* See file COPYING.
*/
+/** \file mp4.c Paraslash's internal mp4 parser. */
+
+/*
+ * This is a stripped down version of the former mp4ff library which used to be
+ * part of the faad decoder project but was removed from the faad code base in
+ * 2017. The original code has been cleaned up substantially and the public API
+ * has been documented. See the git commit log for details.
+ */
+
#include <regex.h>
#include "para.h"
return ret;
}
+/** A macro defining the atoms we care about. It gets expanded twice. */
#define ATOM_ITEMS \
- ATOM_ITEM(MOOV, 'm', 'o', 'o', 'v') \
- ATOM_ITEM(TRAK, 't', 'r', 'a', 'k') \
- ATOM_ITEM(MDIA, 'm', 'd', 'i', 'a') \
- ATOM_ITEM(MINF, 'm', 'i', 'n', 'f') \
- ATOM_ITEM(STBL, 's', 't', 'b', 'l') \
- ATOM_ITEM(UDTA, 'u', 'd', 't', 'a') \
+ ATOM_ITEM(MOOV, 'm', 'o', 'o', 'v') /* movie (top-level container) */ \
+ ATOM_ITEM(TRAK, 't', 'r', 'a', 'k') /* container for a single track */ \
+ ATOM_ITEM(MDIA, 'm', 'd', 'i', 'a') /* media information */ \
+ ATOM_ITEM(MINF, 'm', 'i', 'n', 'f') /* extends mdia */ \
+ ATOM_ITEM(STBL, 's', 't', 'b', 'l') /* sample table container */ \
+ ATOM_ITEM(UDTA, 'u', 'd', 't', 'a') /* user data */ \
ATOM_ITEM(ILST, 'i', 'l', 's', 't') /* iTunes Metadata list */ \
- ATOM_ITEM(ARTIST, 0xa9, 'A', 'R', 'T') \
- ATOM_ITEM(TITLE, 0xa9, 'n', 'a', 'm') \
- ATOM_ITEM(ALBUM, 0xa9, 'a', 'l', 'b') \
- ATOM_ITEM(DATE, 0xa9, 'd', 'a', 'y') \
- ATOM_ITEM(COMMENT, 0xa9, 'c', 'm', 't') \
+ ATOM_ITEM(ARTIST, 0xa9, 'A', 'R', 'T') /* artist */ \
+ ATOM_ITEM(TITLE, 0xa9, 'n', 'a', 'm') /* title */ \
+ ATOM_ITEM(ALBUM, 0xa9, 'a', 'l', 'b') /* album */ \
+ ATOM_ITEM(DATE, 0xa9, 'd', 'a', 'y') /* date */ \
+ ATOM_ITEM(COMMENT, 0xa9, 'c', 'm', 't') /* comment */ \
ATOM_ITEM(MDHD, 'm', 'd', 'h', 'd') /* track header */ \
ATOM_ITEM(STSD, 's', 't', 's', 'd') /* sample description box */ \
ATOM_ITEM(STTS, 's', 't', 't', 's') /* time to sample box */ \
ATOM_ITEM(STSZ, 's', 't', 's', 'z') /* sample size box */ \
ATOM_ITEM(STCO, 's', 't', 'c', 'o') /* chunk offset box */ \
ATOM_ITEM(STSC, 's', 't', 's', 'c') /* sample to chunk box */ \
- ATOM_ITEM(MP4A, 'm', 'p', '4', 'a') \
+ ATOM_ITEM(MP4A, 'm', 'p', '4', 'a') /* mp4 audio */ \
ATOM_ITEM(META, 'm', 'e', 't', 'a') /* iTunes Metadata box */ \
ATOM_ITEM(DATA, 'd', 'a', 't', 'a') /* iTunes Metadata data box */ \
+/** For the C enumeration we concatenate ATOM_ with the first argument. */
#define ATOM_ITEM(_name, a, b, c, d) ATOM_ ## _name,
+/** The enumeration of interesting atoms. */
enum atom {ATOM_ITEMS};
#undef ATOM_ITEM
+/** A cpp version of read_u32_be(). */
+#define ATOM_VALUE(a, b, c, d) ((a << 24) + (b << 16) + (c << 8) + d)
+
static uint8_t atom_name_to_type(uint8_t *p)
{
- #define ATOM_VALUE(a, b, c, d) ((a << 24) + (b << 16) + (c << 8) + d)
+ /** Expands to an instance of the following unnamed structure. */
#define ATOM_ITEM(_name, a, b, c, d) \
{.name = # _name, .val = ATOM_VALUE(a, b, c, d)},
static const struct {
return ret;
if (t->stsz_sample_size != 0)
return 1;
- t->stsz_table = para_malloc(t->stsz_sample_count * sizeof(int32_t));
+ t->stsz_table = arr_alloc(t->stsz_sample_count, sizeof(int32_t));
for (uint32_t n = 0; n < t->stsz_sample_count; n++) {
ret = read_int32(f, &t->stsz_table[n]);
if (ret <= 0)
ret = read_int32(f, &t->stts_entry_count);
if (ret <= 0)
return ret;
