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lark is a free, lite and powerful software audio DSP. It provides a flexible and scalable way to design audio route(s) with high efficiency, small footprint and low latency that enables you to build your audio system like building blocks.
lark is composed by a basic shared library liblark.so, various optional blocks(dynamic load libraries) e.g. libblkmixer.so, and an optional executable debug utility lkdb. Based on lark, you can easily create either simple or complex audio route(s) as you want, start/stop any route in realtime, or set/get parameters to/from any block in realtime.
Since lark depends on the klogging library, you should install klogging at first. Go to https://gitee.com/wksuper/klogging to get klogging installed. Alternatively the prebuilt libklogging.so is also available in this repo. It will be installed along with lark installation.
Install lark on your Linux machine.
cd lark-release
sudo ./install.sh
sudo ldconfig
You can use sudo ./uninstall.sh to remove lark when you don't need it.
Run audio route(s).
RouteA
libblkfilereader.so libblkalsaplayback.so
******************* ******************
* * * *
* filereader_0 *0--->0* alsaplayback_0 *
* * * *
******************* ******************
x86_64-linux-gnu/bin/larkexample1
If no error, the music file should be started to play.
The source code of this example is shown in larkexample1.cpp.
RouteA
libblkfilereader.so libblkdeinterleave.so libblkgain.so libblkmixer.so libblkinterleave.so libblkpaplayback.so
***************** ****************** ************* ************** ******************* ******************
* * * *0-->0* *0-------->0* *0---->0* * * *
* filereader_0 *0-->0* deinterleave_0 *1-->1* *1---+ * mixer_0 * * interleave_0 *0--->0* paplayback_0 *
* * * * * * | +-->1* * +->1* * * *
***************** ****************** * * | | ************** | ******************* ******************
* gain_0 * | | |
***************** ****************** * * | | ************** |
* * * * * * +-|-->0* *0--+
* filereader_1 *0-->0* deinterleave_0 *0-->2* *2-----+ * mixer_1 *
* * * *1-->3* *3-------->1* *
***************** ****************** ************* **************
To run example2, the PortAudio library is needed first.
sudo apt install libportaudio2
Run example2:
x86_64-linux-gnu/bin/larkexample2
If no error, the two files mixed music should be started to play.
Launch another shell where you can adjust their volume gains via lkdb.
$ lkdb status # Shows lark status
RouteA is RUNNING, 319 frames processed OK, 0 error frame
blkmixer_1
(I00) <-- lnk_7 48000Hz S16_LE 1ch 960samples/frame
(I01) <-- lnk_9 48000Hz S16_LE 1ch 960samples/frame
(O00) --> lnk_11 48000Hz S16_LE 1ch 960samples/frame
blkdeinterleave_1
(I01) <-- lnk_3 48000Hz S16_LE 2ch 960samples/frame
(O00) --> lnk_4 48000Hz S16_LE 1ch 960samples/frame
(O01) --> lnk_5 48000Hz S16_LE 1ch 960samples/frame
blkmixer_0
(I00) <-- lnk_6 48000Hz S16_LE 1ch 960samples/frame
(I01) <-- lnk_8 48000Hz S16_LE 1ch 960samples/frame
(O00) --> lnk_10 48000Hz S16_LE 1ch 960samples/frame
blkinterleave_0
(I00) <-- lnk_10 48000Hz S16_LE 1ch 960samples/frame
(I01) <-- lnk_11 48000Hz S16_LE 1ch 960samples/frame
(O00) --> lnk_12 48000Hz S16_LE 2ch 960samples/frame
blkfilereader_0
(O00) --> lnk_0 48000Hz S16_LE 2ch 960samples/frame
blkdeinterleave_0
(I00) <-- lnk_0 48000Hz S16_LE 2ch 960samples/frame
(O00) --> lnk_1 48000Hz S16_LE 1ch 960samples/frame
(O01) --> lnk_2 48000Hz S16_LE 1ch 960samples/frame
blkfilereader_1
(O00) --> lnk_3 48000Hz S16_LE 2ch 960samples/frame
blkgain_0
(I00) <-- lnk_1 48000Hz S16_LE 1ch 960samples/frame
(I01) <-- lnk_2 48000Hz S16_LE 1ch 960samples/frame
(I02) <-- lnk_4 48000Hz S16_LE 1ch 960samples/frame
(I03) <-- lnk_5 48000Hz S16_LE 1ch 960samples/frame
(O00) --> lnk_6 48000Hz S16_LE 1ch 960samples/frame
(O01) --> lnk_7 48000Hz S16_LE 1ch 960samples/frame
(O02) --> lnk_8 48000Hz S16_LE 1ch 960samples/frame
