TuneFUSION DSP Help

TuneFUSION { Help Index > DSP Effects }

DSP (or Digital Signal Processing) Effects fall into two main categories:

Manipulate audio data, such as Graphic Equalizer,

Perform an action, such as ID Tag Processing.

Effects are processed in the order they appear, for example:

Bit Depth (to floating point)
Resample from 192KHz to 44.1KHz
Volume Normalize (Peak to Peak) to 0dB Desired
Bit Depth (to 16 bit with dither)

The Volume Normalize (peak to peak) would declip any samples which are clipping and scale the whole audio file down to prevent clipping, this can only be done whilst the Bit Depth is in Floating Point.

DSP Effects

	Audio CD - Hidden Track Silence Removal	Remove mid-track silence
	Bandpass	Filters frequencies above and below the specified frequencies
	Bit Depth	Set sample bit depth (example 24 bit to 16 bit)
	Channel Count	Increase or decrease channels
	Channel Mapper	Move or combine channels
	CPU Throttle	Slows encoding
	Dynamic Range Compression	Level-out large changes in audio level
	Fade	Fade in or out to silence
	Graphic Equalizer	Boost or reduce frequencies
	Highpass	Filters all frequencies below the specified frequency
	ID Tag Processing	Manipulate ID Tags
	Karaoke	Remove voice or instruments
	Lowpass	Filters all frequencies above the specified frequency
	Maximum / Minimum Length	Increase or decrease length
	ReplayGain	Calculate Replay Gain, or EBU R128 volume adjustment (written to ID Tags)
	ReplayGain (Apply)	Apply Replay Gain adjustment to converted file
	Resample	Change Sample Rate Frequency
	Trim Silence	Remove silence from beginning or end
	Volume Normalize	Adjust volume in many different ways

Effects in Detail

		Audio CD - Hidden Track Silence Removal
		Audio CDs can have a 'hidden' last track which is really the last track with a long period of silence before the hidden track. This effect removes the silence period, set the Detection Threshold large enough to ignore periods of silence normal tracks might contain.

		Bit Depth
		Bit Depth can be used on one of two ways, to force a set bit depth (for example the source audio file is 24 bit, and reduce to 16 bit). Or to increase bit depth to 32 bit (floating point), process other DSP effects (such as Graphic Equalizer), then set the depth back down to 16 bit, by including Bit Depth twice, first and last. 32 bit floating point allows the value of the audio signal to go over the clipping level (+-1.0), certain effects such as Graphic Equalizer can introduce increases over the maximum, before reducing to 16 or 24 bit, include Volume Normalize set to Peak to Peak. Apply Dither can be used to dither when reducing the bit depth, such as after volume normalizing (at 32 bit floating point), dither in the final stage to 16 bit. Triangular dither is the preferred option.

		Channel Count
		Forces a channel count, or set allowed minimum and maximum channel counts as supported by a player.

		Channel Mapper
		Channel Mapper sets a desired number of channels, each channel can be edited, choosing which source channel(s) it is made up from. In the above example Channel 1 and 2 are left untouched, and channel 3 is created from the sum of channel 1 reduced by 50% and channel 2 reduced also.

		CPU Throttle
		Slows Encoding Speed, based on simulated speeds. For example, x2 will encode a track that is 60 seconds long in 30 seconds. This effect can reduce the load on CPU usage (and therefore heat generated), the exact CPU reduction depends on the normal unrestricted CPU usage when encoding. A codec encodes normally at x24, if setting this to x12 then only half the CPU resource would be used when encoding.

		Dynamic Range Compression
		Compresses dynamic range to level-out large changes in audio level and render a "tighter" sound. This DSP is a so-called "hard-knee compressor" and can be used to reduce the effects of over-produced jingles or adverts in combination with under-produced speech (e.g. in Podcasts). A relative threshold can be applied which makes the threshold level, at which the compressor starts working, relative to the file's overall RMS value. When using a relative threshold, the threshold value should be in the range -1 to -6dB for the best results. When using a fixed threshold (i.e. not relative), the value could be quite a bit lower (in the range -3dB to -30dB) depending on audio content. Compression ratio determines how much gain reduction will be applied above the threshold level. Attack time is the time taken to respond to audio level increases above a set threshold level. If this is value is too high, the compressor will let through transient peaks of audio. A short attack time is recommended. Release time is the time taken to reduce gain (or recover) after an decrease in audio level below the set threshold level. A too short release time could give undesirable pumping effects. It is better to use quite a high value for this ( > 500 mS).

