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authorJens Arnold <amiconn@rockbox.org>2005-09-10 12:28:16 +0000
committerJens Arnold <amiconn@rockbox.org>2005-09-10 12:28:16 +0000
commitec9b202a921996945ebd42a7edba1326754d7737 (patch)
treef88c7d9ee1ff94c3a5cefdba0d30c78b84e72d62 /firmware
parent1996dca15a495c09986cefc02086e03a53244f3a (diff)
downloadrockbox-ec9b202a921996945ebd42a7edba1326754d7737.tar.gz
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Reworked handling of MPEG audio frame & file info: * Fixed frame size calculation for layer 1 (all versions) and layer 2 (V2/V2.5). * Exact frame time (expressed as a fraction) for way more precise playtime calculation at 44100/22050/11025Hz sample frequency. * Exact playtime<->position conversion for CBR also used for resume position. * More compact code, long policy.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7505 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'firmware')
-rw-r--r--firmware/export/id3.h38
-rw-r--r--firmware/export/mp3data.h26
-rw-r--r--firmware/id3.c8
-rw-r--r--firmware/mp3data.c187
-rw-r--r--firmware/mpeg.c12
5 files changed, 125 insertions, 146 deletions
diff --git a/firmware/export/id3.h b/firmware/export/id3.h
index 6c6507159a..47a084d67a 100644
--- a/firmware/export/id3.h
+++ b/firmware/export/id3.h
@@ -61,39 +61,37 @@ struct mp3entry {
unsigned char genre;
unsigned int codectype;
unsigned int bitrate;
- unsigned int frequency;
- unsigned int id3v2len;
- unsigned int id3v1len;
- unsigned int first_frame_offset; /* Byte offset to first real MP3 frame.
- Used for skipping leading garbage to
- avoid gaps between tracks. */
- unsigned int vbr_header_pos;
- unsigned int filesize; /* in bytes */
- unsigned int length; /* song length */
- unsigned int elapsed; /* ms played */
-
- int lead_trim; /* Number of samples to skip at the beginning */
- int tail_trim; /* Number of samples to remove from the end */
+ unsigned long frequency;
+ unsigned long id3v2len;
+ unsigned long id3v1len;
+ unsigned long first_frame_offset; /* Byte offset to first real MP3 frame.
+ Used for skipping leading garbage to
+ avoid gaps between tracks. */
+ unsigned long vbr_header_pos;
+ unsigned long filesize; /* without headers; in bytes */
+ unsigned long length; /* song length in ms */
+ unsigned long elapsed; /* ms played */
+
+ int lead_trim; /* Number of samples to skip at the beginning */
+ int tail_trim; /* Number of samples to remove from the end */
/* Added for Vorbis */
- unsigned long samples; /* number of samples in track */
+ unsigned long samples; /* number of samples in track */
/* MP3 stream specific info */
- long bpf; /* bytes per frame */
- long tpf; /* time per frame */
- long frame_count; /* number of frames in the file (if VBR) */
+ unsigned long frame_count; /* number of frames in the file (if VBR) */
/* Xing VBR fields */
bool vbr;
- bool has_toc; /* True if there is a VBR header in the file */
- unsigned char toc[100];/* table of contents */
+ bool has_toc; /* True if there is a VBR header in the file */
+ unsigned char toc[100]; /* table of contents */
/* these following two fields are used for local buffering */
char id3v2buf[300];
char id3v1buf[3][32];
/* resume related */
- int offset; /* bytes played */
+ unsigned long offset; /* bytes played */
int index; /* playlist index */
/* FileEntry fields */
diff --git a/firmware/export/mp3data.h b/firmware/export/mp3data.h
index db1a93b8d6..3961664815 100644
--- a/firmware/export/mp3data.h
+++ b/firmware/export/mp3data.h
@@ -20,9 +20,9 @@
#ifndef _MP3DATA_H_
#define _MP3DATA_H_
-#define MPEG_VERSION2_5 0
-#define MPEG_VERSION1 1
-#define MPEG_VERSION2 2
+#define MPEG_VERSION1 0
+#define MPEG_VERSION2 1
+#define MPEG_VERSION2_5 2
struct mp3info {
/* Standard MP3 frame header fields */
@@ -30,23 +30,25 @@ struct mp3info {
int layer;
bool protection;
int bitrate;
- int frequency;
+ long frequency;
int padding;
int channel_mode;
int mode_extension;
int emphasis;
