Old 05-22-2017, 09:13 AM   #1
cjunekim
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Default Waveform disappearing

Hi

When "Audio format for new recordings" is set to "MP3 (encoder by LAME project)", the mode is CBR, and Bitrate is set to 32kbps in the project setting, the recordings are automatically saved in MPEG-2 Layer 3. Hence, the recording is accordingly resampled from 16kHz, 22.05kHz, or 24kHz. That is, the recorded item file(.mp3) is stored in 16k, 22.05 or 24kHz sample rate. This is undesirable.

Since 32kbps bitrate is supported in MPEG-1 Layer 3 and it has higher sample rates like 32kHz, 40kHz, or 48kHz, it should use MPEG-1 instead.

One more issue. When the mp3 item is resampled, the waveform disappears after recording is punched out. Have a look at the video clip here:



If I switch to another application and the item becomes offline and back again, the waveform appears again.

I think these have something to do with how reaper uses lame mp3 library.

My setting : Windows 10 & Reaper v5.50pre9/x64

Last edited by cjunekim; 06-30-2017 at 05:50 AM.
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Old 05-22-2017, 09:27 AM   #2
bennetng
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32kbps? You must be depressed due the sound quality.
Here is the reason why it is not 32/40/48khz
https://hydrogenaud.io/index.php/top...html#msg932165
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Old 05-22-2017, 03:03 PM   #3
Mike Raine
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Is there a particular reason why you want to record using MP3 as the recording format?

If you recorded as WAV files you (a) will not experience these problems, and (b) enjoy far better quality.
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Old 05-22-2017, 03:14 PM   #4
serr
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This is probably for security camera audio right?
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Old 05-23-2017, 11:31 AM   #5
cjunekim
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Yes, there is. In this case, I use reaper for a different purpose than mixing musics.

The reason I am using low bitrate is:

1) The original source is low bitrate. It is a recording of skype interview via voicemeeter.
2) Secondly, the audio is very long -- almost 1 hour, but I have to record 3 interviews a day on average. I use at least two tracks -- me and the others. It takes up to 2 GB per day if in WAV.

Any other options? I am considering OPUS codec for recording format.

Quote:
Originally Posted by Mike Raine View Post
Is there a particular reason why you want to record using MP3 as the recording format?

If you recorded as WAV files you (a) will not experience these problems, and (b) enjoy far better quality.

Last edited by cjunekim; 05-23-2017 at 11:42 AM.
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Old 05-23-2017, 11:36 AM   #6
cjunekim
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Thanks for the link!

Quote:
Originally Posted by bennetng View Post
32kbps? You must be depressed due the sound quality.
Here is the reason why it is not 32/40/48khz
https://hydrogenaud.io/index.php/top...html#msg932165
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Old 06-30-2017, 05:49 AM   #7
cjunekim
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It's been a while since I posted this here. Now I don't care much about MP3 encoding now. I am using Opus instead. I am satisfied with the quality and the size at the same time.

However, the waveform disappearance issue still persists when using Opus as the Audio format for new recordings. Could anyone confirm this with their system please?

Quote:
Originally Posted by cjunekim View Post
Hi

When "Audio format for new recordings" is set to "MP3 (encoder by LAME project)", the mode is CBR, and Bitrate is set to 32kbps in the project setting, the recordings are automatically saved in MPEG-2 Layer 3. Hence, the recording is accordingly resampled from 16kHz, 22.05kHz, or 24kHz. That is, the recorded item file(.mp3) is stored in 16k, 22.05 or 24kHz sample rate. This is undesirable.

Since 32kbps bitrate is supported in MPEG-1 Layer 3 and it has higher sample rates like 32kHz, 40kHz, or 48kHz, it should use MPEG-1 instead.

One more issue. When the mp3 item is resampled, the waveform disappears after recording is punched out. Have a look at the video clip here:



If I switch to another application and the item becomes offline and back again, the waveform appears again.

I think these have something to do with how reaper uses lame mp3 library.

My setting : Windows 10 & Reaper v5.50pre9/x64
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