[pvrusb2] audio pops and cracks in the recordings

Sun Jan 21 21:09:56 CST 2007

yes, I am getting a very good signal on channel, say, 17 pbs in bay area and pops are heard in that channel.

I rmmod'ed and modprobed pvrusb2, which means the settings were reset to default (I checked to make sure). The pops are heard during playing of livetv thru the mythtv on channel 17 and along with the pops I saw "2007-01-21 18:53:52.306 WriteAudio: buffer underrun" some of the times (not all pops lead to this message). Then, I did 'mplayer /dev/video0' and I could hear pops every 4-5 seconds on channel 17. Just make sure that its not channel 17, I have already reported (mythtv list) about similar pops on channel 12 which was pretty bad. I heard it on many other channels that I watch like 2,3,5,7.

Output from dmesg:

usbcore: registered new interface driver pvrusb2
/home/shared/Installs/pvrusb2-mci-20070119/driver/pvrusb2-main.c: Hauppauge WinTV-PVR-USB2 MPEG2 Encoder/Tuner : 20070119 (from www.isely.net)
/home/shared/Installs/pvrusb2-mci-20070119/driver/pvrusb2-main.c: Debug mask is 15 (0xf)
usb 1-6: reset high speed USB device using ehci_hcd and address 12
cx25840 2-0044: cx25843-23 found @ 0x88 (pvrusb2_a)
cx25840 2-0044: loaded v4l-cx25840.fw firmware (12559 bytes)
tuner 2-0043: chip found @ 0x86 (pvrusb2_a)
tda9887 2-0043: tda988[5/6/7] found @ 0x43 (tuner)
tuner 2-0061: chip found @ 0xc2 (pvrusb2_a)
wm8775 2-001b: chip found @ 0x36 (pvrusb2_a)
lirc_i2c: chip found @ 0x18 (Hauppauge IR)
lirc_dev: lirc_register_plugin: sample_rate: 10
tveeprom 2-00a2: Hauppauge model 24012, rev D3A3, serial# 8657148
tveeprom 2-00a2: tuner model is TCL MFNM05-4 (idx 103, type 43)
tveeprom 2-00a2: TV standards NTSC(M) (eeprom 0x08)
tveeprom 2-00a2: audio processor is CX25843 (idx 37)
tveeprom 2-00a2: decoder processor is CX25843 (idx 30)
tveeprom 2-00a2: has radio, has IR remote
tuner 2-0061: type set to 43 (Philips NTSC MK3 (FM1236MK3 or FM1236/F))
cx25840 2-0044: Video signal:              not present
cx25840 2-0044: Detected format:           NTSC-M
cx25840 2-0044: Specified standard:        NTSC-M
cx25840 2-0044: Specified video input:     Composite 7
cx25840 2-0044: Specified audioclock freq: 48000 Hz
cx25840 2-0044: Detected audio mode:       mono
cx25840 2-0044: Detected audio standard:   no detected audio standard
cx25840 2-0044: Audio muted:               yes
cx25840 2-0044: Audio microcontroller:     running
cx25840 2-0044: Configured audio standard: automatic detection
cx25840 2-0044: Configured audio system:   BTSC
cx25840 2-0044: Specified audio input:     Tuner (In8)
cx25840 2-0044: Preferred audio mode:      stereo
tda9887 2-0043: Data bytes: b=0x14 c=0x30 e=0x44
tuner 2-0061: Tuner mode:      analog TV
tuner 2-0061: Frequency:       175.25 MHz
tuner 2-0061: Standard:        0x00001000
wm8775 2-001b: Input: 2
pvrusb2: Device initialization completed successfully.
pvrusb2: registered device video0 [mpeg]
pvrusb2: registered device radio0 [mpeg]

What does the 'mono' mean in the detected audio mode? Many times it is shown as 'mono SAP'.

-devsk

----- Original Message ----
From: Mike Isely <isely at isely.net>
To: Communications nexus for pvrusb2 driver <pvrusb2 at isely.net>
Sent: Sunday, January 21, 2007 1:40:23 PM
Subject: Re: [pvrusb2] audio pops and cracks in the recordings

On Sun, 21 Jan 2007, devsk wrote:

> Hi,
> 
> I am using 20061119 snapshot with 2.6.19.2 kernel. I get pops and cracks in the sound. My settings are as follows:
> 
> $ cat ctl_audio_layer/cur_val
> Layer II
> 
> $ cat /sys/class/pvrusb2/sn-*/ctl_volume/cur_val
> 53710
> 
> $ cat /sys/class/pvrusb2/sn-*/ctl_audio_bitrate/cur_val
> 224 kbps
> 
> $ cat ctl_audio_mode/cur_val
> Stereo
> 
> $ cat ctl_audio_emphasis/cur_val
> No Emphasis
> 
> $ cat ctl_audio_crc/cur_val
> No CRC
> 
> I have these put into the /etc/init.d/local.start:
>  
> echo "10485760" > /sys/class/pvrusb2/sn-*/ctl_video_bitrate_peak/cur_val
> echo "8388608" > /sys/class/pvrusb2/sn-*/ctl_video_bitrate/cur_val
> echo "Constant Bitrate" > /sys/class/pvrusb2/sn-*/ctl_video_bitrate_mode/cur_val
> echo "224 kbps" > /sys/class/pvrusb2/sn-*/ctl_audio_bitrate/cur_val
> echo "53738" > /sys/class/pvrusb2/sn-*/ctl_volume/cur_val
> 
> One thing I noticed is that most of the pops/cracks happen in the 
> shows which are telecast in HD 5.1 sound. I am using the regular 
> analog cable to record my shows using mythtv. All (mythtv mixer, 
> recorder, transcoder, pvrusb2) volume levels are set at 82%. I hear 
> the pops in the .mpg file, so its not the transcoder.
> 
> Does anybody have any idea about this problem? It has ruined most of 
> recordings because most of the content that I typical record is 
> telecast in HD 5.1.
> 

Do you know if you are getting a strong enough signal?

If you do NOT do those driver settings / tweaks, do you still see the 
problem?  If not, can you identify which key setting(s) influence this?

  -Mike

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