- int frame_size; /* Frame size in bytes */
- int frame_time; /* Frame duration in milliseconds */
+ int frame_size; /* Frame size in bytes */
+ int frame_samples; /* Samples per frame */
+ int ft_num; /* Numerator of frametime in milliseconds */
+ int ft_den; /* Denominator of frametime in milliseconds */
- bool is_vbr; /* True if the file is VBR */
- bool has_toc; /* True if there is a VBR header in the file */
+ bool is_vbr; /* True if the file is VBR */
+ bool has_toc; /* True if there is a VBR header in the file */
bool is_xing_vbr; /* True if the VBR header is of Xing type */
bool is_vbri_vbr; /* True if the VBR header is of VBRI type */
unsigned char toc[100];
- long frame_count; /* Number of frames in the file (if VBR) */
- long byte_count; /* File size in bytes */
- long file_time; /* Length of the whole file in milliseconds */
- int vbr_header_pos;
+ unsigned long frame_count; /* Number of frames in the file (if VBR) */
+ unsigned long byte_count; /* File size in bytes */
+ unsigned long file_time; /* Length of the whole file in milliseconds */
+ unsigned long vbr_header_pos;
int enc_delay; /* Encoder delay, fetched from LAME header */
int enc_padding; /* Padded samples added to last frame. LAME header */
};
diff --git a/firmware/id3.c b/firmware/id3.c
index f1aa821fba..dfbcb9699d 100644
--- a/firmware/id3.c
+++ b/firmware/id3.c
@@ -863,10 +863,10 @@ static int getid3v2len(int fd)
*/
static int getsonglength(int fd, struct mp3entry *entry)
{
- unsigned int filetime = 0;
+ unsigned long filetime = 0;
struct mp3info info;
- int bytecount;
-
+ long bytecount;
+
/* Start searching after ID3v2 header */
if(-1 == lseek(fd, entry->id3v2len, SEEK_SET))
return 0;
@@ -912,8 +912,6 @@ static int getsonglength(int fd, struct mp3entry *entry)
* always multiples of 8, and it avoids overflows. */
}
- entry->tpf = info.frame_time;
- entry->bpf = info.frame_size;
entry->frame_count = info.frame_count;
entry->vbr = info.is_vbr;
diff --git a/firmware/mp3data.c b/firmware/mp3data.c
index 6f4c560578..c2d4cd2c37 100644
--- a/firmware/mp3data.c
+++ b/firmware/mp3data.c
@@ -31,6 +31,7 @@
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
+#include <limits.h>
#include "debug.h"
#include "logf.h"
#include "mp3data.h"
@@ -39,7 +40,7 @@
#define DEBUG_VERBOSE
-#define BYTES2INT(b1,b2,b3,b4) (((long)(b1 & 0xFF) << (3*8)) | \
+#define BYTES2INT(b1,b2,b3,b4) (((long)(b1 & 0xFF) << (3*8)) | \
((long)(b2 & 0xFF) << (2*8)) | \
((long)(b3 & 0xFF) << (1*8)) | \
((long)(b4 & 0xFF) << (0*8)))
@@ -58,37 +59,34 @@
#define ORIGINAL_MASK (1L << 2)
#define EMPHASIS_MASK 3L
-/* Table of bitrates for MP3 files, all values in kilo.
- * Indexed by version, layer and value of bit 15-12 in header.
- */
-const int bitrate_table[2][3][16] =
-{
- {
- {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0},
- {0,32,48,56, 64,80, 96, 112,128,160,192,224,256,320,384,0},
- {0,32,40,48, 56,64, 80, 96, 112,128,160,192,224,256,320,0}
- },
- {
- {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,0},
- {0, 8,16,24,32,40,48, 56, 64, 80, 96,112,128,144,160,0},
- {0, 8,16,24,32,40,48, 56, 64, 80, 96,112,128,144,160,0}
- }
+/* MPEG Version table, sorted by version index */
+static const signed char version_table[4] = {
+ MPEG_VERSION2_5, -1, MPEG_VERSION2, MPEG_VERSION1
};
-/* Table of samples per frame for MP3 files.
- * Indexed by layer. Multiplied with 1000.
- */
-const long bs[3] = {384000, 1152000, 1152000};
+/* Bitrate table for mpeg audio, indexed by row index and birate index */
+static const short bitrates[5][16] = {
+ {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0}, /* V1 L1 */
+ {0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,0}, /* V1 L2 */
+ {0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,0}, /* V1 L3 */
+ {0,32,48,56, 64, 80, 96,112,128,144,160,176,192,224,256,0}, /* V2 L1 */
+ {0, 8,16,24, 32, 40, 48, 56, 64, 80, 96,112,128,144,160,0} /* V2 L2+L3 */
+};
-/* Table of sample frequency for MP3 files.
- * Indexed by version and layer.
