=== Step 3: Extract channels and make a new frame file ===
 * For the initialization and running the pipeline, please refer [[KAGRA/Subgroups/CAL/GstLAL/tutorials/step1|step1]]
 * Access frame cache file by specifying frame_cache and instrument as in [[KAGRA/Subgroups/CAL/GstLAL/tutorials/step2|step2]]
 * Define a frame multiplexer(mux) to write channels into a frame file by specifying frame-type, frame_duration, frames_per_file, compression_scheme and compression_level

{{{#!python
out_path = '.'
frame-type = 'TEST'
frame_duration     = 4 # in seconds
frames_per_file    = 1
compression_scheme = 257 #256: Raw  257: gzip                                   
compression_level  = 9

mux = pp.mkframecppchannelmux(pipeline, None)

mux.set_property("frame-duration",     frame_duration)
mux.set_property("frames-per-file",    frames_per_file)
mux.set_property("compression-scheme", compression_scheme)
mux.set_property("compression-level",  compression_level)

# Link the strain branch to the muxer                                           
strain_queue_length = 0 #short_queue
for pipe, chan in zip(pipe_list, channel_list):
    cp.mkqueue(pipeline, pipe, strain_queue_length).get_static_pad("src").link(mux.get_request_pad(chan[1]))

mux = pp.mkprogressreport(pipeline, mux, "progress_sink_%s" % instrument)

pp.mkframecppfilesink(pipeline, mux, frame_type = frame_type, path = output_path, instrument = instrument)
}}}
 * The python script is available at git repository
{{{
> kagra-cal/Observation/Phase1/tutorials/extr --help
Usage: extr [options]

Options:
  -h, --help            show this help message and exit
  --cache=cache         Set the name of the LAL cache listing the frame files
  --gps-start-time=seconds
                        Set the start time of the segment to analyze in GPS
                        seconds.
  --gps-end-time=seconds
                        Set the end time of the segment to analyze in GPS
                        seconds.
  --ifo=name            Name of the IFO (default= K1)
  --channel=name        Set channel name(s) to extract (default= CAL-
                        CS_PROC_C00_STRAIN_DQ,CAL-CS_PROC_MICH_DELTA_TM_DQ
                        ,CAL-CS_PROC_MICH_RESIDUAL_DQ,CAL-
                        CS_PROC_ERR_STRAIN_DQ,CAL-CS_PROC_CTRL_STRAIN_DQ,LSC-
                        MICH1_IN1_DQ,LSC-MICH1_OUT_DQ)
  --frame-type=name     Set the frame type as input to the frame writing
                        element. (Default=TEST)
  --output-path=name    Set the output path for writing frame files.
                        (Default=.)
  --format=format       Set input channel(s) format (default= F64LE)
  --ch-rate=rate        Set input channel data rate (default= 16384)
  --frame-duration=seconds
                        Set the number of seconds for each frame. (Default =
                        32)
}}}
 * This is an example to extract 7 channels from the full frame file. You can also specify the list of channel names with --channel option.
{{{
> kagra-cal/Observation/Phase1/tutorials/extr --cache=k1.cache
GPS:  1209288320 1209288352
[('K1', 'CAL-CS_PROC_C00_STRAIN_DQ'), ('K1', 'CAL-CS_PROC_MICH_DELTA_TM_DQ'), ('K1', 'CAL-CS_PROC_MICH_RESIDUAL_DQ'), ('K1', 'CAL-CS_PROC_ERR_STRAIN_DQ'), ('K1', 'CAL-CS_PROC_CTRL_STRAIN_DQ'), ('K1', 'LSC-MICH1_IN1_DQ'), ('K1', 'LSC-MICH1_OUT_DQ')]
seeking GPS start and stop times ...
setting pipeline state to playing ...
set to playing successfully
running pipeline ...
progress_src_CH6 (00:00:01): 1209288352 / 32 seconds (3779026100.0 %)
progress_src_CH7 (00:00:01): 1209288352 / 32 seconds (3779026100.0 %)
progress_src_CH1 (00:00:01): 1209288352 / 32 seconds (3779026100.0 %)
progress_src_CH5 (00:00:01): 1209288352 / 32 seconds (3779026100.0 %)
progress_src_CH4 (00:00:01): 1209288352 / 32 seconds (3779026100.0 %)
progress_src_CH2 (00:00:01): 1209288352 / 32 seconds (3779026100.0 %)
progress_src_CH3 (00:00:01): 1209288352 / 32 seconds (3779026100.0 %)
progress_sink_K1 (00:00:21): 1209288320 seconds
progress_sink_K1 (00:00:21): 1209288352 / 32 seconds (3779026100.0 %)
}}}
 * Check the channel names of the output frame file
{{{
> $LAL_PREFIX/bin/framecpp_query --list proc K-TEST-1209288320-32.gwf                                                                         Frame Version: 8 Frame Library: frameCPP Library Revision: 1 Originator: IGWD
Frame Offset: 0
K1:CAL-CS_PROC_C00_STRAIN_DQ
K1:CAL-CS_PROC_CTRL_STRAIN_DQ
K1:CAL-CS_PROC_ERR_STRAIN_DQ
K1:CAL-CS_PROC_MICH_DELTA_TM_DQ
K1:CAL-CS_PROC_MICH_RESIDUAL_DQ
K1:LSC-MICH1_IN1_DQ
K1:LSC-MICH1_OUT_DQ
}}}
 * [[KAGRA/Subgroups/CAL/GstLAL/tutorials/step4|(Next) Step 4: Add two channels and make a strain frame file]]
 * [[KAGRA/Subgroups/CAL/GstLAL/tutorials/step2|(Prev) Step 2: Dump lock flags from a frame cache file]]
 * [[KAGRA/Subgroups/CAL/GstLAL/tutorials|Tutorials]]