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TOPIC: RE: AUDIO ISSUES

RE: AUDIO ISSUES 3 weeks, 4 days ago #207739

Hi,

I'm a bit of a noob when it comes to Lightworks. I use it for work - for marketing. I just don't quite get something - why, when I edit my AVI videos does the sound quality become terrible. I would describe it as 'crackly' and unclear.

I usually use sound clips over it - but now I would like to use the original sound, and it's really unclear, so I can't. What are the potential problems that I can attempt to look at?

Any advice - please...

Re: RE: AUDIO ISSUES 3 weeks, 4 days ago #207740

  • briandrys
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Welcome to the forum.

This can be caused by a number of reasons, please follow the directions in this sticky, so that users can see the technical details of your media.

www.lwks.com/index.php?option=com_kunena&func=view&catid=23&id=66072&Itemid=81

Re: RE: AUDIO ISSUES 3 weeks, 3 days ago #207813

I've downloaded it. What details might you need?

Re: RE: AUDIO ISSUES 3 weeks, 3 days ago #207814

  • jwrl
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Check one of your original media files with MediaInfo and select File > Export. Select the text tab and the location and name that you wish to save the file to, then post it here. What you should have will look something like this.

General
Complete name : F:\190708 Cut 14 Lock\14th Cut_R3_QT Ref.mp4
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (mp42/mp41)
File size : 197 MiB
Duration : 14 min 27 s
Overall bit rate mode : Variable
Overall bit rate : 1 900 kb/s
Encoded date : UTC 2019-07-05 11:12:50
Tagged date : UTC 2019-07-05 11:14:49
TIM : 02:59:50:00
TSC : 24000
TSZ : 1000

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.2
Format settings : CABAC / 2 Ref Frames
Format settings, CABAC : Yes
Format settings, RefFrames : 2 frames
Format settings, GOP : M=2, N=48
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 14 min 27 s
Bit rate mode : Variable
Bit rate : 1 771 kb/s
Maximum bit rate : 768 kb/s
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 24.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.080
Stream size : 183 MiB (93%)
Language : English
Encoded date : UTC 2019-07-05 11:12:50
Tagged date : UTC 2019-07-05 11:12:50
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : mp4a-40-2
Duration : 14 min 27 s
Source duration : 14 min 27 s
Bit rate mode : Variable
Bit rate : 125 kb/s
Maximum bit rate : 194 kb/s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 13.0 MiB (7%)
Source stream size : 13.0 MiB (7%)
Language : English
Encoded date : UTC 2019-07-05 11:12:50
Tagged date : UTC 2019-07-05 11:12:50

Re: RE: AUDIO ISSUES 3 weeks, 3 days ago #207819

General
Complete name : D:\Photos\Nkundusi Village w. Theo Tours (31.10.2019)\DSCN1420.AVI
Format : AVI
Format/Info : Audio Video Interleave
File size : 81.2 MiB
Duration : 1 min 20 s
Overall bit rate : 8 480 kb/s

Video
ID : 0
Format : JPEG
Codec ID : MJPG
Duration : 1 min 20 s
Bit rate : 8 410 kb/s
Width : 640 pixels
Height : 480 pixels
Display aspect ratio : 4:3
Frame rate : 30.000 FPS
Color space : YUV
Chroma subsampling : 4:2:2
Bit depth : 8 bits
Scan type : Progressive
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.913
Stream size : 80.5 MiB (99%)

Audio
ID : 1
Format : PCM
Format settings : Unsigned
Codec ID : 1
Duration : 1 min 20 s
Bit rate mode : Constant
Bit rate : 64.0 kb/s
Channel(s) : 1 channel
Sampling rate : 8 000 Hz
Bit depth : 8 bits
Stream size : 628 KiB (1%)
Alignment : Aligned on interleaves
Interleave, duration : 992 ms (29.75 video frames)
Interleave, preload duration : 1000 ms

Re: RE: AUDIO ISSUES 3 weeks, 3 days ago #207820

Does this help?

Re: RE: AUDIO ISSUES 3 weeks, 3 days ago #207821

  • hugly
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Hello,

Yes, it helps. I think, the format of the audio stream is the cause of the trouble. That should be fixable by converting to a suitable format.

If you are familiar with ffmpeg, I'd suggest trying this template:
ffmpeg -i "<in>" -c:v copy -c:a pcm_s16le -ar 48000 -y "<out>".mov
It copies the video stream and re-encodes the audio into a MOV container.

Converting with most recent Handbrake with the preset "Production.Standard" should work as well, but it will re-encode both streams, audio and video.
It's better to travel well than to arrive...
Last Edit: 3 weeks, 3 days ago by hugly.

Re: RE: AUDIO ISSUES 3 weeks, 3 days ago #207825

  • pfbr6a
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It's worth noting that this particular sound is basically at best phone-quality in the first place (which is quite unusual) so if possible try to change that for future recordings.

The sampling rate of 8000 Hz means that the recording has no frequency above 4000 Hz, and the bit depth of 8 bits gives only 256 levels. You'd normally expect to see numbers like 480000 Hz and 16 or 24 bits (which is hundreds or thousands of times more levels.)

This will always sound bad, and any processing at any stage is only going to make it worse - it won't take much to mess it up completely.
Last Edit: 3 weeks, 3 days ago by pfbr6a.

Re: RE: AUDIO ISSUES 3 weeks, 1 day ago #207931

  • David Rasberry
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I've converted 44.1KHz 16 bit audio files to 48KHz 24 bit for editing to eliminate least significant bit artifacts in low volume segments. It works.
You might try converting your audio track in a similar manner. It might at least eliminate some of the distortion even if your original data is low quality. I use an AVS4YOU audio utility for the conversion.

The other thing you need to watch in Lightworks is your volume levels relative to the mixer meter readings. The mixer meters are calibrated in DBFS where 0Db is the absolute maximum level before digital clipping. Studio standard DBFS reference is -18DB for equal output to analog 0VU reference. Best to keep your audio levels peaking around -6DBFS on the Lighworks mixer meters. Never let it go above 0.
Razz

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Re: RE: AUDIO ISSUES 3 weeks, 1 day ago #207933

Thank you for the assistance - much appreciated!
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