(O03) --> lnk_9 48000Hz S16_LE 1ch 960samples/frame
blkpaplayback_0
(I00) <-- lnk_12 48000Hz S16_LE 2ch 960samples/frame
No fifo
lkdb setparam RouteA blkgain_0 1 0 0.5 # Output volume of kanr-48000_16_2.pcm left channel should be lower
lkdb setparam RouteA blkgain_0 1 1 0.5 # Output volume of kanr-48000_16_2.pcm right channel should be lower
lkdb setparam RouteA blkgain_0 1 0 0.0 # Output volume of kanr-48000_16_2.pcm left channel should be muted
lkdb setparam RouteA blkgain_0 1 1 0.0 # Output volume of kanr-48000_16_2.pcm right channel should be muted
lkdb setparam RouteA blkgain_0 1 2 0.5 # Output volume of pacificrim-48000_16_2.pcm left channel should be lower
lkdb setparam RouteA blkgain_0 1 3 0.5 # Output volume of pacificrim-48000_16_2.pcm right channel should be lower
lkdb setparam RouteA blkgain_0 1 2 0.0 # Output volume of pacificrim-48000_16_2.pcm left channel should be muted
lkdb setparam RouteA blkgain_0 1 3 0.0 # Output volume of pacificrim-48000_16_2.pcm right channel should be muted
lkdb setparam RouteA blkgain_0 1 0 1.0 # Output volume of kanr-48000_16_2.pcm left channel should be recovered back
lkdb setparam RouteA blkgain_0 1 1 1.0 # Output volume of kanr-48000_16_2.pcm right channel should be recovered back
lkdb setparam RouteA blkgain_0 1 2 1.0 # Output volume of pacificrim-48000_16_2.pcm left channel should be recovered back
lkdb setparam RouteA blkgain_0 1 3 1.0 # Output volume of pacificrim-48000_16_2.pcm right channel should be recovered back
The source code of this example is shown in larkexample2.cpp.
**************** ****************** ***************
RouteA * * * * * *
* filereader_0 *0--->0* alsaplayback_0 *0--->0* streamout_0 *
* * * * * *
**************** ****************** ********|******
v
========================================================================================================================================================[FIFO]=====
|
************** ************** ************* *********************** ****************** *********** ***************** *****v********
* * * * * * * * * * * * * * * *
* dummykwd_0 *0<--0* * * * * *0<--0* deinterleave_0 *0<--0* *0<--0* alsacapture_0 * * streamin_0 *
* * * * * * * *1<--1* * * * * * * *
************** * * * * * * ****************** * * ***************** ******0*******
* * * * * * * * v
*duplicator_0*0<--0* dummybf_0 *0<--0* speexpreprocessor_0 * * align_0 * **********0*******
* * * *1<--1* (aec, denoise, ...) * * * RouteB * deinterleave_1 *
* * * * * * * * ********0**1******
* * * * * * * * v v
**************** * * * * * * * * *********** **********0**1******
* * * * * * * *16<------------------------1* * * *0<---0* *
* filewriter_0 *0<--1* * * * * * * *1<--0* mixer_0 *1<---1* speexresampler_0 *
* * * * * * * * * * * * * *
**************** ************** ************* *********************** *********** *********** ********************
To run example3, the speex libaray is needed first.
sudo apt install libspeexdsp-dev
Run example3:
# The two arguments are the alsa playback pcm name and capture pcm name.
# They vary machine by machine.
x86_64-linux-gnu/bin/larkexample3 plughw:0,0 plughw:0,0
If no error, playback and capture will be started.
The captured audio is saved in ./cap-16000_16_1.pcm.
The source code of this example is shown in larkexample3.cpp.
RouteA
libblkfilereader.so libblkformatdapter.so libblksoundtouch.so libblkpaplayback.so
**************** ******************* **************** ****************
* * * * * * * *
* filereader_0 *0--->0* formatadapter_0 *0--->0* soundtouch_0 *0--->0* paplayback_0 *
* * * * * * * *
**************** ******************* **************** ****************
To run example5, the SoundTouch library and the PortAudio library are needed first.
sudo apt install libsoundtouch-dev
sudo apt install libportaudio2
Run example5:
x86_64-linux-gnu/bin/larkexample5
If no error, playback will be started.