- */
+/* Bitrate pointer table, indexed by version and layer */
+static const short *bitrate_table[3][3] =
+{
+ {bitrates[0], bitrates[1], bitrates[2]},
+ {bitrates[3], bitrates[4], bitrates[4]},
+ {bitrates[3], bitrates[4], bitrates[4]}
+};
-const int freqtab[][4] =
+/* Sampling frequency table, indexed by version and frequency index */
+static const long freq_table[3][3] =
{
- {11025, 12000, 8000, 0}, /* MPEG version 2.5 */
- {44100, 48000, 32000, 0}, /* MPEG Version 1 */
- {22050, 24000, 16000, 0}, /* MPEG version 2 */
+ {44100, 48000, 32000}, /* MPEG Version 1 */
+ {22050, 24000, 16000}, /* MPEG version 2 */
+ {11025, 12000, 8000}, /* MPEG version 2.5 */
};
/* check if 'head' is a valid mp3 frame header */
@@ -117,97 +115,77 @@ static bool is_mp3frameheader(unsigned long head)
static bool mp3headerinfo(struct mp3info *info, unsigned long header)
{
- int bittable = 0;
- int bitindex;
- int freqindex;
-
+ int bitindex, freqindex;
+
/* MPEG Audio Version */
- switch((header & VERSION_MASK) >> 19) {
- case 0:
- /* MPEG version 2.5 is not an official standard */
- info->version = MPEG_VERSION2_5;
- bittable = MPEG_VERSION2 - 1; /* use the V2 bit rate table */
- break;
-
- case 1:
+ info->version = version_table[(header & VERSION_MASK) >> 19];
+ if (info->version < 0)
return false;
- case 2:
- /* MPEG version 2 (ISO/IEC 13818-3) */
- info->version = MPEG_VERSION2;
- bittable = MPEG_VERSION2 - 1;
- break;
-
- case 3:
- /* MPEG version 1 (ISO/IEC 11172-3) */
- info->version = MPEG_VERSION1;
- bittable = MPEG_VERSION1 - 1;
- break;
- }
-
- switch((header & LAYER_MASK) >> 17) {
- case 0:
+ /* Layer */
+ info->layer = 3 - ((header & LAYER_MASK) >> 17);
+ if (info->layer == 3)
return false;
- case 1:
- info->layer = 2;
- break;
- case 2:
- info->layer = 1;
- break;
- case 3:
- info->layer = 0;
- break;
- }
- info->protection = (header & PROTECTION_MASK)?true:false;
+ info->protection = (header & PROTECTION_MASK) ? true : false;
/* Bitrate */
- bitindex = (header & 0xf000) >> 12;
- info->bitrate = bitrate_table[bittable][info->layer][bitindex];
+ bitindex = (header & BITRATE_MASK) >> 12;
+ info->bitrate = bitrate_table[info->version][info->layer][bitindex];
if(info->bitrate == 0)
return false;
-
+
/* Sampling frequency */
- freqindex = (header & 0x0C00) >> 10;
- info->frequency = freqtab[info->version][freqindex];
- if(info->frequency == 0)
+ freqindex = (header & SAMPLERATE_MASK) >> 10;
+ if (freqindex == 3)
return false;
+ info->frequency = freq_table[info->version][freqindex];
- info->padding = (header & 0x0200)?1:0;
+ info->padding = (header & PADDING_MASK) ? 1 : 0;
/* Calculate number of bytes, calculation depends on layer */
- switch(info->layer) {
- case 0:
- info->frame_size = info->bitrate * 48000;
- info->frame_size /=
- freqtab[info->version][freqindex] << bittable;
- break;
- case 1:
- case 2:
- info->frame_size = info->bitrate * 144000;
- info->frame_size /=
- freqtab[info->version][freqindex] << bittable;
- break;
- default:
- info->frame_size = 1;
+ if (info->layer == 0) {
+ info->frame_samples = 384;
+ info->frame_size = (12000 * info->bitrate / info->frequency
+ + info->padding) * 4;
+ }
+ else {
+ if ((info->version > MPEG_VERSION1) && (info->layer == 2))
+ info->frame_samples = 576;
+ else
+ info->frame_samples = 1152;
+ info->frame_size = (1000/8) * info->frame_samples * info->bitrate
+ / info->frequency + info->padding;
}
- info->frame_size += info->padding;
-
- /* Calculate time per frame */
- info->frame_time = bs[info->layer] /
- (freqtab[info->version][freqindex] << bittable);
+ /* Frametime fraction calculation.
