Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion. Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules. |
10th June 2012, 11:40 | #1 | Link |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Limiting amplitude of audio spikes
Is there recommended automated way to remove audio spikes,
based on limiting of amplitude of WAV/MP2 of audio record ? I often do processing of DVB-T videos for personal archive purposes. I use ProjectX to fix transmittion errors and process m2v and wav/mp2 files with MeGUI.. There are occasional spikes of maximum amplitude, some dozens ms in duration. The problem with them is they ruin listener comfort. They make squeezing noise and player often set volume temporarily weaker. I fix it eventually by manual way in Audacity by setting silence there. Is there an automated way, best by command line, that either selectively limit amplitude under given values, or fix/replace such a piece ? I have not found in Audacity, or elsewhere, automated way, but I am not familiar with it audio processing so much.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] Last edited by Poutnik; 10th June 2012 at 11:45. Reason: minor edit |
10th June 2012, 12:00 | #2 | Link |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
I tried to search Int/Ext Avisynth filters, but I am afraid nothing usable, possibly some clever script......
There are some filters in Audacity to remove something like that, but it is probably aimed to much shorter analog spikes. These ones seem to be corrupted 24/48 ms mp2 audio chunks, and filters do not catch them at any parameter settings. But I can be wrong, as I am novice in AC. But best way would be command line filter.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] Last edited by Poutnik; 10th June 2012 at 12:06. |
10th June 2012, 12:16 | #3 | Link |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Hm, I got an idea, it should be simple.
Audacity has amp scale -1.0 .. 1.0, the signal amp is usually within -0.5 .. 0.5, with spikes -1 .. 1. If I amplify it in Avisynth by proper coef, it should discriminate the spikes, and not yet the signal. Then I could attenuate it back again.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
11th June 2012, 11:57 | #4 | Link | |
Registered User
Join Date: Mar 2006
Posts: 1,049
|
foobar2000 hard -6dB limiter or advanced limiter - but... what is reason for such spikes? Perhaps improving reception will make stream glitch free - solving spike issue should start from root.
Quote:
Last edited by pandy; 11th June 2012 at 12:00. |
|
11th June 2012, 20:42 | #5 | Link | ||
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Quote:
I agree with improving idea, but this would be problem. It is a block of flat common wall source of TV signal, based on DVB-T receiver. Sometimes there is none, sometimes 2-3, sometimes 20 in case of near thunderstorm. I would say ProjectX would eliminate most of them, but it seems not. Quote:
+/- 1 is relative scale of sound amplitude stored in WAV format. Of course wave format cannot produce more than what can produce.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
||
11th June 2012, 22:33 | #6 | Link |
Registered User
Join Date: Apr 2012
Posts: 38
|
I think this is what you want: http://manual.audacityteam.org/man/Low_Pass_Filter. Your approach isn't so good because of the scaling.
|
12th June 2012, 07:00 | #7 | Link | |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Quote:
but I am afraid it cannot be distinguished by frequency from signal. It would probably attenuate the majority of signal. I think my the approach is acceptable as there are not such quality demands as for CD audio. I can try it. Or, I can look for Avisynth alternative for mp2/wav -> Avisynth -> wav or mp2/wav -> Avisynth -> BEpipe/wavi -> NeroAAC CLI encoder
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
|
12th June 2012, 11:21 | #9 | Link |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Well, currently I have none, no DVB-T MPG to process.
Later at home I will try t get one and upload it. I bet none will occur if I want to find it :-) In Audacity the Hard Limiter within LADSPA Effects does exactly what I want. Even better would be some automated Avisynth processing.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
12th June 2012, 11:49 | #10 | Link |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
As I said . :-)
I have remotely checked some 55 min freshly recorded document, and no spikes there in demuxed ProjectX processed WAV, not even in original MPEG2 PS.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
12th June 2012, 12:05 | #11 | Link | ||
Registered User
Join Date: Mar 2006
Posts: 1,049
|
foobar can decode and encode with DSP processing in real time.