In the other shell,
lkdb status # Shows lark status
lkdb setparam RouteA blksoundtouch_0 1 0.6 # Sound pitch goes lower
lkdb setparam RouteA blksoundtouch_0 1 1.8 # Sound pitch goes higher
lkdb setparam RouteA blksoundtouch_0 1 1.0 # Sound pitch goes normal
lkdb setparam RouteA blksoundtouch_0 2 0.5 # Sound tempo goes slower
lkdb setparam RouteA blksoundtouch_0 2 2.0 # Sound tempo goes faster
lkdb setparam RouteA blksoundtouch_0 2 1.0 # Sound tempo goes normal
lkdb setparam RouteA blksoundtouch_0 3 2.2 # Sound rate goes faster
lkdb setparam RouteA blksoundtouch_0 3 0.4 # Sound rate goes slower
lkdb setparam RouteA blksoundtouch_0 3 1.0 # Sound rate goes normal
The source code of this example is shown in larkexample5.cpp.
RouteA
libblkfilereader.dylib libblkformatdapter.dylib libblkdeinterleave.dylib libblkmixer.dylib libblksoxeffect.dylib libblkinterleave.dylib libblkfilewriter.dylib
******************* ********************** ********************* ************** *************************** ******************* *******************
* * * * * * * *0-->0* blksoxeffect_highpass_0 *0-->0* * * *
* * * * * *0-->0* * *************************** * * * *
* blkfilereader_0 *0-->0* blkformatadapter_0 *0-->0* blkdeinterleave_0 * * blkmixer_0 * * blkinterleave_0 *0-->0* blkfilewriter_0 *
* * * * * *1-->1* * *************************** * * * (stdout) *
* * * * * * * *1-->0* blksoxeffect_lowpass_0 *0-->1* * * *
******************* ********************** ********************* ************** *************************** ******************* *******************
To run example7, the SoX library and ffmpeg are needed first.
brew install sox
brew install ffmpeg
Run example7:
x86_64-apple-darwin/bin/larkexample7 | ffplay -i pipe:0 -f s32le -ar 48000 -ac 2 -autoexit
If no error, playback will be started, and on the ffplay screen, audio spectrum is being drawed like this.
In the other shell,
lkdb status # Shows lark status. Found that the name of higpass/lowpass filter block is 'blksoxeffect_highpass_0'/'blksoxeffect_lowpass_0' respectively.
lkdb setparam RouteA blksoxeffect_highpass_0 0 800 # Only higher than 800Hz music signals go to left speaker
The audio spectrum is being drawed like this.
Tips: In ffplay spectrum, red means left channel and green means right channel. If grey is displayed on a certain frequency at a certain time, it means the power of left channel and of right channel on that frequency at that time is same.
lkdb setparam RouteA blksoxeffect_lowpass_0 0 800 # Only lower than 800Hz music signals go to right speaker
The audio spectrum is being drawed like this.
The real-time change of ffplay spectrum color verified the sox-effects on lark route are taking effect in real time.
The source code of this example is shown in larkexample7.cpp.
Author's blog: <My Engineer Daddy - Audio Application DIY Series> demonstrated by using lark how to deal with the daily audio related affairs of life through a series of short stories.
lkdb in RealtimeWhen lark is running in a process, the debug utility lkdb can communicate with it to get info from lark and send command to lark.
Usage:
lkdb status [--dot]
- Print the lark running status
- Print dot code if enabled '--dot' option
lkdb newroute ROUTENAME
- Create a named route
lkdb newblock ROUTENAME SOLIB ISFIRST ISLAST [ARGS]
- Create a block on the route from the dynamic load library
lkdb newlink ROUTENAME RATE FORMAT CHNUM FRAMESIZEINSAMPLES SRCBLKNAME SRCBLKOUTEPIDX SINKBLKNAME SINKBLKINEPIDX
- Create a link to link the source block and sink block on the route
lkdb start ROUTENAME
- Start the route
lkdb stop ROUTENAME
- Stop the route
lkdb setparam ROUTENAME BLOCKNAME PARAMID [PARAMS]
- Set parameter to the block in the route
lkdb getparam ROUTENAME BLOCKNAME PARAMID
- Get parameter from the block in the route
lkdb delete ROUTENAME LINKNAME
- Delete the link from the route
lkdb delete ROUTENAME BLOCKNAME
- Delete the block and associated link(s) from the route
lkdb delete ROUTENAME !
