diff options
Diffstat (limited to 'magic/scripts')
-rwxr-xr-x | magic/scripts/create_filemagic_flac | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/magic/scripts/create_filemagic_flac b/magic/scripts/create_filemagic_flac new file mode 100755 index 0000000..0ecfb17 --- /dev/null +++ b/magic/scripts/create_filemagic_flac @@ -0,0 +1,71 @@ +#!/usr/bin/env bash + +## bash script to generate file magic support for flac. +## https://github.com/file/file/blob/master/magic/Magdir/audio +## below "#some common sample rates" (line 471), ie: +## >>17 belong&0xfffff0 0x2ee000 \b, 192 kHz + +LANG=C + +target=magic/Magdir/audio + +## construct static list of sample rates based on standard crystal +## oscillator frequencies. +## 16.384 MHz Unknown audio application +## (16384 kHz = 32 kHz * 512 = 32 * 2^9) +## 22.5792 MHz Redbook/CD +## (22579.2 kHz = 44.1kHz * 512 = 44.1 * 2^9) +## also used: 11.2896, 16.9344, 33.8688 and 45.1584 +## 24.576 MHz DAT/Video +## (24576 kHz = 48 kHz * 512 = 48 * 2^9) +## also used: 49.1520 + +## 33.8688 > 16.9344 +## 36.864 > 18.432000 +declare -a a_ground_fs=(16384000 22579200 24576000) + +## multiply ground clock frequencies by 1953 to get usable base +## frequencies, for instance: +## DAT/video: 24.576 MHz * 1000000 / 512 = 48000Hz +## Redbook/CD: 22.5792 MHz * 1000000 / 512 = 44100Hz +## use base rates for calculating derived rates +declare -a samplerates +## min divider: fs/n +def_fs_n=512 +min_fs_n=4 +## start at base_fs/(def_fs*min_fs) +## add each derived sample rate to the array +for base_fs in "${a_ground_fs[@]}"; do + min_fs=$( echo "${base_fs} / ( ${def_fs_n} * ${min_fs_n} )" | bc) + ## max multiplier: fs*n*min_fs + max_fs_n=$(( 8 * min_fs_n )) + n=${max_fs_n} + while [[ ${n} -ge 1 ]]; do + sample_rate=$(( min_fs * n )) + samplerates+=(${sample_rate}) + n=$(( n / 2 )) + done +done + +declare -a stripped_rates +declare -a lines +for samplerate in "${samplerates[@]}"; do + ## use bc with sed to convert and format Hz to kHz + stripped_rate="$(LANG=C bc <<< "scale=5; ${samplerate} / 1000" | \ + sed 's#[0\.]*$##g')" + ## only add uniq sample rates (should be necessary + if [[ ! "${stripped_rates[@]}" =~ ${stripped_rate} ]]; then + printf -v line ">>17\tbelong&%#-15x\t%#08x\t%s, %s kHz\n" \ + "16777200" \ + "$(( samplerate * 16 ))" \ + "\b" \ + "${stripped_rate}" + stripped_rates+=("${stripped_rate}") + lines+=("${line}") + fi + +done +printf "## start cutting >>> \n" +## print out the formatted lines +printf "%s" "${lines[@]}" | sort -k5 -n +printf "## <<< stop cutting\n" |