In this post, we are quickly sharing one of the fix on issue which we encountered after installing Kazam on Ubuntu 20.04 LTS Desktop. In Linux, one of our favorite Desktop Screen Recorder is Kazam. Till Ubuntu 18.04 LTS we have not faced any problem with Kazam after its installation.

We always recommend to use the official stable release from the reliable source. Read our this post if you want to know – “How to install Kazam on Ubuntu“.

Problem:

1. After installing Kazam on Ubuntu 20.04 LTS Desktop when we first tried to create one test video ,it failed.

2. Another observation is when you go to File >> Preference section at tab “General” there is no correct value for ‘Speakers’ and ‘Microphone’

Here is the screenshot, you can see that it clearly depicts the Kazam is crashed.

Reason

Ubuntu 20.04 LTS ships with Python 3.8.2 version. Here Python 3.8.2 in time.clock() is deprecated and should be used with new time.perf_counter()
You can validate the same by checking in your system.

Solution

To fix this issue, follow the given below steps.

1. Take backup of pulseaudio.py

cp -p /usr/lib/python3/dist-packages/kazam/pulseaudio/pulseaudio.py ~/pulseaudio.py.backup

2. Now create a file pulseaudio.py.

vi pulseaudio.py

And paste this given below content in this new file.

# -*- coding: utf-8 -*-
#
#       pulseaudio.py
#
#       Copyright 2012 David Klasinc 
#
#       This program is free software; you can redistribute it and/or modify
#       it under the terms of the GNU General Public License as published by
#       the Free Software Foundation; either version 3 of the License, or
#       (at your option) any later version.
#
#       This program is distributed in the hope that it will be useful,
#       but WITHOUT ANY WARRANTY; without even the implied warranty of
#       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#       GNU General Public License for more details.
#
#       You should have received a copy of the GNU General Public License
#       along with this program; if not, write to the Free Software
#       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#       MA 02110-1301, USA.

import time
import logging
logger = logging.getLogger("PulseAudio")

from kazam.pulseaudio.error_handling import *
from kazam.backend.prefs import *

try:
    from kazam.pulseaudio.ctypes_pulseaudio import *
except:
    raise PAError(PA_LOAD_ERROR, "Unable to load pulseaudio wrapper lib. Is PulseAudio installed?")

class pulseaudio_q:
    def __init__(self):
        """pulseaudio_q constructor.

        Initializes and sets all the necessary startup variables.

        Args:
            None
        Returns:
            None
        Raises:
            None
        """

        self.pa_state = -1
        self.sources = []
        self._sources = []
        self._return_result = []
        self.pa_status = PA_STOPPED

        #
        # Making sure that we don't lose references to callback functions
        #
        self._pa_state_cb = pa_context_notify_cb_t(self.pa_state_cb)
        self._pa_sourcelist_cb = pa_source_info_cb_t(self.pa_sourcelist_cb)
        self._pa_sourceinfo_cb = pa_source_info_cb_t(self.pa_sourceinfo_cb)
        self._pa_context_success_cb = pa_context_success_cb_t(self.pa_context_success_cb)

    def pa_context_success_cb(self, context, c_int, user_data):
        self._pa_ctx_success = c_int
        return

    def pa_state_cb(self, context, userdata):
        """Reads PulseAudio context state.

        Sets self.pa_state depending on the pa_context_state and
        raises an error if unable to get the state from PulseAudio.

        Args:
            context: PulseAudio context.
            userdata: n/a.

        Returns:
            Zero on success or raises an exception.

        Raises:
            PAError, PA_GET_STATE_ERROR if pa_context_get_state() failed.
        """
        try:
            state = pa_context_get_state(context)

            if state in [PA_CONTEXT_UNCONNECTED, PA_CONTEXT_CONNECTING, PA_CONTEXT_AUTHORIZING,
                         PA_CONTEXT_SETTING_NAME]:
                self.pa_state = PA_STATE_WORKING
            elif state == PA_CONTEXT_FAILED:
                self.pa_state = PA_STATE_FAILED
            elif state == PA_CONTEXT_READY:
                self.pa_state = PA_STATE_READY
                logger.debug("State connected.")
        except:
            raise PAError(PA_GET_STATE_ERROR, "Unable to read context state.")

        return  0

    def pa_sourcelist_cb(self, context, source_info, eol, userdata):
        """Source list callback function

        Called by mainloop thread each time list of audio sources is requested.
        All the parameters to this functions are passed to it automatically by
        the caller.

        Args:
            context: PulseAudio context.
            source_info: data returned from mainloop.
            eol: End Of List marker if set to non-zero there is no more date
            to read and we should bail out.
            userdata: n/a.

