Author Topic: How to avoid noise at the start of the videos  (Read 635 times)

arnoldpredator

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How to avoid noise at the start of the videos
« on: October 25, 2017, 09:59:53 PM »
When I select two points A and B and then I save using mpeg xvid and aac options, most of the time there is an annoying sound at the very first frames of the cut, it is a kind of electronic sound that ruins the cut. I have to look for other frames and sometimes even if you don't hear anything in the original video, the new one still has this noise.

Why it happens? How can I avoid this?

Thanks for your time!

eumagga0x2a

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Re: How to avoid noise at the start of the videos
« Reply #1 on: October 26, 2017, 06:38:43 AM »
I never experienced such an issue with Avidemux AAC reencoded audio. Please provide exact steps to reproduce, maybe together with a sample source video.

arnoldpredator

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Re: How to avoid noise at the start of the videos
« Reply #2 on: October 26, 2017, 06:21:13 PM »
Ok, for example, the original video is this one:

https://www.youtube.com/watch?v=xN6uLbi475c

I just made a cut as an example of a simple sentence:

https://mega.nz/#!CIN3iawb!QoVDRsJloPI3UzbprGW6Z7KcRKP_M2eZ9_HRNhNaWb0

this is the key in case you are asked

!QoVDRsJloPI3UzbprGW6Z7KcRKP_M2eZ9_HRNhNaWb0

As you may notice in the original video there is no strange sound, but in the cutted video at the start you can hear something. Can you hear it?

eumagga0x2a

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Re: How to avoid noise at the start of the videos
« Reply #3 on: October 26, 2017, 07:52:04 PM »
Ok, for example, the original video is this one:

https://www.youtube.com/watch?v=xN6uLbi475c

Code: [Select]
[info] Available formats for xN6uLbi475c:
format code  extension  resolution note
139          m4a        audio only DASH audio   48k , m4a_dash container, mp4a.40.5@ 48k (22050Hz), 623.51KiB
249          webm       audio only DASH audio   50k , opus @ 50k, 587.38KiB
250          webm       audio only DASH audio   62k , opus @ 70k, 708.95KiB
171          webm       audio only DASH audio   88k , vorbis@128k, 1.09MiB
251          webm       audio only DASH audio  109k , opus @160k, 1.26MiB
140          m4a        audio only DASH audio  127k , m4a_dash container, mp4a.40.2@128k (44100Hz), 1.62MiB
278          webm       256x144    144p  107k , webm container, vp9, 25fps, video only, 1.27MiB
160          mp4        256x144    DASH video  113k , avc1.4d400c, 25fps, video only, 1.42MiB
242          webm       426x240    240p  239k , vp9, 25fps, video only, 2.42MiB
133          mp4        426x240    DASH video  253k , avc1.4d4015, 25fps, video only, 3.15MiB
243          webm       640x360    360p  449k , vp9, 25fps, video only, 4.41MiB
134          mp4        640x360    DASH video  636k , avc1.4d401e, 25fps, video only, 5.41MiB
244          webm       854x480    480p  842k , vp9, 25fps, video only, 7.44MiB
135          mp4        854x480    DASH video 1163k , avc1.4d401e, 25fps, video only, 10.51MiB
247          webm       1280x720   720p 1717k , vp9, 25fps, video only, 14.75MiB
136          mp4        1280x720   DASH video 2325k , avc1.4d401f, 25fps, video only, 20.08MiB
248          webm       1920x1080  1080p 3115k , vp9, 25fps, video only, 27.25MiB
137          mp4        1920x1080  DASH video 4342k , avc1.640028, 25fps, video only, 38.38MiB
17           3gp        176x144    small , mp4v.20.3, mp4a.40.2@ 24k
36           3gp        320x180    small , mp4v.20.3, mp4a.40.2
43           webm       640x360    medium , vp8.0, vorbis@128k
18           mp4        640x360    medium , avc1.42001E, mp4a.40.2@ 96k
22           mp4        1280x720   hd720 , avc1.64001F, mp4a.40.2@192k (best)

Which formats did you use? What were your exact steps to generate the sample?

Quote
As you may notice in the original video there is no strange sound, but in the cutted video at the start you can hear something. Can you hear it?

Yes, I can hear it. But I can't reproduce. I used format 22 as source with the FDK, lav and FAAC audio encoders as well as in copy mode. No such (or other) sound artifact whatsoever.

arnoldpredator

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Re: How to avoid noise at the start of the videos
« Reply #4 on: October 26, 2017, 08:45:27 PM »
Thanks for your time and your patience.

These are the steps:

video output: Mpeg asp (xvid 4)

Audio output: AAC (fdk)

output format : MP4 muxer

Time A : 36.200

Time B:  39.160

I suppose you will get the same noise if you make a cut using this data.

dosdan

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Re: How to avoid noise at the start of the videos
« Reply #5 on: October 26, 2017, 08:51:16 PM »
Arnoldpredator, is the source file a download from YouTube? If so, what format number, as shown in the youtube-dl list, did you request?

