ATRAC3

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Revision as of 15:52, 18 November 2006 by Merbanan (talk | contribs) (Added extradata parsing and some transform info.)
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Found in some old RealMedia files. Suspected to be similar to, or the same as, Sony ATRAC.

Atrc flavors

0  66 Kbps Stereo Music - RA 8
1  94 Kbps Stereo Music - RA 8
2  105 Kbps Stereo Music - RA 8
3  132 Kbps Stereo Music - RA 8
4  146 Kbps Stereo Music - RA 8
5  176 Kbps Stereo Music - RA 8
6  264 Kbps Stereo Music - RA 8
7  352 Kbps Stereo Music - RA 8

Specification

Extra data format

In rm files the extra data is as follows (big endian order):

INT32	id, always == 4
INT16	samples per frame, always 1024 * 2
INT16	delay, not used but always 0x88E
INT16	stereo coding mode, 2 - normal stereo, 0x12 - joint stereo

It is always 10 bytes of data.

Transforms

QMF

MLT

The transform is the same as the MPEG AAC SSR profile with the exception of a special window.

MLT Window table

atrac_window[256] = {
   9.41253620112548e-06,8.47234623506665e-05,0.000235401996178553,0.000461561692645773,
   0.000763372576329857,0.00114106200635433,0.00159491400700063,0.00212526903487742,
   0.00273252697661519,0.00341714196838439,0.00417962903156877,0.00502056023105979,
   0.00594056397676468,0.00694032711908221,0.00802059844136238,0.00918218307197094,
   0.0104259504005313,0.0117528103291988,0.013163760304451,0.0146598499268293,
   0.0162421800196171,0.017911909148097,0.019670270383358,0.0215185508131981,
   0.023458119481802,0.0254903696477413,0.0276167895644903,0.0298389103263617,
   0.0321583412587643,0.0345767587423325,0.0370958782732487,0.0397174991667271,
   0.0424434691667557,0.04527572914958,0.048216238617897,0.0512670800089836,
   0.0544303394854069,0.0577081888914108,0.0611028708517551,0.0646167024970055,
   0.0682519972324371,0.0720112174749374,0.0758968368172646,0.0799113884568214,
   0.084057442843914,0.0883376598358154,0.0927547365427017,0.0973114371299744,
   0.102010503411293,0.106854900717735,0.111847400665283,0.116990998387337,
   0.122288599610329,0.127743199467659,0.133357793092728,0.139135494828224,
   0.145079404115677,0.151192396879196,0.157477602362633,0.163938298821449,
   0.170577302575111,0.177397698163986,0.184402495622635,0.191594794392586,
   0.198977395892143,0.20655320584774,0.214325100183487,0.222295597195625,
   0.230467602610588,0.238843500614166,0.247425600886345,0.256216287612915,
   0.265217810869217,0.274431705474854,0.283860206604004,0.293504595756531,
   0.303366303443909,0.313446491956711,0.323745906352997,0.334265112876892,
   0.345004290342331,0.355963587760925,0.367142498493195,0.378540098667145,
   0.390155404806137,0.401986807584763,0.414032310247421,0.426289200782776,
   0.438754886388779,0.451425611972809,0.464297711849213,0.477366387844086,
   0.490626811981201,0.504073321819305,0.517699420452118,0.531498670578003,
   0.545463383197784,0.559585571289062,0.573856592178345,0.588267087936401,
   0.602807104587555,0.617465972900391,0.632232785224915,0.647095382213593,
   0.662041485309601,0.677057981491089,0.692131519317627,0.707247793674469,
   0.722392320632935,0.737549722194672,0.752704918384552,0.767841517925262,
   0.782943487167358,0.797994315624237,0.812976777553558,0.827874422073364,
   0.842669785022736,0.857345581054688,0.871884822845459,0.886269986629486,
   0.900484383106232,0.91451108455658,0.928333282470703,0.941935122013092,
   0.955300509929657,0.968414008617401,0.981260776519775,0.993826687335968,
   1.00609803199768,1.01806199550629,1.02970600128174,1.04101896286011,
   1.05199003219604,1.06261003017426,1.07287001609802,1.08276200294495,
   1.09228003025055,1.10141599178314,1.11016702651978,1.118528008461,
   1.12649703025818,1.13407099246979,1.14124798774719,1.14803004264832,
   1.15441703796387,1.16040897369385,1.16601002216339,1.17122399806976,
   1.17605304718018,1.18050396442413,1.18457996845245,1.18828999996185,
   1.19163799285889,1.19463300704956,1.19728195667267,1.1995929479599,
   1.20157599449158,1.20323896408081,1.20459198951721,1.2056440114975,
   1.20640504360199,1.20688498020172,1.20709502696991,1.2070449590683,
   1.20674395561218,1.20620501041412,1.20543599128723,1.20444905757904,
   1.20325398445129,1.20186197757721,1.20028102397919,1.19852304458618,
   1.19659698009491,1.19451296329498,1.19228100776672,1.18991005420685,
   1.18740999698639,1.18478798866272,1.18205404281616,1.17921698093414,
   1.17628395557404,1.17326295375824,1.17016303539276,1.1669909954071,
   1.16375398635864,1.16045904159546,1.15711295604706,1.15372204780579,
   1.15029203891754,1.14683103561401,1.14334201812744,1.13983201980591,
   1.13630700111389,1.13276994228363,1.1292279958725,1.12568402290344,
   1.12214398384094,1.11861002445221,1.11508798599243,1.11158096790314,
   1.10809302330017,1.10462701320648,1.1011860370636,1.09777402877808,
   1.09439396858215,1.09104800224304,1.08773899078369,1.08446896076202,
   1.08124196529388,1.07805800437927,1.07492101192474,1.07183194160461,
   1.06879305839539,1.06580603122711,1.062873005867,1.05999398231506,
   1.05717301368713,1.05440902709961,1.05170500278473,1.04906094074249,
   1.04647898674011,1.0439590215683,1.04150295257568,1.03911197185516,
   1.03678703308105,1.03452801704407,1.03233599662781,1.03021097183228,
   1.028156042099,1.02616894245148,1.0242520570755,1.02240598201752,
   1.02063000202179,1.01892495155334,1.01729202270508,1.01573097705841,
   1.01424205303192,1.01282596588135,1.01148295402527,1.01021301746368,
   1.00901699066162,1.00789403915405,1.00684499740601,1.00587105751038,
   1.00497102737427,1.00414502620697,1.0033940076828,1.00271797180176,
   1.00211596488953,1.00159001350403,1.00113797187805,1.00076198577881,
   1.00046098232269,1.0002349615097,1.00008499622345,1.00000894069672,
};