- t->stts_sample_count = para_malloc(t->stts_entry_count
- * sizeof(int32_t));
+ t->stts_sample_count = arr_alloc(t->stts_entry_count, sizeof(int32_t));
for (uint32_t n = 0; n < t->stts_entry_count; n++) {
ret = read_int32(f, &t->stts_sample_count[n]);
if (ret <= 0)
ret = read_int32(f, &t->stsc_entry_count);
if (ret <= 0)
return ret;
- t->stsc_first_chunk = para_malloc(t->stsc_entry_count * sizeof(int32_t));
- t->stsc_samples_per_chunk = para_malloc(t->stsc_entry_count
- * sizeof (int32_t));
+ t->stsc_first_chunk = arr_alloc(t->stsc_entry_count, sizeof(int32_t));
+ t->stsc_samples_per_chunk = arr_alloc(t->stsc_entry_count,
+ sizeof (int32_t));
for (uint32_t n = 0; n < t->stsc_entry_count; n++) {
ret = read_int32(f, &t->stsc_first_chunk[n]);
if (ret <= 0)
ret = read_int32(f, &t->stco_entry_count);
if (ret <= 0)
return ret;
- t->stco_chunk_offset = para_malloc(t->stco_entry_count
- * sizeof(int32_t));
+ t->stco_chunk_offset = arr_alloc(t->stco_entry_count, sizeof(int32_t));
for (uint32_t n = 0; n < t->stco_entry_count; n++) {
ret = read_int32(f, &t->stco_chunk_offset[n]);
if (ret <= 0)
goto fail;
len = subsize - (header_size + 8);
free(value);
- value = para_malloc(len + 1);
+ value = alloc(len + 1);
ret = read_data(f, value, len);
if (ret <= 0)
goto fail;
tag = f->meta.tags + f->meta.count;
tag->item = para_strdup(get_metadata_name(parent));
tag->value = value;
- tag->len = len;
f->meta.count++;
return 1;
fail:
ret = read_int64(f, &t->duration);
if (ret <= 0)
return ret;
- } else { //version == 0
+ } else { /* version == 0 */
uint32_t temp;
skip_bytes(f, 8); /* creation time (4), modification time (4) */
return 1;
}
-static int32_t read_ilst(struct mp4 *f, int32_t size)
+static int read_ilst(struct mp4 *f, int32_t size)
{
int ret;
uint64_t sumsize = 0;
return 1;
}
-static int32_t read_meta(struct mp4 *f, uint64_t size)
+static int read_meta(struct mp4 *f, uint64_t size)
{
int ret;
uint64_t subsize, sumsize = 0;
return 1;
}
+/**
+ * Deallocate all resources associated with an mp4 file handle.
+ *
+ * \param f File handle returned by \ref mp4_open() or \ref mp4_open_meta().
+ *
+ * This frees the metadata items and various tables which were allocated when
+ * the file was opened. The given file handle must not be NULL.
+ */
+void mp4_close(struct mp4 *f)
+{
+ free(f->track.stsz_table);
+ free(f->track.stts_sample_count);
+ free(f->track.stsc_first_chunk);
+ free(f->track.stsc_samples_per_chunk);
+ free(f->track.stco_chunk_offset);
+ for (uint32_t n = 0; n < f->meta.count; n++) {
+ free(f->meta.tags[n].item);
+ free(f->meta.tags[n].value);
+ }
+ free(f->meta.tags);
+ free(f);
+}
+
static int open_file(const struct mp4_callback *cb, bool meta_only, struct mp4 **result)
{
int ret;
uint64_t size;
uint8_t atom_type, header_size;
- struct mp4 *f = para_calloc(sizeof(*f));
+ struct mp4 *f = zalloc(sizeof(*f));
f->cb = cb;
while ((ret = atom_read_header(f, &atom_type, &header_size, &size)) > 0) {
ret = -E_MP4_BAD_SAMPLERATE;
if (f->track.sample_rate == 0)
goto fail;
+ ret = -E_MP4_MISSING_ATOM;
+ if (f->udta_size == 0 || f->meta_size == 0 || f->ilst_size == 0)
+ goto fail;
*result = f;
return 1;
fail:
*result = NULL;
- free(f);
+ mp4_close(f);
return ret;
}
-int mp4_open_read(const struct mp4_callback *cb, struct mp4 **result)
+/**
+ * Read the audio track and the metadata of an mp4 file.
