[mythtv-users] Razzy/Tinny audio
Stephen Worthington
stephen_agent at jsw.gen.nz
Thu May 22 10:45:43 UTC 2014
On Wed, 21 May 2014 20:00:40 -0400, you wrote:
>On Wed, May 21, 2014 at 7:40 PM, Daryl McDonald <darylangela at gmail.com>wrote:
>
>>
>>
>> On Fri, May 9, 2014 at 12:41 PM, Daryl McDonald <darylangela at gmail.com>wrote:
>>
>>> On Fri, May 9, 2014 at 11:47 AM, Stephen Worthington
>>> <stephen_agent at jsw.gen.nz> wrote:
>>> > On Fri, 9 May 2014 10:48:08 -0400, you wrote:
>>> >
>>> >>On Fri, May 9, 2014 at 3:29 AM, Stephen Worthington
>>> >><stephen_agent at jsw.gen.nz> wrote:
>>> >>> On Thu, 8 May 2014 23:59:10 -0400, you wrote:
>>> >>>
>>> >>>>On Thu, May 8, 2014 at 9:45 PM, Stephen Worthington
>>> >>>><stephen_agent at jsw.gen.nz> wrote:
>>> >>>>> On Thu, 8 May 2014 12:44:23 -0400, you wrote:
>>> >>>>>
>>> >>>>>>Greetings Mythizens, as the subject implies I'm looking into
>>> >>>>>>distortion from recordings on my analog card.
>>> >>>>>>"http://www.mythtv.org/wiki/Hauppauge_PVR-150" this wiki suggests
>>> >>>>>>adding a line to my change-channel.sh, like so: "sleep 5; v4l2-ctl
>>> >>>>>>--set-audio-input 1 -d /dev/video0 > /dev/null 2>&1" . Before
>>> >>>>>>implementing this solution, I'd like to confirm that since my UDEV
>>> >>>>>>rule names the card "/dev/videoPVR150" then the added line of script
>>> >>>>>>should reflect this change thusly? "sleep 5; v4l2-ctl
>>> >>>>>>--set-audio-input 1 -d /dev/videoPVR150 > /dev/null 2>&1" . Should
>>> >>>>>>anything else be changed? The digital cards sound good and the
>>> analog
>>> >>>>>>card has sounded good before, which is why I'm going for this idea
>>> >>>>>>first. TIA, Daryl
>>> >>>>>
>>> >>>>> This problem seems to be caused by mixing of audio from other
>>> sources
>>> >>>>> on the card. I have this problem with my PVR-500 (dual PVR-150).
>>> It
>>> >>>>> happens randomly at the start of using the card for a recording,
>>> and I
>>> >>>>> have never been sure what the cause was, but the drivers have never
>>> >>>>> been patched to fix it. The fix you found does work, but what you
>>> >>>>> need to do depends on what you are using your PVR-150 for. If you
>>> are
>>> >>>>> using it to tune to an analogue TV channel, then that fix is the
>>> right
>>> >>>>> one. If, like me, you are using its S-Video or composite video
>>> inputs
>>> >>>>> to interface to an STB, then the fix is more complex. In the latter
>>> >>>>> case, you also need a command (v4l2-ctl -f <freq>) to tune the TV
>>> >>>>> receiver to a frequency that is currently not in use by a signal it
>>> >>>>> can receive. This is to ensure that the TV audio does not get mixed
>>> >>>>> into the S-Video connection's audio.
>>> >>>>>
>>> >>>>> This is what I have in my ivtv_audio_fix.sh file that I run from my
>>> >>>>> channel change script:
>>> >>>>>
>>> >>>>> #!/bin/sh
>>> >>>>>
>>> >>>>> # Workaround for bug which causes audio distortion on some
>>> recordings.