		Fade
		Fades in, or / and Fade Out, to silence, over specified time. 6000 milli-seconds is 6 seconds.

		Graphic Equalizer
		Graphic Equalizer boosts or reduces selected frequencies. 0 dB leaves the frequency untouched, +12 dB increases the amplitude at that frequency by four and -12 dB is divide by four. Care must be taken when increasing frequencies as clipping can occur (where the signal goes over maximum allowed), if possible reduce other frequencies, leaving the frequency to boost at 0 dB. >> Offers a menu to Load, Save and select Preset values. Also is the option to adjust single bars, instead of moving neighbour bars also.

ID Tag Processing

ID Tag Processing can perform actions on ID Tags / Album Art whilst converting, ensuring best compatibility with players or the new format.

ID Tags can be manipulated by:

Map

Copies a tag to another name, for example map Artist to Album Artist. The original tag is kept, use Deletion if needs removing.

Deletions

Remove All Tags, All Except, or delete a Single Tag value. In the example all ID Tags are removed except the 3 listed.

Manipulation

Capitalization: when using meta data sources such as freedb there is little consistency between discs, this option allows character capitalization to be set. The Smart Capitalization option would create a tag 'A tag and Another' from 'A TAG AND ANOTHER'.

Import & Export Album Art to / from files.

Specify a Maximum Art Size (pixel or KB size).

Force embedded Album Art to JPG art could be PNG which certain players do not support.

Rule Based Manipulation offers advanced programmable actions, such as:

IF Genre=[anyvalue]	set if Genre if contains a value
SET Genre=Rock
IF Genre=	set genre if contains nothing
SET Genre=Unknown
IF Genre=Alt Rock	genre matches Alt Rock, set to Rock
SET Genre=Rock
IF Album=Christmas	example showing setting a different tag
SET Genre=Christmas
IFCONTAINS Album=Best of	for generic albums, add the artist name
SET Album=[album], [artist]
IF Album Artist=	set album artist if empty (from artist)
SET Album Artist=[artist]
IF Artist=	if no artist then set to unknown
SET Artist=Unknown Artist

Word / Character Replacement allows individual characters or whole words to be substituted with another character or word, or to be deleted when no substitution is specified.

Externally Script Tags runs an external script to alter ID Tags see full scripting details

Multiple Artist To 'Artist1; Artist2' dBpoweramp follows standards set by tagging formats when it comes to handling multiple artists, each tag type is different. Problems arise when another programs do not follow these standards, a program might not read the 2nd Artist when stored in a multi artist tag. This option forces all artists into one artist, separated by '; '. Be aware, programs which follow the tagging conventions correctly will not detect 2 separate artists.

Multiple Artist From 'Artist; Artist2' does the opposite of above.

Remove Month & Day from Year takes a 1990 12 30 date and shortens to 1990.

Drop Track Count removes the count from a track number, example 4/12 becomes 4.

Drop Disc Count removes the count from a disc number, example 1/2 becomes 1.

CRC32 and MD5 can be calculated for the audio and embedded in the ID tags, note ID Tag Processing should be the last DSP effect, other effects might change the audio.

Additions

Add new tags, for example it is possible to add a Comment set to (c) Your Company.

The order of manipulations carried out are: Map, Deletions, Manipulation finally Additions.

		Karaoke (Voice, Instrument Removal)
		Either voice or instruments (leaving the voice) can be removed from an audio piece. The effect requires a stereo audio file, where the singer was mastered into the centre of the two speakers, not all audio tracks are like this. Even then there will still be a small amount of instrument or voice in the background.

		Lowpass / Bandpass Filter / Highpass
		Applies a filter to the specified frequencies. For Bandpass frequencies below and above the specified frequencies are filtered. Highpass, filters all frequencies below the set value and lowpass filters all frequencies above. This filter is not a hard cut off filter, it is applied gradually affecting frequencies around the specified point. An example usage of this filter is with the DSD decoder codec, where it might be decoded to 176KHz, a 40KHz lowpass filter can be applied to remove all harmful ultrasonics from DSD.