Dan.
« Last Edit: October 26, 2017, 08:53:36 PM by dosdan »

arnoldpredator

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Re: How to avoid noise at the start of the videos
« Reply #6 on: October 26, 2017, 09:10:51 PM »
Yes it is from youtube, I chose the highest quality:

MP4 HP 1080

But I got the same tipe of errors with videos of 720.

eumagga0x2a

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Re: How to avoid noise at the start of the videos
« Reply #7 on: October 26, 2017, 09:39:05 PM »
Testing completed with current Avidemux builds (all 64 bit) on Linux, Mac and Windows strictly following the given steps: I'm sorry, but no noise.

dosdan

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Re: How to avoid noise at the start of the videos
« Reply #8 on: October 26, 2017, 09:48:19 PM »
Yes it is from youtube, I chose the highest quality:
MP4 HP 1080

This is an audio issue. The info you have provided does not indicate the audio stream included within the MP4 you downloaded. Different YouTube download programs can include different format audio streams.  Use the free MediaInfo (https://mediaarea.net/en/MediaInfo) and report what format, what bitrate and how many channels are shown in the audio section of the original clip.

For example:
Code: [Select]
Audio
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : mp4a-40-2
Duration                                 : 2 s 857 ms
Bit rate mode                            : Constant
Bit rate                                 : 128 kb/s
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 kHz
Frame rate                               : 43.066 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 44.8 KiB (2%)
Language                                 : unk
Default                                  : Yes
Alternate group                          : 1


This is from the cut clip, and you have told us that you have re-encoded the audio part to AAC. But what was the original audio format?


Dan.
« Last Edit: October 26, 2017, 10:03:26 PM by dosdan »

eumagga0x2a

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Re: How to avoid noise at the start of the videos
« Reply #9 on: October 26, 2017, 10:21:02 PM »
I'm even not sure that the TO used youtube-dl (which would have used ffmpeg to mux video and audio)... Providing the source video together with the info about its origin would be better than any MediaInfo output.

I tested with format 22 as the only H.264 video with at least 720p resolution which includes audio.
« Last Edit: October 26, 2017, 10:24:04 PM by eumagga0x2a »

ReefHound

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Re: How to avoid noise at the start of the videos
« Reply #10 on: October 27, 2017, 07:00:08 PM »
I downloaded the video in 720. There was no higher res available to me.

Using ver 2.7 64bit, applied the settings, made the specified cut, no sound anomalies heard.

arnoldpredator

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Re: How to avoid noise at the start of the videos
« Reply #11 on: October 27, 2017, 08:27:17 PM »
Thanks to all the people that tried it, and thanks to all the answers.

The software I used to download the video is IDM.

I myself repeated the process, downloaded the video, WITHOUT CLICKING ON PLAY I choose the times for A and B, I saved the video and got a perfect audio profile.

And I begin to understand what happens. It is related with the space button, it is used to play and stop the video, notice that when you push space to stop the video the video gets frozen, if after that you click on it again, which is play,  for a tenth of a second you see the screen in green color and you hear a weird audio sound. My problem is like if I use the space button then when I make the cut that weird audio is recorded.

I use the space button a lot, and it is the only explanation I can think, but I don't have any manner to prove it, I am trying different ways but when I want to get the weird audio I can't :( it is so frustrating.

I put all the data you requested, I used MediaINfo to get it:


Audio
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : mp4a-40-2
Duration                                 : 1 min 47 s
Bit rate mode                            : Variable
Bit rate                                 : 126 kb/s
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 kHz
Frame rate                               : 43.066 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 1.60 MiB (9%)
Title                                    : ISO Media file produced by Google Inc.
Encoded date                             : UTC 2016-08-14 05:00:32
Tagged date                              : UTC 2016-08-14 05:00:32


eumagga0x2a

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Re: How to avoid noise at the start of the videos
« Reply #12 on: October 27, 2017, 08:59:26 PM »
This is very unlikely that space bar can be related, because the encoding dialog is modal and neither evaluates events from pressing the space bar itself nor allows them to reach the main window (well, for couple of days this was broken in nightlies; this is fixed in the latest 2 or 3 nightlies already).

I don't get any weird sound from unpausing video in Avidemux.

arnoldpredator

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Re: How to avoid noise at the start of the videos
« Reply #13 on: October 27, 2017, 09:35:25 PM »
I got it again, I tell you what process I use to cut videos, so maybe you can reproduce it:

-I look for something interesting

-I pause the video and go back 2 seconds several times so I can hear it again (frame by frame is too slow, 5 seconds is too much, and with 1 second I noticed I had to click too many times)

-Once it is clear I have to cut I try to pause the video as close as possible before the first word

-Then with 1 frame forward, and reading the lips (because there is no audio) I try to cut in the exact frame when the word is pronounced and I mark the point A

-Then I stop when I think it is proper to do so, when the sentence has been said, and I mark the point B

-I try to see if I will get a correct video, so I use "go to A" and then play

-I do the same with B, and play

After that I click on save with the settings I said.

As you see there is a lot of going forward and backward to capture the right sequence, and reading the lips is not always easy, I use a lot the pause button, go to A, go to B, reproduce...

I am sure that it is how I use this buttons, that is producing that weird sound.

I promise it is a real problem because for every, let's say 4 cuts, there is 1 with that weird sound. I try to repare it moving the point A several frames away and sometimes work, but other times I have to move A too much frames away from the original point and I can't record properly the start of the sentence.  The frustrating thing is to notice that in the original audio in those frames there is not any weird sound at all.
« Last Edit: October 27, 2017, 09:38:53 PM by arnoldpredator »

arnoldpredator

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Re: How to avoid noise at the start of the videos
« Reply #14 on: October 30, 2017, 07:25:34 PM »
Just to add that if I close the software, and start it again, and set the points A and B without using the space bar the video is saved properly.

Don't ask me why.