>>> >>>>> # From http://urlgrey.net/?p=231
>>> >>>>>
>>> >>>>> sleep 3
>>> >>>>>
>>> >>>>> if [ $# -eq 0 ]; then
>>> >>>>> device=/dev/video0
>>> >>>>> else
>>> >>>>> device=$1
>>> >>>>> fi
>>> >>>>>
>>> >>>>> # First, set the audio input in turn to each of the unwanted audio
>>> >>>>> inputs.
>>> >>>>> # This only became necessary as of Mythbuntu 12.04.
>>> >>>>> v4l2-ctl -d$device --set-audio-input=2
>>> >>>>> v4l2-ctl -d$device --set-audio-input=0
>>> >>>>>
>>> >>>>> # Next, also set the tuner frequency. This also seems to be
>>> necessary
>>> >>>>> # since Mythbuntu 12.04 to suppress a slightly different audio
>>> >>>>> distortion.
>>> >>>>> # The frequency should be for an unused part of the spectrum, as the
>>> >>>>> unwanted
>>> >>>>> # audio is coming from whatever the TV tuner is tuned to.
>>> >>>>> v4l2-ctl -d$device -f 420
>>> >>>>>
>>> >>>>> # Reset the audio input to source 1 (the wanted input).
>>> >>>>> v4l2-ctl -d$device --set-audio-input=1
>>> >>>>>
>>> >>>>>
>>> >>>>> And this is my channel change script (change-channel-skynz.sh):
>>> >>>>>
>>> >>>>> #!/bin/sh
>>> >>>>>
>>> >>>>> REMOTE_NAME=Pace_RC-30
>>> >>>>> cmd="$1"
>>> >>>>>
>>> >>>>> # If things work OK with sleep 1, try this for faster channel
>>> changes:
>>> >>>>> # sleep 0.3
>>> >>>>> sleep_amt=1.0
>>> >>>>>
>>> >>>>> # See if this helps with missing digits at the start of a channel
>>> >>>>> change.
>>> >>>>> sleep 1.0
>>> >>>>>
>>> >>>>> #echo Change channel: $cmd >>/tmp/irsend.txt
>>> >>>>>
>>> >>>>> case $cmd in
>>> >>>>> [0-9]*)
>>> >>>>> # make sure we unmute by hitting vol up
>>> >>>>> #/usr/bin/irsend SEND_ONCE $REMOTE_NAME Vol+
>>> >>>>> #sleep $sleep_amt
>>> >>>>> for digit in $(echo $1 | sed -e 's/./& /g'); do
>>> >>>>> #echo irsend SEND_ONCE $REMOTE_NAME $digit
>>> >>>>>>>/tmp/irsend.txt
>>> >>>>> /usr/bin/irsend SEND_ONCE $REMOTE_NAME $digit
>>> >>>>> sleep $sleep_amt
>>> >>>>> done
>>> >>>>> ;;
>>> >>>>>
>>> >>>>> *)
>>> >>>>> /usr/bin/irsend SEND_ONCE $REMOTE_NAME $cmd
>>> >>>>> ;;
>>> >>>>> esac
>>> >>>>>
>>> >>>>>
>>> >>>>> # Workaround for bug which causes audio distortion on some
>>> recordings.
>>> >>>>> /usr/local/bin/ivtv_audio_fix.sh &
>>> >>>>> _______________________________________________
>>> >>>>> mythtv-users mailing list
>>> >>>>> mythtv-users at mythtv.org
>>> >>>>> http://www.mythtv.org/mailman/listinfo/mythtv-users
>>> >>>>> http://wiki.mythtv.org/Mailing_List_etiquette
>>> >>>>> MythTV Forums: https://forum.mythtv.org
>>> >>>>
>>> >>>>Thanks Stephen, I use my PVR 150 to record from an analog STB
>>> >>>>connected via RCA jacks, this card has apparently has five possible
>>> >>>>input connections, one "tuner" via coax and two each of "component"
>>> >>>>and "S-video". To leave my system connected as is, I would need to
>>> >>>>create a new " ivtv_audio_fix.sh" file like yours, but change the name
>>> >>>>of the tuner card appropriately and modify my "change-channel.sh" as
>>> >>>>outlined in the original post? Or, maybe more simply, change the input
>>> >>>>connection to "tuner" over coax and add the one line to my
>>> >>>>"change-channel.sh"? with the first solution, I must need one more
>>> >>>>line in the "change-channel.sh" to call the new "ivtv_audio_fix.sh"
>>> >>>>script, right? But I'm not sure where to put it.