- Delete the entire route
lkdb loglevel LEVEL
- Set the logging LEVEL: 0=off 1=fatal 2=error 3=warning 4=info(default) 5=debug 6=verbose
lkdb setdump DIRECTORY
- Enable dumping log & data when DIRECTORY is a valid path
- Disable dumping log & data when DIRECTORY is --
Besides real-time printing status, setting parameters shown in the examples above, lkdb can also manipulate audio routes, take a snapshot of the routes, change logging level, setting audio data dump, etc.
lkdb
In one shell,
x86_64-linux-gnu/bin/larkexample0 # Run lark
In the other shell,
$ lkdb newroute RouteA
Created RouteA
$ lkdb newblock RouteA libblkfilereader.so true false examples/kanr-48000_16_2.pcm
Created blkfilereader_0 from libblkfilereader.so on RouteA
$ lkdb newblock RouteA libblkalsaplayback.so false true
Created blkalsaplayback_0 from libblkalsaplayback.so on RouteA
$ lkdb newlink RouteA 48000 S16_LE 2 960 blkfilereader_0 0 blkalsaplayback_0 0
Created lnk_0 on RouteA
$ lkdb start RouteA # The music playback should be started
Started RouteA
$ lkdb stop RouteA
Stopped RouteA
$ lkdb delete RouteA !
Deleted RouteA
The source code of this example is shown in larkexample0.cpp.
lkdb
While running example3,
lkdb status --dot | dot -Tpng -o larkexample3.png
The routes snapshot will be saved to larkexample3.png.
Note: This requires graphviz(dot) to be installed on your machine.
sudo apt install graphviz
Design the route(s) in your mind. The prebuilt blocks(like gain, mixer, etc.) can be used directly. If you need custom block(s), you can compile the so library file(s) by yourself. BlkPassthrough.cpp is an example of block source code. See MANUAL.md - 4 Build Your Own Block for more detail.
Call lark APIs to make your route(s) implemented in your process. Examples have been listed. Refer to User Manual for detail.
Q1: What is "block"? What is "endpoint"? What is "link"? What is "route"?
A: A "block" is a software DSP processor unit. It is created from a dynamic load so library and managed by lark route. It accepts up-to 32 inputs(called input endpoints) data, processes them, and fills the processed data into the output endpoints (up-to 32 outputs). Usually, one endpoint represents one audio channel. However, one endpoint can also carry multi-channels. e.g. The output endpoint of "interleave" block would carry multi-channels. A "link" links an output endpoint of a block as the source to an input endpoint of the other block as the sink. A "route" is a blocks-linked chain(or graph).
Q2: On one machine, how many larks can I run? Within one lark, how many routes can I create? Within one route, how many blocks can I create? How many first blocks and last blocks can I create?
A: On one machine, only one process is allowed to create the lark. i.e. One machine runs one lark. lkdb will communicate with the unique lark. Within one lark, 26 routes can be created at maximum, with the name "RouteA", "RouteB", ..., "RouteZ" specified manually. For each route, name is required and should be fixed to "Route#"(case sensitive) where "#" stands for [A-Z]. Within one route, no amount limitation to create the blocks. All the blocks/links created from a route belong to this route, which means their resources are managed by this route. Also, no amount limitation to create first blocks and last blocks.
Q3: What is "first block"? What is "last block"?
A: In one route, at least one "first block" and one "last block" have to be created with the "first" flag and the "last" flag specified separately. So that, the route can know from which block(s) to begin processing and from which block(s) to end processing. From the first block(s) to the last block(s), blocks should be linked without cut-off. The route can only start to run when the links are complete. If there is cut-off in the route, it is allowed, but the route won't be able to run. If you insist to run, the route will stay in BROKEN_RUNNING state until the cut-off is linked up.
Q4: What's the difference between "multi-routes" and "multi-first-blocks in one route"? If I have multiple inputs as the first blocks, how to select between "multi-routes" and "multi-first-blocks in one route"?
A: One route has one thread to process data. Normally "multi-first-blocks in one route" can work well. In this case, the multiple inputs are able to provide frames at the same pace, and they shouldn't be blocked by each other. For example, one input is alsacapture, one input is filereader. The scenario that needs multi-routes is, if the multiple inputs running in one route have chance to block each other, then they need to be separated into multi-routes. For example, one input is alsacapture, one input is echo-reference.
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