能否终结音质讨论？看这里
1、原始扫频信号图
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2、基础参考 不完美 / 完美 信号响应对比图（暗色部分均为噪音）
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3、非完美的实例
http://src.infinitewave.ca/help.html在此看完整说明
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上图为正弦波扫频出现非线性失真。
测试中说明低通过滤没有防止超声频率窜入可耳闻频段。
（Spectrogram of the swept sine with non-linear distortions.The sweep test shows that the low-pass filter has not efficiently suppressed the ultrasonic tone and it has been aliased back into the audible band. The background of the spectrogram is almost completely black, indicating the absence of any significant quantization noise.）
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1-kHz tone and non-linear distortions.The tone test indicates that quantization noise is practically absent in this case. However non-linear distortions are present with the relative level of the spectral peaks around -110 dB (their total relative level can be around -100 dB.) This is in agreement with fig. 1 (column around 1.2 sec).
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Frequency response in the passband.
The frequency response in the passband is flat, and it starts to fall-off after 18 kHz, reaching -1 dB at 20 kHz.
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Frequency response in the transition band.The frequency response in the transition band shows the roll-off after Nyquist frequency is very gentle, and this can lead to aliasing if the signal contains significant energy above 22 kHz (as in fig. 1). On the other hand, this gentle slope provides good filter performance in the time domain, reducing the amount of "ringing". It should be noted that the "ringing" of filters during SRC is mostly concentrated near Nyquist frequency because this range contains variations of the frequency response (here it is usually a range of 20-24 kHz). Even though it is in the ultrasonic range, there is some evidence that excessive ringing of an SRC filter negatively affects the overall sound, smearing the stereo image and reducing the clarity of bass.
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Phase response of the resampling filter.As seen in the graph, the example filter has a non-linear phase response similar to minimum-phase.
This is also visible from the impulse response graph (下图的上半部)
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Impulse responses of resampling filters. Top is a minimum-phase filter with a gentle cutoff. Bottom is a linear-phase filter with a steep cutoff.Typical SRC filters have a linear phase response (ringing is equally shared between pre- and post-ringing) and steep cutoff of frequency response (图中下半部).An important option in SRC algorithms is the ability to adjust parameters. Most of the tested algorithms have a "quality" control that usually sets the filter steepness. Other important controls could be trimming of the filter cutoff frequency and selection of the phase response type. Most of the tested algorithms provide reasonably good conversion quality, with the graphs showing very low distortion levels. Performance measurement almost doesn't correlate with the price of the product, in all price ranges there are good and poor-quality units. It is not always possible to judge subjective quality from the presented measurement results.
4、直接在菜单中查看各类DAW或者音频播放器的核心处理效果。
以下是嵌入的网页：http://src.infinitewave.ca/
看完后~ 是不是有点与实际感觉矛盾？
声音作为资源供给给耳朵，就如同水，最干净的声音当然是最合适的声音，
但实际却没有个‘最’字，99.999%理论是也。
无论测试结果如何，听感都有主观因素，所以也不一定是更干净的声音就是最更合适的声音，应优先对待听众群体的主观感。
[ 本帖最后由 Starryson 于 13-1-27 05:29 编辑 ]
2、基础参考 不完美 / 完美 信号响应对比图（暗色部分均为噪音）
3、非完美的实例
http://src.infinitewave.ca/help.html在此看完整说明
上图为正弦波扫频出现非线性失真。
测试中说明低通过滤没有防止超声频率窜入可耳闻频段。
（Spectrogram of the swept sine with non-linear distortions.The sweep test shows that the low-pass filter has not efficiently suppressed the ultrasonic tone and it has been aliased back into the audible band. The background of the spectrogram is almost completely black, indicating the absence of any significant quantization noise.）
1-kHz tone and non-linear distortions.The tone test indicates that quantization noise is practically absent in this case. However non-linear distortions are present with the relative level of the spectral peaks around -110 dB (their total relative level can be around -100 dB.) This is in agreement with fig. 1 (column around 1.2 sec).
Frequency response in the passband.
The frequency response in the passband is flat, and it starts to fall-off after 18 kHz, reaching -1 dB at 20 kHz.
Frequency response in the transition band.The frequency response in the transition band shows the roll-off after Nyquist frequency is very gentle, and this can lead to aliasing if the signal contains significant energy above 22 kHz (as in fig. 1). On the other hand, this gentle slope provides good filter performance in the time domain, reducing the amount of "ringing". It should be noted that the "ringing" of filters during SRC is mostly concentrated near Nyquist frequency because this range contains variations of the frequency response (here it is usually a range of 20-24 kHz). Even though it is in the ultrasonic range, there is some evidence that excessive ringing of an SRC filter negatively affects the overall sound, smearing the stereo image and reducing the clarity of bass.
Phase response of the resampling filter.As seen in the graph, the example filter has a non-linear phase response similar to minimum-phase.
This is also visible from the impulse response graph (下图的上半部)
Impulse responses of resampling filters. Top is a minimum-phase filter with a gentle cutoff. Bottom is a linear-phase filter with a steep cutoff.Typical SRC filters have a linear phase response (ringing is equally shared between pre- and post-ringing) and steep cutoff of frequency response (图中下半部).An important option in SRC algorithms is the ability to adjust parameters. Most of the tested algorithms have a "quality" control that usually sets the filter steepness. Other important controls could be trimming of the filter cutoff frequency and selection of the phase response type. Most of the tested algorithms provide reasonably good conversion quality, with the graphs showing very low distortion levels. Performance measurement almost doesn't correlate with the price of the product, in all price ranges there are good and poor-quality units. It is not always possible to judge subjective quality from the presented measurement results.
4、直接在菜单中查看各类DAW或者音频播放器的核心处理效果。
以下是嵌入的网页：http://src.infinitewave.ca/
看完后~ 是不是有点与实际感觉矛盾？
声音作为资源供给给耳朵，就如同水，最干净的声音当然是最合适的声音，
但实际却没有个‘最’字，99.999%理论是也。
无论测试结果如何，听感都有主观因素，所以也不一定是更干净的声音就是最更合适的声音，应优先对待听众群体的主观感。
[ 本帖最后由 Starryson 于 13-1-27 05:29 编辑 ]