>>> >>>>Daryl
>>> >>>
>>> >>> Create the ivtv_audio_fix.sh file (I have mine in /usr/local/bin where
>>> >>> my change-channel-skynz.sh script is). Then if your existing channel
>>> >>> change script works at all like mine, you can just add these two lines
>>> >>> at the end of it:
>>> >>>
>>> >>> # Workaround for bug which causes audio distortion on some recordings.
>>> >>> /usr/local/bin/ivtv_audio_fix.sh /dev/videoPVR150 &
>>> >>>
>>> >>> What that does is to run the ivtv_audio_fix.sh script as a separate
>>> >>> independent job (that is what & does). The channel change script can
>>> >>> finish and that lets MythTV know that the channel change has been
>>> >>> done. The ivtv_audio_fix.sh script will do its sleep while MythTV
>>> >>> records for the sleep time (you will hear the tinny sound for the
>>> >>> first few seconds of the recording, if it happened for that
>>> >>> recording), then the script will wake up and do its fix. The fix has
>>> >>> to be done after all the recording startup work that MythTV does - if
>>> >>> it is done too early it does not work as the v4l commands sent by
>>> >>> MythTV override it. When the ivtv_audio_fix.sh script has done its
>>> >>> v4l commands it will just stop without reporting back to the script
>>> >>> that called it (which finished several seconds before).
>>> >
>>> >>Hopefully I'm not over-reading this, what I did is create the
>>> >>ivtv_audio_fix.sh file in /usr/local/bin, and I changed (near the top)
>>> >>"device=/dev/video0" to "devive=/dev/videopvr150" and then added the
>>> >>two lines to the end of my "change-channel.sh" exactly as yours is
>>> >>(without the /dev/videoPVR150) [my uDev rule uses lower case pvr, my
>>> >>bad] . This preceding issue is at the heart of my original question;
>>> >>am I correct or wrong in assuming that the new name created by my uDev
>>> >>rule should be reflected in the "ivtv_audio_fix.sh" script? Thanks
>>> >>again Daryl
>>> >
>>> > If you exactly copied the two lines I posted to the bottom of your
>>> > change-channel.sh, then it will not work, due to the mis-spelling of
>>> > /dev/videopvr150 as /dev/videoPVR150 in what I wrote. My
>>> > ivtv_audio_fix.sh script accepts one optional parameter on its command
>>> > line, the name of the device to control. If that parameter is absent,
>>> > it will use the default device setting you changed at the top of
>>> > ivtv_audio_fix.sh. It was not necessary to change that as the two
>>> > lines I posted had the device name as a parameter. So you either need
>>> > to fix the spelling of /dev/videopvr150 on the call to
>>> > ivtv_audio_fix.sh in change-channel.sh, or remove the /dev/videoPVR150
>>> > from there and let ivtv_audio_fix.sh use its default device name that
>>> > you have already fixed.
>>> > _______________________________________________
>>> > mythtv-users mailing list
>>> > mythtv-users at mythtv.org
>>> > http://www.mythtv.org/mailman/listinfo/mythtv-users
>>> > http://wiki.mythtv.org/Mailing_List_etiquette
>>> > MythTV Forums: https://forum.mythtv.org
>>>
>>> What I exactly copied into my change-channel.sh was the last two lines
>>> of your change_channel_skynz.sh, so I think I'm good with the audio
>>> fix script edited to reflect the uDev name of my analog card and my
>>> channel script calling the fix script just like yours does, not the
>>> way you suggested had I not edited.