        Returns:
            self.source_list: Contains list of all Pulse Audio sources.
            self.pa_status: PA_WORKING or PA_FINISHED

        Raises:
            None
        """
        if eol == 0:
            logger.debug("pa_sourcelist_cb()")
            logger.debug("  IDX: {0}".format(source_info.contents.index))
            logger.debug("  Name: {0}".format(source_info.contents.name))
            logger.debug("  Desc: {0}".format(source_info.contents.description))
            self.pa_status = PA_WORKING
            self._sources.append([source_info.contents.index,
                                 source_info.contents.name.decode('utf-8'),
                                 " ".join(source_info.contents.description.decode('utf-8').split())])
        else:
            logger.debug("pa_sourcelist_cb() -- finished")
            self.pa_status = PA_FINISHED

        return 0

    def pa_sourceinfo_cb(self, context, source_info, eol, userdata):
        """Source list callback function

        Called by mainloop thread each time info for a single audio source is requestd.
        All the parameters to this functions are passed to it automatically by
        the caller. This is here for convenience.

        Args:
            context: PulseAudio context.
            index: Source index
            source_info: data returned from mainloop.
            eol: End Of List marker if set to non-zero there is no more date
            to read and we should bail out.
            userdata: n/a.

        Returns:
            self.source_list: Contains list of all Pulse Audio sources.
            self.pa_status: PA_WORKING or PA_FINISHED

        Raises:
            None
        """
        if eol == 0:
            logger.debug("pa_sourceinfo_cb()")
            logger.debug("  IDX: {0}".format(source_info.contents.index))
            logger.debug("  Name: {0}".format(source_info.contents.name))
            logger.debug("  Desc: {0}".format(source_info.contents.description))
            self.pa_status = PA_WORKING
            cvolume = pa_cvolume()
            v = pa_volume_t * 32
            cvolume.channels = source_info.contents.volume.channels
            cvolume.values = v()
            for i in range(0, source_info.contents.volume.channels):
                cvolume.values[i] = source_info.contents.volume.values[i]


            self._return_result  = [source_info.contents.index,
                                    source_info.contents.name.decode('utf-8'),
                                    cvolume,
                                    " ".join(source_info.contents.description.decode('utf-8').split())]
        else:
            try:
                logger.debug("pa_sourceinfo_cb() -- Hit EOL")
                logger.debug("  EOL IDX: {0}".format(source_info.contents.index))
                logger.debug("  EOL Name: {0}".format(source_info.contents.name))
                logger.debug("  EOL Desc: {0}".format(source_info.contents.description))
            except:
                logger.debug("pa_sourceinfo_cb() -- EOL no data!")
            self.pa_status = PA_FINISHED
        logger.debug("pa_sourceinfo_cb() -- finished")
        return 0

    def start(self):
        """Starts PulseAudio threaded mainloop.

        Creates mainloop, mainloop API and context objects and connects
        to the PulseAudio server.

        Args:
            None

        Returns:
            None

        Raises:
            PAError, PA_STARTUP_ERROR - if unable to create PA objects.
            PAError, PA_UNABLE_TO_CONNECT - if connection to PA fails.
            PAError, PA_UNABLE_TO_CONNECT2 - if call to connect() fails.
            PAError, PA_MAINLOOP_START_ERROR - if not able to start mainloop.
        """
        try:
            logger.debug("Starting mainloop.")
            self.pa_ml = pa_threaded_mainloop_new()
            logger.debug("Getting API.")
            self.pa_mlapi = pa_threaded_mainloop_get_api(self.pa_ml)
            logger.debug("Setting context.")
            self.pa_ctx = pa_context_new(self.pa_mlapi, None)
            logger.debug("Set state callback.")
            pa_context_set_state_callback(self.pa_ctx, self._pa_state_cb, None)
        except:
            raise PAError(PA_STARTUP_ERROR, "Unable to access PulseAudio API.")

        try:
            logger.debug("Connecting to server.")
            if pa_context_connect(self.pa_ctx, None, 0, None):
                raise PAError(PA_UNABLE_TO_CONNECT, "Unable to connect to PulseAudio server.")
        except:
            raise PAError(PA_UNABLE_TO_CONNECT2, "Unable to initiate connection to PulseAudio server.")
        try:
            logger.debug("Start mainloop.")
            pa_threaded_mainloop_start(self.pa_ml)
            time.sleep(0.1)  # Mainloop needs some time to start ...
            pa_context_get_state(self.pa_ctx)
        except:
            raise PAError(PA_MAINLOOP_START_ERROR, "Unable to start mainloop.")

    def end(self):
        """Disconnects from PulseAudio server.

