ROQ to AAC
Convert ROQ to AAC, ROQ to AAC Converter
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ROQ to AAC software converts ROQ to AAC. The software is an ALL-IN-ONE audio converter that supports more than 90 audio and video files.
ROQ to AAC software supports batch conversion and is full compatible with Vista and Windows 7.
What is ROQ?
The format runs at a fixed 30 frames per second with an optional 22050 Hz mono or stereo sound track. Videos may technically be up to 65520 x 65520 pixels with both dimensions divisible by 16 and produce a valid RoQ file, but none of id Software's games will play back a video with dimensions that aren't a power of two, most likely because of OpenGL's texture sizing restrictions.
NOTE: It's been reported that movies with dimensions greater than 512 x 512 cause issues in various id Software games. Until this can be positively confirmed or denied it's best to avoid higher resolutions.
RoQ is a motion compensating vector quanitizer format, similar to Cinepak, but higher quality due to the use of the ITU-R BT.601 colorspace (the same one used in component video, PAL televisions, JPEG and MPEG), whereas Cinepak uses a low-quality YUV-like colorspace designed for faster decoding that often results in gamut degradation before compression even begins.
Because it's a vector quantizer, RoQ files are very fast to decode and very slow to encode. Decoding involves nothing more than converting the colorspace of the codebooks and then copying data, whereas encoding involves using several complicated schemes to produce a "palette" of image fragments that will result in the least degradation.
RoQ uses two codebooks per frame, with the second being constructed from pieces of the first, with up to 256 entries each. Due to this, only 1024 new colors can be introduced each frame, severely limiting the color gamut. This could arguably be improved by better predicting which sections will be motion compensated, but doing so is difficult, since codebook entries are generated from non-motion-compensated image sections, but whether or not they'll be used depends on the quality of them compared to motion compensated sections, resulting in a chicken-and-egg problem. This is made worse by the fact that all three major RoQ codecs are single-pass.
While the format is limited and much lower quality than MPEG and Indeo Video, it was presumedly preferred by id Software because of the lack of royalties, the lack of patent liability that presents a serious problem with most video formats, and the absence of complex platform-specific APIs.
What is AAC?
AAC has been standardized by ISO and IEC, as part of the MPEG-2 & MPEG-4 specifications. The MPEG-2 standard contains several audio coding methods, including the MP3 coding scheme. AAC is able to include 48 full-bandwidth (up to 96 kHz) audio channels in one stream plus 15 low frequency enhancement (LFE, limited to 120 Hz) channels and up to 15 data streams. AAC is able to achieve indistinguishable audio quality at data rates of 320 kbit/s (64kbit/s/channel) for five channels. The quality is close to CD also at 96 kbit/s (48kbit/s/channel) for stereo.
AAC's best known use is as the default audio format of Apple's iPhone, iPod, iTunes, and the format used for all iTunes Store audio (with extensions for proprietary digital rights management).
AAC is also the standard audio format for Sony's PlayStation 3 and is supported by Sony's Playstation Portable, latest generation of Sony Walkman, Sony Ericsson Walkman Phone, Nintendo's Wii (with the Photo Channel 1.1 update installed for Wii consoles purchased before late 2007) and the MPEG-4 video standard. HE-AAC is part of digital radio standards like DAB+ and Digital Radio Mondiale.
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