Quote:
https://www.youtube.com/watch?v=gHwZEEFvnVM http://www.cnet.de/praxis/wochenend/...ro_basteln.htm http://wirbel.htpc-forum.de/electron...ad/index2.html Quote:
No, i use +-1 as float values - in fact it should be or +-0.5 or 0 - 1 for integer PCM but i understand your convention and i use this convention. |
||
12th June 2012, 14:15 | #12 | Link | ||
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
I suppose so, for sound it should not be difficult. But I would prefer Avisynth solution I am more familiar with.
Quote:
Quote:
But No, Antenna systems would not help you with signal path, and PX does help to fix the record at least to look nicer for video processing systems, keeping A/V synchronization, and at the worst case to omit 1/2s - 12 frame GOP from MPG. Typical value is 2 clicks per 90min movie, that is too few for just weak signal.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
||
12th June 2012, 18:27 | #13 | Link |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Interesting option for automation would be CLI swiss knife for sound processing
SOX ( Sound Exchange from sourceforge) and/or with Avisynth External_filters#Audio_Filters - Sox Audio Effect Filter by Sh0dan Sox Audio Effect Filters v1.1 beta
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
13th June 2012, 09:10 | #14 | Link |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
The local city DVB-T transmitter is about 2-3 km at direct visibility.
The signal must be strong enough. Stronger signal could make things even worse, with possibility of over saturation of receiver input. Even in opposite case, I cannot imagine I would persuade the council of housekeepers to buy a new antenne.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] Last edited by Poutnik; 13th June 2012 at 09:14. |
13th June 2012, 12:31 | #15 | Link | ||
Registered User
Join Date: Mar 2006
Posts: 1,049
|
Quote:
If your current configuration is susceptible to interferences search for better one even at a cost of signal level, if not use directional antenna to improve immunity for interferences, you can reduce level of signal with simple fixed 10 - 20dB attenuator if You think that this will help. However solve root cause not search for method to fix corrupted signal. Quote:
Of course there is possibility that broadcaster distribute corrupted signal but even today usually broadcaster care about technical side of the RF emission. |
||
13th June 2012, 15:31 | #16 | Link | ||||
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Quote:
Quote:
And, NO real signal is error free, and any processing of real signals must count with errors and their fixing. Note that the cause need not to be in antenne system at all. Quote:
Quote:
to realize nothing helped. Especially if nobody complains about TV quality. It is a common system for the whole block. I would be treated as an overdemanding fool.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] Last edited by Poutnik; 13th June 2012 at 17:58. |
||||
13th June 2012, 22:40 | #17 | Link |
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Another 2h10m recording, not even one spike.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
14th June 2012, 10:33 | #18 | Link |
Registered User
Join Date: Mar 2006
Posts: 1,049
|
Once again - Czech use same standards as surrounding countries, perhaps you can replace common antenna with local antenna - DVB-T use lot of error corrections methods, there COFDM modulation, there is convolutional codding + Reed Solomon, but at some point none of them is efficient enough to correct uncorrectable errors - perhaps antenna and amplifier receive strong EM signal from some electrical motor with poorly done decoupling - such flash of energy can blind (saturate) amplifier and mask signal.
And one thing additional - perhaps something is wrong with your receiver? If no one complain except you. |
14th June 2012, 15:41 | #19 | Link |
Registered User
Join Date: Mar 2009
Location: Germany
Posts: 5,769
|
I assume there are video errors as well
I'd rather spend some hours in adjusting the antenna, rather than in encoding the audio (and/or video) with editing. DVB-T has anyway such a low bitrate that makes transcoding into a "more compact" format merely a waste of time.
__________________
Born in the USB (not USA) |
14th June 2012, 16:32 | #20 | Link | ||
Useless idea generator
Join Date: Apr 2004
Location: Europe, Czech Republic, Brno
Posts: 332
|
Quote:
Quote:
or if not forgot, not remember to mention. It would have be much worse for case otherwise. BTW vendor TV application shows 7/7 dots of signal power.
__________________
Vista64 Premium SP2 / C2D E4700 2.6GHz/ 6GB RAM/ Intel GMA 3100 / DTV Leadtek DONGLE GOLD USB2 / focused to DVB-T MPEG2 PS capture -> ProjectX -> M2V/MP2 -> MeGUI/AVS -> MP4[AVC/AAC] |
||
Tags |
audio, errors, fix, spikes, transmittion |
Thread Tools | Search this Thread |
Display Modes | |
|
|