPerSec &&
                  nBlockAlign && wBitsPerSample && !(wBitsPerSample & 7) &&
                  nBlockAlign == nChannels * wBitsPerSample / 8);
    if (wFormatTag == 3)
        is_float = 1;

    if (wFormatTag != 0xfffe)
        TRY_IO(riff_skip(reader, (size - 15) & ~1));
    else {
        ASSERT_FORMAT(reader, size >= 40);
        TRY_IO(riff_scan(reader, "SSL",
                         &cbSize, &wValidBitsPerSample, &dwChannelMask) != 3);
        TRY_IO(riff_read(reader, guid, 16) != 16);

        if (memcmp(guid, WAV_GUID_FLOAT, 16) == 0)
            is_float = 1;
        else if (memcmp(guid, WAV_GUID_PCM, 16) != 0) {
            reader->last_error = WAV_UNSUPPORTED_FORMAT;
            goto FAIL;
        }
        ASSERT_FORMAT(reader,
                      wValidBitsPerSample &&
                      wValidBitsPerSample <= wBitsPerSample);
        TRY_IO(riff_skip(reader, (size - 39) & ~1));
    }
    reader->sample_format.sample_rate = nSamplesPerSec;
    reader->sample_format.bits_per_channel = wValidBitsPerSample;
    reader->sample_format.bytes_per_frame = nBlockAlign;
    reader->sample_format.channels_per_frame = nChannels;
    reader->sample_format.channel_mask = dwChannelMask;
    if (is_float)
        reader->sample_format.sample_type = PCM_TYPE_FLOAT;
    else if (wBitsPerSample == 8)
        reader->sample_format.sample_type = PCM_TYPE_UINT;
    else
        reader->sample_format.sample_type = PCM_TYPE_SINT;
    return 0;
FAIL:
    return -1;
}

static
int wav_parse(wav_reader_t *reader, int64_t *data_length)
{
    uint32_t container, fcc, chunk_size;

    *data_length = 0;
    container = riff_next_chunk(reader, &chunk_size);
    if (container != RIFF_FOURCC('R','I','F','F') &&
        container != RIFF_FOURCC('R','F','6','4'))
        goto FAIL;
    TRY_IO(riff_read32(reader, &fcc));
    if (fcc != RIFF_FOURCC('W','A','V','E'))
        goto FAIL;
    if (container == RIFF_FOURCC('R','F','6','4'))
        riff_ds64(reader, data_length);
    while ((fcc = riff_next_chunk(reader, &chunk_size)) != 0) {
        if (fcc == RIFF_FOURCC('f','m','t',' ')) {
            if (wav_fmt(reader, chunk_size) < 0)
                goto FAIL;
        } else if (fcc == RIFF_FOURCC('d','a','t','a')) {
            if (container == RIFF_FOURCC('R','I','F','F'))
                *data_length = chunk_size;
            break;
        } else
            TRY_IO(riff_skip(reader, (chunk_size + 1) & ~1));
    }
    if (fcc == RIFF_FOURCC('d','a','t','a'))
        return 0;
FAIL:
    return -1;
}

wav_reader_t *wav_open(wav_io_context_t *io_ctx, void *io_cookie,
                       int ignore_length)
{
    wav_reader_t *reader;
    int64_t data_length;

    if ((reader = calloc(1, sizeof(wav_reader_t))) == 0)
        return 0;
    memcpy(&reader->io, io_ctx, sizeof(wav_io_context_t));
    reader->io_cookie = io_cookie;
    reader->ignore_length = ignore_length;
    if (wav_parse(reader, &data_length) < 0) {
        free(reader);
        return 0;
    }
    if (ignore_length || !data_length ||
        data_length % reader->sample_format.bytes_per_frame != 0)
        reader->length = INT64_MAX;
    else
        reader->length = data_length / reader->sample_format.bytes_per_frame;
    return reader;
}

wav_reader_t *raw_open(wav_io_context_t *io_ctx, void *io_cookie,
                       const pcm_sample_description_t *desc)
{
    wav_reader_t *reader = 0;