+ This fraction is reduced as far as possible. */
+ if (freqindex != 0) { /* 48/32/24/16/12/8 kHz */
+ /* integer number of milliseconds, denominator == 1 */
+ info->ft_num = 1000 * info->frame_samples / info->frequency;
+ info->ft_den = 1;
+ }
+ else { /* 44.1/22.05/11.025 kHz */
+ if (info->layer == 0) {
+ info->ft_num = 147000 * 384 / info->frequency;
+ info->ft_den = 147;
+ }
+ else {
+ info->ft_num = 49000 * info->frame_samples / info->frequency;
+ info->ft_den = 49;
+ }
+ }
- info->channel_mode = (header & 0xc0) >> 6;
- info->mode_extension = (header & 0x30) >> 4;
- info->emphasis = header & 3;
+ info->channel_mode = (header & CHANNELMODE_MASK) >> 6;
+ info->mode_extension = (header & MODE_EXT_MASK) >> 4;
+ info->emphasis = header & EMPHASIS_MASK;
#ifdef DEBUG_VERBOSE
- DEBUGF( "Header: %08x, Ver %d, lay %d, bitr %d, freq %d, "
- "chmode %d, mode_ext %d, emph %d, bytes: %d time: %d\n",
+ DEBUGF( "Header: %08x, Ver %d, lay %d, bitr %d, freq %ld, "
+ "chmode %d, mode_ext %d, emph %d, bytes: %d time: %d/%d\n",
header, info->version, info->layer+1, info->bitrate,
info->frequency, info->channel_mode, info->mode_extension,
- info->emphasis, info->frame_size, info->frame_time);
+ info->emphasis, info->frame_size, info->ft_num, info->ft_den);
#endif
return true;
}
@@ -252,7 +230,7 @@ static unsigned long __find_next_frame(int fd, long *offset, long max_offset,
if(*offset)
DEBUGF("Warning: skipping %d bytes of garbage\n", *offset);
#endif
-
+
return header;
}
@@ -380,9 +358,6 @@ int get_mp3file_info(int fd, struct mp3info *info)
memset(info, 0, sizeof(struct mp3info));
/* These two are needed for proper LAME gapless MP3 playback */
- /* TODO: These can be found in a LAME Info header as well, but currently
- they are only looked for in a Xing header. Xing and Info headers have
- the exact same format, but Info headers are used for CBR files. */
info->enc_delay = -1;
info->enc_padding = -1;
if(!mp3headerinfo(info, header))
@@ -435,7 +410,10 @@ int get_mp3file_info(int fd, struct mp3info *info)
{
info->frame_count = BYTES2INT(vbrheader[i], vbrheader[i+1],
vbrheader[i+2], vbrheader[i+3]);
- info->file_time = info->frame_count * info->frame_time;
+ if (info->frame_count <= ULONG_MAX / info->ft_num)
+ info->file_time = info->frame_count * info->ft_num / info->ft_den;
+ else
+ info->file_time = info->frame_count / info->ft_den * info->ft_num;
i += 4;
}
@@ -510,7 +488,10 @@ int get_mp3file_info(int fd, struct mp3info *info)
vbrheader[12], vbrheader[13]);
info->frame_count = BYTES2INT(vbrheader[14], vbrheader[15],
vbrheader[16], vbrheader[17]);
- info->file_time = info->frame_count * info->frame_time;
+ if (info->frame_count <= ULONG_MAX / info->ft_num)
+ info->file_time = info->frame_count * info->ft_num / info->ft_den;
+ else
+ info->file_time = info->frame_count / info->ft_den * info->ft_num;
info->bitrate = info->byte_count * 8 / info->file_time;
/* We don't parse the TOC, since we don't yet know how to (FIXME) */
diff --git a/firmware/mpeg.c b/firmware/mpeg.c
index ff74cf96a8..8d2d13b6ee 100644
--- a/firmware/mpeg.c
+++ b/firmware/mpeg.c
@@ -348,7 +348,7 @@ static void set_elapsed(struct mp3entry* id3)
/* find wich percent we're at */
for (i=0; i<100; i++ )
{
- if ( id3->offset < (int)(id3->toc[i] * (id3->filesize / 256)) )
+ if ( id3->offset < id3->toc[i] * (id3->filesize / 256) )
{
break;
}
@@ -388,8 +388,8 @@ static void set_elapsed(struct mp3entry* id3)
}
}
else
- /* constant bitrate == simple frame calculation */
- id3->elapsed = id3->offset / id3->bpf * id3->tpf;
+ /* constant bitrate, use exact calculation */
+ id3->elapsed = id3->offset / (id3->bitrate / 8);
}
int audio_get_file_pos(void)
@@ -405,7 +405,7 @@ int audio_get_file_pos(void)
unsigned int percent, remainder;
int curtoc, nexttoc, plen;
- percent = (id3->elapsed*100)/id3->length;
+ percent = (id3->elapsed*100)/id3->length;
if (percent > 99)
percent = 99;
@@ -431,8 +431,8 @@ int audio_get_file_pos(void)
(id3->elapsed / 1000);
}
}
- else if (id3->bpf && id3->tpf)
- pos = (id3->elapsed/id3->tpf)*id3->bpf;
+ else if (id3->bitrate)
+ pos = id3->elapsed * (id3->bitrate / 8);
else
{
return -1;