>>>
>>> The University of Toronto is offering free online computer science
>>> courses this fall, after applying myself in this direction I hope to
>>> get a much better practical understanding of all the things that I've
>>> received excellent coaching on from this list. Thanks Stephen, thanks
>>> list, enormous thanks Devs, I love Mythtv. (BE & FE) Daryl
>>>
>>
>> I've had almost two weeks of clear audio recordings, but a recording
>> yesterday has the Tin/Raz effect. Below are my "change-channel.sh" and
>> "ivtv_audio_fix.sh"
>>
>> REMOTE_NAME=DCT700
>> cmd="$1"
>> lirc_socket="/var/run/lirc/lircdSerial"
>>
>> /usr/local/bin/check_stb 1>/dev/null 2>/dev/null || :
>> sleep 2
>>
>> case $cmd in
>> [0-9]*)
>> for digit in $(echo $1 | sed -e 's/./& /g'); do
>> #irsend -d /dev/lircd SEND_ONCE $REMOTE_NAME $digit
>> irsend -d ${lirc_socket} SEND_ONCE $REMOTE_NAME $digit
>> sleep 0.2
>> # If things work OK with sleep 1, try this for faster channel
>> changes:
>> # sleep 0.3
>> done
>> #irsend -d /dev/lircd SEND_ONCE $REMOTE_NAME OK
>> irsend -d ${lirc_socket} SEND_ONCE $REMOTE_NAME OK
>> sleep 1
>> #irsend -d /dev/lircd SEND_ONCE $REMOTE_NAME EXIT
>> irsend -d ${lirc_socket} SEND_ONCE $REMOTE_NAME EXIT
>> ;;
>>
>> *)
>> #irsend SEND_ONCE $REMOTE_NAME $cmd
>> irsend -d ${lirc_socket} SEND_ONCE $REMOTE_NAME $cmd
>> ;;
>> esac
>>
>>
>> # Workaround for bug which causes audio distortion on some recordings.
>> /usr/local/bin/ivtv_audio_fix.sh &
>>
>>
>> ---------------------------------------------------------------------------------------
>>
>> #!/bin/sh
>>
>> # Workaround for bug which causes audio distortion on some recordings.
>> # From http://urlgrey.net/?p=231
>>
>> sleep 3
>>
>> if [ $# -eq 0 ]; then
>> device=/dev/videopvr150
>> else
>> device=$1
>> fi
>>
>> # First, set the audio input in turn to each of the unwanted audio inputs.
>> # This only became necessary as of Mythbuntu 12.04.
>> v4l2-ctl -d$device --set-audio-input=2
>> v4l2-ctl -d$device --set-audio-input=0
>>
>> # Next, also set the tuner frequency. This also seems to be necessary
>> # since Mythbuntu 12.04 to suppress a slightly different audio distortion.
>> # The frequency should be for an unused part of the spectrum, as the
>> unwanted
>> # audio is coming from whatever the TV tuner is tuned to.
>> v4l2-ctl -d$device -f 420
>>
>> # Reset the audio input to source 1 (the wanted input).
>> v4l2-ctl -d$device --set-audio-input=1
>>
>>
>> --------------------------------------------------------------------------------------------
>>
>> I thought I'd followed Mr Worthington's advice to the letter, maybe not ,
>> or maybe I need to pursue a different angle. If anyone can critique this
>> solution, or point me in a new direction, I'd appreciate it.
>>
>> TIA Daryl
>>
>
>I think I just answered my own question. further investigation revealed
>that I hadn't "chmod 775" ed, my "Ivtv_audio_fix.sh" After tomorrow's
>recording I should be able to report positive results, apologies for
>troubling unnecessarily. Daryl
You can tell if the ivtv_audio_fix.sh script is working as you get a
couple of seconds of tinny audio at the start of a recording, then it
cuts off when the script runs.
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