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authorMagnus Holmgren <magnushol@gmail.com>2006-11-23 19:46:59 +0000
committerMagnus Holmgren <magnushol@gmail.com>2006-11-23 19:46:59 +0000
commit1ac20995c3be1ca890862f0ca24ef76473789fea (patch)
tree9eacf6c12777db947ff6d0704c59d3fc79e078d0
parentf27c2660972b53612c313653556d5b36083cff40 (diff)
downloadrockbox-1ac20995c3be1ca890862f0ca24ef76473789fea.tar.gz
rockbox-1ac20995c3be1ca890862f0ca24ef76473789fea.zip
Read frequency in MP4/AAC files from a different place, if available. Should fix the problem with wrong playback speed for non-44.1kHz files.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11579 a1c6a512-1295-4272-9138-f99709370657
-rw-r--r--apps/metadata.c159
1 files changed, 158 insertions, 1 deletions
diff --git a/apps/metadata.c b/apps/metadata.c
index 2f00787e6f..872dfd72f5 100644
--- a/apps/metadata.c
+++ b/apps/metadata.c
@@ -49,6 +49,7 @@ enum tagtype { TAGTYPE_APE = 1, TAGTYPE_VORBIS };
#define MP4_cART MP4_ID(0xa9, 'A', 'R', 'T')
#define MP4_cnam MP4_ID(0xa9, 'n', 'a', 'm')
#define MP4_cwrt MP4_ID(0xa9, 'w', 'r', 't')
+#define MP4_esds MP4_ID('e', 's', 'd', 's')
#define MP4_ftyp MP4_ID('f', 't', 'y', 'p')
#define MP4_gnre MP4_ID('g', 'n', 'r', 'e')
#define MP4_hdlr MP4_ID('h', 'd', 'l', 'r')
@@ -228,6 +229,14 @@ static unsigned long get_long(void* buf)
return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
}
+/* Read an unaligned 32-bit big endian long from buffer. */
+static unsigned long get_long_be(void* buf)
+{
+ unsigned char* p = (unsigned char*) buf;
+
+ return (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
+}
+
/* Read a string tag from an M4A file */
void read_m4a_tag_string(int fd, int len,char** bufptr,size_t* bytes_remaining, char** dest)
{
@@ -1036,6 +1045,136 @@ static unsigned int read_mp4_atom(int fd, unsigned int* size,
return size_left;
}
+static unsigned int read_mp4_length(int fd, unsigned int* size)
+{
+ unsigned int length = 0;
+ int bytes = 0;
+ unsigned char c;
+
+ do
+ {
+ read(fd, &c, 1);
+ bytes++;
+ (*size)--;
+ length = (length << 7) | (c & 0x7F);
+ }
+ while ((c & 0x80) && (bytes < 4) && (*size > 0));
+
+ return length;
+}
+
+static bool read_mp4_esds(int fd, struct mp3entry* id3,
+ unsigned int* size)
+{
+ unsigned char buf[8];
+ bool sbr = false;
+
+ lseek(fd, 4, SEEK_CUR); /* Version and flags. */
+ read(fd, buf, 1); /* Verify ES_DescrTag. */
+ *size -= 5;
+
+ if (*buf == 3)
+ {
+ /* read length */
+ if (read_mp4_length(fd, size) < 20)
+ {
+ return sbr;
+ }
+
+ lseek(fd, 3, SEEK_CUR);
+ *size -= 3;
+ }
+ else
+ {
+ lseek(fd, 2, SEEK_CUR);
+ *size -= 2;
+ }
+
+ read(fd, buf, 1); /* Verify DecoderConfigDescrTab. */
+ *size -= 1;
+
+ if (*buf != 4)
+ {
+ return sbr;
+ }
+
+ if (read_mp4_length(fd, size) < 13)
+ {
+ return sbr;
+ }
+
+ lseek(fd, 13, SEEK_CUR); /* Skip audio type, bit rates, etc. */
+ read(fd, buf, 1);
+ *size -= 14;
+
+ if (*buf != 5) /* Verify DecSpecificInfoTag. */
+ {
+ return sbr;
+ }
+
+ {
+ static const int sample_rates[] =
+ {
+ 96000, 88200, 64000, 48000, 44100, 32000,
+ 24000, 22050, 16000, 12000, 11025, 8000
+ };
+ unsigned long bits;
+ unsigned int length;
+ unsigned int index;
+ int type;
+
+ /* Read the (leading part of the) decoder config. */
+ length = read_mp4_length(fd, size);
+ length = MIN(length, *size);
+ length = MIN(length, sizeof(buf));
+ read(fd, buf, length);
+ *size -= length;
+
+ /* Decoder config format:
+ * Object type - 5 bits
+ * Frequency index - 4 bits
+ * Channel configuration - 4 bits
+ */
+ bits = get_long_be(buf);
+ type = bits >> 27;
+ index = (bits >> 23) & 0xf;
+
+ if (index < (sizeof(sample_rates) / sizeof(*sample_rates)))
+ {
+ id3->frequency = sample_rates[index];
+ }
+
+ if (type == 5)
+ {
+ sbr = true;
+ /* Extended frequency index - 4 bits */
+ index = (bits >> 15) & 0xf;
+
+ if (index == 15)
+ {
+ /* 17 bits read so far... */
+ bits = get_long_be(&buf[2]);
+ id3->frequency = (bits >> 7) & 0x00FFFFFF;
+ }
+ else if (index < (sizeof(sample_rates) / sizeof(*sample_rates)))
+ {
+ id3->frequency = sample_rates[index];
+ }
+ }
+ else if (id3->frequency < 24000)
+ {
+ /* SBR not indicated, but the file might still contain SBR.
+ * MPEG specification says that one should assume SBR if
+ * samplerate <= 24000 Hz.
+ */
+ id3->frequency *= 2;
+ sbr = true;
+ }
+ }
+
+ return sbr;
+}
+
static bool read_mp4_tags(int fd, struct mp3entry* id3,
unsigned int size_left)
{
@@ -1268,7 +1407,25 @@ static bool read_mp4_container(int fd, struct mp3entry* id3,
read_uint32be(fd, &frequency);
size -= 26;
id3->frequency = frequency;
- /* There're some child atoms here, but we don't need them */
+
+ if (type == MP4_mp4a)
+ {
+ unsigned int subsize;
+ unsigned int subtype;
+
+ /* Get frequency from the decoder info tag, if possible. */
+ lseek(fd, 2, SEEK_CUR);
+ /* The esds atom is a part of the mp4a atom, so ignore
+ * the returned size (it's already accounted for).
+ */
+ read_mp4_atom(fd, &subsize, &subtype, size);
+ size -= 10;
+
+ if (subtype == MP4_esds)
+ {
+ read_mp4_esds(fd, id3, &size);
+ }
+ }
}
break;