diff options
Diffstat (limited to 'lib/rbcodec/metadata/mp3.c')
| -rw-r--r-- | lib/rbcodec/metadata/mp3.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/lib/rbcodec/metadata/mp3.c b/lib/rbcodec/metadata/mp3.c new file mode 100644 index 0000000..feb1a52 --- /dev/null +++ b/lib/rbcodec/metadata/mp3.c @@ -0,0 +1,193 @@ +/*************************************************************************** + * __________ __ ___. + * Open \______ \ ____ ____ | | _\_ |__ _______ ___ + * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / + * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < + * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ + * \/ \/ \/ \/ \/ + * $Id$ + * + * Copyright (C) 2002 by Daniel Stenberg + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY + * KIND, either express or implied. + * + ****************************************************************************/ +/* + * Parts of this code has been stolen from the Ample project and was written + * by David H�deman. It has since been extended and enhanced pretty much by + * all sorts of friendly Rockbox people. + * + */ + + /* tagResolver and associated code copyright 2003 Thomas Paul Diffenbach + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <stdbool.h> +#include "string-extra.h" +#include "config.h" +#include "file.h" +#include "logf.h" + +#include "system.h" +#include "metadata.h" +#include "mp3data.h" +#include "metadata_common.h" +#include "metadata_parsers.h" + +/* + * Calculates the length (in milliseconds) of an MP3 file. + * + * Modified to only use integers. + * + * Arguments: file - the file to calculate the length upon + * entry - the entry to update with the length + * + * Returns: the song length in milliseconds, + * 0 means that it couldn't be calculated + */ +static int getsonglength(int fd, struct mp3entry *entry) +{ + unsigned long filetime = 0; + struct mp3info info; + long bytecount; + + /* Start searching after ID3v2 header */ + if(-1 == lseek(fd, entry->id3v2len, SEEK_SET)) + return 0; + + bytecount = get_mp3file_info(fd, &info); + + logf("Space between ID3V2 tag and first audio frame: 0x%lx bytes", + bytecount); + + if(bytecount < 0) + return -1; + + bytecount += entry->id3v2len; + + /* Validate byte count, in case the file has been edited without + * updating the header. + */ + if (info.byte_count) + { + const unsigned long expected = entry->filesize - entry->id3v1len + - entry->id3v2len; + const unsigned long diff = MAX(10240, info.byte_count / 20); + + if ((info.byte_count > expected + diff) + || (info.byte_count < expected - diff)) + { + logf("Note: info.byte_count differs from expected value by " + "%ld bytes", labs((long) (expected - info.byte_count))); + info.byte_count = 0; + info.frame_count = 0; + info.file_time = 0; + info.enc_padding = 0; + + /* Even if the bitrate was based on "known bad" values, it + * should still be better for VBR files than using the bitrate + * of the first audio frame. + */ + } + } + + entry->bitrate = info.bitrate; + entry->frequency = info.frequency; + entry->layer = info.layer; + switch(entry->layer) { +#if CONFIG_CODEC==SWCODEC + case 0: + entry->codectype=AFMT_MPA_L1; + break; +#endif + case 1: + entry->codectype=AFMT_MPA_L2; + break; + case 2: + entry->codectype=AFMT_MPA_L3; + break; + } + + /* If the file time hasn't been established, this may be a fixed + rate MP3, so just use the default formula */ + + filetime = info.file_time; + + if(filetime == 0) + { + /* Prevent a division by zero */ + if (info.bitrate < 8) + filetime = 0; + else + filetime = (entry->filesize - bytecount) / (info.bitrate / 8); + /* bitrate is in kbps so this delivers milliseconds. Doing bitrate / 8 + * instead of filesize * 8 is exact, because mpeg audio bitrates are + * always multiples of 8, and it avoids overflows. */ + } + + entry->frame_count = info.frame_count; + + entry->vbr = info.is_vbr; + entry->has_toc = info.has_toc; + +#if CONFIG_CODEC==SWCODEC + if (!entry->lead_trim) + entry->lead_trim = info.enc_delay; + if (!entry->tail_trim) + entry->tail_trim = info.enc_padding; +#endif + + memcpy(entry->toc, info.toc, sizeof(info.toc)); + + /* Update the seek point for the first playable frame */ + entry->first_frame_offset = bytecount; + logf("First frame is at %lx", entry->first_frame_offset); + + return filetime; +} + +/* + * Checks all relevant information (such as ID3v1 tag, ID3v2 tag, length etc) + * about an MP3 file and updates it's entry accordingly. + * + Note, that this returns true for successful, false for error! */ +bool get_mp3_metadata(int fd, struct mp3entry *entry) +{ + entry->title = NULL; + entry->filesize = filesize(fd); + entry->id3v2len = getid3v2len(fd); + entry->tracknum = 0; + entry->discnum = 0; + + if (entry->id3v2len) + setid3v2title(fd, entry); + int len = getsonglength(fd, entry); + if (len < 0) + return false; + entry->length = len; + + /* Subtract the meta information from the file size to get + the true size of the MP3 stream */ + entry->filesize -= entry->first_frame_offset; + + /* only seek to end of file if no id3v2 tags were found */ + if (!entry->id3v2len) { + setid3v1title(fd, entry); + } + + if(!entry->length || (entry->filesize < 8 )) + /* no song length or less than 8 bytes is hereby considered to be an + invalid mp3 and won't be played by us! */ + return false; + + return true; +} |