5/28 cplay 2.0b26 音質高於foobar的純播放軟體

cplay 5/28 出了最新版，除了原本的SRC Resampler之外，又多加了SoX模式可使用
喜歡高於foobar音質的電腦訊源，試試看這版吧...

下載點：
http://sourceforge.net/projects/cplay/

以下為相關操作與設定原理：
http://www.audioasylum.com/forums/pcaudio/messages/3/31286.html


For some changes to take effect (ASIO, Buffer, AWE and Output Rate), a restart is required. ASIO changes (from cPlay or external) will cause cPlay to stop (and a restart is required). This is an important safety measure.
When changing rates (e.g. 96 to 44.1), some ASIO soundcards will re-map its channels – cPlay tries to detect this (depending on ASIO driver) and informs you to reset left & right channels. Why? Soundcards using the ADAT interface use channel multiplexing (i.e. 96k gives 2x48k...) hence channels change with rate.

cMP setting disables file browse button (to prevent indefinite waits in cMP²).

Buffer

"DSP Buffer" at Auto (default), Small, Medium or Large is provided. Small sets parameters as per cPlay 1.1, Medium as cPlay 1.0 and Auto selects parameters based on output rate.

Guidance: CPUs with 2MB+ L2 cache, use Auto setting. Small is ideal for high output rates (above 96k) whilst Medium is best for 96k or lower. On CPUs offering less than 2MB L2 cache, Small is recommended for all output rates. 'Large' buffer setting is used by Auto when output rate is 48k or less. Processors with L2 cache size larger than 2MB, its worth testing Medium and Large settings (for any output rate).

These buffer sizes work best with low ASIO buffer or latency setting (less than 512 samples).

Resampler

Phase (0-100)
All resamplers use filters that can sometimes create `echo' (a.k.a. `ringing') artefacts with transient signals such as those that occur with `finger snaps' or other highly percussive sounds. Such artefacts are much more noticable to the human ear if they occur before the transient (`pre-echo') than if they occur after it (`post-echo'). Note that frequency of any such artefacts is related to the smaller of the original and new sampling rates but that if this is at least 44.1kHz, then the artefacts will lie outside the range of human hearing.

A phase response setting may be used to control the distribution of any transient echo between `pre' and `post': with minimum phase (0), there is no pre-echo but the longest post-echo; with linear phase (50), pre and post echo are in equal amounts (in signal terms, but not audibility terms); the intermediate phase (25) setting attempts to find the best compromise by selecting a small length (and level) of pre-echo and a medium lengthed post-echo. Note that phase responses between `linear' (50) and `maximum' (50..100) are rarely useful.


Bandwidth (90-99.7%)
Band-width is the percentage of the audio frequency band that is preserved. A resampler's band-width setting determines how much of the frequency content of the original signal (w.r.t. the orignal sample rate when up-sampling, or the new sample rate when down-sampling) is preserved during conversion. The term `pass-band' is used to refer to all frequencies up to the band-width point (e.g. for 44.1kHz sampling rate, and a resampling band-width of 95%, the pass-band represents frequencies from 0Hz (D.C.) to circa 21kHz). Increasing the resampler's band-width results in a slower conversion and can increase transient echo artefacts (and vice versa).

The -s `steep filter' option (99.0% bandwidth) changes resampling band-width from the default 95% (based on the 3dB point), to 99%. Band-width values greater than 99% are not recommended for normal use as they can cause excessive transient echo.


(Above Bandwidth) Aliasing
Aliasing above the pass-band is allowed. For example, with 44.1kHz sampling rate, and a resampling band-width of 95%, this means that frequency content above 21kHz can be distorted; however, since this is above the pass-band (i.e. above the highest frequency of interest/audibility), this may not be a problem. The benefits of allowing aliasing are reduced processing time, and reduced (by almost half) transient echo artefacts.


More details and measurements is available under cPlay 2.0b26 Release Notes.