122 lines
3.9 KiB
C
122 lines
3.9 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Parsing ADTS and ADIF headers
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*
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* Written by Igor B. Poretsky
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include <stdlib.h>
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#include <stdbool.h>
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#include <string.h>
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#include "platform.h"
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#include "metadata.h"
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#include "metadata_common.h"
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#include "metadata_parsers.h"
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static const int sample_rates[] =
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{
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96000, 88200, 64000, 48000,
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44100, 32000, 24000, 22050,
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16000, 12000, 11025, 8000,
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7350, 0, 0, 0
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};
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static bool check_adts_syncword(int fd)
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{
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uint16_t syncword = 0;
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read_uint16be(fd, &syncword);
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return (syncword & 0xFFF6) == 0xFFF0;
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}
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bool get_aac_metadata(int fd, struct mp3entry *entry)
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{
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unsigned char buf[5];
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entry->title = NULL;
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entry->tracknum = 0;
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entry->discnum = 0;
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entry->id3v1len = 0;
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entry->id3v2len = getid3v2len(fd);
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entry->first_frame_offset = entry->id3v2len;
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entry->filesize = filesize(fd) - entry->first_frame_offset;
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entry->needs_upsampling_correction = false;
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if (entry->id3v2len)
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setid3v2title(fd, entry);
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if (-1 == lseek(fd, entry->first_frame_offset, SEEK_SET))
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return false;
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if (check_adts_syncword(fd))
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{
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int frames;
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int stat_length;
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uint64_t total;
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if (read(fd, buf, 5) != 5)
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return false;
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entry->frequency = sample_rates[(buf[0] >> 2) & 0x0F];
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entry->vbr = ((buf[3] & 0x1F) == 0x1F)
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&& ((buf[4] & 0xFC) == 0xFC);
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stat_length = entry->frequency >> ((entry->vbr) ? 5 : 7);
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for (frames = 1, total = 0; frames < stat_length; frames++)
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{
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unsigned int frame_length = (((unsigned int)buf[1] & 0x3) << 11)
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| ((unsigned int)buf[2] << 3)
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| ((unsigned int)buf[3] >> 5);
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total += frame_length;
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if (frame_length < 7)
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break;
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if (-1 == lseek(fd, frame_length - 7, SEEK_CUR))
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break;
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if (!check_adts_syncword(fd))
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break;
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if (read(fd, buf, 5) != 5)
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break;
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}
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entry->bitrate = (unsigned int)((total * entry->frequency / frames + 64000) / 128000);
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if (entry->frequency <= 24000)
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{
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entry->frequency <<= 1;
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entry->needs_upsampling_correction = true;
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}
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}
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else
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{
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uint32_t bitrate;
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if (-1 == lseek(fd, entry->first_frame_offset, SEEK_SET))
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return false;
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if (read(fd, buf, 5) != 5)
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return false;
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if (memcmp(buf, "ADIF", 4))
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return false;
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if (-1 == lseek(fd, (buf[4] & 0x80) ? (entry->first_frame_offset + 9) : entry->first_frame_offset, SEEK_SET))
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return false;
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read_uint32be(fd, &bitrate);
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entry->vbr = (bitrate & 0x10000000) != 0;
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entry->bitrate = ((bitrate & 0xFFFFFE0) + 16000) / 32000;
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read_uint32be(fd, (uint32_t*)(&(entry->frequency)));
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entry->frequency = sample_rates[(entry->frequency >> (entry->vbr ? 23 : 3)) & 0x0F];
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}
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entry->length = (unsigned long)((entry->filesize * 8LL + (entry->bitrate >> 1)) / entry->bitrate);
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return true;
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}
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