From Hydrogenaudio Knowledgebase
Revision as of 13:42, 25 March 2005 by A Man Eating Duck (Talk | contribs)
The creation of Ivan Dimkovic (who now works on Nero AAC), PsyTEL AAC was one of the first AAC encoders. Its multi-channel support has bugs that make it unusable, but it's 2 channel had the best quality available in its day. Since the implementation of Nero AAC, this codec has become obselete. It's is now outclassed by both Nero AAC and iTunes.
Usability (Psytel aacenc/fastenc)
For music encoding. The quality ranges from -tape (lowest [VBR] quality) to -ultra (highest [VBR] quality). Ultra is considered overkill for most audio tracks, i.e: shouldn't be used except for extremely difficult music signals. Example: aacenc -extreme -if "audio file.wav"
Encoder switches (Psytel aacenc/fastenc)
- Input filename. The name of the track to be encoded (must be a .wav file)
- Output filename. May be omitted, because encoder will automatically set best output file name.
- BitRate switch. Sets the number of bits utilized per second for the encoding process. Example: aacenc -br 192 -if "audio file.wav"
- High quality [VBR] mode. Can be used with -br switch to select base BitRate. If -br is not specified, it takes as default 64kbps/channel. Example: aacenc -br 192 -vbrhi -if "audio file.wav"
- Lower quality [VBR] mode. Recommended for internet streaming. Example: aacenc -vr -if "audio file.wav"
- LowPassFilter cut-off (in hertz). Not recommended. Example: aacenc -br 128 -c 15995 -if "audio file.wav"
- Encoder quality level (1 to 9). 9 is usually taken as default, but you can use smaller numbers if you need high speed and high quality isn't essential. Example: aacenc -br 192 -qual 9 -if "audio file.wav"
- Use adif instead of adts (default) header. For compatibility with some decoder software and hardware players. Example: aacenc -br 192 -adif -if "audio file.wav"
- No headers (raw iso aac stream). For decoder compatibility, and can improve. Example: aacenc -br 192 -nh -if "audio file.wav"
- -profile "x"
- Choose iso aac encoding profile:
- 0 - low complexity (default, recommended)
- 1 - main (not recommended, buggy)
- 2 - main ltp (mpeg-4 only)
- Only lc profile is playable on hardware players so far. Example: aacenc -br 192 -profile 2 -if "audio file.wav"
- Improved human speech coding. Best for human voice encoding. Not recommended for low Bitrates or [CBR] coding. Example: aacenc -vbrhi -br 192 -ihsc -if "audio file.wav"
- Tells encoder to use highest sensitivity threshold of audibility. Not recommended on Bitrates lower than 192kbps. Example: aacenc -br 192 -low_ath -if "audio file.wav"
- (perceptual noise substitution) - Improves the quality at very low Bitrates. Should be used only at 64kbps or less. Example: aacenc -br 56 -pns -if "audio file.wav"