    if ((reader = calloc(1, sizeof(wav_reader_t))) == 0)
        return 0;
    memcpy(&reader->io, io_ctx, sizeof(wav_io_context_t));
    memcpy(&reader->sample_format, desc, sizeof(pcm_sample_description_t));
    reader->io_cookie = io_cookie;
    if (io_ctx->seek && io_ctx->tell) {
        TRY_IO(riff_seek(reader, 0, SEEK_END));
        reader->length = riff_tell(reader) / desc->bytes_per_frame;
        TRY_IO(riff_seek(reader, 0, SEEK_SET));
    } else
        reader->length = INT64_MAX;
    return reader;
FAIL:
    if (reader)
        free(reader);
    return 0;
}
Commit	Line	Data
48e2f01c	1	/*
	2	* Copyright (C) 2013 nu774
	3	* For conditions of distribution and use, see copyright notice in COPYING
	4	*/
	5	#if HAVE_CONFIG_H
	6	# include "config.h"
	7	#endif
	8
	9	#if HAVE_STDINT_H
	10	# include <stdint.h>
	11	#endif
	12
	13	#include <stdio.h>
	14	#include <stdlib.h>
	15	#include <string.h>
	16	#include <stdarg.h>
	17	#include "wav_reader.h"
	18	#include "m4af_endian.h"
	19
	20	#define RIFF_FOURCC(a,b,c,d) ((a)\|((b)<<8)\|((c)<<16)\|((d)<<24))
	21
	22	#define TRY_IO(expr) \
	23	do { \
	24	if (expr) \
	25	goto FAIL; \
	26	} while (0)
	27
	28	#define ASSERT_FORMAT(ctx, expr) \
	29	do { \
	30	if (!expr) { \
	31	if (!ctx->last_error) \
	32	ctx->last_error = WAV_INVALID_FORMAT; \
	33	goto FAIL;\
	34	} \
	35	} while (0)
	36
	37	struct wav_reader_t {
	38	pcm_sample_description_t sample_format;
	39	int64_t length;
	40	int64_t position;
	41	int ignore_length;
	42	int last_error;
	43	wav_io_context_t io;
	44	void *io_cookie;
	45	};
	46
	47	static const uint8_t WAV_GUID_PCM[] = {
	48	1, 0, 0, 0, 0, 0, 0x10, 0, 0x80, 0, 0, 0xaa, 0, 0x38, 0x9b, 0x71
	49	};
	50	static const uint8_t WAV_GUID_FLOAT[] = {
	51	3, 0, 0, 0, 0, 0, 0x10, 0, 0x80, 0, 0, 0xaa, 0, 0x38, 0x9b, 0x71
	52	};
	53
	54	const pcm_sample_description_t wav_get_format(wav_reader_t reader)
	55	{
	56	return &reader->sample_format;
	57	}
	58
	59	int64_t wav_get_length(wav_reader_t *reader)
	60	{
	61	return reader->length;
	62	}
	63
	64	int64_t wav_get_position(wav_reader_t *reader)
65	{
66	return reader->position;
67	}
68
69	void wav_teardown(wav_reader_t **reader)
70	{
71	free(*reader);
72	*reader = 0;
73	}
74
75	static
76	int riff_read(wav_reader_t reader, void buffer, uint32_t size)
77	{
78	int rc;
79	uint32_t count = 0;
80
81	if (reader->last_error)
82	return -1;
83	do {
84	rc = reader->io.read(reader->io_cookie, buffer, size - count);
85	if (rc > 0)
86	count += rc;
87	else if (rc < 0)
88	reader->last_error = WAV_IO_ERROR;
89	} while (rc > 0 && count < size);
90	return count > 0 ? count : rc;
91	}
92
93	static
68543176	94	int riff_skip(wav_reader_t *reader, int64_t count)
48e2f01c	95	{
	96	char buff[8192];
	97	int rc;
	98
	99	if (reader->last_error)
	100	return -1;
	101	if (count == 0)
	102	return 0;
	103	if (reader->io.seek &&
	104	reader->io.seek(reader->io_cookie, count, SEEK_CUR) >= 0)
	105	return 0;
	106
	107	do {
	108	if ((rc = riff_read(reader, buff, count > 8192 ? 8192 : count)) > 0)
	109	count -= rc;
	110	} while (rc > 0 && count > 0);
	111
	112	if (count > 0)
	113	reader->last_error = WAV_IO_ERROR;
	114	return reader->last_error ? -1 : 0;
	115	}
	116
68543176	117	static
	118	int riff_seek(wav_reader_t *reader, int64_t off, int whence)
	119	{
	120	int rc;
	121	if (reader->last_error)
	122	return -1;
	123	if (!reader->io.seek)
	124	goto FAIL;
	125	if ((rc = reader->io.seek(reader->io_cookie, off, whence)) < 0)
	126	goto FAIL;
	127	return 0;
	128	FAIL:
	129	reader->last_error = WAV_IO_ERROR;
	130	return -1;
	131	}
	132
	133	static
	134	int64_t riff_tell(wav_reader_t *reader)