+ *
+ * \param cb Only the ->read() and ->seek() methods need to be supplied.
+ * \param result Initialized to a non-NULL pointer iff the function succeeds.
+ *
+ * This detects and parses the first audio track and the metadata information
+ * of the mp4 file. Various error checks are performed after the mp4 atoms have
+ * been parsed successfully.
+ *
+ * This function does not modify the file. However, if the caller intents to
+ * update the metadata later, the ->write() and ->truncate() methods must be
+ * supplied in the callback structure.
+ *
+ * \return Standard. Several errors are possible.
+ *
+ * \sa \ref mp4_open_meta().
+ */
+int mp4_open(const struct mp4_callback *cb, struct mp4 **result)
{
struct mp4 *f;
int ret;
ret = -E_MP4_BAD_SAMPLE_COUNT;
if (f->track.stsz_sample_count == 0)
goto fail;
+ ret = -E_MP4_CORRUPT;
+ if (f->track.time_scale == 0)
+ goto fail;
*result = f;
return 1;
fail:
return ret;
}
-void mp4_close(struct mp4 *f)
-{
- free(f->track.stsz_table);
- free(f->track.stts_sample_count);
- free(f->track.stsc_first_chunk);
- free(f->track.stsc_samples_per_chunk);
- free(f->track.stco_chunk_offset);
- for (uint32_t n = 0; n < f->meta.count; n++) {
- free(f->meta.tags[n].item);
- free(f->meta.tags[n].value);
- }
- free(f->meta.tags);
- free(f);
-}
-
static int32_t chunk_of_sample(const struct mp4 *f, int32_t sample,
int32_t *chunk)
{
}
/**
- * Return the number of milliseconds of the audio track.
+ * Compute the duration of an mp4 file.
+ *
+ * \param f See \ref mp4_close().
*
- * \param f As returned by \ref mp4_open_read(), must not be NULL.
+ * \return The number of milliseconds of the audio track. This function never
+ * fails.
*/
uint64_t mp4_get_duration(const struct mp4 *f)
{
const struct mp4_track *t = &f->track;
- if (t->time_scale == 0)
- return 0;
return t->duration * 1000 / t->time_scale;
}
+/**
+ * Reposition the read/write file offset.
+ *
+ * \param f See \ref mp4_close().
+ * \param sample The number of the sample to reposition to.
+ *
+ * The given sample number must be within range, i.e., strictly less than the
+ * value returned by \ref mp4_num_samples().
+ *
+ * \return Standard. The only possible error is an invalid sample number.
+ */
int mp4_set_sample_position(struct mp4 *f, uint32_t sample)
{
const struct mp4_track *t = &f->track;
return 1;
}
+/**
+ * Look up and return the size of the given sample in the stsz table.
+ *
+ * \param f See \ref mp4_close().
+ * \param sample The sample number of interest.
+ * \param result Sample size is returned here.
+ *
+ * For the sample argument the restriction mentioned in the documentation of
+ * \ref mp4_set_sample_position() applies as well.
+ *
+ * \return Standard. Like for \ref mp4_set_sample_position(), EINVAL is the
+ * only possible error.
+ */
int mp4_get_sample_size(const struct mp4 *f, uint32_t sample, uint32_t *result)
{
const struct mp4_track *t = &f->track;
return 1;
}
-uint32_t mp4_get_sample_rate(const struct mp4 *f)
+/**
+ * Return the sample rate stored in the stsd atom.
+ *
+ * \param f See \ref mp4_close().
+ *
+ * The sample rate is a property of the audio track of the mp4 file and is thus
+ * independent of the sample number.
+ *
+ * \return The function always returns a positive value because the open
+ * operation fails if the sample rate happens to be zero. A typical value is
+ * 44100.
+ */
+uint16_t mp4_get_sample_rate(const struct mp4 *f)
{
return f->track.sample_rate;
}
+/**
+ * Return the number of channels of the audio track.
+ *
+ * \param f See \ref mp4_close().
+ *
+ * \return The returned channel count is guaranteed to be positive because the
+ * open operation fails if the mp4a atom is missing or contains a zero channel
+ * count.
