Ubuntu Studion 10.10 + Audacity 1.3.12 clipping

[solo16]

Greeting all,

Previously i'm using windows vista + wavelab 6 as my media playback os and player. Recently i've changed to Ubuntu studio 10.10 with real time kernel and using Audacity as my major playback app. However ever since i "upgraded" to UBS, for the very same .wav file (eac ripped from cd) i come across clipping problem, but i did not change any hardware or setting. Now for most of the songs i need to reduce the master volume (or gain?) in audacity to about 0.5 in order to completely avoid the clipping. This never happen when using vista + wavelab.

I've tried to just reduce the volume on my preamp but nope i still can hear the clipping/distortion, so the only way to avoid it is to reduce the gain in audacity. I'm using 44.1khz with 32bit floating, and file is loaded to ram.

So my question is what causes this happen?

Thx!

[bgravato]

Where do you exactly get the clipping? When you import the wav file into audacity do you see red vertical lines in the blue waveform? Or you just "hear" the clipping when playing?

[solo16]

Hi,

I saw the red lines in audacity, and it clips when "playing the red lines". Sometimes audacity does not show any red line for the file but i still hear the clipping. FYI, those most likely apply to modern pop music, for those song i bought online, e.g. 16/44.1 flac from DG, it plays find without any clipping can be hear eventhough it hits to 0dB. Also i set the quality to 32bit floating rate @ 44.1. I tried to reduce the master volume on audacity but it loses some details eventhough i fire up my amp still cannot "gain" it back.

So any idea what causes this happend? Btw, the very same file played fine under windows + wavelab 6, and my soundcard is set to 0dB as well.

Thx!

Here is my system details:
OS: Ubuntu Studio 10.10 with rt kernel 2.6.31-11 (Previous os is Windows Vista 64bit)
Soundcard: RME HDSPe AES (using alsamixer and set the channel volume to 80 on both ch1 and ch2 with I assume this is = 0dB)
Alsa version: Installed 1.0.23 but it shows 1.0.20 from /proc/asound/version

[bgravato]

If you get red lines in the imported file, that means that probably the file already has some clipping. I don't know wavelab so maybe it did some clip fixing automatically?
Instead of playing with the master gain volume (that just affects the playback volume) try to amplify negatively (use the Amplify effect from the Effects menu). Set the new peak value to -1dB or -2dB and see if you still hear the clipping. If so that probably means the clipping is already present in the original file. You can try to fix it with the Clip Fix effect.

[solo16]

Hi bgravato,

Thx for your help! The amplify effect works! Just wondering if it will applied to the original file or it just write a header to it?

Thx!

[bgravato]

Hi bgravato,

Thx for your help! The amplify effect works! Just wondering if it will applied to the original file or it just write a header to it?

Thx!

It imports the audio data into audacity and it applies it to the audio data in audacity, then if you export it, it will write a new file (with new data).

If it's a WAV and if you have the "Read uncompressed audio files directly from the original (faster)" option selected in preferences I think that if you save a project it will actually overwrite the original final with the new data.

Either way amplification is real audio data processing effect, there's no header to set the "volume" of an audio file.

[steve]

If it's a WAV and if you have the "Read uncompressed audio files directly from the original (faster)" option selected in preferences I think that if you save a project it will actually overwrite the original final with the new data.

No it doesn't.

If you import a WAV file and have "Read uncompressed audio files directly from the original (faster)" option selected in preferences, then Audacity will "link" to the data in the original file rather than copying it into the project, but if you change the data (for example by applying the Amplify or other effect), then the data will be copied into the Audacity Project, and the copied data is changed, not the original file.

[bgravato]

If it's a WAV and if you have the "Read uncompressed audio files directly from the original (faster)" option selected in preferences I think that if you save a project it will actually overwrite the original final with the new data.

No it doesn't.

If you import a WAV file and have "Read uncompressed audio files directly from the original (faster)" option selected in preferences, then Audacity will "link" to the data in the original file rather than copying it into the project, but if you change the data (for example by applying the Amplify or other effect), then the data will be copied into the Audacity Project, and the copied data is changed, not the original file.

Yes you're right and I knew that already... sorry for messing it up (I'll blame it on the sleep deprivation!).

[solo16]

Thx you guys!!!

[gegejoven]

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