	135	{
	136	int64_t off;
	137
	138	if (reader->last_error \|\| !reader->io.tell)
	139	return -1;
	140	off = reader->io.tell(reader->io_cookie);
	141	if (off < 0) {
	142	reader->last_error = WAV_IO_ERROR;
	143	return -1;
	144	}
	145	return off;
	146	}
	147
48e2f01c	148	static
	149	int riff_read16(wav_reader_t reader, uint16_t value)
	150	{
	151	TRY_IO(riff_read(reader, value, 2) != 2);
	152	value = m4af_ltoh16(value);
	153	return 0;
	154	FAIL:
	155	return -1;
	156	}
	157
	158	static
	159	int riff_read32(wav_reader_t reader, uint32_t value)
	160	{
	161	TRY_IO(riff_read(reader, value, 4) != 4);
	162	value = m4af_ltoh32(value);
	163	return 0;
	164	FAIL:
	165	return -1;
	166	}
	167
	168	static
	169	int riff_read64(wav_reader_t reader, uint64_t value)
	170	{
	171	TRY_IO(riff_read(reader, value, 8) != 8);
	172	value = m4af_ltoh64(value);
	173	return 0;
	174	FAIL:
	175	return -1;
	176	}
	177
	178	static
	179	int riff_scan(wav_reader_t reader, const char fmt, ...)
	180	{
	181	int c, count = 0;
	182	va_list ap;
	183
	184	va_start(ap, fmt);
	185	while ((c = *fmt++)) {
	186	switch (c) {
	187	case 'S':
	188	TRY_IO(riff_read16(reader, va_arg(ap, uint16_t*)));
	189	++count;
	190	break;
	191	case 'L':
	192	TRY_IO(riff_read32(reader, va_arg(ap, uint32_t*)));
	193	++count;
	194	break;
	195	case 'Q':
	196	TRY_IO(riff_read64(reader, va_arg(ap, uint64_t*)));
	197	++count;
	198	break;
	199	}
	200	}
	201	FAIL:
	202	va_end(ap);
	203	return count;
	204	}
	205
	206	static
	207	uint32_t riff_next_chunk(wav_reader_t reader, uint32_t chunk_size)
	208	{
	209	uint32_t fcc;
	210	if (riff_scan(reader, "LL", &fcc, chunk_size) == 2)
	211	return fcc;
212	return 0;
213	}
214
215	int wav_read_frames(wav_reader_t reader, void buffer, unsigned nframes)
216	{
217	int rc;
218	unsigned nbytes;
219
220	if (!reader->ignore_length && nframes > reader->length - reader->position)
221	nframes = reader->length - reader->position;
222	nbytes = nframes * reader->sample_format.bytes_per_frame;
223	if (nbytes) {
224	if ((rc = riff_read(reader, buffer, nbytes)) < 0)
225	return -1;
226	nframes = rc / reader->sample_format.bytes_per_frame;
227	reader->position += nframes;
228	}
229	return nframes;
230	}
231
232	static
233	int riff_ds64(wav_reader_t reader, int64_t length)
234	{
235	uint32_t fcc, chunk_size, table_size;
236	uint64_t riff_size, sample_count;
237
238	fcc = riff_next_chunk(reader, &chunk_size);
239	ASSERT_FORMAT(reader,
240	fcc == RIFF_FOURCC('d','s','6','4') && chunk_size >= 28);
241	TRY_IO(riff_scan(reader, "QQQL",
242	&riff_size, length, &sample_count, &table_size) != 4);
243	if (table_size == 0)
244	return 0;
245	reader->last_error = WAV_UNSUPPORTED_FORMAT;
246	FAIL:
247	return -1;
248	}
249
250	static
251	int wav_fmt(wav_reader_t *reader, uint32_t size)
252	{
253	uint16_t wFormatTag, nChannels, nBlockAlign, wBitsPerSample, cbSize;
254	uint32_t nSamplesPerSec, nAvgBytesPerSec, dwChannelMask = 0;
255	uint16_t wValidBitsPerSample;
256	uint8_t guid[16];
257	int is_float = 0;
258
259	ASSERT_FORMAT(reader, size >= 16);
260	TRY_IO(riff_scan(reader, "SSLLSS", &wFormatTag, &nChannels,
261	&nSamplesPerSec, &nAvgBytesPerSec, &nBlockAlign,
262	&wBitsPerSample) != 6);
263	wValidBitsPerSample = wBitsPerSample;
264
265	if (wFormatTag != 1 && wFormatTag != 3 && wFormatTag != 0xfffe) {
266	reader->last_error = WAV_UNSUPPORTED_FORMAT;
267	goto FAIL;
268	}
269	ASSERT_FORMAT(reader,
270	nChannels && nSamplesPerSec && nAvgBytesPerSec &&
271	nBlockAlign && wBitsPerSample && !(wBitsPerSample & 7) &&
272	nBlockAlign == nChannels * wBitsPerSample / 8);
273	if (wFormatTag == 3)
274	is_float = 1;
275