        Disconnects from PulseAudio server, it should be called after all the
        operations are finished.

        Args:
            None

        Returns:
            None

        Raises:
            PAError, PA_MAINLOOP_END_ERROR - if not able to disconnect.
        """
        try:
            logger.debug("Disconnecting from server.")
            pa_context_disconnect(self.pa_ctx)
            self.pa_ml = None
            self.pa_mlapi = None
            self.pa_ctx = None
        except:
            raise PAError(PA_MAINLOOP_END_ERROR, "Unable to end mainloop.")

    def get_audio_sources(self):
        try:
            logger.debug("get_audio_sources() called.")
            pa_context_get_source_info_list(self.pa_ctx, self._pa_sourcelist_cb, None)
            t = time.perf_counter()
            while time.perf_counter() - t < 5:
                if self.pa_status == PA_FINISHED:
                    self.sources = self._sources
                    self._sources = []
                    return self.sources
            raise PAError(PA_GET_SOURCES_TIMEOUT, "Unable to get sources, operation timed out.")
        except:
            logger.debug("Unable to get audio sources.")
            raise PAError(PA_GET_SOURCES_ERROR, "Unable to get sources.")

    def get_source_info_by_index(self, index):
        try:
            logger.debug("get_source_info_by_index() called. IDX: {0}".format(index))
            pa_context_get_source_info_by_index(self.pa_ctx, index, self._pa_sourceinfo_cb, None)
            t = time.perf_counter()
            while time.perf_counter() - t < 5:
                if self.pa_status == PA_FINISHED:
                    time.sleep(0.1)
                    ret = self._return_result
                    self._return_result = []
                    return ret
            raise PAError(PA_GET_SOURCE_TIMEOUT, "Unable to get source, operation timed out.")
        except:
            raise PAError(PA_GET_SOURCE_ERROR, "Unable to get source.")

    def set_source_volume_by_index(self, index, cvolume):
        try:
            pa_context_set_source_volume_by_index(self.pa_ctx, index, cvolume,
                                                  self._pa_context_success_cb, None)
            t = time.perf_counter()
            while time.perf_counter() - t < 5:
                if self.pa_status == PA_FINISHED:
                    return 1
            raise PAError(PA_GET_SOURCES_TIMEOUT, "Unable to get sources, operation timed out.")
        except:
            raise PAError(PA_GET_SOURCES_ERROR, "Unable to get sources.")

    def set_source_mute_by_index(self, index, mute):
        try:
            pa_context_set_source_mute_by_index(self.pa_ctx, index, mute,
                                                  self._pa_context_success_cb, None)
            t = time.perf_counter()
            while time.perf_counter() - t < 5:
                if self.pa_status == PA_FINISHED:
                    return 1
            raise PAError(PA_GET_SOURCES_TIMEOUT, "Unable to get sources, operation timed out.")
        except:
            raise PAError(PA_GET_SOURCES_ERROR, "Unable to get sources.")

    def cvolume_to_linear(self, cvolume):
        avg = 0
        for chn in range(cvolume.channels):
            avg = avg + cvolume.values[chn]
        avg = avg / cvolume.channels
        volume = pa_sw_volume_to_linear(uint32_t(int(avg)))
        return volume

    def cvolume_to_dB(self, cvolume):
        avg = 0
        for chn in range(cvolume.channels):
            avg = avg + cvolume.values[chn]
        avg = avg / cvolume.channels
        volume = pa_sw_volume_to_dB(uint32_t(int(avg)))
        return volume

    def linear_to_cvolume(self, index, volume):
        info = self.get_source_info_by_index(index)
        cvolume = pa_cvolume()
        v = pa_volume_t * 32
        cvolume.channels = info[2].channels
        cvolume.values = v()
        for i in range(0, info[2].channels):
            cvolume.values[i] = pa_sw_volume_from_linear(volume)
        return cvolume

    def dB_to_cvolume(self, channels, volume):
        cvolume = pa_cvolume()
        v = pa_volume_t * 32
        cvolume.channels = channels
        cvolume.values = v()
        value = pa_sw_volume_from_dB(volume)
        for i in range(0, channels):
            cvolume.values[i] = value
        return cvolume

4. Once you have new pulseaudio.py file with new content is ready. Just copy the file to this location.

sudo cp -f pulseaudio.py /usr/lib/python3/dist-packages/kazam/pulseaudio/pulseaudio.py

5. Now Open the Kazam, you will find the problem is solved. Do some testing by taking screen recording and screenshot using Kazam.

Reference:
https://bugs.launchpad.net/kazam/+bug/1875530
https://docs.python.org/3.8/library/time.html