		Maximum / Minimum Length
		Maximum Length, if the audio file is longer than the length set, it is truncated. If the audio file is has a less length than the maximum specified, it is left at the original length. It is also possible to limit the length based on a percentage of the original length. Minimum Length increases an audio file to the minimum length set, silence is used to increase the file. If the file is longer than the minimum length it is left at its original length. This effect is a non-live DSP Effect.

		ReplayGain
		ReplayGain calculates average loudness of audio files on a track or album basis, a compatible player will play all tracks with the same loudness. ReplayGain values are written to ID Tags, audio is untouched. There are two types of ReplayGain: Track Gain: volume levels are calculated for on a track-by-track basis, Album Gain: calculated levels are for the whole album, an intentionally quiet track remains so. Write specifies which tags are written, including iTunes compatible tags. Advanced page enables fine tuning of: Albums identified by either the album ID tag, or all files in same batch, or all tracks in the same folder regardless of the ID Tags. Gain Calculation EBU R128 is recommended, to the reference target loudness of -18 LUFS. It is also possible to disable the clip prevention, the player should have clip prevention if disabled. True peak oversamples the file on calculation, which often happens on playback by DACs, this allows oversampled clipping to be calculated and taken into account.

		ReplayGain (Apply)
		This DSP is for those who have files already tagged with ReplayGain tags, but do not have a compatible player, the volume is adjusted as the file is converted. Replay Gain calculates the average loudness of audio files, normally the gain adjustment is written to the ID Tags for a compatible player. Use the effect Volume Normalize if want the same effect but source files do not already contain RG ID Tags. Mode sets which type of ReplayGain tag to use, Track or Album Gain. Limit peaks to X dB uses ReplayGain to remove clipping using stored clip values. Preamp can be used to set a lower target volume, inactive ReplayGain refers to source files with no ReplayGain tags.

		Resample
		Sample Rate Conversion (SRC): audio is resampled from one frequency to another, typically a higher frequency to a lower frequency for compatibility reasons (audio player which cannot play higher frequencies). There is an option to set Minimum and Maximum frequencies, this enables the supported frequencies of a player to be set and files will be resampled within this range, frequencies already within the range are left untouched. Advanced options page allows SRC conversion routine to be selected. See SRC conversion tutorial and view test results of various different SRC.

		Trim Silence
		On certain tracks is silence present at the beginning or end of the track. This DSP effect can detect and remove such silence. Detection Threshold sets the minimum time average audio levels have to go over the set silence value before it is classed as non-silence. If Trim Silence is eating audio it should not, enter a lower dB value, such as -44. This effect is non-live.

		Volume Normalize
		Adjusts volume by amplification of the audio signal. There are 6 different ways of adjusting volume. Note the process is lossy, that if the volume is halved the reduction is lost forever and cannot be reversed, as such it should be done on a copy of a lossless library, keeping the originals safe: Peak to Peak: simplest, peak (or maximum) value is found and the whole track volume is adjusted so that peak touches the desired volume, ReplayGain: a more advanced, the average loudness is calculated and the volume is adjusted. This method does not use ID Tags to store ReplayGain values, rather the audio is adjusted. If a Replay Gained track is played next to a non-Replay Gained track, it will sound quieter, as Replay Gain requires head-room to prevent clipping. EBU R128: a newer standard of ReplayGain, the average loudness is calculated and the volume is adjusted. This method adjusts the audio. Internally the audio is calculated to a -18LUFS level which is adjustable. Adaptive: the best way to describe adaptive, is like having your hand on the volume knob, constantly adjusting it up and down (a window is used to detect loudness) to compensate for quiet parts, ideal for creating a track to play in a noisy environment (such as car). Adaptive is offered for EBU and Peak to Peak volume calculation. Fixed Amplification: Amplifies the audio by a fixed amount, +6 dB is x2, where -6 dB is divide by 2, be careful not to clip audio (go over the maximum). Reduce if Above: Allows the volume to be reduced to match a set value (based on peak to peak). Ideal if using a DSP effect chain with the audio set to floating point, to reduce the audio to a set peak value, prior to setting the audio to PCM. Differs from Peak to Peak, in that if the existing peaks are below the desired value, it is not scalled up. Maximum Amplification sets a limit on the amount of amplification applied (set too high, on adaptive and silence will become noise). Desired Volume can be set higher than 0 dB (which is maximum), setting 12 dB is 4x the maximum, use with care otherwise the signal will clip. This effect is non-live.

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