276	if (wFormatTag != 0xfffe)
277	TRY_IO(riff_skip(reader, (size - 15) & ~1));
278	else {
279	ASSERT_FORMAT(reader, size >= 40);
280	TRY_IO(riff_scan(reader, "SSL",
281	&cbSize, &wValidBitsPerSample, &dwChannelMask) != 3);
282	TRY_IO(riff_read(reader, guid, 16) != 16);
283
284	if (memcmp(guid, WAV_GUID_FLOAT, 16) == 0)
285	is_float = 1;
286	else if (memcmp(guid, WAV_GUID_PCM, 16) != 0) {
287	reader->last_error = WAV_UNSUPPORTED_FORMAT;
288	goto FAIL;
289	}
290	ASSERT_FORMAT(reader,
291	wValidBitsPerSample &&
292	wValidBitsPerSample <= wBitsPerSample);
293	TRY_IO(riff_skip(reader, (size - 39) & ~1));
294	}
295	reader->sample_format.sample_rate = nSamplesPerSec;
296	reader->sample_format.bits_per_channel = wValidBitsPerSample;
297	reader->sample_format.bytes_per_frame = nBlockAlign;
298	reader->sample_format.channels_per_frame = nChannels;
299	reader->sample_format.channel_mask = dwChannelMask;
300	if (is_float)
301	reader->sample_format.sample_type = PCM_TYPE_FLOAT;
302	else if (wBitsPerSample == 8)
303	reader->sample_format.sample_type = PCM_TYPE_UINT;
304	else
305	reader->sample_format.sample_type = PCM_TYPE_SINT;
306	return 0;
307	FAIL:
308	return -1;
309	}
310
311	static
312	int wav_parse(wav_reader_t reader, int64_t data_length)
313	{
314	uint32_t container, fcc, chunk_size;
315
316	*data_length = 0;
317	container = riff_next_chunk(reader, &chunk_size);
318	if (container != RIFF_FOURCC('R','I','F','F') &&
319	container != RIFF_FOURCC('R','F','6','4'))
320	goto FAIL;
321	TRY_IO(riff_read32(reader, &fcc));
322	if (fcc != RIFF_FOURCC('W','A','V','E'))
323	goto FAIL;
324	if (container == RIFF_FOURCC('R','F','6','4'))
325	riff_ds64(reader, data_length);
326	while ((fcc = riff_next_chunk(reader, &chunk_size)) != 0) {
327	if (fcc == RIFF_FOURCC('f','m','t',' ')) {
328	if (wav_fmt(reader, chunk_size) < 0)
329	goto FAIL;
330	} else if (fcc == RIFF_FOURCC('d','a','t','a')) {
331	if (container == RIFF_FOURCC('R','I','F','F'))
332	*data_length = chunk_size;
333	break;
334	} else
335	TRY_IO(riff_skip(reader, (chunk_size + 1) & ~1));
336	}
337	if (fcc == RIFF_FOURCC('d','a','t','a'))
338	return 0;
339	FAIL:
340	return -1;
341	}
342
343	wav_reader_t wav_open(wav_io_context_t io_ctx, void *io_cookie,
344	int ignore_length)
345	{
346	wav_reader_t *reader;
347	int64_t data_length;
348
349	if ((reader = calloc(1, sizeof(wav_reader_t))) == 0)
350	return 0;
351	memcpy(&reader->io, io_ctx, sizeof(wav_io_context_t));
352	reader->io_cookie = io_cookie;
353	reader->ignore_length = ignore_length;
354	if (wav_parse(reader, &data_length) < 0) {
355	free(reader);
356	return 0;
357	}
358	if (ignore_length \|\| !data_length \|\|
359	data_length % reader->sample_format.bytes_per_frame != 0)
360	reader->length = INT64_MAX;
361	else
362	reader->length = data_length / reader->sample_format.bytes_per_frame;
363	return reader;
364	}
68543176	365
	366	wav_reader_t raw_open(wav_io_context_t io_ctx, void *io_cookie,
	367	const pcm_sample_description_t *desc)
	368	{
	369	wav_reader_t *reader = 0;
	370
	371	if ((reader = calloc(1, sizeof(wav_reader_t))) == 0)
	372	return 0;
	373	memcpy(&reader->io, io_ctx, sizeof(wav_io_context_t));
	374	memcpy(&reader->sample_format, desc, sizeof(pcm_sample_description_t));
	375	reader->io_cookie = io_cookie;
	376	if (io_ctx->seek && io_ctx->tell) {
	377	TRY_IO(riff_seek(reader, 0, SEEK_END));
	378	reader->length = riff_tell(reader) / desc->bytes_per_frame;
	379	TRY_IO(riff_seek(reader, 0, SEEK_SET));
	380	} else
	381	reader->length = INT64_MAX;
	382	return reader;
	383	FAIL:
	384	if (reader)
	385	free(reader);
	386	return 0;
	387	}
	388
	389