+ */
uint16_t mp4_get_channel_count(const struct mp4 *f)
{
return f->track.channel_count;
}
-int32_t mp4_num_samples(const struct mp4 *f)
+/**
+ * Return the number of samples of the audio track.
+ *
+ * \param f See \ref mp4_close().
+ *
+ * \return The sample count is read from the stsz atom during open.
+ */
+uint32_t mp4_num_samples(const struct mp4 *f)
{
- const struct mp4_track *t = &f->track;
- int32_t total = 0;
-
- for (uint32_t n = 0; n < t->stts_entry_count; n++)
- total += t->stts_sample_count[n];
- return total;
+ return f->track.stsz_sample_count;
}
+/**
+ * Open an mp4 file in metadata-only mode.
+ *
+ * \param cb See \ref mp4_open().
+ * \param result See \ref mp4_open().
+ *
+ * This is similar to \ref mp4_open() but is cheaper because it only parses the
+ * metadata of the mp4 file. The only functions that can subsequently be called
+ * with the file handle returned here are \ref mp4_get_meta() and \ref
+ * mp4_update_meta().
+ *
+ * \return Standard.
+ *
+ * \sa \ref mp4_open(). The comment about ->write() and ->truncate() applies to
+ * this function as well.
+ */
int mp4_open_meta(const struct mp4_callback *cb, struct mp4 **result)
{
struct mp4 *f;
if (ret < 0)
return ret;
- if (f->udta_size == 0 || f->meta_size == 0 || f->ilst_size == 0) {
- mp4_close(f);
- *result = NULL;
- return -E_MP4_MISSING_ATOM;
- }
*result = f;
return 1;
}
/**
* Return the metadata of an mp4 file.
*
- * \param f As returned by either \ref mp4_open_read() or \ref mp4_open_meta().
+ * \param f See \ref mp4_close().
*
* The caller is allowed to add, delete or modify the entries of the returned
- * structure in order to pass the modified version to \ref mp4_meta_update().
+ * structure with the intention to pass the modified version to \ref
+ * mp4_update_meta().
+ *
+ * \return This never returns NULL, even if the file contains no metadata tag
+ * items. However, the meta count will be zero and the ->tags pointer NULL in
+ * this case.
*/
struct mp4_metadata *mp4_get_meta(struct mp4 *f)
{
{
int ret;
uint64_t total_base = f->moov_offset + 8;
- uint32_t total_size = (uint32_t) (f->moov_size - 8);
+ uint32_t total_size = f->moov_size - 8;
uint32_t new_ilst_size = 0;
void *out_buffer;
uint8_t *p_out;
new_ilst_size += TAG_LEN(strlen(f->meta.tags[n].value));
size_delta = new_ilst_size - (f->ilst_size - 8);
*out_size = total_size + size_delta;
- out_buffer = para_malloc(*out_size);
+ out_buffer = alloc(*out_size);
p_out = out_buffer;
set_position(f, total_base);
ret = read_data(f, p_out, f->udta_offset - total_base);
return 1;
}
-int mp4_meta_update(struct mp4 *f)
+/**
+ * Write back the modified metadata items to the mp4 file.
+ *
+ * This is the only public function which modifies the contents of an mp4 file.
+ * This is achieved by calling the ->write() and ->truncate() methods of the
+ * callback structure passed to \ref mp4_open() or \ref mp4_open_meta().
+ *
+ * \param f See \ref mp4_close().
+ *
+ * The modified metadata structure does not need to be supplied to this
+ * function because it is part of the mp4 structure.
+ *
+ * \return Standard.
+ */
+int mp4_update_meta(struct mp4 *f)
{
void *new_moov_data;
uint32_t new_moov_size;
/**
* Return the value of the given tag item.
*
- * \param f Must not be NULL.
+ * \param f See \ref mp4_close().
* \param item "artist", "title", "album", "comment", or "date".
*
- * \return The function always returns NULL if the given item is not in the
- * above list. Otherwise, if the file does not contain a tag for the given
- * item, the function also returns NULL. Otherwise a copy of the tag value is
- * returned and the caller should free this memory when it is no longer needed.
+ * \return The function returns NULL if the given item is not in the above
+ * list. Otherwise, if the file does not contain a tag for the given item, the
+ * function also returns NULL. Otherwise a copy of the tag value is returned
+ * and the caller should free this memory when it is no longer needed.
*/
-char *mp4_get_tag_value(const struct mp4 *f, const char *item)
+__malloc char *mp4_get_tag_value(const struct mp4 *f, const char *item)
{
for (unsigned n = 0; n < f->meta.count; n++)
if (!strcasecmp(f->meta.tags[n].item, item))
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