Az AAC több lehetõséget nyújt az mp3-nál (wikipedia AAC), meg kisebb méretbe lehet bekódolni... tehát az mp3-al szemben csak elõnyei vannak (de van olyan eszköz, ami nem támogatja!).
Ugyanakkora bitrátán a mérete lesz kisebb, de nem fog jobban szólni (illetve tömörítõ minõségétõl is függ). Olcsóbb fülhallgatóval, vagy gyengébb minõség hangszórónál (pl. telefon hangszóróval) egyébként nem valószínû, hogy feltûnik valami különbség.
Ettõl függetlenül én szerintem maradok inkább az mp3-nál :)
Én egyébként videókat Super -el szoktam konvertálni, 3gp -be, aac-s hangal, és nagyon jó minõségben marad a hang (k750i telefonom van).
AAC was designed to fix many of the serious performance flaws in the MP3 format (which was specified in MPEG-1 and MPEG-2) by the ISO/IEC in 11172-3 and 13818-3.
Improvements include:
* More sample frequencies (from 8 kHz to 96 kHz) than MP3 (16 kHz to 48 kHz)
* Up to 48 channels (MP3 supports up to two channels in MPEG-1 mode and up to 5.1 channels in MPEG-2 mode)
* Arbitrary bit-rates and variable frame length. Standardized constant bit rate with bit reservoir.
* Higher efficiency and simpler filterbank (rather than MP3's hybrid coding, AAC uses a pure MDCT)
* Higher coding efficiency for stationary signals (AAC uses a blocksize of 1024 samples, allowing more efficient coding than MP3's 576 sample blocks)
* Higher coding accuracy for transient signals (AAC uses a blocksize of 128 samples, allowing more accurate coding than MP3's 192 sample blocks)
* Can use Kaiser-Bessel derived window function to eliminate spectral leakage at the expense of widening the main lobe
* Much better handling of audio frequencies above 16 kHz
* More flexible joint stereo (separate for every scale band)
* Adds additional modules (tools) to increase compression efficiency: TNS, Backwards Prediction, PNS etc... These modules can be combined to constitute different encoding profiles.
Overall, the AAC format allows developers more flexibility to design codecs than MP3 does, and corrects many of the unfortunate design choices made in the original MPEG 1 audio specification. This increased flexibility often leads to more concurrent encoding strategies and, as a result, to more efficient compression. However in terms of whether AAC is better than MP3, the advantages of AAC are not entirely decisive, and the MP3 specification, while outdated, has proven surprisingly robust in spite of considerable flaws. AAC and HE-AAC are universally accepted as better than MP3 at low bitrates (typically less than 128 kbit/s). This is especially true at very low bitrates where the superior stereo coding, pure MDCT, and more optimal transform window sizes leave MP3 unable to compete. However, as bitrate increases, the efficiency of an audio format becomes less important relative to the efficiency of the encoder's implementation, and the intrinsic advantage AAC holds over MP3 no longer dominates audio quality.
Informatika és tudomány
